WORLD HEALTH l QUARTERLY· RAPPORT TRIMES I RIEL DE SANITAIRES MONDIALES INl=ORMATION SUPPORT TO HEALTH SYSTEM • DEVELOPMENT AND MANAGEMENT I \ ~ rJ1 APPUI INl=ORMATIONNEL ""'~ AU DEVELOPPEMENT ET A LA GESTION DES SYSTEMES DE SANTE Vol. 41, No. 1, 1988 World Health Organization Organisation mondiale de la Santi Genive The World Health Organization is a specialized agency of the United Nations with pri- mary responsibility for international health matters and public health. Through this organi- zation, which was created in 1948, the health professionals of some 160 countries exchange their knowledge and experience with the aim of making possible the attainment by all citizens of the world by the year 2000 ofa level of health that will permit them to lead a socially and economically productive life. By means of direct technical cooperation with its Member States, and by stimulating such cooperation among them, WHO promotes the development of comprehensive health ser- vices, the prevention and control of diseases, the improvement of environmental conditions, the development of health manpower, the coordination and development of biomedical and health services research, and the planning and implementation of health programmes. These broad fields of endeavour encompass a wide varietyofactivities, such as developing systems of primary health care that reach the whole population of Member countries; pro- moting the health of mothers and children; combating malnutrition; controlling malaria and other communicable diseases including tuberculosis and leprosy; having achieved the era- dication of smallpox, promoting mass immunization against a number of other preventable diseases; improving mental health; providing safe water supplies; and training health per- sonnel of all categories. Progress towards better health throughout the world also demands international cooper- ation in such matters as establishing international standards for biological substances, pes- ticides and pharmaceuticals; formulating environmental health criteria; recommending international nonproprietary names for drugs; administering the International Health Regu- lations; revising the International Classification of Diseases, Injuries, and Causes of Death; and collecting and disseminating health statistical information. Further information on many aspects ofWHO's work is presented in the Organization's publications. The World Health Statistics Quarterly replaces (since 1978) the monthly World Health Statistics Report (published since 1967) and its forerunner the Epidemiological and Vital Statistics Report (published since 1947). It contains Special Subjects dealing with the detailed analysis of selected health topics of current interest. Annual subscription ( 1988) Sw. fr. 85.- Material from the Quarterly may be reproduced providing due acknowledgement is made. L'Organisation mondiale de la Sante (OMS), creee en 1948, est une institution specialisee des Nations Unies a qui incombe, sur le plan international, la responsabilite principale en matiere de questions sanitaireset de sante publique. Au sein de l'OMS, les professionnelsde la sante de quelque 160 pays echangent des connaissances et des donnees d'experience en vue de faire acceder d'ici l'an 2000 tous les habitants du monde a un niveau de sante qui leur permette de mener une vie socialement et CC.Onomiquement productive. Grace a la cooperation technique qu'elle pratique avec ses Etats Membres ou qu'elle stimule entre eux., l'OMS s'emploie a promouvoir la mise sur pied de services de santC complets, la pl'Cvention et l'endiguement des maladies. l'amClioration de l'environnement, le developpement des personnels de sante, la coordination et le progres de la recherche bio- medicale et de la recherche sur les services de santC, ainsi que la planification et l'exCcution des programmes de sante. Le vaste domaine oil s'exerce !'action de l'OMS comporte des activites trcs di verses: developpement des soins de sante primaires pour que toutes les populations puissent y avoir acces; promotion de I.a sante maternelle et infantile; la lutte contre la malnutrition; lutte contre le paludisme et d'autres maladies transmissibles, dont la tuberculose et la lepre; l'Cradication de la variole Ctant rC3.liSCe, promotion de la vaccination de masse contre un cenain nombre d'autres maladies Cvitables; amClioration de la santC mentale; approvision- nement en eau saine; formation de personnels de sante de toutes categories. II est d'autres secteurs encore oU une cool)Cration intemationale s'impose pour assurer un meilleur etat de sante a travers le monde et l'OMS collabore notamment au, tiches sui- vantes: etablissementd'etalons internationaux pour les produits biologiques, les pesticides et les preparations pharmaceutiques; formulation de criteres de salubrite de l'environnement; recommandations relatives aux dCnominations communes intemationales pour les subs- tances pharmaceutiques; application du Reglement sanitaire international; revision de la Oassification internationale des maladies, traumatismes et causes de deces; rassemblement et diffusion d'informations statistiques sur la sante. On trouvera dans les publications de !'OMS de plus amples renseignements sur de nom- breux aspects des travaux de !'Organisation. Le Rapport trimestriel de Sta11s11ques sanitaires mondiales remplace (depuis 1978) le Rapport de Statistiques sanitaires mondiales(publie depuis 1967) et son precurseur le Rapport epidemiologique et demographique (public depuis 1947). II contient des Sajets speclaux qui presentent des analyses detaillees sur des sujets specifiques d'interet courant. Prix de l'abonnement annuel (1988) .................... . Fr. s. 85,- La reproduction d'extraits du Rapport trimestriel est autorisee, sous reserve d'indication de la source. IX ISSN 0043 • 8510 Cover design: Fabienne Kiefer Couverture: Fabienne Kiefer • T M F N Symbols used in tables Explication des signes Preliminary, approximate or estimated data. Data not available. Nil or magnitude negligible. Category not applicable. Total. Male. Female. Absolute numbers. © World Health Organization 1988 ... T M F N Donnee preliminaire, approximative ou estimative. Donnee non disponible. Zero OU quantite negligeable. Categorie non applicable. Total. Masculin. Feminin. Nombres absolus. © Organisation mondiale de la Sante 1988 PRINTED IN SWITZERLAND 88/7579 - Atar SA. Geneva - 4600 WORLD HEALTH STATISTICS QUARTERLY RAPPORT TRIMESTRIEL DE STATISTIQUES SANITAIRES MONDIALES VOL. 41, No. 1, 1988 INFORMATION SUPPORT TO HEALTH SYSTEM DEVELOPMENT AND MANAGEMENT CONTENTS Introduction: epidemiological approaches to health planning, Page APPUI INFORMATIONNEL AU DEVELOPPEMENT ET A. LA GESTION DES SYSTlMES DE SANTE SOMMA IRE Introduction : approches epidemiologiques de la planification Pages management and evaluation. John P. Woodall ....... . 2 sanitaire: gestion et evaluation. John P. Woodall [resume) .. 9 Une methode d'evaluation des systi!mes de surveillance epide- miologique. Stephen B. Thacker, R. Gibson Parrish, Frederick A method for evaluating systems of epid,emiological surveil- lance. Stephen B. Thacker, R. Gibson Parrish, Frederick L. Trowbridge & Surveillance Coordination Group . 11 L. Trowbridge & Surveillance Coordination Group (resume) 16 24 Local Area Monitoring (LAM). Thomas D. Kirsch Community-based health reporting. Wolf Scott . 19 Surveillance locale (LAM). Thomas D. Kirsch [resume) .... 26 Notification de la situation sanitaire fondee sur la communaute. Wolf Scott (resume) ...................... . 30 Classification statistique internationale des maladies et autres International Statistical Classification of Diseases and Related Health Problems - Tenth Revision. Gerlind R. Bramer .... 32 problemes de sante - Dixieme revision. Gerlind R. Bramer [resume) ............ ' ' ............... . 34 The International Health Regulations: results and prospects. Le Reglement sanitaire international: bilan et perspectives. Alain Vessereau (summary) .................. . 44 Alain Vessereau . . . . . . . . . . . . . . . . . . . . . . . . . 37 The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the World Health Organization concerning the legal status of any country, terri- tory, city or area or of its authorities, or concerning the delim- itation of its frontiers or boundaries. The statistics which relate to the Federal Republic of Ger- many and the German Democratic Republic include the rele- vant statistics regarding Berlin for which separate data have not been supplied. This is without prejudice to any question of status which may be involved. Where the designation "country or area" appears in the headings of tables, it covers countries, territories, cities or areas. Signed articles express the opinions of the authors and do not necessarily represent the findings or policy of the World Health Organization. Les appellations employees dans cette publication et la pre- sentation des donnees qui y figurent n'impliquent de la part du Secretariat de l'Ot-ganisation mondiale de la Sante aucune prise de position quant au statutjuridique des pays, territoires, villes ou zones. ou de leurs autorites, ni quant au trace de leurs frontieres ou limites. Les statistiques se rapportant a la Republique democratique allemande et a la Republique federale d' Allemagne compren- nent les statistiques pertinentes concernant Berlin pour lequel des donnees separees n'ont pas ete fournies. Toute question de statut demeure reservee. Lorsque !'appellation «pays ou zone» apparait dans le titre des tableaux, elle couvre les pays, territoires, villes ou zones. Les articles signes expriment les vues de leurs auteurs et ne correspondent pas necessairement a'-'x conclusions ou a la politique adoptee par !'Organisation mondiale de la Sante. -2- INTRODUCTION: EPIDEMIOLOGICAL APPROACHES TO HEAL TH PLANNING, MANAGEMENT AND EVALUATION John P. Woodalla In the future, major advances in health will come, not from technological breakthroughs, but from improve- ments in two other spheres: the planning and manage- ment of the use of existing technology, and changes in lifestyles. Good planning and management depend on the availability of reliable, accurate and timely informa- tion about the health situation. Evaluation of the effect of interventions related to lifestyle also requires valid infor- mation. Information support is aimed at providing health planners and managers with the information they need to manage their programmes effectively and decide whether or not the situation is improving, and how much of any improvement is due to their intervention. All countries have institution-based systems for the col- lection of routine information on the number of inpatients and outpatients seen. But these account for only a frac- tion of the population suffering from health problems, and often only a fraction of the population attending institutions, since figures from the nongovernmental and private health-care sectors are frequently not included. The usual response to this problem has been to conduct surveys. Methods have been worked out to allow for drawing samples that will be representative of a given population while meeting the necessary constraints of size and cost. b, c Repeat surveys using the same sam- pling units (cohort studies) or the same populations can show how the situation changes with time. Correlations can be sought between the results of a survey and those of institution-based reporting of the same disease or condition, which may then permit extrapolations from the routine data system to the whole of the population surveyed. The literature on health surveys is extensive (see, for example, lists of references in b).A simple series of guides to the planning and conduct of such surveys has been produced by Lutz (1-6). This issue of the World health statistics quarterly ex- plores some alternatives to nationwide institution-based reporting and national sample surveys, as means for collecting the information required for health-system planning and management. One article describes a household health-and-development survey based on a small number of representative districts in Kerala (lndia).d Another presents a preview of the sentinel city project of the Expanded Programme on Immunization (EPl).e This project is designed to study the impact of immunization on the incidence of the six EPI target dis- eases in 25 major cities of the developing world with a • Scientist (Epidemiologist), Development of Epidemiological and Health Statistical Services, WHO, Geneva. b World health statistics quarterly, 38 ( 1): 126 pp ( 1985). c World Health Organization. Sample size determination: a user's manual. (Document HST/ESM/86.1 (Rev. 1), 1986). d Community-based health reporting, p. 26. • Local area monitoring (LAM), p. 19. f A method for evaluating systems of epidemiological surveillance, p. 11. g International Statistical Classification of Diseases and Related Health Problems- Tenth Revision, p. 32. h Le Reglement sanitaire international: bi/an et perspectives. p. 37. combined population of over 115 million. A third paper describes a method for evaluating surveillance systems, which is very practical for determining the usefulness, cost-effectiveness and quality of a system. f Related arti- cles detail the ways in which the International Classifica- tion of Diseases (ICD)9 and the International Health Regu- lations (IHR)h contribute to health planning and manage- ment by facilitating : the recording and reporting of mor- bidity and mortality; the comparison of health and dis- ease status between countries ; the detection of trends over time within countries; and the rapid exchange of information on diseases of importance to international travel and trade. Sentinel surveillance Various attempts have been made to find a system that would provide a measure of disease incidence in a coun- try in the absence of good nationwide, institution-based surveillance and without having to resort to large, expen- sive sample surveys. One popular solution has been to designate health-care facilities or physicians as sentinel sites. Sentinel sites may be entire cities, or one or more major or specialized institutions within a city. A sentinel network may consist of a number of sentinel sites or physicians distributed around the country. Important considerations in selecting sentinel sites are the quality of the data they provide, the volume of case reports they produce, and their ability and willingness to act as sentinels. Quality is judged on the basis of accu- racy of diagnosis, completeness and promptness of reporting and provision of additional details. Large num- bers of patients should be seen in order for the site to be representative. But if a site meets all these requirements and yet the personnel are not willing to cooperate in reporting the data, due to overwork or any other reason, then it is no good as a sentinel station. The way sentinel sites are selected for systematic sur- veillance of the EPI target diseases, and their effective- ness in operation, may be illustrated by the following examples. In Malawi, 60 hospitals and outpatient clinics were con- tacted to provide details of the age and vaccination sta- tus of all the 4 590 children they diagnosed as measles cases during the first five months of 1984 (7). The results revealed regional differences in age-specific at- tack rates and in the immunization history of cases. A complementary special study was done at Kasungu District Hospital of the 354 measles cases seen there during the first four months of 1985. The percentage of measles cases with a history of vaccination seen at the hospital (36%) was similar to that found in the 60-insti- tution study (32%), and the case-fatality rate for measles ( 10.5%) was similar to that derived from routine surveil- lance reports from all Malawi hospitals ( 1978-1983 average of 7.8%). Thus, Kasungu District Hospital ap- pears to be a good sentinel site, representative of the whole country for measles surveillance. Rapp. trimest. ststist. sanit. mond .. 41 (1988) -3- In Dhaka (Bangladesh) the Dhaka Medical College Hospi- tal (DMCH) was selected for preliminary testing. A retro- spective survey was made of all 10 44 7 admissions to the two paediatric units between January 1982 and November 1985 (8). For each of the 875 cases found with a discharge diagnosis of an EPI target disease, a note was made of the sex, residence and outcome. Around 55% of admissions were boys, which suggests that hospital data may not be representative of the dis- ease situation in girls. Residents of Dhaka Municipality accounted for 100% of neonatal tetanus cases but only 81 % of poliomyelitis cases, with the other target dis- eases (diphtheria, measles, pertussis, tuberculosis) ranging in between. One hundred per cent of patients with neonatal tetanus, 88% of other tetanus cases and 61 % of diphtheria cases were transferred to other hos- pitals, compared with 1 % or less for the other target diseases. The conclusion was that the DMCH would be a good sentinel site, but that the institutions to which the tetanus and diphtheria cases were transferred should also be included as sentinel sites for the city. Dhaka, with its population of 3.5 million, was included in the list of 25 major cities in the developing world to be surveyed in the Local Area Monitoring Project of the EPI. e Istanbul (Turkey) is another of the 25 cities. In Istanbul, municipal data on incidence of the EPI target diseases, collected from 169 inpatient and outpatient services citywide, were compared with the number of cases of those diseases seen at the Istanbul Children's Hospital.0 The Children's Hospital sees over 4000 inpatients and 40 OOO outpatients per year. Inpatient records are regu- larly reported to the Istanbul Health Office, but outpatient visits are not routinely reported or analysed. Since only a small proportion of measles cases are hospitalized, a retrospective review of the outpatient registers was made for records of measles for the years 1980-1986, and the curve obtained was found to match very closely the curve for citywide reports of measles for the same years, which include both inpatient and outpatient re- cords. The Children's Hospital inpatient records did not show such a good fit, and there were gaps in reporting. The curves for poliomyelitis and pertussis for the same seven years, comparing citywide data with inpatient data from the Children's Hospital, have been published elsewhere (9). The fit for pertussis is good up to the end of 1983, while for poliomyelitis it is less good because the overall number of cases is small. The correlation is also poor for diphtheria, which is similarly seen less fre- quently. Thus, this single sentinel hospital could ad- equately substitute for the citywide reporting system for at least measles and pertussis, with concomitant eco- nomies in time, effort and expense. From the pro- gramme-management point of view, the value of the Istanbul data is that they show persisting low levels of measles and pertussis incidence since the mass immu- nization campaign held at the end of 1985. In Bombay (India), measles cases and deaths at the Kasturba Infectious Disease Hospital (inpatient and out- patient services) were recorded from 1980 to 1984 (10). They showed little change from year to year (measles vaccination was only begun in 1983, and cov- erage was less than 10%). The Public Health Department of the Bombay Municipal Corporation (BMC) registers death by cause and records morbidity and mortality from communicable diseases. For the same period, the BMC records show measles deaths peaking in 1981 and 1984 (a large epidemic), plus an anomaly-the number of measles deaths reported to the BMC in 1980 (32) was less than the number recorded at Kasturba Hospital alone (35). It appears that this particular hospital serves a population that is not representative of the BMC area. For Bombay, the BMC is the sentinel site of choice, especially as it records poliomyelitis cases by residence, Wld hlth statist. quan .• 41 ( 1988) and since 1982 has reported neonatal tetanus sepa- rately from other tetanus. The separate poliomyelitis records allow the impact of the city's own vaccination programme to be measured without being confounded by cases in non-residents. The separate tetanus records mean that the impact of maternal versus child vaccina- tion can be followed. An 11-year review (1974-1984) of BMC records showed that diphtheria cases had declined more than tenfold, and that although the number of poliomyelitis cases had remained at around the same level in the face of a 36% population increase in the interval, the incidence rate of poliomyelitis had also declined. These findings are consistent with the results of immunization coverage surveys of Bombay that showed rising levels of coverage with OPT and polio vaccines from 1980 to 1983. The BMC records are there- fore useful for immunization programme evaluation: In the United Republic of Tanzania, a questionnaire was sent in mid-1986 to each of the 391 hospitals and health centres in the country requesting retrospective morbi- dity and mortality data on the six EPI target diseases (11). By the end of the year over 150 replies had been receiv- ed. These included 60 institutions with monthly measles records going back to 1981, and 42 with monthly per- tussis records since that date. Plotting the average mon- thly number of cases for each year revealed consistent and rapid declines in both diseases, correlating with the introduction of the cold chain in 1982, the implementa- tion of the vaccine distribution system in 1984 and its expansion to all peripheral health units in 1985. The 42 institutions reporting pertussis since 1981, assuming they all also reported measles, would be the logical sen- tinel network for continuing surveillance of these disea- ses. Some additions or subtractions might be necessary to ensure representative geographic coverage of the country. As for the other country sentinel systems des- cribed above, the results from the Tanzanian sites are useful for evaluating the impact of the national immuni- zation programme. Turning from the EPI target diseases to other communi- cable diseases, an outstanding example is the network of sentinel cities in the United States of America. Since 1918 a large group of cities has reported weekly to the United States Public Health Service the number of deaths from all causes and the number of deaths from pneumo- nia and influenza. At present, the number of cities parti- cipating is 121. Each city health department sends infor- mation every week on a postcard on the number of death certificates filed the previous week, classified by age group at death, and the subtotal of pneumonia and influenza deaths (12). This sample covers approximately 32% of all deaths in the United States, and the age dis- tribution of deaths is virtually identical to that for the entire United States population as determined from Na- tional Center for Health Statistics (NCHS) figures. For planning purposes, the 121-city surveillance system is more rapid than the 10% sample of death certificates published by the NCHS 3-4 months after death, and cor- rectly identified all epidemics of excess mortality be- tween 1962 and 1979 as corroborated by independent sources (13). It has been used to monitor the impact of influenza on mortality throughout the United States, to alert health officials to the severity and extent of in- fluenza activity, and to identify areas where unusual clus- ters of death occur. Besides identifying influenza epide- mics, it documented excess mortality from the 1966 heat wave, and may be used in future to measure infant mor- tality. The Islamic Republic of Iran has, since 1974, reported to WHO morbidity and cause-of-death data for up to 21 cities in place of national data, which are not availa- ble (14). -4- In the area of chronic disease, the United States also provides an example of a sentinel network. The National Cancer Institute operates a Surveillance Epidemiology and End Results (SEER) Programme which provides de- tailed information on incidence of and mortality due to malignant neoplasms (15). The sentinel sites, which have been reporting since 1972-1974, comprise four major metropolitan areas, five states (including Hawaii) and the Commonwealth of Puerto Rico. This is the only system, apart from other state cancer registries, that permits the detection of trends in cancer incidence, and has been responsible for documenting the continuing increase in cancer of the lung and bronchus, and the decline in sto- mach cancer. Case-finding audits have shown that the data are 99% complete, with both sensitivity and speci- ficity greater than 95%. However, although the popula- tion covered by the 10 sites is almost 13% of the total population, it is not at all representative, since although it includes 12% each of the white, black and Hispanic popu- lations, it contains 27% of all American Indians and 32%, 38% and 47% respectively of United States residents of Chinese, Filipino and Japanese origin. Since the focus of this issue of the Quarterly is on methods applicable at national level, only passing refe- rence will be made here to international sentinel net- works. A prime example of those is the WHO-sponsored MONICA project (MONltoring of trends and determi- nants in CArdiovascular disease). Planned to run for the decade 1984-1993, it involves 40 centres in 26 countries and covers a population of 11 million. Its principal objec- tives are to measure trends in cardiovascular morbidity and mortality, and to relate these to changes in risk fac- tors, health care and socioeconomic conditions. The results will be of major assistance in the planning of actions to be taken to reduce mortality from cardiovas- cular disease (16). These versions of sentinel surveillance may be com- pared with those instituted by five European countries based on sentinel physicians. Four of the countries report influenza through their networks, and four cover measles and mumps; otherwise a wide variety of condi- tions is included, different for each country and often changing from year to year (Table 1). The British system is the oldest, having been started in 1967 (17), followed by the Netherlands (18), Belgium (19), France (20) and Switzerland (21). In these countries, networks of volun- teer physicians report every week the number of cases of certain specified diseases or conditions seen in their practices. The physicians are selected as far as possible to be a representative sample by geographical distribu- tion (in France, the 570 physicians participating are selected also on the basis of age, sex and type of prac- tice, to be representative of all French physicians, inclu- ding those in overseas departments). Their reports are rapidly collated by computer and the results sent back every week to the participants as tables and maps. In France, both reporting and feedback are through a "mi- nitel" computer terminal connected to the doctor's tele- phone. This enabled, for example, participating physi- cians to follow the spread of an influenza epidemic throughout France with only a week's delay. The United Kingdom also has sentinel physician net- works at regional level in South Wales, at county level in Surrey, and at city level in Oxford (D.M. Fleming, perso- nal communication, 1987). The Netherlands has two city TABLE 1. CHARACTERISTICS OF FIVE SENTINEL PHYSICIAN NETWORKS TABLEAU 1. CARACTERISTIQUES DE CINQ RESEAUX SENTINELLES DE MEDECINS Reference - Reference . . . . . . . . . . . . Year begun - Annee du debut ....... . Population covered - Population couverte Number of doctors - Nombre de medecins . Number of practices - Nombre de cabinets Reporting mode - Moyen de notification . . Frequencyc - Periodicitec ......... . Feedback frequencyc - Periodicite de la retro· information c . . . . . . . . . . . . . . Conditions reponedd - Etats notifiesd Influenza - Grippe . . Measles - Rougeole . . Mumps - Oreillons . . . . . . Rubella - Rubeole . . . . . . . Pertussis - Coqueluche . . . . Otitis media - Otite moyenne Upper respiratory infection - Infection des voies respiratoires superieures Hepatitis - Hepatite . . . . . . . Chickenpox - Varicelle ..... Herpes zoster - Zona . . . . . . Mononucleosis - Mononucleose Accidents ............ . Attempted suicide - Tentative de suicide Hay fever - Rhume des foins . . . . . . . . Cancer (new cases) - Cancer (nouveaux cas) Myocardial infarction - lnfarctus du myocarde Sexually transmitted diseases -Maladies sexuellement transmissibles Other - Divers . . . . . . . . . . . . . . . . . . • Target - But. United Kingdom Royaume-Uni (17) 1967 0.4% 106 40 mail courrier W/H W/H x x x x x x x x x x x x O Percentage of physicians covered - Pourcentage de mt!decins inclus. 'W /H = weekly - hebdomadaire; Q/T = quanerly - trimestrielle. d Not all reponed every year - Ne sont pas tous notifit!s chaque annt!e. Netherlands Pays-Bas (18) 1970 1.1% 62 46 mail courrier W/H W/H x x x x x x x x Belgium Belgique (19) 1979 150 W/H Q/T x x x x x x x France (20) 1984 1%a, b 57oa 57oa computer ordinateur W/H W/H x x x x x x Switzerland Suisse (21) 1986 200• mail courrier W/H W/H x x x x x x x x x x x Rapp. trimest. statist. sanit. mond .• 41 (1988) -5- networks, in Amsterdam and the Hague; the latter had 25 physicians covering 12% of the population of the Hague in 1983 (18). Norway has operated a national net- work since 1975, which requests a weekly return from most practices, but in fact the coverage is around 60% (National Institute for Public Health, Oslo, personal com- munication, 1987). Even for the more restricted sentinel networks referred to above, participation is affected by public holidays and vacations. The percentage of possi- ble reporting days (based on a five-day week) for which reports were received by the Netherlands system in 1983 was 88%, and the number of physicians reporting from the Swiss network varied between 92 and 125 for weeks 39 and 41 of 1987 (22). Community-based reporting The article by Scottd relates an interesting experiment in community-based reporting in Kerala State (India) which is still continuing. The study collects socioeconomic data from the community plus information on infant deaths, illness, and height and weight of children through household surveys using paid local interviewers. The conclusions that can be drawn from this account of the first five years include the following. The initial samples were found to be too small (10 OOO people) and were expanded to include entire administrative districts (over 25 000). Even so, they were still too small to produce reliable estimates of the infant mortality rate. The trends in weight-for-height, height-for-age and weight-for-age in relation to average income produced the reverse of the expected result, with the trend deteriorating with time in the more affluent areas. The difference between areas was statistically significant, and no satisfactory explana- tion has been found for this result. The morbidity rate, measured as the inability to pursue normal activities because of illness on at least one day during the week before interview, was 19.3 per 1 OOO. This is low com- pared with that found in other studies, which have usually used a two-week recall period. Morbidity rates per 1 OOO from two survey rounds in Ethiopia (1982- 1983) were 183 and 169 respectively (J.E. Dowd, per- sonal communication, 1987); in Nigeria (1982) the rate was 208 (23); and in Colombia (1977-1980), for the population aged 6 years and above, it was 107 (24). The rates for Kerala (1979-1980) can be derived from Table 3 of Scott's article in this issued and were 19.3 for the whole population, or 17.7 for those aged 5 years and above (both for the previous seven days). Assuming the probability of having one or more days of restricted acti- vity due to illness is proportional to time, then a two- week rate for Kerala is obtained by doubling, giving 38.6 for the whole population or 35.4 for those aged 5 years and above. This is 3-6 times less than the other countries quoted, but comparable to the rate of 37 .8 per 1 OOO found in Burma for one or more morbid conditions (not l'}ecessarily incapacitating) in the previous 14 days (25). It could be hypothesized that the lower rates for the Asian countries are due to cultural differences, such as reluc- tance to admit to being diseased or incapacitated, or greater fortitude in continuing normal activities in spite of sickness. The rates could also be markedly affected by the season of the survey, for example whether the study was done at the height of the malaria or diarrhoea sea- son. The design of the surveys was changed after the first two years, so that the early results are not comparable to the later ones, and there were a number of other difficul- ties. The detailed discussion of the methodology of the Kerala survey and possible modifications, given in the original paper on which the article is based, should be consulted by anyone interested in performing similar stu- dies. Wld hlth statist. quart., 41 (1988) Evaluating surveillance systems The article by Thacker and the Surveillance Coordination Group ~SCG) of the United States Centers for Disease Control in this issue outlines a very practical method for evaluating surveillance systems. The basic criterion should always be usefulness: whether a system leads to prompt action to reduce morbidity and mortality or to promote health. Once this criterion is fulfilled, what is the cost? Can the system be improved at no additional expense, or maintained at lower cost? Finally, its quality should be assessed on the basis of seven other criteria: sensitivity, specificity, representativeness, timeliness, simplicity, flexibility and acceptability. Using these crite- ria, it is likely that community-based health reporting as described by Scottd would not qualify without some changes in methodology, whereas some sentinel cities' systems would qualify. The SCG has produced a Surveillance Evaluation Manual, and has applied the method to the 121-city influenza mor- tality surveillance system and the SEER Programme, both mentioned above, and also to the Behavioural Risk Factor Surveillance System (BRFSS). The BRFSS is a state-based telephone-survey system, which interviews approximately 100 adults each month in each participa- ting state using a random digit dialling technique (Centers for Disease Control, personal communication, 1987). It is only applicable in situations where domestic telephone density in relation to population is very high. The risk behaviours studied include current smoking status, alco- hol use, drinking and driving, hypertension, obesity, seatbelt use and physical activity. Following the sugges- ted evaluation criteria, the system's usefulness is for the study of trends in risk behaviour and the detection of epidemics of such behaviour. The system can identify demographic characteristics associated with the beha- vioural risk factors and be used to estimate the impact of risk-factor reduction measures on morbidity and mortal- ity, thereby permitting cost-effectiveness analysis of the measures. The cost at state level represents about US$20 per completed interview and at national level about US$29 per interview, including the costs of train- ing state personnel. This total of US$49 compares favourably with about US$78 per patient studied in the SEER Programme. Regarding simplicity, the system, being active, is not as simple as a passive system, but concerning flexibility, it is very adaptable, since the ques- tionnaire can be readily modified. Acceptability is high (80% completion rate for questionnaires). Sensitivity and specificity are not measurable, given the nature of the behaviours being studied, such as drinking and smoking. As for representativeness, the system covers 25 states and the District of Columbia, accounting for 60% of the United States adult population. The lower socioeconomic status group without telephones is by definition excluded. An attempt is made to weight data to the age, race and sex distribution within each state. Finally, regarding timeliness, quarterly and annual re- ports are generally available within three months of the end of each period. International Classification of Diseases The International Classification of Diseases (ICD) has evolved through various revisions, as described here by Bramer.9 Its primary purpose is for the recording and reporting of morbidity and mortality statistics, and as such it has been made as comprehensive as possible. It has been criticized on the grounds of its complexity, yet in some developing countries such as Malaysia, health workers have been observed to be able to code patient records from memory (K. Kupka, personal communica- tion, 1987). It suffers from the changes in certain cate- -6- gories of disease introduced in some rev1s1ons. For example, since Japan and the United States switched over to using the Ninth Revision of the ICD (ICD-9) they 'have reported a decline in ischaemic heart disease which is disproportionate to the decline in heart disease as a whole in those countries. This suggests an artefact due to internal reassignments within the group of heart dis- eases (26). Other countries have problems with coding other diseases. One African country never reports any cases of cholera, and includes them under the category ·'diseases of the gastro-intestinal tract'·. This is mislead- ing, and in addition it is not in compliance with the Inter- national Health Regulations. Fourteen countries or territories stopped reporting mor- tality data to WHO when ICD-9 was introduced in 1979. Five European countries plus Turkey and the Islamic Republic of Iran have continued to report using the older ICD-8, which means that their mortality data for recent years cannot be directly compared with that from other countries. One hundred countries or areas have reported diseases to WHO using either ICD-8 or ICD-9, account- ing for nearly 40% of the world population (Map 1). China will raise that to 60% when it begins reporting shortly, but most of Asia does not report, and Egypt remains the only country on the entire African continent that reports using the ICD.i The recent publication of the Evaluation of the strategy for health for all (2 7) reporting the results obtained by most countries of the world, has brought into the fore- ground the problem of how leading causes of morbidity and mortality should be categorized so that they can be both useful to the country and comparable between countries. Some countries use the main ICD chapter headings, so that their five leading causes of death, for example, would be diseases of the circulatory system, neoplasms, accidents and injuries, diseases of the res- piratory system and infectious and parasitic diseases. Other countries use a more detailed level of the classifi- cation, so that, for example, ischaemic heart disease, hypertension and cerebrovascular disease all rank among the five leading causes. One country lists normal childbirth as a leading cause of morbidity. While this is undoubtedly a leading cause of hospital-bed occupancy, it is not helpful to include it among the priority causes of ill health for the country. Several countries include the cate- gory of symptoms, signs and ill-defined conditions as a leading cause, which is only useful in so far as it gives a measure of the lack of specific diagnoses available through the health services. There is need for a consen- sus on the most useful categories for ranking leading causes of morbidity and mortality before the next evalu- ation process in 1990. The International Health Regulations The evolution of the International Health Regulations (IHR) is reviewed by Vessereau.h Paradoxically, the spread of cholera, one of the diseases responsible for the introduction of the IHR, has never been effectively prevented by the Regulations, and it was not the deter- mining factor in the eradication of smallpox. But they have shown results in containing the spread of two other notifiable diseases, yellow fever and plague. The rea- sons are to be found in the different characteristics of the diseases. While the cholera vaccine does not provide significant protection, yellow-fever vaccine is highly i South Africa uses the ICD-9, but does not report to WHO. i Most countries subscribe to the IHR, notable exceptions being Australia and Papua New Guinea. effective in protecting travellers from infection and, together with vector control, in aborting epidemics. However, because it is carried by mosquitos and forest monkeys, yellow fever is still able to cross frontiers undetected and to escape eradication. Smallpox was controlled and eventually eliminated by means of an effective vaccine and vaccine-delivery technique, and the lack of a wild vector or reservoir made its eradication possible. In the case of plague, on the other hand, although there is no vaccine practical for mass immuni- zation and a wild rodent reservoir exists, urban and ship- board rat-control methods have become so effective that there is no longer any serious threat of the importa- tion of plague into ports or airports, nor of its spread from its wild reservoir into controlled urban areas. It is recognized that there has been considerable under- reporting of cases of the diseases notifiable under the IHR. As mentioned earlier, at least one country does not report cholera cases as such. Jungle yellow fever has a relatively low case-fatality rate, and it is often only the fatal cases that are reported, so that the actual numbers of people falling ill during a jungle-yellow-fever epidemic are never known, although subsequent serological sur- veys for post-infection immunity may provide an esti- mate. For this reason, the figures for the IHR diseases reported by individual countries have been consolidated by continent in Vessereau's article,h to give an idea of trends while diminishing any false impression of preci- sion. There is still misunderstanding in some countries about the exact meaning of the IHR, to which they have sub- scribed) There is no epidemiological justification for demanding a yellow-fever immunization certificate from a traveller coming from a country in the yellow-fever- endemic area, or even from a country that has reported a current yellow-fever outbreak if that person has not visited the infected area. For example, many tourists will visit only major cities, which are normally not involved when there is a local outbreak of jungle yellow fever. On the other hand, some physicians do not understand that many yellow-fever-endemic countries do not require yellow-fever vaccination from visitors, simply because they are already infected. Since there is no formal requirement, physicians do not recommend yellow- fever vaccination to clients planning to travel to such countries, whereas in fact they should strongly recom- mend it for the client's protection, at least if travel in rural areas is planned. An example was the case of two unvaccinated French travellers in rural areas of West Africa who contracted yellow fever there and died after their return to France (28). The obligation under the IHR for countries to notify cases of certain diseases means, when followed faithfully and when the notifications are accompanied by epi- demiological information, that other countries can take appropriate measures to meet the possibility of impor- tation, rather than excessive measures to meet the threat of an unknown situation. A topical example of the application of the IHR is the question of whether AIDS should be included under the Regulations. WHO's position is that no measures, and no health document, other than those provided for in the Regulations, may be imposed on arriving travellers. Also since carriers far outnumber those people who could be identified as ill with the infection, there is no practical method for preventing the spread of the virus across borders, and any attempt at mass serological screening of visitors with quarantine of positives would be useless as a protective measure, since it would miss some true positives and in addition turn up a large number of false positives. It would also be prohibitively expensive, and Rapp. trimest. statist. sanit. mond., 41 (1988) ~ § .. is ~· .0 c: ., ~ ~ "' 00 E? I I # D MAP.1. CARTE 1. _ .. COUNTRIES/TERRITORIES EVER REPORTING CAUSES OF DEATH TO WHO, BY ICD REVISION USED PAYS/TERRITOIRES AVANT DEJA NOTIFIE DES CAUSES DE DECES A L'OMS, PAR REVISION DE LA CIM UTILISEE { ~ ;::: "' i Negotiations are in progress to obtain cause-of-death data from China - Des n0gociations sont en cours pour obteriir de la Chine des donnees sur les causes de deces. No report - Aucune notification ill ICD-8 - CIM-8 II11] ICD-9 - CIM-9 * All the countries/territories in the Lesser Antilles use ICD-9 except for Anguilla, Cayman Islands and Montserrat (ICD-8) - Tous les pays/territoires des Petites Antilles utilisent la CIM-9, ~ !'exception d' Anguilla. des lies Caimanes et de Montserrat (CIM-8). -...J -8- would divert resources from more effective measures such as blood-bank screening and public information and education on the means of prevention. Also there is no risk of infection for people sharing public transport with someone infected with human immunodeficiency virus, even if that person is clinically ill with AIDS.k Conclusions To sum up, every country needs a system to provide valid information on the health situation rapidly enough to form the basis for the decisions to be taken for the planning and management of its health programmes. Routine institutional surveillance should be restricted to the minimum data items essential to proper manage- ment of health services. Time and scarce resources should not be wasted on collecting figures for cases of a disease for which no intervention programme is either in place or planned. It may well be advantageous to sup- plement or partly replace a nationwide surveillance sys- tem by local sentinel physician- or site-based networks, if these can be selected so as to be sufficiently repre- sentative. In countries which do not have a national sys- tem, a sentinel network might be the first step towards establishing such a system. k World Health Organization. Repon of the consultation on interna- tional travel and HIV infection, Geneva, 2-3 March 1987. (Document SPA/GL0/87 .1, 1987). Documenting a decrease in the incidence of the target disease is the only direct way to measure the impact of an immunization programme. Even then, it is necessary to distinguish the portion attributable to the programme as against that due to other possible factors such as seasonal or other periodic cycles. Hence the importance of continuous, consistent, sensitive and specific collec- tion of data on diseases and health events for which interventions are to be made. International notification of diseases should be based on the International Health Regulations. Restrictions on travel should not be applied to diseases which are not covered by these Regulations. National notifications should be based on the categories of the International Classification of Diseases, carefully chosen to empha- size the country's priority health problems. All countries should use the most recent revision of the ICD (currently ICD-9) so that their rates can be directly compared with those from other countries. Information on that part of the population not contacting the health services may be sought through surveys, either mounted by specialist teams or conducted by local personnel. In each case, the information sought should again be restricted to the minimum required for effective management of health programmes. Finally, every sys- tem of surveillance should be regularly evaluated to ensure that it is doing the job expected of it, at reason- able cost, and producing results of acceptable quality. SUMMARY The promotion of health and the prevention of disease depend to a large extent on the good planning and man- agement of health programmes. Good planning and management in turn depend on the availability of reliable, accurate and timely information about the health situa- tion. All countries have institution-based systems for the collection of routine information about health-services delivery. Many countries also use surveys to obtain information about other aspects of the health situation. This issue of the World health statistics quarterly de- scribes two types of surveillance which may be used to supplement (or compensate for the absence of) nation- wide routine systems or surveys, and a method for evaluating surveillance systems. It also includes articles on the International Classification of Diseases and Causes of Death (ICD) and the International Health Regu- lations (IHR) in relation to their use for planning and man- agement. Two alternative surveillance systems are described. One uses institution- or city-based records of incidence of target diseases of the Expanded Programme on Immu- nization (EPI) in a number of developing countries to determine the impact of minimization on the reduction of disease. In this article, some additional background material is reviewed on sentinel hospitals and cities in India, Bangladesh, Turkey, Malawi and United Republic of Tanzania. The other system is based on district-level household surveys of mortality, morbidity and nutrition- related indicators in Kerala State (India) carried out by trained local personnel who live in the districts. These methods are compared with two sentinel-site systems for influenza and cancer reporting in the United States of America, and sentinel physician networks in six Euro- pean countries for reporting the incidence of measles, mumps, influenza and a number of other diseases and conditions such as accidents and attempted suicides. The basic criterion for evaluating any surveillance sys- tem should be whether it leads to prompt action to reduce illness or promote health. Once this criterion is satisfied, questions of cost-effectiveness and quality arise. Quality should be assessed on the basis of sensi- tivity, specificity, representativeness, timeliness, sim- plicity, flexibility and acceptability. These aspects are discussed in detail in the article on evaluation, and their application is discussed in this introduction in relation to the Behavioural Risk Factor Surveillance System in the United States. The ICD is a basic tool for standardizing the reporting of causes of illness and death within a country and between countries, and thus facilitating epidemiological analysis, the study of trends and the planning and management of programmes. There are some problems due to countries misclassifying diseases, and due to changes between revisions of the ICD. Also, only some 40% of the world's population is covered by ICD-based reporting, although this will rise to 60% when China begins reporting soon. The IHR have shown their value in the control of the spread of yellow fever and plague, and in the interna- tional dissemination of epidemiological information on disease outbreaks so as to permit countries to take properly-measured precautions against importation of epidemic diseases. It is strongly recommended that visi- tors intending to travel in rural areas of a yellow-fever- endemic country be vaccinated for their own protection, even if the country does not require that travellers be vaccinated. WHO recommends against invoking meas- ures restricting the travel of persons suffering from AIDS or infected with human immunodeficiency virus. Rapp. trimest. statist. sanit. mond., 41 ( 1988) -9- RESUME Introduction: approches epidemiologiques de la planification sanitaire: gestion et evaluation La promotion de la sante et la prevention des maladies dependent pour une large part d'une p!anification et d'une gestion satisfaisantes des programmes sanitaires. Pour etre satisfaisantes, la planification et la gestion exi- gent de leur cote que I' on dispose d'informations fiables, exactes et opportunes sur la situation sanitaire. Tousles pays possedent des systemes fondes sur les etablisse- ments pour la collecte des renseignements de routine sur les prestations sanitaires. Nombreux sont les pays qui ont aussi recours a des enquetes pour obtenir des infor- mations sur d'autres aspects de la situation sanitaire. Le present numero du Rappon trimestriel de statistiques sanitaires mondia/es decrit deux types de surveillance qui peuvent etre utilises pour completer (ou compenser I' absence) de systemes ou enquetes de routine appli- ques a l'echelle nationale, ainsi qu'une methode d'eva- luation des systemes de surveillance. II comprend aussi des articles sur la Classification internationale des mala- dies et causes de deces (CIM) et sur le Reglement sani- taire international (RSI) pour ce qui est de leur emploi dans la planification et la gestion. Deux systemes de surveillance differents sont decrits. L • un utilise les releves indiquant par etablissement ou par ville !'incidence des maladies visees par le Programme elargi de vaccination (PEV) dans un certain nombre de pays en developpement, afin de determiner !'impact que la minimalisation peut avoir sur la reduction de la mala- die. Cet article passe en revue une documentation com- plementaire sur les hopitaux et les villes jouant le role de « sentinelles » en lnde, au Bangladesh, en Turquie, au Malawi et dans la Republique-Unie de Tanzanie. L'autre systeme repose sur des enquetes dans les manages au niveau du district, portant sur les indicateurs lies a la mortalite, a la morbidite et a la nutrition dans l'Etat de Kera la (lnde) et menees par un personnel local qualifie qui reside dans les districts. Ces methodes sont comparees avec deux systemes a « sentinelles » utilises pour la noti- fication de la grippe et du cancer aux Etats-Unis d' Ame- rique, ainsi qu'avec des reseaux sentinelles de medecins dans six pays d'Europe pour la notification de !'incidence de la rougeole, des oreillons, de la grippe et d'un certain nombre d'autres maladies et etats, notamment les acci- dents et les tentatives de suicide. Le critere de base pour I' evaluation de tout systeme de surveillance consiste a verifier s'il permet d'intervenir rapidement pour r~duire la maladie ou promouvoir la sante. Ce critere une fois satisfait, ii se pose des ques- tions de rentabilite et de qualite. La qualite doit etre eva- luee en fonction de la sensibilite, de la specificite, de la representativite, de l'opportunite, de la simplicite, de la souplesse et de l'acceptabilite. L'article sur ('evaluation traite en detail de ces aspects, tandis que leur application au regard du Systeme de surveillance des facteurs de risque lies au comportement, en vigueur aux Etats-Unis, est traitee dans cette introduction. La CIM est un instrument fondamental pour normaliser la notification des causes de maladie et de deces dans un pays et d'un pays a l'autre et, partant, faciliter !'analyse epidemiologique, l'etude des tendances et la planifica- tion et la gestion des programmes. II existe quelques problemes dus au fait que des pays classent certaines maladies de fa~on erronee et que des changements sont intervenus entre les diverses revisions de la CIM. D'autre part, quelque 40% seulement de la population du globe sont couverts par la notification fondee sur la CIM, encore que la proportion atteindra 60% des que la Chine commencera a notifier, ce qui ne saurait tarder. Le RSI a demontre sa valeur dans la lutte contre ta pro- pagation de la fievre jaune et de la peste et dans la dif- fusion internationale des informations epidemiologiques sur les flambees de maladies afin de permettre aux pays de prendre des precautions judicieuses pour eviter l'im- portation de maladies epidemiques. II est vivement re- commande aux personnes qui se proposent de voyager dans les zones rurales d'un pays a endemicite amarile de se faire vacciner pour assurer leur propre protection, meme si le pays en question n'exige pas la vaccination des voyageurs. L'OMS recommande de ne prendre au- cune mesure pour restreindre les deplacements des per- sonnes atteintes du SIDA-maladie ou infectees par le virus de l'immunodeficience humaine. REFERENCES - REFERENCES 1. LUTZ. W. Planning and organizing a health survey-a guide for health workers. Geneva, International Epi- demiological Association, 1981. (Community health surveys No. 1). LUTZ, W. Planification et organisation des enquetes sur la sante - guide pratique destine aux profes- sionnels de la sante. Geneve, Association interna- tionale d'epidemiologie, 1983. (Enquetes sur ta sante de la collectivite N° 1). 2. LUTZ. W. Sampling: how to select people, house- holds, places to study community health-a guide for health workers. Geneva, International Epidemio- logical Association, 1982. (Community health sur- veys No. 2). LuTz. W. Sandage: comment former des echantil- lons d'individus, de manages, de zones, pour l'etude des problemes de sante de la collectivite - guide pratique destine aux professionnels de la san- te. Geneve, Association internationale d'epidemio- logie, 1983. (Enquetes sur ta sante de la collectivite N° 2). Wld hlth statist. quart., 41 ( 1988) 3. LUTZ. W. Finding and using information-a guide for health workers. Geneva, International Epidemiologi- cal Association, 1983. (Community health surveys No. 3). LUTZ. W. Utilisation de /'information disponible - guide pratique destine aux professionnels de la san- te. Geneve, Association internationale d'epidemio- togie, 1984. (Enquetes sur la sante de la collectivite N°3). 4. LOCKERBIE. L. & LUTZ. W. Questionnaire design-a guide for health workers. Geneva, International Epi- demiological Association, 1986. (Community health surveys No. 4). LOCKERBIE, L. & LUTZ, w. Elaboration d'un question- naire - guide pratique destine aux professionnels de la sante. Geneve, Association internationale d'epidemiologie, 1986. (Enquetes sur la sante de la collectivite N° 4). 5. HEPBURN. W. & LUTZ. W. Interviewing and recor- ding-a guide to interviewer training for health wor- - 10 kers. Geneva, International Epidemiological Asso- ciation, 1986. (Community health surveys No. 5). HEPBURN, W. & LUTZ, W. Techniques d'entretien et enregistrement des reponses - guide pratique des- tine aux professionnels de la sante. Geneve, Asso- ciation internationale d'epidemiologie, en prepara- tion. (Enquetes sur la sante de la collectivite N° 5). 6. CHALMERS. J. & LUTZ. W. Presenting survey informa- tion-a guide for health workers. Geneva, Interna- tional Epidemiological Association, in press. (Com- munity health surveys No. 6). CHALMERS. J. & LUTZ. W. Presentation des resultats - guide pratique destine aux professionnels de la sante. Geneve, Association internationale d'epide- miologie, en preparation. (Enquetes sur la sante de la collectivite N° 6). 7. Expanded Programme on Immunization-measles surveillance methodology. Weekly epidemiological record, 61 (25): 191-193 (1986). Programme elargi de vaccination - methodologie de la surveillance de la rougeole. Re/eve epidemio- logique hebdomadaire, 61 (25): 191-193 (1986). 8. Expanded Programme on Immunization-local area monitoring: Bangladesh. Weekly epidemiological record, 62 (45): 341-342 (1987). Programme elargi de vaccination - surveillance locale: Bangladesh. Re/eve epidemiologique hebdo- madaire, 62 (45): 341-342 (1987). 9. Expanded Programme on Immunization-local area monitoring: Turkey. Weekly epidemiological re- cord, 62 (43): 325-327 (1987). Programme elargi de vaccination - surveillance locale: Turquie. Re/eve epidemiologique hebdoma- daire, 62 (43): 325-327 (1987). 10. Expanded Programme on Immunization-local area monitoring: India. Weekly epidemiological record, 62 (5): 25-27 (1987). Programme elargi de vaccination - s.urveillance locale: lnde. Re/eve epidemiologique hebdomadai- re, 62 (5): 25-27 (1987). 11. Expanded Programme on Immunization-local area monitoring: United Republic of Tanzania. Weekly epidemiological record, 62 (34): 252-254 (1987). Programme elargi de vaccination - surveillance locale: Republique-Unie de Tanzania. Re/eve epide- miologique hebdomadaire, 62 (34): 252-254 (1987). 12. CHOI, K. & THACKER, S. B. An evaluation of influenza mortality surveillance, 1962-1979. I - Time series forecasts of expected pneumonia and influenza deaths. American journal of epidemiology, 113: 215-226 (1981). 13. CHOI, K. & THACKER. S. B. An evaluation of influenza mortality surveillance, 1962-1979. II - Percentage of pneumonia and influenza deaths as an indicator of influenza activity. American journal of epidemiolo- gy, 113: 227-235 (1981). 14. WORLD HEAL TH ORGANIZATION. World health statistics annual. Geneva, WHO, 1983. (pp. 281-282, 375-376). ORGANISATION MONDI ALE DE LA SANTI:. Annuaire de sta- tistiques sanitaires mondiales. Geneve, OMS, 1983. (pp. 281-282, 375-376). 15. HoRM. J. W. ET AL SEER Program: cancer incidence and mortality in the United States, 1973-1981. Bethesda, MD, Department of Health and Human Services, 1984. (NIH publication 85-1837). 16. THE PRINCIPAL INVESTIGATORS. WHO MONICA Project: geographic variation in mortality from cardiovascu- lar diseases. World health statistics quarterly, 40 (2): 171-184 (1987). LES PRINCIPAUX CHERCHEURS. Projet MONICA de l'OMS: variation geographique de la mortalite par maladies cardio-vasculaires. Rapport trimestriel de statistiques sanitaires mondia/es, 40 (2): 171-184 (1987). 17. FLEMING. D. M. & ROMBIE, D. L. The incidence of com- mon infectious diseases: the weekly returns service of the Royal College of General Practitioners. Health trends, 17: 13-16 (1985). 18. FOUNDATION OF THE NETHERLANDS INSTITUTE FOR GENE- RAL PRACTICE. Continuous morbidity registration sen- tinel stations- The Netherlands, 1983. Utrecht, Ministry of Welfare, Public Health and Culture, 1983. 19. Disease surveillance: sentinel physicians. Weekly epidemiological record, 62 (15): 105-106 (1987). Surveillance des maladies: medecins vigies. Re/eve epidemio/ogique hebdomadaire, 62 (15): 105-106 (1987). 20. Communicable diseases: teleprocessing surveil- lance network. Weekly epidemiological record, 61 (48): 369-371 (1986). Maladies transmissibles: reseau teleinformatique de surveillance. Re/eve epidemiologique hebdoma- daire, 61 (48): 369-371 (1986). 21. Epidemiological surveillance: "sentinel" notifica- tion system. Weekly epidemiological record, 61 (14): 105-106 (1986). Surveillance epidemiologique: systeme de declara- tion «sentinelle». Re/eve epidemiologique hebdo- madaire, 61 (14): 105-106 (1986). 22. OFFICE Fl:Dl:RAL DE LA SANTI: PUBLIQUE. Sentinella-De- clarations. Bulletin (41): 364 (1987). 23. FEDERAL OFFICE OF STATISTICS. The health of Nige- rians, results from a pilot survey in four states in September 1982. Lagos, FOS, 1983. (Interim report). 24. RODRIGUEZ, A. P. [Population and general morbidity. Vol. /-Perceived morbidity, 1977-80]. Bogota, Ministry of Health, 1983. (p. 105, Table 50). (In Spanish). RODRIGUEZ, A. P. [Population et morbidite generate. Vol. I - Morbidite per<;ue, 1977-80]. Bogota, Ministere de la sante, 1983. (p. 105, tableau 50). (En espagnol). 25. KHIN MANUNG THWIN. Household survey on morbidi- ty, mortality and health care. Rangoon, Socialist Republic of the Union of Burma/United States Agency for International Development, 1983. (Joint study). 26. WORLD HEAL TH 0RGANIZA TION. Mortality from ischae- mic heart disease in industrialized countries. World health statistics annual. Geneva, WHO, 1987. (pp. 25-29). 0RGANISA TION MONDI ALE DE LA SANTI:. Mortalite par cardiopathie ischemique dans les pays industriali- ses. Annuaire de statistiques sanitaires mondiales. Geneve, OMS, 1987. (pp. 25-29). 2 7. WORLD HEAL TH ORGANIZATION. Evaluation of the stra- tegy for health for all by the year 2000-Seventh report on the world health situation. (7 volumes, various publishers, places and dates). ORGANISATION MONDIALE DE LA SANTI:. Evaluation de la strategie de la sante pour tous d'ici /'an 2000 - Septi(}me rapport sur la situation sanitaire dans le monde. (7 volumes, divers editeurs, lieux et dates). 28. Yellow fever surveillance-France. Weekly epide- miological record, 54 (46 & 47): 359 & 368 (1979). Surveillance de la fievre jaune - France. Re/eve epi- demiologique hebdomadaire, 54 (46 & 4 7) : 359 & 368 (1979). Rapp. trimest. statist. sanit. mond., 41 (1988) - 11 - A METHOD FOR EVALUATING SYSTEMS OF EPIDEMIOLOGICAL SURVEILLANCE a Stephen B. Thacker,b R. Gibson Parrish,b Frederick L. Trowbridgeb & Surveillance Coordination Groupe Epidemiological surveillance is the systematic collection, analysis, interpretation and timely dissemination of health data for the planning, implementation and evalu- ation of public health programmes. The application of these data to disease-prevention and health-promotion programmes completes a surveillance cycle in public health (1). Health data have been collected on a routine basis for over a century (2). In 1847, for example, William Farr used routinely collected mortality data to describe the impact of epidemic influenza in England and Wales (3). It was not until the middle of this century, however, that Alexander Langmuir developed the concept of surveil- lance as the routine process of collection, analysis and dissemination of health data (1). Subsequently, the con- cept of epidemiological surveillance has expanded to include broader issues in public health and the applica- tion of new methodologies (4, 5). There is little written, however, in either textbooks of epidemiology and public health or in the medical literature that serves as a guide to programmes wanting to evaluate their surveillance activ- ities. Established surveillance systems should be periodically reviewed on the basis of their quality as well as their usefulness and cost. They may then be modified accord- ingly. In assessing the quality of a surveillance system, one should review the following seven attributes: (i) sen- sitivity, (ii) specificity, (iii) representativeness, (iv) timeli- ness, (v) simplicity, (vi) flexibility and (vii) acceptability. Specific measurable criteria should be developed based on these attr_ibutes and linked to utility and cost. Most published evaluations of surveillance systems have been limited to infectious diseases (4, 6-9), al- though there have been some efforts to assess the appropriateness of various data sources for the surveil- lance of other kinds of health problems (10-12). The pur- pose of this paper is to build on these fragmentary descriptions and to propose an evaluation method that can be applied to all types of systems of epidemiological surveillance. This method will beginwith an assessment of usefulness and cost, and will include review of the seven attributes listed above. Usefulness and cost Usefulness A surveillance system is useful if it generates a public health response leading to the control and prevention of • Correspondence and reprint requests should be addressed to : Dr. S. B. Thacker, Assistant Director for Science, Center for Environ- mental Health, Centers for Disease Control, Atlanta, Georgia 30333, United States of America. b Epidemiology Program Office, Center for Environmental Health, Center for Health Promotion and Education, Centers for Disease Control, Atlanta, United States of America c William D. Adams, Henry A. Anderson, Edward L. Baker, John V. Bennett, Wayne G. Brown, Barbara R. Holloway, Wilma G. Johnson, Jeffrey P. Kaplan, J. Michael Lane, Ladene H. Newton, Howard W. Ory, Calvin W. Parrish, William R Taylor, Richard L. Vogt, Richard J. Waxweiler. Wld hlth statist. quart., 41 ( 19881 adverse health events or to a better understanding of the process leading to an adverse outcome. An additional consideration is the extent to which the knowledge obtained from surveillance data about the epidemiology of a health event leads to better understanding of a health problem (e.g. the identification of foreign travel as a risk factor in disease transmission) (13-16). Even a very crude system of surveillance may be useful to public health practitioners (e.g. counting the total number of deaths seen by a medical examiner during a heat wave (17)). The simplest way to assess usefulness is to ask those involved in public health practice. Surveys of public health officials at the state and local level, for example, have indicated that routine notifiable disease reports for viral hepatitis and measles are useful for disease pre- vention and control (18, 19). A more rigorous approach to defining usefulness is through assessment of the impact of surveillance data on policies and interventions, and ultimately their impact on the occurrence of a health event. While policy analyses have been conducted elsewhere in the health field (20), there are no such stud- ies of surveillance systems. Such policy analysis requires both observation and understanding of the decision- making process and quantification of the impact of sur- veillance information on the measures of interest (i.e. morbidity, mortality, disability and quality of life). The latter can be accomplished by a quantifiable score such as the Disease Impact Score, which expresses as a sin- gle index the estimated impact of prevention on morbid- ity, mortality and cost, and attributes a portion of that score to surveillance (21). Although surveillance data may be important to health decision making and policy formation, decisions affecting surveillance are often based on changes in more general programme directions rather than detailed analysis of a particular system (e.g. directing resources away from routine contact tracing for gonorrhoea control to programmes for the pre- vention and control of acquired immunodeficiency syn- drome). We recommend that the evaluation of the usefulness of a surveillance system be based on answers to the follow- ing questions. Does the system: • detect trends signalling new problems and lead to control and prevention activities? • detect epidemics leading to control and prevention activities? • provide quantitative estimates of the magnitude of morbidity and mortality related to the health event under surveillance? • identify factors involved in disease occurrence? • facilitate research likely to lead to control or pre- vention? • permit assessment of the effects of control meas- ures? The usefulness of a surveillance system should be re- viewed periodically as illness patterns change and new priorities emerge. If a system is not directed towards high-priority health events and used as a tool to drive - 12 - public health activities, either efforts must be made to improve the surveillance system or these resources should be directed elsewhere. For example, public health programmes to prevent unintentional injuries have re- ceived increasing emphasis in recent years. Data on inju- ries are available from emergency-room records (22), medical-examiner information (23), vital statistics (24) and police-arrest records (25). The usefulness of a sur- veillance system based on these data should be as- sessed in terms of the specific goals of injury-prevention programmes. If the injury-control efforts in a community focus on a particular problem such as adolescent drink- ing and driving, the surveillance system must be able to measure the specific impact on the target popu- lation (26). In this example police records, as well as population- and age-specific morbidity and mortality data, must be identified and linked to programme activ- ities. Cost Surveillance can be costly, particularly in the develop- ment of new systems or the enhancement of current ones. One can assess current systems in terms of costs and benefits and can apply the lessons from these efforts to further surveillance activities. The economic analysis of surveillance systems has received little meth- odical attention apart from the accounting of direct costs to health agencies. To assess direct and indirect costs, all elements of a surveillance system, including data col- lection, analysis and dissemination, must be identified and costs assigned to them. To calculate a benefit/cost ratio, the benefits such as illness prevented can be esti- mated, including the reduction of medical-care costs and of time lost from school or work. A 1983 Vermont report of active surveillance (initiated by the health department) of four infectious diseases estimated that costs were too high to justify active surveillance in that setting unless unquantified subjective benefits involving value judge- ments were great, such as improved relations with phy- sicians (8). A 1985 report from Kentucky, on the other hand, found a positive benefit/cost ratio associated with health-department-initiated surveillance of hepatitis A (27). Beyond these state-based efforts, however, there is much to be accomplished in the assessment of the benefits and costs of epidemiological surveillance. Evaluation of the quality of surveillance systems The seven attributes we have identified to measure the quality of surveillance systems can be subdivided into qualitative and quantitative attributes. The quantitative attributes-sensitivity, specificity, timeliness and repre- sentativeness-can be readily defined by numerical measures. Simplicity, flexibility and acceptability, on the other hand, are more subjective measures and are thus less easily quantified. Sensitivity Sensitivity is defined as the ability of a surveillance sys- tem to detect true health events. Health events may be defined as (a) instances in which persons have a particu- lar health problem or risk factor; (b) a more narrowly defined subset of (a) (e.g. fatal events); or, more broadly, as (c) an epidemic of a particular health event. Quantita- tively, sensitivity is the ratio of the total number of health events detected by the system over the total number of true health events as determined by an independent and more complete means of ascertainment (Fig. 1). In pub- lished reports, sensitivity has been termed complete- ness of reporting and has been studied more than the other six attributes (6, 7, 13, 14, 28). A variety of activities and circumstances will have an impact on sensitivity. For example, an uncommon, highly virulent disease for which there is an intervention (e.g. plague) is more likely to be reported than a common condition which is rarely fatal (e.g. gonorrhoea or vari- cella). A surveillance system monitoring a large number of events can be very useful even with a low sensitivity if the reports are representative (see below). Alternatively, health-department-initiated (active) disease-reporting systems are also likely to increase reporting over pro- vider-initiated (passive) systems (8, 10, 29). The level of sensitivity can also vary to address specific programme goals. When control activities are contingent upon the identification and reporting of every case (e.g. the late stages of the international smallpox eradication cam- paign (30) and the United States Measles Elimination Program (29)1 sensitivity is the critical criterion for as- sessing a surveillance system. FIG. 1 MEASURES OF SURVEILLANCE SYSTEM PRECISION• DETERMINATION DE LA PRECISION DU SYSTtME DE SURVEILLANCE- .. " c .. ~~ ; 2: =::, ·a; Cl) 2:.!! ::, ~ .... >"' .c.., ~!E "~ ;;;<= ·c:e ~" ·-.: ~ .. "'·"' c> .. "., ,:. ~ ~; :e :i::" c .., > ... Health event present - Ev6nement sanitaire existant c 0 z I 0 z ·;; 0 I .. " > Yes - Oui No - Non A 8 True positive False positive A+8 Vrais positifs Faux positifs c D False negative True negative C+D Faux n6gatils Vrais n6gatifs A+C 8+0 N • Sensitivity: the proponion of persons with the health event that are identified by the surveillance system (A/A+ C) - Sensibilit6 : la proponion des personnes subissant I' 6v6ne- ment sanitaire qui sont identili6es par le syst6me de surveil· lance (A/A+C). Rapp. trimest. starist. sanit. mond .• 41 ( 19881 - 13 - Sensitivity may also be defined in terms of epidemics detected by the surveillance system rather than indi- vidual cases (Fig. 1). If one could enumerate all epidemics of a certain condition, the sensitivity of a surveillance system could be calculated as the proportion of the total epidemics detected by the system. For example, death- certificate data on pneumonia and influenza are reported weekly to the Centers for Disease Control (CDC) from 121 United States cities as part of a national mortality sur- veillance system. Using estimates based on historical data, the system is used to detect epidemics of influen- za-related mortality. In an assessment of methods to analyse these data, alternative approaches were evaluated in terms of sensitivity, specificity and timeli- ness (31). Specificity Specificity is a measure of how infrequently a system detects false-positive health events. Quantitatively, it is the number of individuals identified by the system as not being diseased or not having a risk factor divided by the number of all persons who truly do not have the disease or risk factor of interest (Fig. 1). When applied to surveil- lance, specificity can be difficult to determine if the total population at risk is unknown. General population data may be available, but if a large portion of the population is not at risk (e.g. immune) the use of the total population as a denominator will provide an overestimate of specifici- ty. Use of the true population at risk provides a more accurate estimate. Given these difficulties in ascertainment, determination of the number of misclassified cases or false positives can be used as a measure of the failure of the system to correctly classify health events. In Fig. 1 the false-posi- tive rate is 8/ A+ B. For example, if 100 cases of silicosis were reported, but only 95 of those met an accepted case definition of silicosis, the false-positive rate would be 5/100 or 5%. A high rate of false positivity suggests that the system may be too sensitive (i.e. the case defi- nition in use is too permissive). While resources may be wasted in tracking these incorrectly classified reports, the system may still be useful if the risk to public health of a missed case is great (e.g. parathion contamination of a commercial food product). Specificity, like sensitivity, can be applied to epidemics. Pseudo-epidemics (false positives) are not common, but recognition of such situations is important to avoid unne- cessary concern of the lay and medical community, to identify previously unrecognized laboratory problems, and to minimize the misuse of resources (32-34). Representativeness A surveillance system that is representative accurately observes both the occurrence of a health event over time and the distribution by person and place of that event in the population at any point in time. To measure repre- sentativeness one can compare surveillance data cover- ing part of a population to a sample assumed to be complete (e.g. death certificates for selected fatal ev- ents) or to a random sample ofthe population at risk (e.g. the Health Interview Survey of the National Center for Health Statistics). If a surveillance system collects re- ports on essentially all occurrences of a health event (e.g. total deaths to a vital registrar) then the system is by definition representative and further assessment of this attribute is not necessary. The importance of the degree of representativeness depends on its possible effect on the public health response. The report of a few cases of a disease may Wld hlth statist. quan .• 41 (1988) trigger appropriate control efforts; non-representative reports may focus prevention activities away from popu- lations at high risk (7). A precise assessment of repre- sentativeness requires carefully designed studies to ob- tain complete and accurate data for the health event in question. A study of medical-examiner records in Fulton County, Georgia, found that this data source was repre- sentative for intentional and unintentional injury, but was a poor reflection of other causes of death (P. Graitcer, personal communication, 1986). A 1982 study of shigel- losis reporting in Washington, D.C., found that the rou- tine surveillance system was both incomplete and unre- presentative in terms of the socioeconomic status, race and residence of the population affected (7). Timeliness Timeliness is the interval between the occurrence of an adverse health event and (1) the report of the event to the appropriate public health agency, (ii) the identification by that agency of trends or outbreaks, or (iii) the implemen- tation of control measures. Timeliness is related both to the incubation or latency period of the health event and to the efficiency of the preventive intervention. Because these parameters vary according to the health event in question, timeliness must be interpreted from the stand- point of the user. Recognition of an epidemic after it has run its course is of little immediate use for disease con- trol, although the results of an investigation of such an outbreak may be useful in future control efforts (e.g. recognition of the role of cooling towers in the spread of Legionnaires' disease (35)). Timeliness is particularly important for acute diseases that may occur in epidemic form. An epidemic of salmonellosis due to exposure to a contaminated commercial food product needs to be detected quickly and investigated rapidly to prevent fur- ther illness and possibly deaths (36). The surveillance of cancer, on the other hand, may not require as rapid a response although identification of particularly virulent kinds of carcinogen should be accomplished as soon as is feasible, so as to interrupt the exposure process. Con- sequently, data are typically reported on an annual basis which is sufficiently timely for designing and implement- ing intervention strategies. In a 1982 CDC survey of state epidemiologists, the re- spondents cited lack of timeliness as a major deficiency in national surveillance systems. A study of national Shighella surveillance data indicated that the typical case of recognized shigellosis is brought to the attention of local health officials 11 days after onset of symptoms-a time sufficient for the occurrence of secondary and ter- tiary transmission to have already occurred (13). Such delays are common in infectious disease surveillance systems and, as a result, have prompted efforts to improve the timeliness of disease reporting (8, 10, 16). In two controlled studies of disease surveillance strategies for four acute infectious diseases, active, health-depart- ment-initiated surveillance was found not to improve the timeliness of disease reporting (8, 10). In fact, in one of those studies, reports tended to be more rapidly re- ceived from physicians passively reporting to the local health department than from active, health-department- initiated surveillance (10). The results of a 1980 survey of state epidemiologists emphasized the increasing interest of health officials in the use of computers for the collation and analysis of surveillance data (37). The subsequent development and use of computer-linked telecommunication net- works has decreased the time of data turnaround and enabled more complete analysis of reports (38). Within states, computers have been used to link local and state health departments (39). In France, a national system for the reporting of selected infectious diseases has been - 14 - formed based on sentinel physician practices that are linked by computer (40). It remains to be documented whether computer-based reporting systems will lead to more rapid and effective interventions. The existence of a recognized surveillance system indi- cates to a community the interest by the health depart- ment in certain health events and may lead to more rapid reporting. Providers as well as the public can use alter- native reporting channels, such as the telephone, that would not be used in the absence of a recognized sys- tem. Simplicity Simplicity should be a guiding principle for epidemiologi- cal surveillance. Simple systems are easy to understand and implement, cost less than complex systems, and provide flexibility. At the same time, surveillance sys- tems should not be so simple that they provide data that are not useful or may even be misleading. The impact that an increase in the complexity of a surveillance sys- tem would have on effective use of the system must be weighed against its increased cost. In a voluntary sys- tem, increased reporting burden might have a deleter- ious effect on the level of cooperation and productivity of those who report data. If the addition of information to a surveillance form compromises data quality or causes delays in data collection, the public health value of that system will diminish. Before asking for additional infor- mation, the impact of this added burden on these health departments should first be assessed in terms of data quality and reporter acceptance (see below). Flexibility Flexibility is a measure of the ability of a surveillance system to be easily adapted to new reporting needs in response to changes in the nature or the importance of the health event, the population monitored, or the avail- able resources. When penicillinase-producing Neisseria gonorrhoeae (PPNG) was introduced into the United States in 1976, this new strain of bacteria was detected by the state-based system for the surveillance of gonor- rhoea (41). While laboratory methods had to be adapted to isolate the new organism, the same state-based epi- demiological system previously established for gonor- rhoea surveillance was used to monitor the spread of the disease in the United States, to direct prevention and control programmes and to assess the impact of inter- vention procedures. This flexibility is a desirable feature of a surveillance system and is best assessed as new health problems emerge or alternative intervention strat- egies are adopted. The flexibility of a surveillance system can be assessed by the additional costs involved in modifying the system in some way. For example, a flexi- ble system for homicide surveillance should be adapta- ble to both rural and urban settings. for hand guns, sharp instruments and other weapons, and for large and small health departments. Flexibility can also be observed at another level. A sur- veillance system that can be used for monitoring new or emerging problems can be seen as flexible. The notifi- able disease-reporting system maintained by state health departments, for example, has frequently been expanded to monitor new diseases such as toxic-shock syndrome, AIDS and silicosis. Acceptability Acceptability is measured by the willingness of persons conducting surveillance and those providing data to gen- erate accurate, consistent and timely data. The accepta- bility of a particular system-especially one that is volun- tary-is dependent upon the perceived public health importance of the health event under surveillance, recog- nition of the individual's contribution to the system as it relates to control and prevention, and the time burden relative to available time. Surveillance methods must also be acceptable to those who provide the data. For example, as ill and well persons are asked for increasing amounts of information about their health status and lifestyle, the methods of data collection must ensure confidentiality while providing the data necessary for programme planning and evaluation. Even very sensitive data can be obtained for surveillance if questions are asked properly and data are not misused (42). In this context, acceptability is measured by the proportion who refuse to participate. The individuals working at each step in the surveillance system must be willing to collect and handle the relevant data in a prescribed manner. As new systems are devel- oped, the burden on data handlers must be ascertained and the impact of modifications in surveillance must be taken into account. The quantitative assessment of acceptability of a sur- veillance system has never been carefully conducted. Two 1980 national surveys of local health departments regarding the existing surveillance systems for measles and viral hepatitis found that both systems were accept- able to the staff of local health departments (97% and 96%, respectively, would continue routine reporting of these diseases) (18, 19), but this is only an indirect meas- ure of acceptability. Because refusal to participate and incompleteness are not sufficient evidence of the unac- ceptability of a surveillance system, more careful evalu- ation of this attribute should be developed. Discussion This article describes an approach to the evaluation of systems of epidemiological surveillance. The primary question to be addressed in the assessment of a surveil- lance system is whether or not the information produced by the system is useful. Does the system contribute to understanding a public health problem or prompt action that leads to the reduction of morbidity and mortality or the promotion of health? If not, is the health event under surveillance of sufficient importance to warrant a more effective surveillance system? If the system is useful, can it be improved or maintained at less expense? In either event, the quality of epidemiological surveillance systems can be assessed using the evaluation criteria based on seven attributes of surveillance systems for- mulated in this article. CDC is in the process of making this method operational so as to permit optimal manage- ment of public health activities at the local. state and federal levels. The attributes of surveillance discussed in this article are interdependent, and the improvement of one may im- prove or compromise another. Increasing the sensitivity of a system to detect a greater proportion of a given health event in a population may also improve represen- tativeness and usefulness yet lead to greater cost, lower specificity and more false-positive events. With some conditions such as influenza, investigators will use multi- ple sources of data in a surveillance system, some with high sensitivity (e.g. morbidity reports) and others with increased specificity (e.g. laboratory data). Similarly, efforts to increase timeliness may lead to increased cost and a loss of specificity as more resources are expended and incomplete, less accurate diagnostic information is collected. The incidence of a health event also affects the Rapp. trimest. statist. sanit. mond .. 41 ( 1988) - 15 - interaction of sensitivity, specificity and timeliness of surveillance activities. For example, the surveillance of low-incidence health events often requires significant resources to increase sensitivity and timeliness, a phe- nomenon currently illustrated by efforts to control mea- sles as part of the Measles Elimination Program (29). Some aspects of evaluation are not addressed in this article. The proposed evaluation of both sensitivity and representativeness, for example, does not address the epidemiology of undiagnosed cases or problems asso- ciated with detection bias. A controversy arose around the importance of diagnostic and reporting biases inher- ent in the surveillance of toxic-shock syndrome that could lead both to unwarranted conclusions about the epidemiology of that health problem and to differences in interpretation among investigators (43, 44). In addition, changes in representativeness or sensitivity over time can result in misinterpretation of the data. For example, if reports of asbestosis increase because of increased availability and diagnostic facilities in selected industries, this may be a result of the reporting change rather than any changes in the actual occurrence or distribution of the disease in the population. Deficiencies detected in the evaluation of a surveillance system may relate to any part of the surveillance pro- cess-collection, analysis, dissemination or application of results to prevention. For example, the validity and reliability of surveillance reports are serious concerns for anyone using surveillance data. Quality control typically takes the form of review of coding accuracy and com- pleteness of information on surveillance forms and is conducted periodically by health agencies. Follow-back to source data is a less common practice. While well- financed data-collection activities that have been used for surveillance such as the Surveillance, Evaluation, and End Results Registry of the National Cancer Institute have rather sophisticated methods of quality control. other sources of routine surveillance are less rigor- ous (8, 45). Deficiencies in quality control within a surveillance sys- tem may adversely affect its effectiveness and efficiency as reflected in the measures of the usefulness, cost and quality of such systems. Upon detecting problems, one can look at data analysis, dissemination or application to ascertain precisely at what point improvements in the system can be effected most efficiently. Assessment of both ongoing and developing systems of epidemiological surveillance will help to make them more efficient and more effective. The public health commu- nity should continue to develop appropriate methods for the evaluation of surveillance, and individuals working in public health programmes at the national, state and local levels should be involved in the ongoing assessment of their surveillance activities. SUMMARY Epidemiological surveillance is the systematic collection, analysis and dissemination of health data for the plan- ning, implementation and evaluation of public health pro- grammes. Established surveillance systems should be regularly reviewed on the basis of explicit criteria of use- fulness, cost and quality; systems should be modified as a result of such review. Attributes of quality include: (i) sensitivity, (ii) specificity, (iii) representativeness, (iv) timeliness, (v) simplicity, (vi) flexibility and (vii) ac- ceptability. To date, evaluation of surveillance systems has been limited in scope and content. The evaluation method proposed in this article offers an organized approach to the evaluation of epidemiological surveil- lance systems. The usefulness of a surveillance system is measured by whether it leads to prevention or control or a better understanding of adverse health events. The measure can be qualitative, in terms of the subjective views of those using the system, or quantitative in terms of the impact of surveillance data on policies, interventions or the occurrence of a health event. The cost of a system includes indirect as well as direct costs, and should be measured in relation to the benefits obtained, such as reduction of medical-care expenses and of time lost from work. All elements of the system should be included in the cost: data collection, analysis and dissemination. The sensitivity of a surveillance system is its ability to detect health events (completeness of reporting). Its specificity is inversely proportional to the number of false positives it reports. Reports of a disease that do not meet the case definition are false positives, and may result in resources being wasted in investigating them. However, in circumstances where it is extremely impor- Wld hlth statist. quan .. 41 ( 1988) tant not to miss a single true case, a certain level of false positives may be acceptable. Representativeness can be measured by comparing sur- veillance data covering part of the population to either nationwide data, where available, or to random sample- survey data. A source may be representative for one particular disease or condition but not for another. Re- presentativeness involves such factors as age, sex, eth- nic group, socioeconomic status and residence. Time- liness involves not only the interval between the occur- rence of the event and the receipt of the report at the health agency, but also the time subsequently required for identifying a problem or epidemic and the initiation of control measures. Timeliness is relative to the event concerned; for example, for most infectious diseases, the response should be made in a matter of days, whereas for cancer surveillance annual reporting may be adequate. Simplicity in a system means it is easy to understand and implement, and is therefore usually relatively cheap and flexible. A flexible system is easily adapted by adding new notifiable diseases or conditions or extending it to additional population groups. However, care should be taken that the reporting burden is not thereby increased to an unacceptable level, leading to loss of data quality or timeliness. The acceptability of a system depends on the perceived public health importance of the event under surveillance, recognition of the contribution of indi- viduals to the system, and the time required to make the reports. The surveillance method must be acceptable not only to the collectors of the data, for the reasons just mentioned, but also to the providers (both ill and well persons) in terms of confidentiality and cultural sensitiv- ities. Thus, acceptability can be measured by the pro- portion of persons asked who actually complete a ques- tionnaire. - 16 - The attributes of surveillance discussed are interdepen- dent. increasing the sensitivity of a system to detect a greater proportion of a health event may improve repre- sentativeness and usefulness, but also increase the cost and lead to the reporting of more false positives. Para- doxically, the less frequent the event, the more expen- sive it may be to keep under surveillance. It is also necessary to bear in mind that changes in representa- tiveness or sensitivity can occur with time and lead to misinterpretation of the data, such as when improved diagnostic facilities lead to increased case reporting. Quality control of the system should go beyond spot checking of questionnaire completeness to periodic checking against the source data. Evaluation of surveil- lance systems is an essential prerequisite to improving their efficiency and effectiveness. RESUME Une methode d' evaluation des systemes de surveillance epidemiologique On entend par surveillance epidemiologique la collecte, !'analyse et la diffusion systematiques de donnees sani- taires pour la planification, I' execution et I' evaluation des programmes de sante publique. Les systemes de sur- veillance en vigueur doivent etre revus periodiquement en fonction de criteres precis en matiere d'utilite, de coOt et de qualite; les systemes doivent etre modifies si les resultats de cet examen le justifient. Les attributs relatifs a la qualite sont: i) la sensibilite; ii) la specificite, iii) la representativite, iv) l'opportunite, v) la simplicite, vi) la souplesse et vii) l'acceptabilite. Jusqu'a present !'eva- luation des systemes de surveillance a ete limitee quanta son ampleur et a son contenu. La methode proposee dans cet article offre une approche rationnelle pour eva- luer les systemes de surveillance epidemiologique. L' utilite d'un systeme de surveillance se determine par la mesure dans laquelle ii aboutit a une action de prevention ou de lutte ou permet de mieux comprendre les evene- ments sanitaires defavorables. Cette determination peut etre qualitative, en fonction de !'opinion subjective des usagers du systeme, ou quantitative en fonction de !'im- pact des donnees de surveillance sur les politiques, les interventions ou la survenue d'un evenement sanitaire. Le coat d'un systeme englobe les depenses indirectes aussi bien que directes et doit etre mesure au regard des avantages obtenus, tels que la reduction des depenses pour soins medicaux et l'absenteisme. Tous les ele- ments du systeme doivent etre inclus dans le coot: col- lecte, analyse et diffusion des donnees. On entend par sensibilite d'un systeme de surveillance son aptitude a deceler les evenements sanitaires (com- pletude de la notification). La specificite du systeme est inversement proportionnelle au nombre des evenements faussement positifs signales. Les notifications d'une maladie qui ne correspondent pas a la description des cas sont dites faussement positives et ii peut en resulter que l'enquete y afferente entraine un gaspillage. Nean- moins, lorsqu'il est extremement important de ne pas omettre un seul cas reel, un certain taux de notifications faussement positives peut etre acceptable. On peut mesurer la representativite d'un systeme en comparant les donnees de surveillance relatives a une partie de la population soit a des donnees concernant la totalite de celle-ci, si elles sont disponibles, soit aux donnees issues d'un sondage aleatoire. II se peut qu'une source de donnees soit representative de telle maladie ou affection, mais non de telle autre. La representativite fait entrer en ligne de compte des facteurs tels que rage, le sexe, l'origine ethnique, la situation socio-economique et le lieu de residence. La notion d' opportunite met en jeu non seulement l'intervalle entre la survenue de I' evene- ment et la reception de la notification par r etablissement sanitaire, mais aussi le delai ensuite necessaire pour identifier un probleme ou une epidemie et engager des moyens de lutte. Le degre d'opportunite varie selon r evenement considere; par exemple, pour la plupart des maladies infectieuses ii taut reagir en r espace de quel- ques jours, tandis que pour la surveillance du cancer une notification annuelle peut etre suffisante. Par simplicite d'un systeme, ii taut entendre qu'il est facile a comprendre et a appliquer, de sorte qu'en gene- ral ii est relativement souple et peu onereux. Un systeme doue de souplesse peut etre facilement adapte par rad- dition de nouvelles maladies ou affections a declaration obligatoire ou par son extension a de nouveaux groupes de population. Toutefois, ii taut veiller ace que la charge que represente la notification n'atteigne pas de ce fait un niveau inacceptable, ce qui aurait pour effet de reduire la qualite ou l'opportunite des donnees. L' acceptabilite d'un systeme depend de !'importance attribuee a l'eve- nement sous surveillance du point de vue de la sante publique, de la reconnaissance de la contribution que les particuliers apportent au systeme, et du delai requis pour communiquer les notifications. La methode de surveil- lance doit etre acceptable non seulement pour les res- ponsables de la collecte des donnees, pour les raisons que l'on vient d'evoquer, mais aussi pour ceux qui com- muniquent les donnees (qu'il s'agisse de malades au de sujets bien portants). eu egard au caractere confidentiel des renseignements et aux sensibilites culturelles. L'ac- ceptabilite peut done se mesurer par la proportion des personnes interrogees qui ant effectivement complete un questionnaire. II existe une interdependance entre ces attributs de la surveillance. Si l'on augmente la sensibilite d'un systeme afin de deceler une plus forte proportion d'un evenement sanitaire, cela peut ameliorer la representativite et l'utili- te, mais cela peut aussi accroitre le coot et le nombre des notifications faussement positives. Si paradoxal que cela puisse paraitre, mains un evenement est frequent, plus son maintien sous surveillance se revele coOteux. De meme, ii ne taut pas perdre de vue que la representativite au la sensibilite peuvent evoluer a la longue, d'ou une interpretation erronee des donnees, par exemple quand !'amelioration des moyens diagnostiques entraine un accroissement du nombre des cas notifies. Le controle de la qualite d'un systeme doit aller au-dela d'une verifi- cation ponctuelle de la completude des questionnaires et comprendre une verification periodique au regard des donnees d'origine. L'evaluation des systemes de sur- veillance est une condition prealable essentielle pour en ameliorer l'efficience et l'efficacite. Rapp. trimest. statist. sanit. mond., 41 (1988) - 17 - REFERENCES - REFERENCES 1. LANGMUIR. A. D. The surveillance of communicable diseases of national importance. New England jour- nal of medicine, 268: 182-192 (1963). 2. FARR. W. Tenth annual report of the Registrar Gen- eral. London, HMSO, 1847. 3. LANGMUIR. A. D. William Farr: founder of modern concepts of surveillance. International journal of epidemiology, 5: 13-18 (1976). 4. THACKER. S. B. ET AL. The surveillance of infectious diseases. Journal of the American Medical Associa- tion, 249: 1181-1185 (1983). 5. CENTERS FOR DISEASE CONTROL. Morbidity and mortal- ity weekly report (CDC surveillance summaries), 32 ( 1 SS) : February ( 1983). 6. MARIER. R. The reporting of communicable diseases. American journal of epidemiology, 105: 587-590 (1977). 7. KIMBALL. A. M. ET AL. Shigella surveillance in a large metropolitan area: assessment of a passive report- ing system. American journal of epidemiology, 70; 164-166 (1980). 8. VOGT. R. L. ET AL. Comparison of active and passive surveillance systems of primary care providers for hepatitis, measles, rubella and salmonellosis in Vermont. American journal of public health, 73: 795-797 (1983). 9. THACKER. S. B. ET AL. A controlled trial of disease surveillance strategies. American journal of pre- ventive medicine, 2: 345-350 (1986). 10. SONDIK. E. J. ET AL. 1985 annual cancer statistics review. Bethesda, Maryland, Department of Health and Human Services, 1986. (National Institutes of Health publication no. 86-2789). 11. SHAW. G. M. ET AL. Characteristics of hazardous material spills from reporting systems in California. American journal of public health, 76: 540-543 (1986). 12. KIRCHER. T. ET AL. The autopsy as a measure of accu- racy of the death certificate. New England journal of medicine, 313: 1263-1269 (1985). 13. ROSENBERG. M. L. Shigella surveillance in the United States, 1975. Journal of infectious diseases, 136: 458-459 (1977). 14. EISENBERG, M. & WIESNER P. Reporting and treating gonorrhoea: results of a statewide survey in Alaska. Journal of the venereal disease association, 3: 79-83 (1976). 15. WEISSMAN,J. ET AL. Impact in the United States of the Shiga dysentery pandemic of Central America and Mexico: a review of surveillance data through 1972. Journal of infectious diseases, 129: 218-223 (1974). 16. LEVY, B. ET AL. Intensive hepatitis surveillance in Minnesota: methods and results. American journal of epidemiology, 105: 127-134 (1977). 17. VONALLMEN, S. D. Summer mortality surveillance from selected city and county medical examiners. Morbidity and mortality weekly report (CDC Surveil- lance summaries), 32 ( 1 SS): February ( 1983). 18. CENTERS FOR DISEASE CONTROL. Survey of measles sur- veillance activities in state and local health depart- ments. Morbidity and mortality weekly report, 29 (160): 165-166 (1980). 19. CENTERS FOR DISEASE CONTROL. Survey of viral hepati- tis surveillance activities in state and local health departments. Morbidity and mortality weekly re- port, 30 (164): 169-170 (1981). Wld hlth statist. quan., 41 ( 19881 20. THACKER. S. B. ET AL. Health care decision making in Southern County. Journal of community health, 3: 347-356 (1978). 21. DEAN.A. G. Measuring loss of life, health and income due to disease and injury. Public health reports, 97: 39-47 (1982). 22. COLEMAN P. & SANDERSON L. Surveillance of occupa- tional injuries treated in hospital emergency rooms-United States, 1982. Morbidity and mortality weekly report (CDC surveillance summar- ies), 32 (2SS): 31SS-37SS (1983). 23. BERKELMAN, R. L. ET AL. A surveillance system for alcohol- and drug-related fatal injuries. American journal of preventive medicine, 1: 21-28 (1985). 24. CENTERS FOR DISEASE CONTROL. Premature death- United States. Morbidity and mortality weekly re- port, 32: 118-119 (1983). 25. NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION. Fatal Accident Reporting System. Washigton, D.C., National Highway Traffic Safety Administration, 1984. 26. CENTERS FOR DISEASE CONTROL. Project graduation- Maine. Morbidity and mortality weekly report, 34: 233-235 (1985). 27. HINDS. M. ET AL. Benefit-cost analysis of active sur- veillance of primary care physicians for hepatitis A. American journal of public health, 75: 176-177 (1985). 28. BARKER, w. & MULLOOLY J. Underestimation of the role of pneumonia and influenza in causing excess mortality. American journal of public health, 71: 643-645 (1982). 29. HINMAN. A. ET AL. Progress in measles elimination. Journal of the American Medical Association, 24 7 : 1592-1595 ( 1982). 30. FoEGE. W. ET AL. Smallpox eradication in West and Central Africa. Bulletin of the World Health Organi- zation, 52 (2): 209-222 (1975). FOEGE. W. ET AL. Eradication de la variole en Afrique occidentale et centrale [resume]. Bulletin de /'Organ- isation mondiale de la Sante, 52 (2): 221 ( 1975). 31. CHOI, K. & THACKER, S. B. An evaluation of influenza mortality surveillance, 1962-1979.11. Percentage of pneumonia and influenza deaths as an indication of influenza activity. American journal of epidemi- ology, 113: 227-235 (1981). 32. CENTERS FOR D(SEASE CONTROL. Pseudo outbreak of hepatitis A-Louisiana. Morbidity and mortality weekly report, 28: 473-474 (1979). 33. EDMONDS. L. ET AL. Congenital malformations surveil- lance: two American systems. International journal of epidemiology, 10: 24 7-252 ( 1981). 34. SCHOTTENFELD. D. & FRAUMENT. J. Cancer epi- demiology and prevention. Philadelphia, W. G. Saunders, 1982. 35. BROOME. C. V. Epidemiologic assessment of meth- ods of transmission of legionellosis. Zentralblatt far bakteriologie, mikrobiologie und hygiene 1 ABT Originale, 255: 52-57 (1983). 36. CENTERS FOR DISEASE CONTROL. Listeriosis outbreak associated with Mexican-style cheese-California. Morbidity and mortality weekly report, 34: 357- 359 (1985). 37. CENTERS FOR DISEASE CONTROL. National surveillance survey. Morbidity and mortality weekly report, 29: 105-106 (1980). - 18 - 38. GRAITCER, P. & BURTON, A. H. The epidemiologic surveillance project: report of the pilot phase. American journal of preventive medicine, 1987 (in press). 39. GRAITCER, P. & THACKER. s. The French connection (editorial). American journal of public health, 76: 1285-1286 (1986). 40. V ALLERON. A. ET AL Computer network for the sur- veillance of communicable diseases: the French experiment. American journal of public health, 76: 1289-1292 (1986). 4 1 . CENTERS FOR DISEASE CONTROL. Penicillinase-produc- ing Neisseria gonorrhoeae. Morbidity and mortality weekly report, 25: 261 (1976). 42. SHANDS, K. ET AL Toxic shock syndrome: case-con- trol studies at the Centers for Disease Control. Annals of internal medicine, 96: 895-898 ( 1982). 43. TODD, J. ET AL Toxic shock syndrome, II. Estimated occurrence in Colorado as influenced by case ascer- tainment methods. American journal of epidemi- ology, 122: 857-867 (1985). 44. REINGOLD. A. L. On the proposed screening definition for toxic shock syndrome by Todd et al. American journal of epidemiology, 122: 918-919 ( 1985). 45. HORM. J. ET AL SEER Program: cancer incidence and mortality in the United States, 19 73-1981. Bethes- da, Maryland, Department of Health and Human Ser- vices, 1984. (National Institutes of Health publica- tion no. 85-1837). Rapp. trimast. statist. sanit. mond., 41 (1988) - 19 - LOCAL AREA MONITORING (LAM) Thomas D. Kirscha A countrywide disease-surveillance system is an impor- tant part of any national health programme. The system provides essential information for planning program- mes, evaluating their successes and failures, and identi- fying outbreaks of infectious diseases so that interven- tions can prevent further spread. This type of informa- tion is also needed by international organizations for their own planning and evaluation. However, such large data bases are often incomplete and subject to long reporting delays (1). More importantly, the incomplete- ness itself is inconsistent, making trend analysis very difficult. Within the World Health Organization, the Expanded Programme on Immunization (EPI) has a routine surveil- lance system in which each Member country reports its cases of the EPI target diseases (tuberculosis, diphthe- ria, pertussis, tetanus, neonatal tetanus, poliomyelitis and measles) through the Regional Offices. This routine system has not been accurate or sensitive enough to demonstrate the impact of the programme on the inci- dence of the target diseases (2). Fig. 1 shows the repor- • Medical Officer, Expanded Programme on Immunization, World Health Organization, Geneva. b The Expanded Programme on Immunization. A proposal for local area monitoring. The EPI Global Advisory Group Meeting, Alexandria, 21-25 October 1984. (Document EPI/GAG/84/WP.8, 19851. ted global incidence of measles, tetanus and poliomye- litis for the years 1974-1986. The incidence ofthe disea- ses appears constant until the past few years where a downward trend is noted. However, previous expe- rience suggests that this downward trend is largely a result of underreporting due to delayed reports, not from a real reduction in the cases of disease reported. Thus, late reports tend to increase the totals to pre-1982 levels, which are essentially flat curves. It appears from the graph that the EPI has had only limited impact on the incidence of the target diseases, but at country and local levels the impact of immunizations has been demonstrated repeatedly. The existing EPI surveil- lance system is simply not sensitive or accurate enough to demonstrate these changes. Within the countries themselves the ability of a single routine surveillance system to monitor programme im- pact and disease incidence varies greatly. Attempts have been made in many nations to strengthen the rou- tine reporting system and supplement the data with reporting from sentinel sites. It was felt that the benefits of sentinel reporting could be applied on an international scale to provide additional information for monitoring the global trends of infectious diseases. b With this goal in mind the EPI started the Local Area Monitoring Project (LAM) to supplement the routine disease-reporting sys- tem with sentinel-site reporting. FIG. 1 REPORTED GLOBAL INCIDENCE OF MEASLES, TETANUS AND POLIOMYELITIS (PER 100000 POPULATION), 1974-1986 INCIDENCE MONDIALE NOTIFIEE POUR LA ROUGEOLE, LE TETANOS ET LA POLIOMYELITE (POUR 100 OOO HABITANTS), 1974-1986 100 .. i 80 :a 60 .! § : 8 § ~ 8. I 0.1 j 0.6 0.4 0.3 -------...... ___ _..__. .....,_________ Measles - Rougeole -----, -- -- '\\ "--~------..___..., _________ .... 1:tanus -:;::,nos -·-·-- ........... ,__... __ ___.._._ ........ ·-· """-• ..__:oliomyelitis - Poliomy61ite .......... ____ .,,,,,.,. 0.2.__.,___.....__-L.,---,L----''----,-:':,-:---,..,,,.,..-~--="=,:------e,:'=---:..,,,.,..-=,---="-c--' ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Year - Ann6e Wld hlth statist. quan., 41 ( 1988) 20 - The Local Area Monitoring Project Data requirements The primary goal of the LAM project is to provide disea- se-incidence data of sufficient quality to evaluate more fully the global impact of the EPI on the six target disea- ses. c Data required for this include the morbidity of the target disease and background information on popula- tion and the history and coverage levels of the local EPI programmes. The population statistics are necessary to calculate incidence rates so that the data from different sites are comparable. The programme and coverage information is used to assess the impact of individual EPI programmes on disease trends. To evaluate the impact of the EPI it is necessary to have baseline information on the target diseases prior to the start of the programme. This makes the availability of retrospective data an essential part of the LAM project and a prerequisite for sentinel-site selection. In many countries a consistent disease-surveillance system has existed only in major cities in the past. In others disease- surveillance systems have only been developed recent- ly. and retrospective health records are only available at large, well-established hospitals. Because of this, and the growing importance of urban centres in health care, it was decided to use the major city of the 25 largest developing countries to act as the sentinel sites. These 25 countries account for an estimated 85 % of all births in the developing world. The total population of their prin- cipal cities of over 115 million is exceeded only by the population of the four largest developing countries in the world. Table 7 lists these sentinel cities and their most recent estimated populations. The listed populations are c The Expanded Programme on Immunization. Local area monitoring. The EPI Global Advisory Group Meeting, New Delhi, 13-17 October 1986. (Document EPI/GAG/86/WP.9, 1987). d Dondero, T. EPI target disease surveillance and disease reduction targets. (Document EPI/GEN/84.6, 1984). most commonly for the city centre and grossly underes- timate the true population of the urban and peri-urban metropolis. As an example of this, the listed population for Manila is 1.63 million, but the actual estimated popu- lation of metropolitan Manila for 1985 is almost 7 million people. Citywide disease-incidence statistics from municipal or governmental health authorities are the primary source of data for the LAM project. The data are screened to assess the completeness and consistency of reporting practices and to validate the number of reported cases in comparison to estimated figures. In cities where munici- pal data are unavailable or do not provide a clear picture of disease. trends, discussions are held with local authorities to identify appropriate health-care facilities to use as sentinel reporting sites for each of the target diseases. Sentinel-site selection The use of hospitals as sentinel sites is common and its advantages and disadvantages are widely discussed (3). The advantages for the LAM project include: the exis- tence of retrospective data; the often consistent quality of the record system; the existence of more detailed records; and improved case diagnosis. The drawbacks arise from questions of whether the data are represen- tative, since only a small portion of the total cases will actually seek hospital treatment. The other difficulty is in determining the population served by the hospital. The impact of the potential problems of sentinel-site reporting can be minimized by careful selection of the sentinel hospitals. d The sentinel sites are chosen to be the most representative of the individual diseases and may require the use of multiple sites to cover all the EPI target diseases. The most common first choice for a reporting site for the EPI would be a city's infectious disease hospital, or even more appropriately a paediatric infectious disease hospital. An example of this comes TABLE 1. THE 25 LOCAL AREA MONITORING (LAM) CITIES TABLEAU 1. LES 25 VILLES INCLUSES DANS LE SYSTl:ME DE SURVEILLANCE LOCALE (LAM) WHO Region Country Population LAM city Population R~gion OMS Pays (millions) Ville LAM (millions) AFR Ethiopia - Ethiopie 36 Addis-Ababa - Addis-Abeba 1.48 AFR Algeria - Algerie 22 Alger 1.74 AFR United Republic of Tanzania - Dar Es Salaam 0.76 Republique-Unie de Tanzanie 22 AFR Zaire - Zaire 33 Kinshasa 2.24 AFR Nigeria - Nigeria 95 Lagos 1.06 AFR Kenya 20 Nairobi 1.05 AMR Columbia - Colombie 29 Bogota 2.86 AMR Argentina - Argentine 31 Buenos Aires 10.79 AMR Mexico - Mexique 79 Mexico City - Mexico 14.75 AMR Brazil - Brasil 135 Sao Paulo 7.03 EMR Egypt - Egypte 47 Cairo - Le Caire 5.07 EMR Morocco - Maroc 24 Casablanca 2.41 EMR Pakistan 96 Karachi 5.11 EMR Sudan - Soudan 22 Khartoum 0.56 EMR Iran, Islamic Rep. of /Rep. islamique d' 45 Tehran - Teheran 4.59 EUR Turkey - Turquie 49 Istanbul 2.95 SEAR Thailand - Thailande 51 Bangkok 4.71 SEAR India - lnde 761 Bombay 9.17 SEAR Bangladesh 99 Dhaka 3.46 SEAR Indonesia - lndonesie 163 Jakarta - Djakarta 6.51 SEAR Burma - Birmanie 39 Rangoon 2.28 WPR Viet Nam 60 Ho Chi Min City - Ho Chi Min Ville 1.83 WPR Philippines 55 Manila - Manille 1.63 WPR Rep. of Korea - Rep. de Coree 41 Seoul - Seoul 8.36 WPR China - Chine 1 063 Shanghai 11.30 Rapp. trimest. statist. sanit. mond., 41 (1988) - 21 - from Manila (Philippines) where there is a single hospital to which all cases of infectious disease are referred, and have been for over 100 years. Other logical choices are paediatric hospitals and tuberculosis hospitals or specia- lity hospitals such as rehabilitation centres for poliomye- litis. Istanbul is also an excellent example of the ability of a single, well-chosen sentinel site to reflect the disease incidence of the whole city. The Istanbul Health Office has a well-developed citywide surveillance system that collects data from 169 sources. These sources include inpatient statistics from 27 hospitals, as well as the cases treated at 62 primary health centres, 20 maternal and child health clinics and 60 "other" health sites. Reporting completeness is very high and compiled muni- cipal figures are available within four to six weeks. Within Istanbul there exists a large, university-based paediatric hospital that treats a large percentage of chil- dren's infectious diseases in the city. To evaluate the hospital for potential use as a sentinel site, a review of inpatient and outpatient records since 1980 was under- taken. Fig. 2 compares the total reported cases of meas- les from Istanbul to the cases seen at the Children's Hospital from 1980 to 1986. The trends of each of the sources closely reflect one another, with peaks occur- ring in two-year cycles. These matching trends suggest that the hospital is an excellent sentinel site for measles, and would be particularly useful as an early indicator of measles epidemics by following outpatient measles cases. In most cities a single hospital would not be able to reflect accurately the incidence of all of the target diseases, and so multiple sites have been chosen. The referral patterns within a city will determine where spe- cific diseases are sent for treatment, depending on the specialities of individual hospitals. In Jakarta, for instan- ce, records from seven hospitals give a more accurate picture of disease incidence in the city and assure that each of the target diseases is included in the reporting. In Rangoon there are two hospitals which specialize in dif- ferent infectious diseases, while a third treats only tuber- culosis cases. These three hospitals, combined with a physical rehabilitation centre for poliomyelitis, are being used as sentinel sites for the entire city. Data collection Information from each LAM city was originally sollicited by written request through the WHO Regional Offices, which in turn contacted the individual countries. The data were not readily available in the majority of the countries and it was necessary for national or local EPI staff to collect it. The amount of work necessary varied greatly between cities, as did the effort put into the collection. In general, much more effort has been required to compile accurate data than was originally anticipated. The selec- tion of the sentinel cities without considering the ability of the municipal system to report has led to a wide variety in the quality of the data being reported. Some cities have good surveillance systems that accurately reflect disease trends, but in many the system suffers FIG. 2 REPORTED QUARTERLY MEASLES INCIDENCE FROM ISTANBUL HEALTH OFFICE AND CHILDREN'S HOSPITAL, ISTANBUL, TURKEY, 1980-1986 RAPPORTS TRIMESTRIELS DE L'OFFICE DE LA SANTE D'ISTANBUL ET DE L'H6PITAL PEDIATRIQUE SUR L'INCIDENCE DE LA ROUGEOLE, ISTANBUL, TURQUIE, 1980-1986 2000.-------------------------------~1000 1800 1600 1400 1200 1000 BOO 600 400 200 Wld hlth statist. quart., 41 ( 1988) Reponed city data in Istanbul Donn6es de la ville d'lstanbul Children's inpatient Hospitalisations .!I l'HOpital P'diatrique Children's outpatient Consultations extemes de l'HOpital p6diatrique Years/quaners -Ann6es/trimestres 900 BOO 700 600 500 400 300 200 100 0 tti/10171010 - 22 - from the same problems of incomplete, inaccurate and delayed reporting as any large surveillance system. In two of the LAM cities retrospective records were not available from either municipal or hospital sources. The wide variety of surveillance systems and informa- tion available, and the amount of work needed to gather the data, require active supervision to ensure the pro- ject's success. Site visits by WHO staff from Regional Offices or headquarters are useful to assist municipal authorities in choosing good sentinel sites and gathering comparable data. Currently, reports have been received from all but two of the cities, but only 12 have retro- spective and population data of sufficient quality for full analysis. Not all cities or hospitals reported data on all of the EPI target diseases. Table 2 shows the percentage of re- ports received for each disease. While data are available from 80% of the cities, they remain very incomplete for many of them. Two of the largest areas of missing data are those on population and estimates of coverage. Measles is the most widely reported of the diseases (80%), but in some ofthe countries in the LAM project it has only become reportable recently. Retrospective data are therefore often not available or accurate prior to 1980. Poliomyelitis is the second most widely reported disease (76% of the cities reporting data) and appears to have the most accurate retrospective records in most of the cities. Neonatal tetanus is still not a reportable disease in many countries; only 28% of the cities had information on it. The BCG vaccine has its greatest effect on the childhood forms of the disease, but tuberculosis is not usually reported separately as a childhood disease or in its miliary or meningeal forms. Quality assessment In order to assess the quality of the data and to choose the best sentinel site, background information on the reporting system is important. The source of the reports, changes in the number of units reporting or in informa- tion reported, improvements in the system, reporting completeness and time lag are important in under- standing a municipal reporting system. At the hospital level a review of the medical records, the population and referral base, and the inpatient and outpatient infectious disease cases and bed availability are useful to judge the continuity and quality of the records and the appropria- teness of the hospital as a sentinel site. Further studies of reporting completeness can be per- formed by comparing reported figures to known dis- ease rates from previous surveys, or to expected rates. It is also possible to compare rates between sentinel sites or between sentinel sites and municipal data as well as to the countrywide figures. Estimating the denominator Analysis of data so diverse in content, quality and source is very difficult. The first step in standardizing figures on cases of infectious diseases is to calculate incidence rates. For data from a municipal data base this simply requires division by the total city population. For most sentinel sites it is difficult to calculate rates because the size of the population served by the hospital is not known. Some large referral hospitals serve the whole city and the total population may be used to calculate rates, but the majority of the hospitals serve only a portion of the city, and using the total population as a denominator is only a crude method of compensating for population growth. Percentage change from baseline Because the incidence rate of the diseases varies greatly between cities, it is not possible to simply average the rates for a composite trend. This gives too much weight to those cities with higher disease rates. In order to compensate for this and to give each city equal weight in the final analysis, the average of each city's percentage change from baseline is used. The baseline is the ave- rage of the incidence of each disease from 1974 to 1978, prior to the start of the EPI programme. From this baseline the percentage of increase or decrease for each year, by disease, is calculated. Global disease trends Table 3 shows the percentage change from an average baseline in the incidence of the six target diseases for the LAM cities reporting thus far. Fig. 3 is a graph of these numbers for 12 cities for measles and poliomyelitis, and for 9 cities for total tetanus cases. There has been a steady decrease in reported poliomyelitis, with a 62% reduction in incidence when compared with the average reported incidence over the period 19 7 4-19 7 8. The reductions in measles and tetanus have occurred only later, and have not been as great (39% and 32% in 1985, respectively). The trends for all of the diseases (Table 3) are similar to what would be expected from previous studies of the impact of immunizations. This is further confirmed by disease trends from individual cities. Polio- myelitis and diphtheria have both decreased steadily and shown a large impact, while the change in the tubercu- losis rate has been inconsistent over the years. The latter is expected because the majority of cases reported are respiratory tuberculosis in unimmunized adults. The TABLE 2. PERCENTAGE OF CITIES REPORTING ON LOCAL AREA MONITORING (LAM) INDICATORS AND THE SIX TARGET DISEASES TABLEAU 2. POURCENTAGE DES VILLES SOUMETTANT DES NOTIFICATIONS EN FONCTION DES INDICATEURS DU SYSTEME DE SURVEILLANCE LOCALE (LAM) ET DES SIX MALADIES CIBLES Measles - Rougeole .................. ·} Poliomyelitis - Poliomyelite . . . . . . . . . . . . . . . >75% Diphthe_ria - Diphterie ................. ·} Pertussis - Coqueluche . . . . . . . . . . . . . . . . . Tetanus - Tetanos .................. . 50-75% Neonatal te_tanus - Tetanos neonatal ........ ·} Tuberculosis - Tuberculose ............. . 25-50% Coverage estimate - Estimation de la couverture . . >50% Rapp. trimest. statist. sanit. mond .• 41 (1988) - 23 - TABLE 3. PERCENTAGE CHANGE IN DISEASE INCIDENCE CALCULATED FROM THE DATA OF LAM CITIES, 1974/78-1985 TABLEAU 3. VARIATION EN POURCENTAGE DE L'INCIDENCE DE LA MALADIE CALCULEE A PARTIR DES DONNEES POUR LES VILLES DU PROJET LAM, 1974/78-1985 1. Bangkok 5. Nairobi 9. Ho Chi Minh City/Ville 2. Tehran - Teheran 6. Manila - Manille 10. Mexico City - Mexico 3. Karachi 7. Istanbul 11. Bombay 4. Jakarta - Djakarta 8. Shanghai 12. Rangoon Total incidence Taux d'incidence totale Parcentage change from baseline - Variation en pourcentage par rapport aux donntles de base Year - Anntle Number of cities 1974· 1979 1980 1981 1982 1983 1984 1985 Nombre de villes 1978 Diphtheria - Diphterie . . . . . . . . . . . . . . . Pertussis - Coqueluche . . . . . . . . . . . . . . Tetanus (non-neonatal) - Tetanos (non neonatal) Neonatal tetanus - T etanos neonatal . Tetanus total - Total tetanos Poliomyelitis - Poliomyelite Measles - Rougeole . . . . Tuberculosis - Tuberculose . 11 10 5 7 9 12 12 7 decrease in the incidence of measles occurs later be- cause the vaccine was the last one to be adopted by the majority of the country programmes. Conclusions Preliminary analysis of the 12 cities with the best data suggests that the impact of the EPI on the incidence of the target diseases has been greater than previously 0 -29% -31% -43% -54% -54% -67% -59% 0 36% 3% -10% -23% -22% -44% -35% 0 -27% -21% -10% -27% -29% -31% -47% 0 -18% -18% -29% -38% -51% -57% -61% 0 -1% -13% 5% -5% -21% -39% -32% 0 -15% -27% -40% -48% -53% -60% -62% 0 -1%-11% 7%-23%-18%-28%-39% 0 -15% -2% -12% 0% -9% -20% -24% shown by the routine system. The LAM information is useful for global and regional analysis of programme impact, but for the countries themselves its utility may be even greater. It is hoped that the project will help to improve the country's surveillance system by encourag-· ing the use of sentinel reporting as a means of supple- menting the routine data. The information on the impact of the EPI may further increase political and public sup- port for the programme. The data will also be useful for FIG.3 MEALES, TETANUS, POLIOMYELITIS: PERCENTAGE CHANGE FROM BASELINE IN LOCAL AREA MONITORING (LAM) CITIES, 1979-1985 ROUGEOLE, TETANOS, POLIOMYELITE: CHANGEMENT EN POURCENTAGE PAR RAPPORT AUX DONNEES DE BASE DANS LES VILLES INCLUSES DANS LE SYSTiME DE SURVEILLANCE LOCALE (LAM), 1979-1985 0.3 0.2 0.1 .i 2 -0.1 .!-8 'ii!! .! • -0.2 &l ,1: .. -0.3 ., ~ g> Ii ..... ii f -0.4 &c . ., c" 0 5 fl~ - . Iii 8. 0.. c ! -0.6 '-0.7 .! u -0.8 -0.9 ·,., ·,. '· '·, -1 1974-1978 ·, ·"· ...... ............... 1979 Wld hlth statist. quart., 41 (1988) .............. , .... .... 1980 '·,. .... , ........... ................ 1981 ·--·-·-·-·-·-·-· ....... 1982 1983 Year - Anntle ......... Poliomyelitis ( 12 cities) •·-·- Poliomytllite (12 villes) ___ Measles (12 cities) Rougeole ( 12 villes) _ Tetanus (8 cities) Ttltanos (8 villes) ............... .............. ·,., ... ... ... .... .... ·,., 1984 1985 1986 - 24 - planning and evaluation at national level as well as to start the process of microplanning which becomes in- creasingly important as a programme improves. The final benefit of the project will be to focus attention on ever-expanding urban centres, whict:i will soon include the majority of the world's population. SUMMARY Routine surveillance of the incidence of vaccine-prevent- able diseases has not proved sensitive enough to de- monstrate the impact of the Expanded Programme on Immunization (EPI) in many countries. In order to docu- ment progress since the start of the EPI in 1979, data are needed for several years prior to that. In most devel- oping countries these can be found only in major cities or large hospitals. Therefore a system of sentinel surveil- lance, the Local Area Monitoring Project (LAM). is being set up in selected institutions in the major cities of the developing world. The goal is to include the major city of each of the 25 largest developing countries, with a total population of 115 million. These 25 countries together account for 85% of all births in the developing world. In some cases the city was selected because it had an excellent municipal reporting system. For example, the Istanbul Health Of- fice collects data from 169 hospitals, primary health centres, maternal and child health clinics and other insti- tutions, and provides compiled municipal figures within six weeks. The trend of measles cases seen at the Child- ren's Hospital exactly matches the trend for the city as a whole, indicating that for measles, at least, the Child- ren's Hospital is an excellent sentinel site representative of the whole city. Manila has a hospital to which all cases of infectious disease are routinely referred, which is also a good sentinel site. In Rangoon it has been necessary to survey four hospitals, and in Jakarta seven, to cover all the target diseases. By the first half of 1987. 12 years of retrospective data from 5-12 cities (depending on the disease) had been collected. Reporting was most complete for poliomy- elitis and measles (76-80% of cities reporting), least complete for tetanus and neonatal tetanus (20-28%). An attempt was made to assess the quality of the data from each sentinel site by reviewing the records for con- tinuity. and comparing the number of cases of infectious disease with those expected or those found from other surveys. If the site was a hospital, the size of the popu- lation served had to be calculated in order to compute incidence rates, or else the total city population was used as a proxy. In order to compensate for variations between cities in the incidence rates, and to give each city equal weight in the analysis, the average of each city's percentage change from baseline ( 197 4-1978) was used. Judging from this, for the cities concerned. there has been a 62% reduction in the incidence of reported polio- myelitis by 1985, a 61 % reduction for neonatal tetanus, 59% for diphtheria, 39% for measles, 35% for pertussis, and a decrease fluctuating between 0% and 24% for tuberculosis. Measles vaccination was added late to many country immunization programmes; therefore, the decrease in incidence began later than for the other dis- eases. BCG vaccine has its greatest effect on the severe childhood forms of tuberculosis, but the sentinel institu- tions do not usually report separately childhood, miliary or meningeal disease, hence the lack of a demonstrable trend. For the other target diseases, sentinel-site surveil~ lance is proving to be a useful method for measuring programme impact. RESUME Surveillance locale (LAM) La surveillance systematique de !'incidence des maladies evitables par la vaccination ne s' est pas revelee suffi- samment sensible pour mettre en evidence !'impact du Programme elargi de vaccination (PEV) dans beaucoup de pays. Pour pouvoir attester les progres accomplis depuis le demarrage du PEV en 1979, ii taut reunir des donnees pour plusieurs annees avant cette epoque. Dans la plupart des pays en developpement, on n'en trouve que pour les grandes villes ou les principaux hf>pi- taux. C'est pourquoi un systeme de surveillance par sen- tinelles (Local Area Monitoring Project-LAM) est ac- tuellement mis sur pied dans certains etablissements des grandes villes du monde en developpement. Le but est d'y inclure la ville principale de chacun des 25 pays en developpement les plus importants, soit une population totale de 115 millions d'habitants. Ensemble, ces 25 pays comptent 85% de toutes les naissances dans le monde en developpement. Dans certains cas, on a pu constater que la ville disposait d'un excellent sys- teme municipal de notification. C'est ainsi que le Bureau sanitaire d'lstanbul reunit des donnees provenant de 169 hf>pitaux, centres de soins de sante primaires, dis- pensaires de protection maternelle et infantile et autres etablissements et fournit une compilation des chiffres concernant la municipalite en l'espace de six semaines. La tendance pour les cas de rougeole observes a l'Hf>pi- tal pedriatrique correspond exactement a celle qu'on a constatee pour la ville dans son ensemble, ce qui indique que, pour la rougeole tout au mains, l'Hf>pital pedriatique est un excellent etablissement sentinelle, representatif de toute la ville. Manille possede un hf>pital sur lequel sont systematiquement aiguilles tous les cas de mala- dies infectieuses, de sorte qu'il constitue aussi un tres bon etablissement sentinelle. A Rangoon ii a fallu enqu~- ter dans quatre hf>pitaux et a Djakarta dans sept pour couvrir toutes les maladies cibles. A la mi-1987. des donnees retrospectives pour 12 ans provenant de 5-12 villes (selon la maladie consideree) avaient ete recueillies. C'est pour la poliomyelite et la rougeole que la notification etait la plus complete (76- 80% des villes notifiant les maladies), tandis que les renseignements les mains complets concernaient le te- tanos et le tetanos neonatal (20-28%). Rapp. trimest. statist. sanit. mond., 41 ( 1988) - 25 - On a cherche a evaluer la qualite des donnees provenant de chaque etablissement sentinelle en verifiant la conti- nuite des releves et en comparant le nombre des cas de maladies infectieuses avec le nombre prevu ou constate lors d'autres enqu~tes. Si l'etablissement etait un hopi- tal, pour calculer les taux d'incidence ii fallait calculer l'effectif de la population desservie, sinon on se basait, faute de mieux, sur la population totale de la ville. A fin de compenser les variations des taux d'incidence d'une ville a l'autre et pour que chaque ville beneficie d'une ponde- ration equivalente dans !'analyse, on a pris la moyenne du pourcentage de changement dans chaque ville par rapport aux donnees de base (1974-1978). A en juger d'apres les resultats, dans les villes conside- rees la reduction de !'incidence etait de 62% des 1985 pour la poliomyelite notifiee, de 61 % pour le tetanos neonatal, de 59% pour la diphterie, de 39% pour la rou- geole et de 35% pour la coqueluche, la diminution de !'incidence pour la tuberculose oscillant entre 0% et 24%. La vaccination antirougeoleuse n'a ete incluse que tardivement dans les programmes de vaccination de beaucoup de pays, de sorte que pour cette maladie !'in- cidence a commence a baisser plus tard que pour les autres. La vaccination par le BCG produit son meilleur effet sur les formes les plus graves de la tuberculose dans l'enfance, mais, en regle generale, les etablisse- ments sentinelles ne notifient pas separement la maladie pour l'enfance, la forme miliaire, ou la forme meningee, d'ou l'impossibilite de pouvoir mettre en evidence une tendance quelconque. Pour les autres maladies cibles, la surveillance par etablissements sentinelles se revele une methode utile pour mesurer l'impact du programme. REFERENCES - REFERENCES 1. THACKER. S. B. ET AL. The surveillance of infectious diseases. JAMA. 249: 1181-1185 (1983). 2. KEJA K. ET AL. Effectiveness of the Expanded Pro- gramme on Immunization. World health statistics quarterly, 39 (2): 161-170 ( 1986). Wld hlth statist. quan., 41 (1988) KEJA. K. ET AL. Efficacite du Programme elargi de vac- cination. Rapport trimestriel de statistiques sanitaires mondiales, 39 (2): 161-170 (1986). 3. BASU, R. N. Sentinel surveillance. Delhi, National Insti- tute of Communicable Diseases, 1985. - 26 - COMMUNITY-BASED HEALTH REPORTING Wolf Scotta This article discusses systematic data collection at the local level, the principal purpose of which is to supple- ment national-level information. Another purpose, to supply data for the use of the local population, is dis- cussed in the final section. The Development Monitoring Service at the Local Level (OMS) attempts to highlight a small and as far as possible representative sample of local areas for close analysis, and to do so systematically and continuously to obtain a picture of change over time. While the idea is based on the occasional ad hoe com- munity study, the distinction between it and the OMS is the latter's more consistent approach, including features such as relative representativeness and continuity. Health variables figure prominently, but they take their place within a wider range of data comprising other socioeconomic variables (e.g. income, education, hous- ing, water, sanitation, electricity), as well as the appro- priate economic and social structure. Use of a small area as the unit of analysis makes it possible to study the interrelationships of certain variables that are not readily captured in national surveys, in particular those with a geographic orientation. On the other hand, the sample of local areas is too small to give representative data at the national level. In this way national and local data com- plement each other. Background A pilot study to test the modalities of a OMS at the local level was set up by the United Nations Research Institute for Social Development (UNRISD) in the late 1970s in Kerala (India). The government of Indonesia, jointly with UNICEF, followed suit, as did the state government of Uttar Pradesh in India. The government of the southern region of the Sudan planned a similar activity at the insti- gation of UNICEF. A first phase which consisted of a regionwide survey of population and social infrastruc- ture was completed in Sudan in the early 1980s. Political events have since frustrated implementation of the prin- cipal phase. This article is concerned with the OMS in Kerala, where in spite of a financially-checkered career the structure of the scheme is most clearly seen and first results are available (1, 2). Within the OMS, 12 socio- economic observation areas were set up in 1978/79 by the Kerala Statistical Institute, with financial support from UNRISD. Work in nine of the areas lapsed after two years, but since 1986 the state government of Kerala has supported the scheme financially within its current five-year development plan. Altogether 15 areas are now covered. For three years the World Health Organi- zation financed a special study of factors associated with nutritional status as expressed by weight and height of children under 10 in three of the areas. • The author is a former Senior Research Officer. United Nations Research Institute for Social Development, Palais des Nations, Geneva. The views expressed here are his own and do not necessarily reflect those of the Institute. Structure of the DMS A sample of local areas is selected, as far as possible representative of varying local conditions (socio- economic observation areas). In each selected area data are collected from house- holds in respect of characteristics of households and individuals, from key respondents in respect of the area as a whole (on services, economic and social infrastructure, natural catastrophes likely to affect development, etc.). In addition, studies of specific problems are conducted from time to time in the same areas. The intention is to integrate data from these various sources in analysis and reporting. The system is continuous in the sense that data are collected each year so as to have a consistent record of change over time Paid local staff are used, subject to training, supervi- sion and control as regards data quality, in contrast to systems where interviewers are sent from the centre to the local areas for each survey. Where feasible, participation of the local community is obtained through full consultation with the local councils. The fullest possible coordination between users and producers of the data is sought. The following statistics have been collected in Kerala : • information about each area, collected from key re- spondents; • information by short individual interview from a sam- ple of about 2 OOO households per area, namely: household size, type of house, whether there is elec- tricity, kinds of sanitation and sources of drinking- water, number of days of illness during the week pre- ceding interview, births, deaths (including infant deaths during the previous year), education, religion, caste of head of household, household income; • for a subsample of about 200 households per area more detailed information is obtained (again by inter- view) on the demographic and socioeconomic charac- teristics of household members, possession of house- hold durables, livestock, land-holding, expenditure on major items of food during the previous week and on items such as clothing, medical and education ex- penses during the past year; • wage rates in selected occupations, obtained from key respondents; • special studies, for example surveys of weight, height and morbidity. Illustration of available data Data are now available on conditions in each area at a point in time and on changes overfive years. Emphasis in analysis has been on the pattern of interrelationships, on seeing the area as a whole. Examples are taken from three panchayats (the smallest rural administrative area in India) for which data have been collected continuously since 1978/79. The brief account that follows should be read in the context of overall conditions in Kerala, the Rapp. trimt1st. statist. sanit. mond .• 41 (1988) - 27 - significant features of which are the highest literacy and lowest mortality rates among states in India, in spite of only a moderate economic level by Indian standards. The relatively high social profile is common to the three areas, which nonetheless each have a unique set of char- acteristics. Community Ab is a fishing village whose inhabitants crowd together on the shore of the Indian Ocean in rela- tively unhygienic conditions (virtually no sanitary facil- ities, 50% drawing their drinking-water from polluted sources) and a large majority with incomes that are low even by Kerala's standards, no agricultural land and dependent on the vagaries of offshore fishing and a declining activity in rope making. On the other hand, communications with nearby towns are fairly good, mainline electricity is available and was used by about a quarter of the population. A primary health care centre and primary and secondary schools also exist. This situation contrasts with that of a highland pan- chayat (community B). Here land is relatively plentiful (for Kerala), incomes are higher, safe water more abundant. The area also benefits from a large government vegeta- ble farm with employment opportunities for both men and women. On the other hand until recently, because of relative inaccessibility, health services have been of poor quality and electricity unavailable. The third area examined here, community C, is again different in that it has ready access to the capital and its facilities, including health services (half an hour by bus at low fares). It is primarily an agricultural community with moderate land-holdings and incomes. Most households have safe water from their own shallow wells, about one-fifth have some kind of sanitary facility, as com- pared with 4-7% in the other two localities. The essential difference between the areas extends also to the change seen over a five-year period, although if the change continues along present lines the end result may well be greater similarity. In line with government policy the most backward of the areas in terms of income and hygienic facilities (the fishing village), benefited more than the others. Fishing was in part motorized, a govern- ment scheme provided employment on a protective sea wall, and even a tidal wave that caused severe damage to houses in the end favoured the local people since funds were attracted that were used to rebuild many houses in a better style. In contrast, incomes did not significantly change in the other two areas. However, the highland village for the first time received mainline elec- tricity for use by private consumers, while road com- munications have been greatly improved. Health condi- tions should be seen against this background. Three kinds of information have been obtained: (1) on infrastructure; (ii) on variables such as infant mortality and morbidity; and (iii) on variables relating to indi- viduals. The distinction is important because only the latter type provides distributional data to identify those most in need or for analytic purposes (with the individual as unit of analysis). Regrettably, health statistics are rarely of this type. b In order to protect the anonymity of the communities concerned, they are identified by initials only in the original report: TKA (community A); ALM (community B); and VPM (community C). c Primary health care centres in Kerala are the principal local health institutions, and are fairly generously equipped. d Only changes in fixed facilities were reported. Additional services (not reported upon) include the various preventive measures such as inoculation, prenatal or school health services. These should eventually be included in the monitoring. Wld hlth statist. quan .• 41 (1988) The first category, health-service infrastructure, was briefly referred to in previous paragaphs. Community C had no primary health care centre,c but the inhabitants made use of a centre just outside the panchayat area. In any case, the people in community C who could afford it sought medical treatment in Trivandrum, about half an hour away by bus. This was not a solution readily avail- able for people in community A and even less so in community B, for whom the nearest specialized services are at some considerable distance. However, both com- munities A and B had primary health care centres staffed by a doctor and other qualified medical personnel, as well as various other, partly private, medical facilities. The principal problems were inadequate maternity facil- ities and particularly lack of drugs. The primary health centre in community A initially had no water, though this had been installed by 1984. There were modest changes during the period.d Thus, in community Ca new government Ayurvedic dispensary was created in 1982. On the other hand, a private hos- pital with 15 beds and a full-time doctor closed down. The only change in community A, which has a homeo- pathic dispensary staffed by a doctor apart from its pri- mary health care centre, was the supply of piped water to the centre during the fourth round (1982/83). In com- munity B, the government dispensary was upgraded as a primary health care centre in 1979, with nominally 10 beds and improved staffing. However, no new building has been constructed so far and there has not yet been any inpatient treatment. A new government homeo- pathic dispensary was built in 1980, and the tribal Ayurvedic dispensary upgraded in 1983 to the status of tribal hospital with 10 beds. Expenditure on medica- ments at the primary health care centre, a perennial source of complaint, increased between 1978/79 and 1982 from 50 OOO to 130 OOO rupees, though much of this reflected the rising cost of drugs. Two variables were used within the second category: infant mortality and overall morbidity; weight and height of children under 10 were in the third category. As noted, the former two are area indicators in the sense that the data are accumulated for the area as a whole, and do not give meaningful results for any particular household, for which an infant death in a given year or a case of mor- bidity in a given week is a random event with low prob- ability. With a population of about 12 OOO (the size of the large sample) producing, at current levels of fertility in Kerala, about 260 births annually, with approximately 10 infant deaths on average, a figure which could easily be doubled or halved in any given year as a result of chance events. Table 1 shows infant mortality rates. Because of a change in method (at first only half of the panchayat area was surveyed, after the second round (1980/81) the entire panchayat) rounds 1 and 2 are not comparable with later rounds. Even in the comparable years changes are too great to reflect more than chance events in any one area (for example, the jump from 24 to 42 per 1 OOO live births in community C from round 4 to round 5). The only tentative conclusion is that of the nine annual changes between comparable years (rounds 1-2, 3-4, 4-5 in each of the three areas), seven were negative, reflecting the overall decline in infant mortality in rural Kera la recorded by the government's sample registra- tion (3). The populations per area are too small, and the time span too short, to permit conclusions on the indi- vidual areas. At the prevailing birth and death rates, populations of 100 000-150 OOO per area would be required. Alternatively, trends may be derived from moving averages, but these would require a period of many years. - 28 - TABLE 1. INFANT MORTALITY RATES (PER 1 OOO LIVE BIRTHS) IN THREE PANCHAYATS IN KERALA, INDIA, 1978/80-1983/84 TABLEAU 1. TAUX DE MORTALITE INFANTILE (POUR 1 OOO NAISSANCES VIVANTES) DANS TROIS PANCHAYATA DU KERALA, INDE, 1978/80-1983/84 Rounds a - T ournilesa Community - Communaute 1 2 3 4 5 1978/80 1980/81 1981/82 1982/83 1983/84 A 91 30 26 24 17 B. 57 14 47 30 20 c 39 25 24 24 42 • The broken line indicates a change in baseline between rounds 2 and 3 (see text) - La ligne en pointille indique un changement des donnees de base entre les deuxieme et troisieme tournees (voir le texte). The morbidity measure used in the OMS is the number of person-days of absence from the person's usual activity due to illness during the week preceding the interview. divided by 7 and expressed as per 1 OOO of the popu- lation at risk. The rate has its problems. It is common experience that in the course of development it is the pattern and not necessarily the frequency of morbidity that changes, and slowly at that. Absence of significant and consistent change in the overall morbidity rate in the three areas over five years thus comes as no surprise (Table 2). The time span is too short, nor would changes in the pattern be captured by an overall morbidity rate. The 1979/80 figures were analysed in detail and symp- toms of those reported ill recorded (Table 3). The symp- toms were grouped in terms of diseases with which they are commonly associated. In communities A and C, the most frequent symptoms were those normally asso- ciated with diseases of the respiratory tract, such as bronchitis and broncho-pneumonia, that account for about half the cases, although in the absence of indi- vidual clinical examination it is impossible to be precise about the relationship of symptoms to disease. In any case, it is the pattern of symptoms (whether or not associated with disease) rather than the overall morbid- ity rate that should be regularly monitored. The third indicator is weight and height of children under 10. Anthropometric measures have been used in the past for at least three distinct purposes: (1) to indicate to • In reference (2) it is stated in error that the mean was used. mothers and to child health staff whether an individual child is growing the way it should; (ii) for community surveillance in conditions where there is gradual rather than drastic deterioration by way of undernutrition or obesity; and (iii) as a comparative analytic device to better understand factors associated with abnormally low or high weight and height. These three purposes by no means coincide. It is not always appreciated for example that the first (clinical) purpose. although essen- tial in its own right, tends not to yield valid statistics, because the population examined is often unrepresenta- tive of the total, or the quality of the measurement is inconsistent. Within the OMS, the second and third purposes were uppermost. Weight and height were used, together with other social indicators, to examine change over time. Table 4 shows an improvement in weight and height over time in community C which is astonishing in its magnitude. The principal interest of WHO was the study of associated factors. The role of the area as a unit of analysis is of interest in this context. Whereas there is clear association within each of the three areas between weight and height on the one hand and parental income as well as some other factors on the other, nonetheless the area with the highest average income (community B) also had the greatest number of children with /ow weight and height (two or more standard deviations below the median of the reference population) (Table 5).e There appear to be area factors influencing weight and height over and above the household factors such as income, source of drinking-water or housing conditions. It was suggested by local spokesmen in community B that the deficiency of health services. until very recently, may TABLE 2. MORBIDITY RATES• IN THREE PANCHAYATA IN KERALA, INDIA, 1978/80-1983/84 TABLEAU 2. TAUX DE MORBIDITE• DANS TROIS PANCHAYATA DU KERALA, INDE, 1978/80-1983/84 A B. c Community - Communaute • Rate - Taux - 1 OOO 2.... 7(P) 1 1978/80 9 29 9 2 1980/81 20 10 22 Rounds• - T ournees• 3 4 5 1981/82 1982/83 1983/84 17 19 18 9 8 9 18 23 19 Where Sis the number of person-days of illness causing restricted activity during the reference week, and P the number of persons in the sample. The definition is likely to locate only fairly serious illness. Thus children with worm infestation, a widespread problem in Kerala, are not likely to be reported as ill unless other more urgent symptoms also occur - Ou S est le nombre de jours/homme de maladie entrainant une baisse d·activite pendant la semaine de reference et P le nombre de personnes dans l'echantillon. La definition ne permet vraisemblablement de recenser que les maladies relativement graves. C'est ainsi que les enfants atteints d'infestation vermineuse, tres repandue au Kerala, risquent de ne pas Atre signales comme etant malades s'ils n·accusent pas aussi d'autres symptomes rev~tant un plus grave caractere d'urgence. • The broken line indicates a change in baseline between round 2 and 3 (see text) - La ligne en pointille indique un changement des donnees de base entre les deuxieme et troisi0me tourn,es (voir le texte). Rapp. trimest. statist. sanit. mond., 41 (1988) - 29 - TABLE 3. NUMBER OF SYMPTOMS REPORTED AND SELECTED ASSOCIATED DISEASES DURING THE WEEK PRECEDING THE INTERVIEW BY AGE, SEX AND SYMPTOM, KERALA, INDIA, 1979-1980 TABLEAU 3. NOMBRE DE SYMPT6MES SIGNALES ET CERTAINES MALADIES RETENUES PENDANT LA SEMAINE PRECEDANT L'ENTREVUE PAR AGE, SEXE ET SYMPT6MES, KERALA, INDE, 1979-1980 Number of cases - Nombre de cas Community A - Communaut6 A Community B - Communaute B Community C - Communaut6 C 0-4 5-14 15+ 0-4 5-14 15+ 0-4 5-14 15+ years years years years years years years years years ans ans ans ans ans ans ans ans ans M F M F M F Principal symptoms - Sympt6mes principaux Cold - Rhume ............... 40 22 77 63 5 3 15 8 40 14 29 25 Cough (no phlegm) - Toux (sans pituite) 16 5 14 14 6 2 1 1 8 6 11 15 Cough (with phlegm/blood) - Toux (avec 35 pituite/sang) ....... 27 13 79 61 - 2 32 17 37 19 47 Fever - Fievre ...... 113 45 151 151 18 14 22 24 138 82 130 96 Diarrhoea - Diarrhee ... 26 - 16 17 2 - 2 2 16 10 12 8 Palpitation - Palpitations 17 5 33 41 1 1 7 6 - 4 17 14 Breathlessness- Dyspnee 39 12 61 70 22 6 18 13 28 11 40 33 Abdominal pain - Douleurs abdominales 5 3 14 26 1 2 14 7 6 6 16 16 Passing worms - Expulsion de vers ... 29 4 3 10 1 - - - 7 3 3 - Vomiting - Vomissements ........ 24 7 20 21 - 1 1 4 4 6 4 10 Nodular swelling - Tumefaction nodulaire - 13 10 12 - 4 1 - - 2 9 1 Headache - Cephalees ...... 4 13 53 65 2 4 16 22 6 24 43 47 Chest pain - Douleurs thoraciques .... 6 3 83 77 - 6 19 18 - 9 58 44 Giddiness - Etourdissements ....... - 3 43 58 - 1 4 6 1 9 29 24 Difficulty in passing urine - Difficulte de mic- tion ....................... 17 7 30 42 - - - 2 - 2 18 10 Pains in joints - Arthralgie .......... 1 4 26 43 1 2 7 2 - - 33 23 Selected diseases commonly associated with groups of symptoms - Maladies couram- ment associees cl des groupes de sympt6- mes Bronchitis - Bronchite ............ 5 5 34 30 1 1 15 16 7 6 32 20 Influenza - Grippe . . . . . . . . . . . . . . - 2 15 8 - 1 - - 1 4 7 11 Broncho-pneumonia - Broncho-pneumonie 9 11 9 6 3 1 - 4 25 3 3 1 Diseases of the upper respiratory tract - Maia- dies des voies respiratoires superieures .. 5 - 3 8 2 2 1 - 5 4 6 2 Population at risk - Population ii risques .. 1 232 2 656 3 534 3 812 1 896 4 110 4 955 4970 1 390 2 922 3 653 3 818 Number of persons ill - Nombre de personnes malades . . . . . . . . . . . . . . . . . . . . 57 28 115 104 16 22 79 50 68 37 91 84 TABLE 4. STANDARDIZED WEIGHT AND HEIGHT OF CHILDREN: CHANGE IN COMMUNITY C, 1981/82-1983/84 TABLEAU 4. POIDS ET TAILLE NORMALISES DES ENFANTS: CHANGEMENTS DANS LA COMMUNAUTE C, 1981/82-1983/84 Round - T ournee 3 (1981/82) 4 (1982/83) 5 (1983/84) Percentage of children with 2 or more standard deviations below the median of a reference population• Pourcentage d'enfants avec 2 6cans types ou plus au-dessous de la m6diane d'une population de r616rence• Height-for-age T aille pour I' age 41.6 39.1 33.2 Weight-for-age Poids pour I' age 58.5 63.2 44.7 Weight-for-height Poids pour la taille 28.5 21.5 16.4 • For details see reference (4) - Pour plus de pr6cisions, voir la ref6rence (4). TABLE 5. COMPARISON OF STANDARDIZED HEIGHT AND WEIGHT IN ALL THREE COMMUNITIES, 1982/83 TABLEAU 5. COMPARAISON POUR LATAILLE ET LE POIDS NORMALISES, POUR LES TROIS COMMUNAUTES, 1982/83 Height-for-age - Taille pour l'ilge Weight-for-age - Poids pour l'ilge .. Weight-for-height Poids pour la taille Percentage of children with 2 or more standard deviations below the median of a reference populationa Pourcentage d'enfants avec 2 6cans types ou plus au-dessous de la mMiane d'une population de ref6rence• Community A CommunityB CommunityC Communaute A Communaute B Communaute C 43.7 49.2 39.1 56.0 63.8b 63.2b 26.1 31.6 21.5 • For details see reference (4) - Pour plus de pr6cisions, voir la reference (4). b All differences are significant at p .a;0.01 except between these two - Toutes les differences sont significatives, p . .a;0,01 sauf pour ces deux chiffres. Wld hlth statist. quan .. 41 ( 19881 - 30 have played a role (but note in Table 2 the relatively low morbidity rate in that community); also that more wo- men than in the other two areas leave their home for work, at a state farm some distance away, possibly without suitable provision for their children's meals. Data for local use The data were intended for local as well as national (i.e. state) use, but other than the involvement of the local people in data collection, local participation has been virtually nil. The reasons are related in turn to each of the three stages: measurement, analysis (or interpretation) and remedial action. (1) Although it is the simplest of the three stages, accu- rate measurement is not as easy as may appear. For example, even one of the trained DMS interviewers read the height on the wrong side of the measuring rod for some time. The error was found when the data were compared with the previous year's fig- ures. Problems of obtaining valid morbidity data in surveys are well known. (ii) Interpretation poses a more serious problem. As noted earlier, items such as infant mortality or mor- bidity rates are either invalid at this level or, at the very least, require expert analysis. Even if a moder- ate change (e.g. in infant mortality) were statistically valid, careful analysis of causes would be required, unless the reasons are obvious-a measles epidemic for instance-in which case the statistics would be superfluous. As regards low height and weight, interrelations are often complex. Slow growth may be the result of malnutrition or ill-health or the inter- action of both; each may be linked to a variety of social and environmental factors but, as we found here, the association is by no means straightfor- ward. (iii) As regards remedies, there is an understanding locally that the health service is a matter for the state, and indeed there is no provision for health in the panchayat budgets. Nor is the potential role of local people by way of stimulated self-help well under- stood in a society that in earlier days was accus- tomed to patriarchal intervention by the maharajas, and more recently to action of a political kind. The people would be more inclined to mount a lorry and demonstrate for effective services outside Govern- ment House in Trivandrum than set up self-help schemes. Indeed, in the DMS' contacts with the elected panchayat councils the demand most fre- quently made has been for comparative information on the area, relative to other areas, by way of ammu- nition for the local councils to prod the central authorities into action. This does not mean that remedial action involving the local people is not possible. However, even if significant causes are known and a remedy-within reasonable financial and other limits-were feasible, the institutional arrangements would have to be initiated by an external agency, government or private. The logic evidently ap- plies with equal force to information for use at the central level. The links between producers and users of data at this level are by no means clear as regards the DMS, or indeed in general. But there may be an institutional framework at the central level, potentially able to utilize information, which usually has no counterpart at the local level. SUMMARY A development monitoring service at the local level was established in 1978/79 in several communities in Kerala State (India) to collect socioeconomic and health-related data. These were collected from key community mem- bers and by household surveys using paid local staff as interviewers. Selected results for five years from three geographically distinct areas are presented, for three categories of data: health service infrastructure, infant mortality and overall morbidity, and weight and height of children under 10 years old. The three areas were a fishing village (A), a relatively remote highland commu- nity (B) and an agricultural area close to the state capital (C).b During the five-year period there were rather modest improvements in the delivery of health and other servi- ces. Infant mortality rates fluctuated between 14 and 91 per 1 OOO live births, reflecting the fact that the sample size ( 10 OOO to around 25 OOO for each area) was ina- dequate for calculating that rate. Morbidity rates also fluctuated markedly, without showing any definite trend. However, morbidity was defined as illness resulting in the inability to carry out normal activities, thus excluding cases of worm infestation and much diarrhoea, for example. A detailed analysis of reported symptoms for one year showed that respiratory tract diseases ac- counted for about half the cases of illness reported. The percentage of children with abnormally low weight- or height-for-age fell markedly in one area over three successive years (height-for-age from 41.6% to 33.2%, weight-for-age from 58.5% to 44. 7%), but were signifi- cantly greater in another area with a higher average in- come, indicating that economic factors alone were not responsible for the improvement. Problems of data col- lection, interpretation and use are discussed. RESUME Notification de la situation sanitaire fondee sur la communaute Un service de surveillance du developpement au niveau local a ete cree en 1978/79 dans plusieurs communau- tes de l'Etat de Kerala (lnde) pour rassembler des don- nees socio-economiques ou en rapport avec la sante. Ces donnees ont ete recueillies aupres de membres influents de la communaute et au moyen d'enquetes dans les menages, l'anamnese etant effectuee par un personnel local remunere. Certains resultats pour cinq annees provenant de trois lieux geographiquement dis- tincts sont presentes pour trois categories de donnees: Rapp. trimest. statist. sanit. mond., 41 (1988) - 31 - infrastructure des services de sante, mortalite et morbi- dite globales infantiles, et poids et taille des enfants de mains de 10 ans. Les trois lieux etaient un village de p~cheurs (A), une communaute montagnarde relative- ment isolee (B) et une zone agricole proche de la capitale de rEtat (C).f Pendant la periode quinquennale consideree, on a enre- gistre des ameliorations assez modestes dans la distri- bution des prestations sanitaires et autres. Les taux de mortalite infantile variaient entre 14 et 91 pour 1 OOO naissances vivantes, ce qui reflate le fait que la taille de r echantillon (de 10 OOO ii environ 25 OOO pour chaque lieu) etait insuffisante pour calculer ce taux. Les taux de morbidite accusaient eux aussi des fluctuations conside- rables, sans qu'il se degage une tendance bien nette. 'Pour proteger ranonymat des communautes en cause, on les a desi- gnees dans le rapport original par leurs seules initiales: TKA (commu- naute Al; ALM (communaute BI; et VPM (communaute q. Toutefois, la morbidite etait definie comme etant une maladie conduisant ii l'incapacite d' exercer des activites normales, si bien que les cas d'infestation vermineuse et une grande partie des cas de diarrhee, par exemple, etaient exclus. Une analyse detaillee des symptOmes signales pendant un an a revele que la moitie environ des cas notifies concernaient des maladies des voies respi- ratoires. Le pourcentage des enfants ayant un poids ou une taille anormalement faibles pour leur Age a baisse notable- ment dans un des lieux consideres pendant trois annees consecutives (le pourcentage est tombe de 41,6% ii 33,2% pour la taille en fonction de rage et de 58,5% ii 44,7% pour le poids en fonction de rage), mais ii etait nettement superieur dans un autre lieu ou les revenus moyens etaient plus eleves, ce qui indique que !'amelio- ration n'etait pas imputable aux seuls facteurs economi- ques. Les problemes que posent la collecte, !'interpreta- tion et I' exploitation des donnees sont passes en revue. REFERENCES - REFERENCES 1. SCOTT, w. & MATHEW, N. T. Levels of living and poverty in Kera/a. A development monitoring service at the local level-Vo/. II. Geneva, United Nations, 1983. (UNRISD Report No. 83.2). 2. SCOTT. W. & MATHEW, N. T. Monitoring change in Kera la: the first five years. A development monitor- ing service at the local level-Vo/. Ill. Geneva, United Nations, 1985. (UNRISD Report No. 85. 7). 3. GOVERNMENT OF KERALA. Sample registration: annual report 1980. Trivandrum, Government of Kerala, Wld hlth statist. quart., 41 ( 19881 1980. (Unpublished figures for 1981-1983 were also used). 4. WORLD HEAL TH ORGANIZATION. Development of indica- tors for monitoring progress towards health for all by the year 2000. Geneva, WHO, 1981. (Health for All Series No. 4). (Annexes 1-3). ORGANISATION MONDIALE DE LA SANTE. Elaboration d'in- dicateurs pour la surveillance continue des progres realises dans la voie de la sante pour tous d'ici /'an 2000. Geneve, OMS, 1981. (Serie sante pour tous N° 4). (Annexes 1-3). - 32 - INTERNATIONAL STATISTICAL CLASSIFICATION OF DISEASES AND RELATED HEALTH PROBLEMS TENTH REVISION Gerlind R. Bramer3 The International Classification of Diseases (ICD) has, under various names, been for many decades the essen- tial tool for national and international comparability in public health. It has been the basis for the collection, classification, presentation and statistical analysis of mortality data for more than 80 years, has been used for morbidity statistics and studies for almost 40 years and is today one of the most quoted references in scientific journals on public health and epidemiology. The ability to exchange comparable data from region to region and from country to country, to allow comparisons from one population to another and to permit study of diseases over long periods is the particular strength of the ICD. This statistical classification has customarily been re- vised every 10 years in order to try to keep up with advances in medicine. Since its creation, the World Health Organization has carried out its statutory mandate of periodic revision of the ICD and the related nomenclature regulations, medi- cal certification and rules, as well as definitions and recommendations in the field of vital events. The Sixth Revision of the ICD in 1948 was the first to be carried out under the auspices of WHO. Since then the Organization has been responsible for the Seventh Revision (1955), the Eighth Revision (1965) and the Ninth Revision (1975), which came into force in 1979. The World Health Organization is now proceeding with the Tenth Revision and is assisted in this work by eight WHO col- laborating centres in different parts of the world. The preparation of a decennial revision of the ICD involves a set of remarkably varied activities, such as: meetings of the heads of WHO collaborating centres for the classification of diseases, Expert Committee meet- ings, presentation of proposals which in turn elicit the presentation of counterproposals, field trials, submis- sion of successive drafts to WHO Member States, analy- sis of comments and suggestions from nongovernmen- tal and governmental organizations and institutions as well as from individuals. Thus, each revision represents a series of transactions amongst multiple opinions. As the culmination of the work a final draft is presented for the approval of an International Revision Conference and then for adoption by the World Health Assembly. The International Conference for the Tenth Revision has been scheduled for 1989 and ICD-10 is expected to come into force in countries in 1993. In the course of the last revisions, the traditional uses of the ICD have been expanded. Beyond the obvious epi- demiological uses, the classification is used nowadays for the planning and management of health services, the storage and retrieval of patient records, and in a wide variety of settings in medicine and public health. Compared with its predecessors, the Ninth Revision (ICD-9) presented many new features in its content and • Medical Officer, Development of Epidemiological and Health Statis- tical Services, World Health Organization, Geneva. quality as well as its structure, making it more flexible, up-to-date and also more adaptable to various purpose- oriented uses. However, already during the preparation of ICD-9 it became apparent that in the future only a family of classifications could meet the needs of the ever-increasing number and variety of professional groups in the health field, and satisfy the demands for uniform assessment of health problems for decision making in prevention, in provision of health care and in research on particular problems. In the build-up to the Tenth Revision a number of meet- ings have been held that evaluated the experience of countries in the use of ICD-9 and considered the direction the classification should take in the future. The prepara- tory meeting on ICD-10 held in 1983 dealt with the results of those meetings and recommended that the ICD-10 should follow the well-established pattern of ICD, but be developed as a core of a family of classifi- cations from which a series of modules could be derived, each reaching a different degree of specificity and ad- apted to a particular speciality or type of user. In order to facilitate the function of the future ICD as a core classification the first Expert Committee on ICD-10 held in San Francisco in 1984 decided to base the ICD on an alphanumeric coding scheme using an alphabetic character followed by two numbers at the basic level instead of the traditional code of three numbers. Further detail would still be provided by means of decimal num- eric subdivisions at the four-character level. The use of codes ranging from A00-299 would more than double the size of the coding frame compared with ICD-9 and would provide the space for the regular ICD chapters as well as for the two supplementary classifications of ICD-9 - External causes of injury and poisoning and Fac- tors influencing health status and contact with health services. As the contents of the ICD-10 will cover more than just categories of diseases, the Committee recom- mended that the title of ICD be amended to "International Statistical Classification of Diseases and Related Health Problems· but its abbreviation should still be "ICD". The family of disease and health-related classifications (Fig. 1) should include speciality-based adaptations (e.g. oncology, dentistry, etc.), where the chief difference lies in the further expansion of the ICD itself, and also clas- sifications such as for general medical practice where the difference lies more in condensation of categories and in giving emphasis to some less precise diagnostic termi- nology. Those speciality-based adaptations of ICD-10 should not amend the classification at the fourth-charac- ter level but only provide extension of detail at the fifth character and beyond. A further group of classifications would cover information not presented in the main ICD but having important medical or health implications (e.g. disabilities, handicaps, procedures in medicine and rea- sons for encounters). The ICD will be further supplemented by the International Nomenclature of Diseases (IND) which should be clearly distinguished from the ICD. The ICD is particularly de- signed for the recording and reporting of morbidity and Rapp. trimest. statist. sanit. mond .. 41 ( 19881 - 33 - FIG.1 SCHEMA FOR A FAMILY OF DISEASE AND HEALTH-RELATED CLASSIFICATIONS INTERNATIONAL STATISTICAL CLASSIFICATION OF DISEASES AND RELATED HEAL TH PROBLEMS INFORMATION SUPPORT TO ICD 3-CHARACTER CORE SPECIALITY-BASED PRIMARY HEAL TH CARE Diagnoses ADAPTATIONS Lay reporting Symptoms Oncology Community-based information <---- Impairments - Dentistry and stomatology for health Abnormal laboratory findings Ophthalmology (country- or community-based Injuries and poisonings Dermatology schemes) External factors influencing health Paediatrics status SHORT TABULATION LISTS OTHER HEALTH-RELATED CLASSIFICATIONS Disablement Procedures Reason for encounter mortality statistics, and for this purpose it groups dis- eases into categories; its primary concern is not the name that should be given to a disease, but the category under which an occurrence of the disease should be reported. The IND is a nomenclature, not a classification; it is a list of recommended names for all diseases, with no attempt to specify the manner in which those dis- eases should be classified for the purposes of statistical reporting. The difference between ICD and IND can be seen from the fact that ICD contains inclusion and exclu- sion notes as well as subcategories for other diseases of a particular organ or system which group but do not name the diseases. In August 1984 a first draft proposal for ICD-10 contain- ing three-character category titles only was circulated to WHO Member States, WHO collaborating centres for the classification of diseases, nongovernmental organi- zations (NGOs) in official relations with WHO, and other interested groups and individuals. The main purpose of that circulation was to obtain views on the proposed alphanumeric structure, the relative number of catego- ries provided for each chapter and the amount of space left for future expansions and revisions within chapters. The vast majority of replies supported the alphanumeric approach and were in agreement with the general direc- tion that the Tenth Revision was taking. While it was known that the alphanumeric scheme of the future ICD would cause some difficulties and increased costs, par- ticularly in computer processing, the advantages of the expanded coding frame were considered to outweigh the disadvantages. Wld hlth statist. quart .• 41 ( 1988) Otorhinolaryngology Neurology, etc. General medical practice ICD 4-CHARACTER LEVEL INTERNATIONAL NOMENCLA- TURE OF DISEASES (IND) The second draft proposal for ICD-10 containing both three- and four-character category titles was distributed in July 1986 in the same way as the first proposal. It incorporated comments received on the first draft pro- posal from countries; recommendations of the annual meetings of WHO collaborating centres for the classifi- cation of diseases; input from WHO divisions and units; and contributions from temporary advisers and other sources. The Second Expert Committee on ICD-10 held in Geneva from 23-27 November 1987 considered the updated draft proposal for ICD-10 at the three- and four- character levels with inclusion terms and exclusion notes, the revised mortality and morbidity coding rules and the definitions to be used with the Tenth Revision. The draft proposal for ICD-10 which was submitted to the Second Expert Committee for ICD-10 and which will, with further minor amendments, be presented to the International Conference on the Tenth Revision of ICD to be held in 1989, has been constructed so that the man- datory tabulations requested by WHO for international comparisons can be based exclusively on three-charac- ter categories. The dagger/asterisk system of dual clas- sification that was introduced at ICD-9 has been refined and extended. The asterisk classification is contained in homogeneous categories at the three-character level for ease of use and interpretation. The draft proposal for ICD-10, comprising 21 chapters, is outlined in the Annex and shows a different chapter arrangement to that of ICD-9. The two supplementary classifications of ICD-9 are included under the characters V, W, X, Y and Z. The - 34 - Tenth Revision of ICD has used (where available) the names of diseases recommended by IND and tries thus to promote the internationally-agreed nomenclature. The volumes of the IND that have been completed so far cover infectious and parasitic diseases as well as dis- eases of the lower respiratory tract. Those in prepara- tion now comprise diseases of the cardiovascular, digestive, nervous and female genital systems. In discussing the advantages and disadvantages of the ICD one has to bear in mind that: • the ICD is primarily an international standard statistical tool and thus subject to international agreement; • it has to serve many purposes in countries at different stages of economic development throughout the world; • it has to be applied by physicians educated at different medical schools, at different times and with different interests in the application of ICD; • it is faced on the one hand with sophisticated com- puter users and on the other hand still has to serve manual and summary uses - thus the ICD can be, at best, only a compromise. For the establishment of the family of classifications, WHO activities are planned as follows: Assistance and guidance in the development and revision of country-specific instruments facilitating data collection in the field of primary health care. Development of special tabulation lists on the basis of ICD-10 to be submitted to the International Con- ference for the Tenth Revision. Assistance to nongovernmental organizations and other international bodies producing adaptations and applications of ICD-10 for special purposes. Further consultation on the use and revision of the International Classification of Impairments, Disabili- ties and Handicaps (ICIDH) that was published for trial purposes by WHO in 1980. Further development of the IND in cooperation with the Council for International Organizations of Medical Sciences. Assistance to countries producing national-language versions of ICD-10. Familiarization and reorientation courses on the Tenth Revision of ICD to be organized at regional, intercountry and country level during 1991-1992 by WHO Regional Offices, WHO collaborating centres for the classification of diseases and countries. SUMMARY The International Classification of Diseases has, under various names, been for many decades the essential tool for national and international comparability in public health. This statistical tool has been customarily revised every 10 years in order to keep up with the advances of medi- cine. At first intended primarily for the classification of causes of death, its scope has been progressively wi- dening to include coding and tabulation of causes of morbidity as well as medical record indexing and retrie- val. The ability to exchange comparable data from region to region and from country to country, to allow compari- son from one population to another and to permit study of diseases over long periods, is one of the strengths of the International Statistical Classification of Diseases, Injuries, and Causes of Death (ICD). WHO has been responsible for the organization, coordi- nation and execution of activities related to ICD since 1948 (Sixth Revision of the ICD) and is now proceeding with the Tenth Revision. For the first time in its history the ICD will be based on an alphanumeric coding scheme and will have to function as a core classification from which a series of modules can be derived, each reaching a different degree of specificity and adapted to a particu- lar speciality or type of user. It is proposed that the chapters on external causes of injury and poisoning, and factors influencing health status and contact with health services, which were supplementary classifications in ICD-9, should form an integral part of ICD-10. The title of ICD has been amended to "International Statistical Clas- sification of Diseases and Related Health Problems'·, but the abbreviation "ICD" will be retained. The use of the codes ranging from AOO-Z99 doubles the size of the coding frame compared with ICD-9. The draft proposals for ICD-10 chapters at three- and four-character levels were distributed worldwide in 1984 and 1986 respec- tively and the comments received were incorporated in a draft proposal presented to the Second Expert Commit- tee on ICD-10 in November 1987. A slightly revised draft will be submitted to the Interna- tional Conference on the Tenth Revision scheduled for 1989. The Tenth Revision of ICD itself will come into use in countries in 1993. RESUME Classification statistique internationale des maladies et autres problemes de sante - Dixieme revision Bien que son titre ait varie plusieurs fois, la Classification internationale des maladies est depuis de nombreuses decennies !'instrument essentiel de comparaison des donnees nationales et internationales en sante publi- que. Cet instrument statistique est normalement revise tous les 10 ans pour tenir compte des progres de la medecine. Destine essentiellement au depart a fournir une classifi- cation des causes de deces, ii a peu a peu ete elargi pour servir au codage et a la mise en tableaux des caus~s de morbidite ainsi qu'a l'indexage des dossiers medicaux. La possibilite d'echanger des donnees comparables de region a region et de pays a pays, de faire des compa- raisons entre populations et d' etudier les maladies sur de longues periodes est l'une des forces de la Classification statistique internationale des maladies, traumatismes et causes de deces (CIM). L'OMS a pris en main !'organisation, la coordination et I' execution des activites interessant la CIM en 1948 (Sixieme revision de la CIM) et travaille actuellement a la Dixieme revision. Pour la premiere fois de son histoire, la CIM sera etablie d'apres un systeme de codage alpha- Rapp. trimest. statist. sanit. mond .. 41 (1988) - 35 - numerique et elle servira de classification de base dont pourront ~tre derives une serie de modules, chacun Visant Un degre de specificite different OU etant adapte a une specialite OU a un type d'utilisateurs donne. II est prevu que les chapitres « causes exterieures de trauma- tismes et empoisonnements» et «facteurs influant sur I' etat de sante et motifs de recours aux services de san- te », qui etaient des classifications supplementaires dans la CIM-9, fassent partie integrante de la CIM-10, dont ii a ete decide par ailleurs de modifier le titre (Classification statistique internationale des maladies et autres proble- mes de sante), tout en conservant !'abbreviation «CIM». La possibilite d'utiliser des codes allant AOO a Z99 dou- ble I' espace de codage par rapport a la CIM-9. Les avant- projets des chapitres de la CIM-10 a trois et a quatre caracteres ont.ete distribues dans le monde entier, res- pectivement en 1984 et 1986, et ii a ete tenu compte des observations rec;ues dans le texte propose au Deuxieme comite d'experts sur la CIM-10, en novembre 1987. Un texte legerement remanie sera soumis a la Confe- rence internationale sur la dixieme revision, prevue pour 1989, la Dixieme revision elle-m~me entrant en vigueur dans les pays en 1993. FIG.1 SCHEMA D'UNE ccFAMILLE•• DE CLASSIFICATION DES MALADIES ET AUTRES CLASSIFICATIONS SANITAIRES CONNEXES CLASSIFICATION ST A TISTIOUE INTERNATIONALE DES MALADIES ET AUTRES PROBLEMES OE SANTE APPUI INFORMATIONNEL AUX SOINS DE SANTE PRIMA IRES RUBRIOUES CIM OE BASE A 3 CARACTERES ADAPTATIONS PAR SPECIALITE Diagnostics Sympt6mes Oeficiences Oncologie Renseignements fournis par des non-medecins Informations pour la sante re- cueillies sur place Resultats laboratoire anormaux Traumatismes et empoisonne- Oentisterie et stomatologie Ophtalmologie Dermatologie Pediatrie O.R.l. ments (systemes a base nationale ou communautaire) Facteurs exterieurs influant sur r etat de sante Neurologie, etc. AUTRES CLASSIFICATIONS SANIT AIRES CONNEXES lncapacites Procedures Motifs de l'examen I LISTES ABREGEES POUR LA MISE EN TABLEAUX CIM RUBRIOUES A 4 CARACTERES Medecine generale NOMENCLATURE INTERN A TIONALE DES MALADIES (NIM) BIBLIOGRAPHY - BIBLIOGRAPHIE 1 . WORLD HEAL TH ORGANIZATION. Manual of the interna- tional classification of diseases, injuries and causes of death. Ninth Revision. Geneva, WHO, 1977. ORGANISATION MONDI ALE DE LA SANTE. Manuel de Ja clas- sification statistique internationale des maladies, traumatismes et causes de deces. Neuvieme revi- sion. Geneve, OMS, 1977. 2. WORLD HEAL TH ORGANIZATION. International classifica- tion of impairments, disabilities and handicaps. Geneva, WHO, 1980. ORGANISATION MONDI ALE DE LA SANTE. Classification in- ternationale des deficiences, incapacites et handi- caps. OMS/INSERM, 1981. 3. COUNCIL FOR INTERNATIONAL ORGANIZATIONS OF MEDICAL SCIENCES. International nomenclature of diseases. Vol. /I-infectious diseases. Geneva, CIOMS, 1982. Wldhlthstatist. quan.,41 (19881 4. KUPKA, K. International Classification of Diseases: Ninth Revision. WHO Chronicle, 32: 219-225 (1978). KUPKA, K. Classification internationale des maladies: neuvieme revision. Chronique OMS, 32: 235-242 (1978). 5. WORLD HEALTH ORGANIZATION. Report of the Expert Committee on the International Classification of Dis- eases. Second meeting on the Tenth Revision. (Document WHO/DES/EC/ICD-10/87.38, 1987). 6. ISRAEL, A.A. The International Classification of Disea- ses: two hundred years of development. Public health reports, 93 (2): 150-152 (1978). 7. MANUILA, A. Progress in medical terminology. Basel/Munich/Paris/London/New York/Sydney, S. Karger, 1981. Chapters I II Ill IV v VI VII VIII IX x XI XII XIII XIV xv XVI XVII XVIII XIX xx XXI Chapitres I II Ill IV v VI VII VIII IX x XI XII XIII XIV xv XVI XVII XVIII XIX xx XXI - 36 - ANNEX - ANNEXE Outline of ICD-10 Certain infectious and parasitic diseases Neoplasms Diseases of the blood and blood-forming organs, and certain disorders involving the immune mechanisms Endocrine, nutritional and metabolic diseases Mental, behavioural and developmental disorders Diseases of the nervous system Diseases of the eye and adnexa Diseases of the ear Diseases of the circulatory system Diseases of the respiratory system Diseases of the digestive system Diseases of the skin and subcutaneous tissue Diseases of the musculoskeletal system and connective tissue Diseases of the genitourinary system Pregnancy, childbirth and the puerperium Certain conditions originating in the perinatal period Congenital malformations, deformations, and chromosomal abnormalities Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified Injury, poisoning and certain other consequences of external causes External causes of morbidity and mortality Factors influencing health status and contact with health services Plan de la CIM-10 Certaines maladies infectieuses et parasitaires Tumeurs Maladies du sang et des organes hematopoi"etiques et certains troubles du mecanisme immunitaire Maladies endocriniennes, de la nutrition et du metabolisme Troubles mentaux et troubles du comportement et du developpement Maladies du systeme nerveux Maladies de I' reil et de ses annexes Maladies de l'oreille Maladies de l'appareil circulatoire Maladies de I' appareil respiratoire Maladies de I' appareil digestif Maladies de la peau et du tissu cellulaire sous-cutane Maladies du systeme osteo-articulaire, des muscles et du tissu conjonctif Maladies des organes genito-urinaires Grossesse, accouchement et suites de couches Certaines affections dont l'origine se situe dans la periode perinatale Malformations et deformations congenitales et aberrations chromosomiques Symptomes, signes et resultats anormaux des examens cliniques et des analyses de laboratoire, non classes ailleurs Lesions traumatiques, empoisonnements et certains autres effets dus a des causes externes Causes externes de morbidite et de mortalite Facteurs qui influencent l'etat de sante et le contact avec les services de sante Range of codes AOO-A99, 800-899 COO-C99, 000-049 050-099 EOO-E99 FOO-F99 GOO-G99 HOO-H59 H60-H99 100-199 JOO-J99 KOO-K99 LOO-L99 MOO-M99 NOO-N99 000-099 POO-P99 Q00-099 ROO-R99 SOO-S99, TOO-T99 VOO-V99, WOO-W99, XOO-X99, YOO-Y99 ZOO-Z99 Codes correspondants AOO-A99, 800-899 COO-C99, 000-049 050-099 EOO-E99 FOO-F99 GOO-G99 HOO-H59 H60-H99 100-199 JOO-J99 KOO-K99 LOO-L99 MOO-M99 NOO-N99 000-099 POO-P99 Q00-099 ROO-R99 SOO-S99, TOO-T99 VOO-V99, WOO-W99 XOO-X99, YOO-Y99 ZOO-Z99 Rapp. trimest. statist. sanit. mond., 41 (1988) - 37 - LE REGLEMENT SANITAIRE INTERNATIONAL BILAN ET PERSPECTIVES Alain Vessereaua De tout temps les hommes et les marchandises ant passe d'un pays a l'autre et si les voyages et le com- merce internationaux ant, de nos jours, pris une impor- tance croissante, c'est depuis plusieurs siecles qu'ils constituent des composantes essentielles de I' econo- mie. Et depuis des siecles les Etats ant cherche a se premunir contre les maladies propagees a I' occasion de ces echanges. Rien d'etonnant done ace que l'une des principales puissances maritimes et commerciales que le monde ait connues, Venise, ait des 1348 institue des mesures de «quarantaine» c'est-a-dire !'obligation de maintenir les navires, equipages et chargement, a l'ecart pendant 40 jours. Des cette date et au cours des siecles suivants, des pays de plus en plus nombreux ant pris exemple sur Venise et ant etabli des reglements qui s'en inspiraient. Au XIXe siecle, la proliferation de reglements disparates et arbitraires apportait une gene considerable au trafic international et en 1851 le gouvernement fran<;:ais convoqua a Paris une conference pour preparer un accord sur !'application des meilleures mesures de pre- vention contre le cholera, la peste et la fievre jaune, et pour discuter de !'adoption d'un code sanitaire commun pour le trafic international. Ce code sanitaire n'entra jamais en vigueur, et d'autres conferences reunies a plu- sieurs reprises jusqu'a la fin du x1xe siecle se revelerent incapables d'aboutir a un accord. Les progres accomplis dans les sciences biologiques et bacteriologiques, en apportant la preuve de l'etiologie et des mecanismes de propagation de certaines maladies, donnerent un nouvel elan a ces efforts de coordination et en 1907 fut etabli a Paris !'Office international d'hygiene publique. lnterrompus par la premiere guerre mondiale, ses travaux aboutirent a la Convention sanitaire de 1926. Des la fin de la seconde guerre mondiale, ii fut decide de mettre de I' ordre dans une situation quelque peu chaotique qui avait continue a se developper et ce fut la premiere version du Reglement sanitaire international (RSI) adoptee par la Quatrieme Assemblee mondiale de la Santa en 1951 . II devait etre ulterieurement revise a diverses occasions, la version actuellement en vigueur etant celle du RSI (troisieme edition annotee) adoptee en 1969 par I' Assemblee mondiale de la Santa et modifiee en 1973 et 1981. Des sa fondation, le but du RSI a ete d'assurer la plus grande protection possible contre la propagation des maladies transmissibles d'un pays a un autre, tout en causant le mains d'inconvenients possibles au com- merce et au trafic international. La premiere maladie visee fut le cholera, plus tard rejointe par d · autres maladies « pestilentielles » telles que la fievre jaune, la variole, la peste, le typhus et la fievre recurrente. c· est pour I utter contre elles et uniformiser les conduites a tenir qu'a ete edicte le RSI qui etablit un code universe! • Chef. Surveillance epidemiologique et appreciation de la situation sanitaire dans le monde, Organisation mondiale de la Sante, Geneve. Wld hlth statist. quan., 41 ( 1988) des pratiques a observer, qui definit les mesures autori- sees d'un commun accord, qui determine les vaccina- tions qui peuvent etre exigees et les conditions dans lesquelles elles peuvent l'etre, qui prescrit les disposi- tions a prendre pour assurer la desinfection et la derati- sation des navires, des avians et des marchandises qu'ils transportent. A chacune de ses revisions, le RSI a fait l'objet de reo- rientations, modestes mais continues, vers une appro- che plus epidemiologique des principes a appliquer. Com me le precise son avant-propos: « Compte tenu de !'importance croissante que revet la surveillance epide- miologique comme moyen de deceler et d'enrayer les maladies transmissibles, le nouveau Reglement a ete con~u de maniere a renforcer I' application des principes de l'epidemiologie sur le plan international, a faciliter !'identification, l'endiguement au !'elimination des sour- ces d'infection, a ameliorer !'hygiene dans les ports, les aeroports et les zones avoisinantes, a prevenir la disse- mination des vecteurs et, d'une fa~on generale a encou- rager les activites epidemiologiques a !'echelon national de telle sorte qu'il y ait peu de risques qu'une infection venue de l'exterieur puisse s'implanter». Cet accent mis sur !'application des principes epidemio- logiques explique que le RSI ne soit pas rigoureusement contraignant mais, jusqu' a uncertain point, facultatif. Par exemple, si elles le desirent, les autorites sanitaires peu- vent renoncer a exiger la remise par les commandants de bard, a leur arrivee, de la Declaration maritime de sante au la Declaration generale d'aeronef. De meme, certains pays, comme c'est deja le cas, peuvent decider de ne pas exiger le Certificat de deratisation au d' exemption de la deratisation, lorsqu'elles considerent que cela n'est pas epidemiologiquement justifie. II peut etre interessant d'examiner quel role le RSI a joue, et joue, vis-a-vis des maladies contre lesquelles ii a ete dresse. Le cholera est une maladie qui, de nos jours, comporte encore une forte connotation emotionnelle. La preuve en est le nombre et !'importance des mesures excessives trap souvent prises par un pays envers un autre pays au des cas de cholera ant ete observes, conduisant a un renforcement rigide des mesures preventives, au soit disant telles, visant le trafic international. Mais ii faut bien constater que ni la fermeture des frontieres, ni I' exigence d'un certificat de vaccination, ni !'interdiction du debar- quement de marchandises ou produits alimentaires n'ont mis un pays a l'abri de !'importation de la maladie. Malgre ces mesures exagerees on pourrait conclure que le RSI n'a pas rempli son role. Et de fait, ii est bien admis maintenant que ce qui importe c'est la qualite de l'envi- ronnement. Les territoires qui beneficient d'un niveau eleve d'hygiene du milieu ne sont pas receptifs aux epi- demies de cholera tandis que ceux au les systemes d'ali- mentation en eau au d'elimination des dechets sont defectueux constituent des terrains propices aux epide- mies des lors que le vibrion cholerique y a ete intro- duit. - 38 - La fievre jaune ne represente une preoccupation que pour les zones ou le vecteur existe ou pourrait exister. Depuis des decennies ii n'y a pas eu de preuve de pro- pagation de la maladie a cause du trafic international. Depuis des annees, la plupart des cas observes ont ete des cas de fievre jaune selvatique, c' est-a-dire survenant dans des zones ecartees, et sans consequences pour le trafic international. On ne peut cependant exclure le fait que !'absence de diffusion de la fievre jaune d'un pays a un autre soit due au soin apporte a ce que les voyageurs internationaux soient porteurs d'une vaccination valable dans les conditions prescrites par le RSI. II parait done raisonnable de maintenir I' exigence de cette vaccination pour les personnes provenant d'une zone infectee et se rendant dans un pays ou des conditions favorables a la fievre jaune existent. Par example, en Asie, bien que le virus puisse y trouver des conditions climatiques ideales et un vecteur privilegie, I' Aedes aegypti, aucun cas de fievre jaune n'a jamais ete signale. Les raisons en sont mal connues mais ii est difficile d'affirmer que le risque potential d'une epidemie soit absent, surtout a une epo- que ou la rapidite des transports permettrait a un voya- geur non vaccine d'arriver a destination avant que ne se soit declaree la maladie qu'il aurait contractee dans des pays ou la fievre jaune est endemique. La peste n'est plus depuis longtemps un probleme d'or- dre international. Elle continue a exister chez les ron- geurs a l'etat sauvage en Afrique, en Amerique et en Asie et de petites epidemies surviennent de temps a autre dans certains pays. II y a done toujours un risque possible de transmission d'un pays a un autre par les rongeurs, essentiellement les rats, par l'intermediaire des navires ou des avians. Cependant, depuis des an- nees de tels cas n'ont pas ete enregistres. Certains pre- tendent que ceci n'est pas du tant a !'application du RSI qu'a la lutte menee contre les rats a bard des bateaux et des avians, en raison des pertes economiques qu'ils peuvent occasionner ou des situations dangereuses qu'ils peuvent creer. II n'en est pas mains vrai que les dispositions du RSI pour I' extermination de rongeurs dans les aeroports, les ports et a bard des navires, ont grandement contribue a I' elimination de la peste en tant que probleme international. Meme si de plus en plus de bateaux sont construits de telle sorte que les rongeurs ne peuvent plus facilement s'y maintenir, !'exigence de cer- tificats de deratisation, ou d'exemption de la deratisa- tion, n'est parfois pas inulile, ne serait-ce que par les inspections qu'elle provoque et qui permettent de reme- dier a des situations incorrectes. Le typhus et la fievre jaune recurrente figuraient autrefois au nombre des six maladies quarantenaires du RSI. L'ex- perience n'a pas mis en evidence que le trafic internatio- nal jouait un role dans leur propagation et c' est pourquoi elles ont disparu du Reglement en 1971. La variole merite une mention speciale. Ce n'est qu'a partir de la Convention internationale de 1926 que cette maladie a ete reconnue comme « maladie pestilentielle » ayant une importance internationale. Mais toutes les dis- positions du RSI autres que celles imposant la vaccina- tion et le depistage, et la surveillance etroite de malades ou suspects, se sont reveles incapables d'empecher la transmission de la maladie d'un pays a un autre. Et ce n'est que lorsque tousles pays du globe se sont embar- ques dans un programme d'action coordonne et ont fait le necessaire, au niveau national d'abord, que !'eradica- tion de la variole a ete possible et que cette maladie a pu etre retiree du RSI. La variole est done une maladie exem- plaire qui illustre combien le RSI peut constituer un cadre fixant les principes selon lesquels chaque pays doit agir en assumant la responsabilite premiere. De la reglementation a la surveillance Le RSI a ete trap longtemps considere comme une bar- riere derriere laquelle les pays pouvaient se retrancher pour eviter !'introduction d'une maladie. lls se donnaient ainsi a bon compte un faux sentiment de securite. Cette attitude n'a pas encore completement disparu. II est devenu evident que les mesures appliquees d'une maniere administrative, plus ou mains correctement d'ailleurs, ne suffisent pas a empecher !'importation d'une maladie. Les principales defenses contre sa disse- mination internationale se trouvent, d'une part dans la detection et la reduction ou !'elimination des foyers de la maladie, d'autre part dans !'amelioration des activites epidemiologiques au niveau national. Les pays doivent accorder une attention particuliere, en premier lieu, a leur propre developpement interne et a leurs propres servi- ces de sante publique. Le renforcement des services nationaux de surveillance des maladies transmissibles apporte une meilleure protection contre les epidemies que ne pourrait le faire n'importe quel accord internatio- nal. Aux moments ou etaient etablies les Conventions sani- taires et les premieres versions du RSI, la surveillance etait vue avec une certaine perspective policiere et I' on parlait de «quarantaine», de «police sanitaire», de «cor- don sanitaire ». Ceci trouvait son explication dans le fait qu'au debut si les conventions visaient a prevenir la pro- pagation de certaines maladies, on en ignorait encore l'etiologie et le mode de transmission. Les seules mesu- res de sante publique qui paraissaient possibles etaient de recourir a des actions restrictives visant les individus, telles que de mettre « en quarantaine » les sujets contacts des personnes atteintes d'une maladie «pestilentielle» pour eventuellement detecter les premiers symptomes de la maladie et instituer un traitement. Progressivement a ete abandonnee l'idee simpliste qu'une maladie transmissible n'etait due qu'a un seul facteur, !'existence a un moment donne du facteur infec- tieux. II est maintenant largement admis que, bien que la presence d'un agent specifique soit necessaire pour pro- duire !'infection, la presence de cet agent n'entraine pas necessairement le developpement d'une maladie et, ul- terieurement, sa propagation. D'autres facteurs tels que l'intensite de !'infection, le type et la duree de !'exposi- tion, I' etat physiologique de la personne touchee et nom- bre de caracteristiques du milieu sont enjeu. Les chances de succes de la lutte contre les maladies transmissibles dependent done non seulement de la connaissance de ces multiples facteurs mais aussi de I' apprehension de leurs relations mutuelles. La collecte systematique de !'information pertinente conduit naturellement a I' evaluation des problemes po- ses au niveau de telle ou telle zone, de tel ou tel pays, afin de discerner les tendances a moyen et long termes ainsi que les schemas epidemiologiques. La surveillance ap- porte les informations indispensables sur les change- ments intervenant dans la distribution et les caracteris- tiques des agents infectieux. Elle permet egalement une mise en evidence rapide des modifications du compor- tement de la maladie et un ajustement approprie des mesures de lutte. Ceci implique le recours a des metho- des epidemiologiques de plus en plus elaborees et inte- grant divers types d'activites pour guider les responsa- bles de la sante publique dans les decisions a prendre. Car, ce qui importe n'est pas de rassembler !'information dans un but academique mais de rechercher !'informa- tion qui conduit a !'action. Le developpement de syste- mes nationaux de surveillance des maladies transmissi- bles a pour but la reconnaissance des problemes aigus Rapp. trimest. statist. sanit. mond., 41 ( 1988) - 39 - aussitl>t qu'ils se posent et la mise au courant de tous ceux qui sont concernes, en particulier ceux qui ont une responsabilite operationnelle dans le pays ou sevit la maladie ou dans le pays ou elle pourrait etre transpor- tee. C'est en visant cet objectif que le RSI a fixe des regles precises pour la notification des cas observes pour cer- taines maladies. Le respect de ces obligations est une condition essentielle pour une action efficace. Encore faut-il que les informations soient communiquees en temps utile et contiennent suffisamment d'elements epi- demiologiques pour permettre des decisions justifiees. raisonnables et adequates. Ce n'est pas toujours le cas et ii faut deplorer que, encore trop souvent, les informa- tions soient transmises sans explications suffisantes, avec retard, ou pas du tout. II y a plusieurs raisons a cela, qu'elles soient dues a des facteurs politiques internes, a un amour-propre national exagere, a la crainte de repercussions sur le tourisme. etc. Cependant, une des raisons le plus frequemment observee, et comprehensible, est la peur qu'une infor- mation objective donnee par un pays conscient de ses responsabilites se retourne contre lui parce que d'autres pays prendraient a son encontre des mesures irration- nelles et excessives, et non sans repercussions pour ses ressortissants ou son economie. La consequence en est que meme si la situation reelle est cachee ou minimisee, les autres pays en sont quand meme avertis par les moyens mediatiques qui existent aujourd'hui et prennent des mesures excessives et irrationnelles qu'une informa- tion correcte aurait pu eviter. Ainsi se cree un cercle vicieux dont ii est bien difficile de sortir. Le Reglement sanitaire international est-ii toujours d'actualite? Le RSI et la fac;:on dont ii est applique ont depuis long- temps ete un sujet de discussion. Certains reconnaissent le rl>le essential qu'il a joue mais considerent qu'il ne sert pratiquement plus a rien et devrait etre aboli etant donne les efforts et les coGts requis pour le mettre en pratique. D'autres considerent qu'il conserve des merites indiscu- tables et qu'il doit etre maintenu, au prix de quelques adaptations. II est vrai que les maladies qui y figurent ont un interet largement historique et, en tout cas, ne representent plus les fleaux qu' elles etaient jadis. II est de fait que, de nos jours, des methodes efficaces d'immunisation. de lutte contre les vecteurs, de therapie, ont reduit le besoin des contrl>les aux frontieres. II est certain que la solution a court terme du probleme du cholera, par exemple. est un renforcement de la surveillance et la prise de mesures appropriees au niveau local tandis que la solution a long terme se trouve dans !'amelioration des conditions d'hy- giene jusqu'a ce que les zones sensibles ne le soient plus. D'autre part, plusieurs autres maladies preoccupantes non considerees comme « quarantenaires » par le RSI peuvent etre transmises d'un pays a un autre. C'est le cas par exemple de la grippe, qui cause parfois des pan- demies sur une grande echelle avec une mortalite elevee et toujours des effets prejudiciables a l'economie. Parmi les maladies transmissibles par des vecteurs, autres que celles figurant dans le RSI, certaines sont responsables d'epidemies importantes, telles que la dengue ou l'ence- phalite japonaise. C'est la raison pour laquelle si la surveillance au niveau mondial a ete initialement limitee aux six maladies qua- rantenaires, elle a plus recemment ete etendue a plu- Wld hlth statist. quart., 41 (1988) sieurs autres maladies d'importance internationale. Le virus de la grippe est continuellement sous le controle d'un reseau de centres collaborateurs de l'OMS dans les diverses parties du monde pour etre sGr que si un nou- veau type de virus apparait ii est detecte aussitl>t que possible. L'effort des programmes de lutte contre les treponematoses est constamment evalue grace a une surveillance clinique et sero-epidemiologique. Le palu- disme est sous surveillance permanente dans le cadre du Programme d'action antipaludique. L'OMS apporte sa collaboration a la surveillance de maladies d'importance internationale telles que la dengue et la fievre hemorra- gique en Asiedu Sud-Est et dans le Pacifique occidental, ou les salmonelloses en Europe. La surveillance de la rage est maintenue avec soin. II faut souligner egalement que ces programmes de sur- veillance auxquels participe l'OMS ne se limitent pas aux maladies transmissibles elles-memes. Une attention particuliere est accordee aux vecteurs, c' est-a-dire a leur distribution, leur densite, la resistance qu'ils peuvent developper vis-a-vis des insecticides et les facteurs eco- logiques qui favorisent leur role dans la transmission des agents infectieux. On est ainsi parvenu peu a peu a une cooperation inter- nationale de plus en plus active dont les examples en sont le Programme d'eradication de la variole, le Pro- gramme elargi de vaccination, le Programme de lutte contre l'onchocercose, etc. Les succes de ces program- mes coordonnes servent parfois d'arguments a ceux qui considerent le RSI comme perime. II y aurait done maintes raisons pour que les maladies inscrites au RSI, sinon le Reglement lui-meme, disparais- sent. c· est une proposition souvent avancee et le fait que trois d'entre elles (typhus, fievre recurrente et vario- le) aient deja ete retirees semble apporter une justifica- tion. Quant aux trois qui restent, elles n'ont en realite qu'un interet tres limite pour la plupart des pays. Pour eux elles ne comportent pas d'obligations effectives si ce n'est en ce qui concerne la delivrance de certificats d'exemption de la deratisation ou plus rarement, de cer- tificats de deratisation. On trouvera au tableau 1 et aux figures 1-4 I' evolution du nombre de cas observes de 1948 a 1987 pour quatre des maladies soumises au RSI pendant cette periode. En outre, lorsque les conditions sont remplies pour un plein effet du RSI, on constate souvent que son applica- tion ne se fait pas dans des conditions satisfaisantes et apporte plus de gene que de sauvegarde aux voyageurs internationaux ou aux pays concernes. Cependant, les discussions a ce sujet se traduisent gene- ralement par une attitude conservatrice, et ii en est pro- bablement bien ainsi. Le RSI a etabli un code universe! des pratiques a observer. Meme les Etats non lies juridi- quement les appliquent dans !'ensemble. D'ailleurs, si une des maladies qui y figure en etait sup- primee elle n'en perdrait pas pour autant son impact emotionnel. Les Etats Membres se sentiraient autorises a prendre n'importe quelle mesure ad hoe sans meme avoir a en rendre compte et personne ne saurait a quoi s'attendre en se rendant dans tel ou tel pays. De toute fac;:on, !'absence dans un pays des risques contre les- quels les dispositions du RSI ont ete etablies ne suffit pas a autoriser ce pays a lui denier toute valeur et a demander son abolition. Et ii faut souligner quelles mesures sani- taires prescrites par le RSI constituent le « maximum de ce qu'un Etat peut exiger a l'egard du trafic international pour la protection de son territoire contre les maladies soumises au Reglement» (Article 23). II suffit aux admi- nistrations sanitaires concernees de decider de ne pas TABLE 1. CASES OF FOUR QUARANTINABLE DISEASES NOTIFIED TO WHO, 1948-1987 TABLEAU 1. NOMBRE DE CAS DE QUATRE MALADIES SOUMISES AU RSI NOTIFIEES A. L'OMS, 1948-1987 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 CHOLERA - CHOLERA Africa - Afrique ...... Cholera was noted in Africa for the first time in 1970 - Le cholera a ete observe en Afrique pour la premiilre fois en 1970 Americas - Ameriques . . Asia - Asie . . . . . . . . 260 530 247419 33724 115541 123308 242378 40535 40110 66425 65620 103018 52606 35054 62509 45571 59564 83346 56244 33325 24160 Europe ........... Oceania - Oceania .... Total ............ 260530 247419 33724 115541 123308 242378 40535 40110 66425 65620 103018 52606 35054 62509 45571 59564 83346 56816 33325 241&0 YELLOW FEVER - FIEVRE JAUNE Africa - Afrique ...... 7 34 17 39 55 29 6 14 4 5 60 133 7 300 10 3 7 243 - 5 Americas - Ameriques . . 31 12 64 297 292 89 83 34 26 81 71 30 50 82 52 141 98 87 159 12 ~ Total ............ 38 46 81 336 347 118 89 48 30 86 131 163 57 382 62 144 105 330 159 17 0 I PLAGUE - PESTE Africa - Afrique ...... 632 255 238 692 891 207 106 55 107 113 110 51 69 21 124 49 540 55 18 18 Americas - Ameriques . . 511 141 115 72 166 264 171 165 115 151 97 93 258 308 527 423 653 845 897 223 Asia - Asie ........ 38370 39271 4389 8965 10845 6657 1617 1112 682 290 119 178 114 453 788 380 417 424 2903 5763 Europe ........... 8 2 Oceania - Oceanie .... - 1 Total ............ 39521 39670 4742 9729 11902 7128 1894 1332 904 554 326 322 441 782 1439 852 1610 1324 3818 6004 ~ SMALLPOX - VARIOLE ~ Africa - Afrique ...... 26180 25680 42039 26850 31571 22344 26383 26079 22432 35153 17456 16927 18034 27526 25031 17585 13583 17049 14759 15529 ~- Americas - Ameriques . . 27765 16769 22803 9638 9805 8947 12077 8349 8722 7469 5301 6974 9075 9045 10032 7385 3712 3632 3665 4544 .. .. Asia - Asie ........ 10534 590244 361047 517954 125459 62802 60715 57306 64935 114018 257706 72354 39989 53960 63558 108406 58903 91958 74303 111619 ,. .. Europe 414 165 117 314 249 42 57 88 12 12 15 47 24 136 128 1 72 5 iil . . . . . . . . . . . - -ii· Oceania - Oceania 1 1 1 ,. .... - - - - - - - - - - !:: Total ............ 161893 632858 426006 554756 167085 94135 99232 91823 96089 156652 280475 96270 67146 90555 98757 133504 76198 112280 92799 131697 ::, ~- ~ ,Q. ~ <D CD $ ~ 2: 3- .. iil ~- ,.. .Q & ? ~ 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987° "' co CHOLERA - CHOLERA !!? Africa - Afrique ...... - - 10 759 74 645 5 386 8 845 9 667 7160 3180 9 586 24 640 20794 19 204 19 251 37 427 64061 17060 27 108 40626 22 681 Americas - Ameriques . . - - - - - 1 1 - - 4 12 1 13 21 - 3 1 4 18 6 Asia - Asie ........ 36444 36 299 57 343 103 369 76 257 103 092 99 782 89 184 72 766 69 718 53 486 45 318 25 201 33 191 15 191 27005 11801 13383 5 774 15191 Europe ........... - - 726 97 4 303 2 484 1 089 16 8 5 281 19 46 21 12 11 9 52 19 Oceania - Oceania .... - 4 - - 44 - 2 - - 1310 533 646 3 6 2 217 319 20 6 3 1 Total . . . . . . . . . . . . 36 444 36303 68828 178111 81 691 112 241 111 938 97443 75962 80626 78676 66458 44440 52515 54856 64061 28893 40510 46473 37898 YELLOW FEVER - F1£VRE JAUNE Africa - Afrique ...... - 322 23 70 6 9 27 134 3 110 249 508 17 7 31 728 31 13 3 361 789 Americas - Ameriques . . 47 48 86 28 55 207 76 168 44 102 240 205 120 231 140 50 95 125 159 182 Total ............ 47 370 109 98 61 216 103 302 47 212 489 713 137 238 171 778 126 139 3 520 971 ~ ..... PLAGUE - PESTE Africa - Afrique ...... 145 144 63 37 75 32 184 147 93 172 203 251 81 53 250 251 179 212 729 403 Americas - Ameriques . . 387 424 327 96 399 185 321 521 146 48 97 23 142 128 182 225 500 128 162 16 Asia - Asie ........ 951 1225 4 111 4184 1 271 573 2 251 811 1 266 1 258 485 387 283 13 281 239 229 143 112 102 Europe - - 1 Oceania - Oceanie Total ............ 1483 1793 4502 4317 1745 790 2 756 1479 1505 1478 785 661 506 194 713 715 908 483 1 003 521 SMALLPOX - VARIOLE Africa - Afrique ...... 11069 3 584 3 220 27 679 18999 5 462 4 467 3949 954 3 234 Americas - Ameriques . . 4 375 7 410 1 795 19 Asia - Asie ........ 64 578 43208 28 669 25 108 45 978 130 392 213 900 15 329 Europe ........... 2 - 22 - 176 5 - - - - 2 Oceania - Oceania .... Total . . . . . . . . . . . . 80 024 54202 33706 52806 65 153 135 859 218 367 19 278 954 3234 2 • Provisional - Pr61iminaire. - 42 - FIG. 1 CHOLERA: CASES NOTIFIED TO WHO, AFRICA AND ASIA, 1948-1986 CHOLERA: CAS NOTIFIES A. L'OMS, AFRIQUE ET ASIE, 1948-1986 250 ' I I I I E I II !200 I II fl I 11 ~ I 11 i I I I z I I I I 150 \ I \ - I 1.)1 - AFRICA - AFRIOUE --- ASIA - ASIE .. : 100 tl 0 I I I I I I ,4, 1, r-...., 11 I ,, 1\I \ I f I I \ 1\ I v '-, v II 11- \ J\ /I \ I \ f L.I \/ \, \ _II '\ 50 \/ \;- '\ \/ '-, ! o..._.._.__._--'-"L-L-'--_.__.___._._......__._.._.__.__.__.___._._-&-...,_.__.__.__.__,_,L-L_.__....._.L......L_.__.__,_,L-L.,,,,-'i 800 700 600 .. .. " " 500 .,, ~ E i I 400 .. " .. .. " 0 300 ~ ... E :, z 200 1950 1955 1960 1965 1970 1975 1980 1985 Year - Ann6e FIG. 2 YELLOW FEVER: CASES NOTIFIED TO WHO, AFRICA AND AMERICAS, 1948-1987 Fll:VRE JAUNE: CAS NOTIFIES A. L'OMS, AFRIQUE ET AMERIQUES, 1948-1987 336lt - AFRICA - AFRIOUE -·- AMERICAS -AMtRIOUES 1950 1955 1960 1965 1970 1975 1980 1985 Year - Ann,e Rapp. trimest. statist. sanit. mond., 41 ( 1988) - 43 - FIG. 3 PLAGUE: CASES NOTIFIED TO WHO, AFRICA, AMERICAS AND ASIA, 1948-1987 PESTE: CAS NOTIFIES A L'OMS, AFRIQUE, AMERIQUES ET ASIE, 1948-1987 c ;:: r::; ~ Ill r-... ~ 1 :_;: $ . J, \lo {F- \ I 1 ~ \ i . ~ i . I e c 5 .!!. ./ \ .. .. v I " -8 I!! \ .0 4 E c . z \ I ., .., . c 3 \ .. .. :, _g -- AFRICA - AFRIOUE --- AMERICAS - AMtRIQUES .... \ .. ., .. .. " 2 0 ~ Iii .0 E :, \ z \. ~ 0 1950 1955 1960 1965 1970 1975 1980 1985 Year -AnnH FIG.4. SMALLPOX: CASES NOTIFIED TO WHO, AFRICA, AMERICAS AND ASIA, 1948-1978 VARIOLE: CAS NOTIFIES A L'OMS, AFRIQUE, AMERIQUES ET ASIE, 1948-1978 ... i ,.. 1 !il ! ~ lr\ I ... 1 \ ~ ~ I . ,· ·, -8200 \ I ~ . \ i \ I . ~ 150 \ , \ --- AFRICA - AFRIQUE - -- AMERICAS - AMtRIQUES -·- ASIA - ASIE l \ j I \ I i /\ r---t\ I 100 0 \._ ,,) \ /' V' 'v .\ Year - Anntle Wld hlth statist. quan., 41 (1988) 1 - 44 - appliquer les dispositions qui leur paraissent inutilement contraignantes sur une base epidemiologique. Mais ce cadre restera necessaire aussi longtemps que I' acceptation universelle et la mise en pratique de princi- pes epidemiologiques authentiques ne l'auront pas rendu obsolete. Ceci peut se faire progressivement a la faveur des revisions du RSI dont les dispositions doivent etre modifiees aussi souvent que le justifient les change- ments dans la situation epidemiologique, !'experience acquise et les progres intervenus dans les sciences et les techniques. Ainsi, le RSI devrait etre un stimulant pour les activites epidemiologiques au niveau national pour aboutir a une detection precoce de la maladie permettant de la juguler avant qu'elle ne soit installee. Le Reglement prendrait alors toute sa place dans un service de surveillance epi- demiologique integre, lui-meme partie integrante des services de sante du pays, un tel service ayant pour tilches la recherche, la detection, l'enregistrement et la notification des maladies. Sa responsabilite est non seu- lement nationale mais egalement internationale, ayant pour role de rendre compte a l'OMS et aux autres pays des cas de maladie observes en meme temps que des mesures prises sur des criteres epidemiologiques, aussi bien pour prevenir I' exportation de ces cas que pour indiquer les dispositions raisonnables decidees vis-a-vis des cas importes. On ne devrait plus voir un comparti- mentage, comme cela est encore trop souvent le cas, des differents services administratifs detenant chacun une parcelle d'information, dont chaque element ne peut etre utile isolement, mais dont seule I' agregation permet une vision complete et operationnelle. De telles procedures, si elles sont generalement suivies sur une base reciproque d'objectivite, sont la cle pour le developpement d'une meilleure comprehension et d'une cooperation plus sincere entre les services epidemiolo- giques de tousles pays et la restauration d'une confiance qui fait trop souvent defaut. Nul doute que, lorsque le moment en sera venu, le RSI progressera encore dans cette direction, s'efforc;ant de definir des principes generaux que tous pourront obser- ver et developper plutot que des actions specifiques pour des maladies particulieres. Celles-ci pourraient faire I' objet de guides dont la preparation ne subit pas les memes contraintes formelles, ce qui leur permet d'etre plus facilement mis a jour pour tenir compte des evolu- tions techniques. RESUME L'actuel Reglement samta1re international (RSI) a ete adopte par la Vingt-Deuxieme Assemblee mondiale de la Santa en 1969, puis modifie en 1973 et 1981. II est le resultat d'une revision et d'une refonte du precedent Reglement sanitaire international adopte par la Qua- trieme Assemblee mondiale de la Santa en 1951 . lui- meme base sur les precedentes Conventions sanitaires internationales. Le RSI a pour but d'assurer le maximum de securite centre la propagation des maladies d'un pays a l'autre moyennant le minimum d'entraves au trafic mondial. Au cours des annees, le RSI a englobe le cholera, la fievre jaune, la peste, la variole, le typhus et la fievre recurrente, mais les trois dernieres maladies en ont ete exclues par suite de I' eradication mondiale de la variole et du declin du typhus et de la fievre recurrente comme facteurs de risque au niveau international. Le RSI a joue et joue encore un role important au regard des maladies pour lesquelles ii avait ete etabli. La propa- gation internationale de la fievre jaune a ete endiguee par I' administration aux voyageurs d'un vaccin extremement efficace et celle de la peste par !'inspection des navires et des aeronefs pour le depistage des rats et par les ame- liorations apportees a la conception des transporteurs de fret aeriens et maritimes en vue de les rendre de moins en moins susceptibles d'heberger des rats. D' aucuns ont mis en doute le role du RSI en ce qui concerne la variole et le cholera en faisant valoir que I' eradication de la variole avait ete realisee grace a de rigoureux programmes nationaux de vaccination par foyers et que le cholera devait etre vaincu par une meilleure salubrite de l'envi- ronnement. Cependant, ii ne faut pas perdre de vue qu'un element important du RSI est I' obligation de notifier les cas des maladies qui y figurent, en communiquant le plus d'infor- mations epidemiologiques possible, afin de permettre aux autres pays de prendre les mesures qui s'imposent. Les reactions excessives posent souvent un probleme, mais ii ressort de I' experience acquise que la revelation complete de la situation est preferable a ce qu'il advient du commerce et du tourisme dans un pays lorsqu'on laisse circular des rumeurs sans fondement. L • avant-propos au RSI souligne que ce dernier a pour but, entre autres, d'encourager les activites epidemiologi- ques a I' echelon national et ii est incontestable que le depistage et le traitement des cas ace niveau constituent le moyen le plus efficace d'empecher la poursuite de la propagation des maladies a l'interieur ou a l'exterieur du pays. Dans ce contexte, ii apparait que la valeur actuelle du RSI stimule les activites epidemiologiques a I' echelon national et !'integration des tilches des services natio- naux de sante concernant le depistage, I' endiguement, la prevention et l'enregistrement des maladies, ainsi que la notification de celles qui sont importantes pour la com- munaute internationale. Le moment est peut-etre venu de reviser le Reglement sanitaire international en fonction des principes moder- nes de l'epidemiologie afin d'en faire !'instrument d'une cooperation accrue entre les services epidemiologiques de tous les pays. SUMMARY The International Health Regulations: results and prospects The current International Health Regulations (IHR) were adopted by the Twenty-second World Health Assembly in 1969 and amended in 1973 and 1981. They are a revised and consolidated version of the International Sanitary Regulations which were adopted by the Fourth World Health Assembly in 1951, themselves based on the previous International Sanitary Conventions. Rapp. trimest. statist. sanit. mond., 41 (1988) - 45 - The purpose of the IHR is to ensure maximum security against the international spread of diseases with a mini- mum interference to world traffic. Over the years the IHR included cholera, yellow fever, plague, smallpox, typhus and relapsing fever, and then dropped the last three as a result of the global eradication of smallpox and the decline of typhus and relapsing fever as international threats. The IHR have played and still play an important part with respect to the diseases for which they were drawn up. The international spread of yellow fever has been contai- ned by the application of a highly effective vaccine to travellers, and of plague by the inspection of ships and aircrafts for rats, and improvements in the design of air and sea cargo carriers to make them increasingly unin- habitable for rats. The role of the IHR was questioned as far as smallpox and cholera are concerned by arguing that smallpox was eradicated by rigorous national local vaccination programmes and cholera must be defeated by improved environmental sanitation. However, one must not lose sight of the fact that an important element of the IHR is the obligation to notify cases of the diseases listed, together with as much epi- demiological information as possible, in order to permit other countries to take appropriate action. Overreaction is often a problem but experience has shown that full disclosure of the situation is preferable to what happens to a country's trade and tourism when unsubstantiated rumours are allowed to circulate. In the foreword to the IHR it is underlined that one of their purposes is to encourage epidemiological activities at the national level, and it cannot be disputed that detect- ing and treating cases at this level is the most effective way of preventing further spread either internally or externally. In this context, the IHR should be a stimulus for epidemiological activities at the national level and for the integration of the national health services' tasks of detecting, controlling, preventing and recording disea- ses as well as notifying those of importance to the inter- national community. Perhaps the time has come for a revision of the Interna- tional Health Regulations along the lines of modern epi- demiological principles in order to make them a tool for increased cooperation between the epidemiological ser- vices of all countries. BIBLIOGRAPHY - BIBLIOGRAPHIE 1. WORLD HEAL TH ORGANIZATION. International Health Regulations (1969)-first annotated edition. Geneva, WHO, 1971. ORGANISATION MONDI ALE DE LA SANTE. Reglement sani- taire international ( 1969) - premiere edition anno- tee. Geneve, OMS 1971. 2. WORLD HEALTH ORGANIZATION. International Health Re- gulations (1969)-second annotated edition. Geneva, WHO, 1974. Wld hlth statist. quan., 41 ( 1988) ORGANISATION MONDI ALE DE LA SANTE. Reglement sani- taire international (1969)-deuxieme edition anno- tee. Geneve, OMS, 1974. 3. WORLD HEAL TH ORGANIZATION. International Health Regulations (1969)-third annotated edition. Geneva, WHO, 1983. ORGANISATION MONDIALE DE LA SANTE. Reglement sani- taire international ( 1969)-troisieme edition annotee. Geneve, OMS, 1983. PUBLICATIONS OF THE WORLD HEALTH ORGANIZATION 1988 WORLD HEALTH FORUM An international journal of health development (Separate editions in English, French, Spanish, Arabic, Chinese and Russian) World health forum is a quanerly journal for policy-makers, health planners, adminis- trators, health educators, and public health workers of all kinds. It provides a medium for the presentation and discussion of new concepts in public health and new approaches to health problems, and it is devoted to the improvement of health through the promotion of health services covering the entire population and the undertaking ofa wide variety of public health measures, whether or not they are supported by WHO. The Forum is the main organ of WHO's Member States for the international exchange of health information and an active instrument in technical cooperation among developing countries. Subscription (4 numbers) ... Price per copy . . . . . . . . . . BULLETIN Sw. fr. 55.- Sw. fr. 16.- OF THE WORLD HEALTH ORGANIZATION The Bulletin is the principal scientific organ of WHO; its role is to review progress in medical and related sciences ("update" articles) and to bring to light new knowledge by publishing original papers on scientific research in the laboratory and field The Bulletin contains original articles in either English or French, with a summary in the other language. One volume is published annually, consisting of six numbers. Subscription (6 numbers) ... Price per copy . . . . . . . . WEEKLY EPIDEMIOLOGICAL RECORD (Bilingual : English and French) Sw. fr. 130.- Sw. fr. 22.- Prepared for the guidance of health administrations and health authorities, the Weekly epidemiological record contains notifications made under the International Health Regula- tions and information concerning their application. The Record also contains epi- demiological information on communicable diseases of international importance. Annual subscription . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sw. fr. 140.- WORLD HEALTH STATISTICS QUARTERLY The World health statistics quarterly replaces (since 1978) the World health statistics report (published since 1967) and its forerunner the Epidemiological and vital statistics report (published since 1947). It deals with the detailed analysis of selected health topics of current interesL Starting with Vol. 41 (1988), the Quarterly will contain articles in either French or English with a summary in both languages. Annual subscription . . . . . . . . . . . . . . . . . Price per copy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . WORLD HEALTH STATISTICS ANNUAL (Bilingual: English and French) Sw. fr. 85.- Sw. fr. 23.- The forerunner of this series was the Annual epidemiological report of the LeaguR of Nations. It was followed by the Annual epidemiological and vital statistics issued by the World Health Organization. Latest publications : 1983, Vital statistics and causes of death, morbidity, health resources (single volume), 804 pages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sw. fr. 57.- 1984, Vital statistics and life tables, morbidity, causes of death (single volume), 402 pages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sw. fr. 40.- 1985, Vital statistics and life tables, environmental health, causes of death (single volume), 531 pages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sw. fr. 80.- 1986, Vital statistics and life tables, evaluation of the Global Strategy for Health for All, causes of death (single volume). 692 pages . . . . . . . . . . . . . . Sw. fr. 90. - PUBLICATIONS DE L'ORGANISATION MONDIALE DELASANTE 1988 FORUM MONDIAL DE LA SANTE Revue intemationale de developpernent sanitaire (Editions separees en fran~is, anglais, espagnol, arabe, chinois et russe) Forum mondilll de la sante est une revue trimestrielle destinee aux responsables des politiques sanitaires, aux planificateurs, administrateurs et Cducateurs sanitaires, enfin aux travailleurs de la sante publique de toutes categories. Tribune pour la presentation et la discussion de nouveaux concepts en sante publique et de nouvelles approches des problemes de sante, Forum se consacre a l'amClioration de la sante par la promotion de services de santC couvrant la population tout entii:re et d'une vaste gamme de mesures de sante publique, qu'elles soient ou non soutenues par l'OMS.11 est le principal organe a la disposition des Etats Membres de l'OMS pour l'cchange international d'inforrnations sanitaires en meme temps qu'un instrument de cooperation technique entre pays en developpement. Abonnement (4 numeros) ....... . L.e numCro ................... . BULLETIN Fr. s. SS.- Fr. s. 16.- DE L'ORGANISATION MONDIALE DE LA SANTE Le Bulletin est le principal organe scientifique de l'OMS; ii a pour role de passer en revue les progres des sciences medicales et apparentees (articles de la rubrique « Le point») et de mettre en lumiCre les connaissances nouvelles en pttSentant dans des articles originaux les rCsultats de recherches scientifiques au laboratoire et sur le terrain. Le Bulletin contient des articles originaux en fran,;ais ou en anglais, accompagnes d'un resume dans l'autre langue. Un volume est public annuellement, etant forme de six numi:ros. Abonnement (6 numeros) ............ . L.e numCro ...... . RELEVE EPIDEMIOLOGIQUE HEBDOMADAIRE (Bilingue: fran~is et anglais) Fr.s.130.- Fr. s. 22.- Destine aux administrations sanitaires et aux services de sante, le Re/eve epidemiologique hebdomadairecontient les notificationsexigees par le Reglement sanitaire international, ainsi que d'autres renseignements concemant !'application de ce reglement. Le Re/eve contient egalement des informations epidemiologiques concemant les maladies transmissibles d'une importance intemationale. Prix de l'abonnement annuel . . . . . . . . . . . . . . . . . . . . . . . . . Fr. s. 140.- RAPPORT TRIMESTRIEL DE STATISTIQUES SANITAIRES MONDIALES Le Rapport trimestriel de statistiques sanitaires mondiales, remplace (depuis 1978) le Rapport de statistiques sanitaires mondiales (public depuis 196 7) et son precurseur le Rapport t!pidt!miologique et demographique(publie depuis 194 7). II presente des analyses detaillees sur des sujets specifiques d'interit courant. A compter du Vol. 41 (1988), le Trimestriel present era des articles originaux en fran,;ais ou en anglais, accompagnes d'un resume dans les deux langues. Prix de l'abonnement annuel L.e numCro ....... . ANNUAIRE Fr. s. 85.- Fr. s. 23.- DE STATISTIQUES SANITAIRES MONDIALES (Bilingue: fran,;ais et anglais) Cet annuaire remplace les Statistiques t!pidemiologiques et demographiques annuelles publiees par !'Organisation mondiale de la Sante et qui avaient, elles-memes, remplace le Rapport epidt!mio/ogique annuel public par la Socicte des Nations. Publications recentes: 1983, Mouvement de la population et causes de deces, morbidite, resources de sante (I seul volume), 804 pages . • . . . . . . . . . . . . . . . . . . . . . . . . . Fr. s. 57.- 1984, Mouvements de la population et tables de survie, morbiditc, causes de deces ( I seul volume), 402 pages . . . . . . . . . . . . . . . . . . . . . . . Fr. s. 40.- 1985, Mouvementde la population et tables de survie, salubrite de l'environnement, causes de deces (I seul volume), 531 pages . . . . . . . . . . . . . . . . . . . Fr. s. 80.- 1986, Mouvement de la population et tables de survie, evaluation de la Strategic mondiale de la santc pour tous, causes de deces (I seul volume), 692 pages . . Fr. s. 90.- WHO publications may be obtained, direct or through booksellers, from: Les publications de l'OMS peuvent etre commandees, soit directement, soit par l'intermediaire d'un libraire, aux adresses suivantes : ALGERIE: Entreprisc nationale du Livre (ENAL), 3 bd Zirout Youccf, AWER ARGENTINA: Carlos Hirsch SRL, Aorida 165, Galerias Gucmes, Escritorio 453/465, BUENOS AIRES AUSTRALIA: Hunter Publications, SSA Gipps Street, COLLINGWOOD, VIC 3066 AUSTRIA:Gerold&Co.,Grabcn31, 1011 WIEN! BAHRAIN: United Schools International, Arab Region Ollice, P.O. Box 726, BAHRAIN BANGLADESH: The WHO Programme Coordinator, G.P.O. Box 250, DHAKA S BELGIQUE: Pour toute commande hors ab<Jnnement: Office International de Librairie s.a., avenue Mamix 30, 1050 BRUXELLES. A.b<Jnnements: Olli.cc International des P~riodiqucs, avenue Louise 485, 1050 BRUXELLES BHUTAN: see India, WHO Regional Olli.cc BOTSWANA: Botsalo Books (Pty) Ltd., P.O. Box 1532. GABORONE BRAZlL: Centro Latinoamericano de lnfonnacao cm Cicncias de Saoldc (BIREME), Organi~o Panamerica- na de Saolde, Sector de Publica~. C.P. 20381 - Rua Botucatu 862, 04023 SAO PAULO, SP BURMA: see India, WHO Regional Olli.cc CAMEROON: Cameroon Book Centre, P.O. Box 123, South West Province, VICTORIA CANADA: Canadian Public Health Association, 1335 Carling Avenue, Suite 210, 01TAWA, Ont. KIZ 8N8. (Tel: (613) 725-3769. Telex: 21-053-3841) CHINA: China National Publications lmpon & Expon Corporation, P.O. Box 88, BEUING (PEKIN) DEMOCRATIC PEOPLE'S REPUBLIC OF KOREA: see India, WHO Regional Office DENMARK: Munksgaard Expon and Subscription Ser- vice, Nerre Segadc 35, 1370 K0BENHAVN K (Tel: +45 I 12 85 70) ESP AGNE: Comcrcial Athcncum S.A., Consejo de Ciento 130-136, 08015 BARCELONE; General Moscard6 29, MADRID 20-Librcria Diaz de Santos, P.O. Box 6050, 28006 MADRID; Balmes 417 y 419, 08022 BARCE· LONE FIJI: The WHO Representative, P.O. Box 113, SUVA FINLAND : Akatccmincn Kirjakauppa, Keskuskatu 2, 00 IOI HELSINKI I O FRANCE: Arnette, 2, rue Casimir-Dclavignc, PARIS 75006 GERMAN DEMOCRATIC REPUBLIC: Buchbaus Leip- zig, Postfach 140, 70 I LEIPZIG GERMANY, FEDERAL REPUBLIC OF: Govi-Vcrlag GmbH, Ginnhcimcrstrasse 20, Postfach 5360, 6236 ESCHBORN - Bucbbandlung Alexander Hom, Kirch- gasse 22, Postfach 3340, 6200 WIESBADEN GRECE: G.C. Eleftberoudakis S.A., Librairic intcr- nationale, rue Nikis 4, 105-63 ATHENES HONG KONG: Hong Kong Government Information Ser- vices, Publication (Sales) Office, Information Services Dcpanment, No. I, Battery Path, Central, HONG KONG HUNGARY: Kultura P.O.B. 149, BUDAPEST 62 ICELAND: Snacbjorn Jonsson & Co., Hafnarstraeti 9, P.O. Box 1131, IS-IOI REYKJAVIK INDIA: WHO Regional Office for South-East Asia, World Health House, lndraprastba Estate, Mahatma Gandhi Road, NEW DELHI 110002 IRAN (ISLAMIC REPUBLIC OF) : Iran U Diversity Press, 85 Park Avenue, P.O. Box 54/SSI, TEHERAN IRELAND : TDC Publishers, 12 Nonh Frederick Street, DUBLIN I (Tel: 744835-749677) ISRAEL: Heiliger & Co., 3 Nathan Strauss Street, JERU- SALEM 94227 ITALIE: Edizioni Minerva Medica, Corso Bramante 83-85, 10126 TURIN; Via Lamarmora 3, 20100 MI- LAN ; Via Spallanzani 9, 00161 ROME JAPAN: Maruzcn Co. Ltd, P.O. Box SOSO, TOKYO Inter- national I 00-31 JORDAN: Jordan Book Centre Co. Ltd., University Street, P.O. Box 301, (AI-Jubciha), AMMAN KENYA: Text Boole Centre Ltd, P.O. Box 47540, NAIROBI KUWAIT: The Kuwait Bookshops Co. Ltd, Tbunayan AI- Ghancm Bldg, P.O. Box 2942, KUWAIT LAO PEOPLE'S DEMOCRATIC REPUBLIC: The WHO Representative, P.O. Box 343, VIENTIANE LUXEMBOURG: Librairic du Centre, 49 bd Royal, LUXEMBOURG MALAYSIA: The WHO Representative, Room 1004, IOth Aoor, Wisma Lim Foo Yong (formerly Fitzpatriclc's Building), Jalan Raja Chulan, KUALA LUMPUR OS-10; P.O. Box 2250, KUALA LUMPUR 01--02 - Parry's Book Center, 124-1 Jalan Tun Sambanthan, P.O. Box 10960, 50730 KUALA LUMPUR MALDIVES: see India, WHO Regional Olli.cc MAROC: Editions La Pone, 281 avenue Mohammed V, RABAT MEXICO: Libreria lntcracadcmica S.A., Av. Sonora 206, 06100-MJ!!:XICO, D.F. MONGOLIA: see India, WHO Regional Olli.cc NEPAL: see India, WHO Regional Olli.cc NETHERLANDS: Medical Books Europe BV, Noordcr- wal 38, 7241 BL LOCHEM NEW ZEALAND: New Zealand Government Printing Olli.cc, Publishing Administration, Private Bag, WEL- LINGTON; Walter Street, WELLINGTON; World Trade Building, Cubacadc, Cuba Street, WELLINGTON. Go•- ernment Bookshops at: Hannaford Bunon Building, Rutland Street, Private Bag, AUCKLAND; I 59 Hereford Street, Private Bag, CHRISTCHURCH; Alexandra Street, P.O. Box 857, HAMILTON; T & G Building, Princes Street, P.O. Box 1104, DUNEDIN- R. Hill & Son Ltd. Ideal House, Cnr Gillies Avenue & Eden St., New-Market, AUCKLAND I NORWAY: Tanum - Karl Joban A.S., P.O. Box 1177, Scntrum, N-0107 OSLO I PAKISTAN: Mirza Boole Agency, 65 Sbahrah- E-Quaid E-Azam, P.O. Box 729, LAHORE 3 PAPUA NEW GUINEA: The WHO Representative, P.O. Box 646, KONEDOBU PHILIPPINES: World Health Organization, Regional Office for the Western Pacific, P.O. Box 2932, MANILA; National Boole Store Inc., 701 Rizal Avenue, P.O. Box 1934, MANILA PORTUGAL: Livraria Rodrigues, 186 Rua do Ouro, LISBOA 2 REPUBLIC OF KOREA: The WHO Representative, Cen- tral P.O. Box 540, SEOUL SAUDI ARABIA: World of Knowledge for Publishing and Distribution, P.O. Box 576, JEDDAH SINGAPORE: The WHO Representative, 144 Moulmein Road, SINGAPORE 1130; Newton P.O. Box 31, SINGA- PORE 9122 SOUTH AFRICA: Contact major book stores SRI LANKA: see India, WHO Regional Olli.cc SUISSE: Medizinischer Verlag Hans Huber, Uinggass- strasse 76, 3012 BERN 9 SWEDEN: For books: Aktiebolagct C.E. Fritzcs Kung!. Hovbokbandcl, Rcgcringsgatan 12, 103 27 STOCK- HOLM. For periodicals: Wcnncrgren-Williams AB, Box 30004, 104 25 STOCKHOLM THAILAND: see India, WHO Regional Office UNITED KINGDOM: H.M. Stationery Olli.cc: 49 High Holbom, LONDON WCIV 6HB; 71 Lothian Road, EDINBURGH EH3 9AZ; 80 Chichester Street, BELFAST BT! 4JY; Brazcnnose Street, MANCHESTER M60 SAS; 258 Broad Street, BIRMINGHAM BI 2HE; Southey House, Wine Street, BRISTOL BS I 2BQ. All mail orders should be sent to: HMSO Publications Centre, SI Nine Elms Lane, LONDON SW8 SDR UNITED STATES OF AMERICA: Copies ofindMdual publications (not subscriptions): WHO Publications Cen- ter USA, 49 Sheridan Avenue, ALBANY, NY 12210. Subscription orders and correspondence concerning sub- scriptions should be addressed to the World Health Or- ganization. Distribution and Sales Service, 1211 GENE- YA 27, Switzerland. Publications are also a•ailable from the United Nations Bookshop, NEW YORK, NY 10017 (retail only) USSR: For readers in the USSR requiring Russian editions: Komsomolskij prospclct 18, Mcdicinskaja Kniga. MOS- COW - For readers outside the USSR requiring Russian editions: Kuzncckij most 18, Mczdunarodnaja Kniga, MOSCOW G-200 VENEZUELA: Librcria M~ica Paris, Apanado 60.681, CARACAS 106 YOUGOSLAVIE: Jugoslovcnska Knjiga, Tcrazijc 27/11, 11000 BEOGRAD ZIMBABWE: Textbook Sales (PVT) Ltd, I Norwich Union Centre, MUTARE Special terms for developing countries are obtainable on application to the WHO Representatives or WHO Regional Offices listed above or to the World Health Organization, Distribution and Sales Service, 1211 Geneva 27. Switzerland. Orders from countries where sales agents have not yet been appointed may also be sent to the Geneva address, but must be paid for in pounds sterling, US dollars, or Swiss francs. Unesco book coupons may also be used. Prices are subject to change without notice. Des conditions speciales sont consenties pour les pays en developpement sur demande adressees aux Representants de l'OMS ou aux Bureaux regionaux de l'OMS enumeres ci-dessus ou bien a !'Organisation mondiale de la Sante, Service de Distribution et de Vente, 1211 Geneve 27, Suisse. Dans les pays ou un depositaire n'a pas encore ete designe, les commandes peuvent etre adressees egalement a Geneve, mais le paiement doit alors etre effectue en francs suisses, en livres sterling ou en dollars des Etats-Unis. On peut egalement utiliser les bons de livres de l'Unesco. Prix sujets a modification sans prliavis. Price Sw. fr. 23.- 8/1/88 Prix: Fr. s. 23. -
World Health Organization (WHO) · Journal articles
Information support to health system development and management = Appui informationnel au développement et à la gestion des systèmes de santé [full issue]
View original document
The full text is hosted by the publishing organisation. lawenc.com indexes the metadata and links to the official source.
Back to article viewFull text
Key facts
Organisation
World Health Organization (WHO)
Document type
Journal articles
Source
World Health Organization