-228-
THE ENDEMIC TREPONEMATOSES: NOT YET ERADICATED A Meheus• & G. M. Antalb
At the beginning of this century endemic treponematoses (yaws, bejel, pinta) were rampant in almost all areas of the tropical belt but occurred as well in some communities in the temperate zone. Typically, the endemic treponematoses were confined to underprivileged population groups in remote areas with little or no access to health care and low standards of hygiene. Disease transmission occurs early in life by direct contact with infectious lesions and, in the case of bejel, also by sharing drinking vessels. The disease persists for years and may lead to gummatous lesions and the destruction of cartilage and bone. Late pinta is less distinctive, but is marked by disfiguring pigmentary changes. The diagnosis is made on clinical grounds but syphilis serological tests are a helpful adjunct. The causative treponemes cannot yet be distinguished from each other or from the treponeme causing venereal syphilis, neither morphologically nor by laboratory tests. During the 1920s and 1930s treatment campaigns against yaws using multiple-dose injections of arsenical preparations and bismuth were launched at hospitals or by mobile units. Results of yaws treatment were spectacular, and a system of rural dispensaries was established to consolidate the results obtained by the mobile teams. In this way, yaws control in Central Africa was the starting point for the system of basic health services (1); the treatment of yaws by injection also firmly established the success of Western-style medicine in tropical countries (2). However, as treatment was limited to clinical cases only, control was not always achieved and by 1950 it was estimated that there were 50 million cases of yaws worldwide. The acceptance by the Second World Health Assembly in 1949 of an epidemiological approach for the control of the endemic treponematoses set the scene for a global control programme under the technical guidance of the World Health Organization (WHO) and with material support from the United Nations Children's Fund (UNICEF). Long-acting penicillin was the "magic bullet" for treatment of yaws, bejel and pinta in a single intramuscular injection. It is estimated that in the course of the worldwide campaigns against endemic treponematoses, approximately 160 million persons were examined during initial treatment surveys and more than 300 million re-examinations were done during re-surveys. In the course of these activities, approximately 50 million persons with clinical and latent infections were treated (3, 4). The control of the endemic treponematoses thus became a major success and the burden of these diseases was drastically reduced (5, 6). From 1965 onwards, control activities were greatly reduced, while the diseases were not yet eradicated. The static rural • Programme Manager, Sexually Transmitted Diseases, Global Pro· gramme on AIDS, World Health Organization, Geneva. b Former Chief, Sexually Transmitted Diseases, Division of Communicable Diseases, World Health Organization, Geneva.
health services were often ineffective in the surveillance of the endemic treponematoses and in the search for and treatment of cases and contacts in the community. As endemic foci remained, the last 20 years have witnessed a resurgence of the endemic treponematoses, in particular in parts of West and Central Africa and in South-East Asia (4, 7, 8). Renewed control efforts are needed, but the lack of financial and technical resources is a major barrier to effective disease control in the most affected areas. Among other important considerations are the following: (i) because of the success of the mass campaigns in the 1950s, endemic treponematoses are thought to be fully under control; (ii) as the diseases are not fatal and are restricted to poor, remote, rural populations, they are not perceived as high-priority problems by many decision makers; (iii) there is the potential for development of resistance of the treponeme against long-acting penicillin; (iv) in areas where endemic treponematoses still occur, health services are inadequate or nonexistent; (v) programmes aiming at a single disease are now frowned upon by the international public health establishment; (vi) the emphasis is now on establishing broad-based primary health care services in currently underserved areas of the world (9). Therefore innovative approaches are needed for renewed control efforts against the endemic treponematoses (10, 11, 12). These diseases can be lastingly controlled and finally eradicated by active community involvement in control activities integrated with the primary health care (PHC) services. Where PHC is inadequate, yaws control can be used as a catalyst to strengthen PHC and drastically increase the utilization of health services (13). Detailed data on endemic treponematoses were last published in 1985 (4); more recent information on the epidemiology of these diseases according to WHO region and epidemiological areas is extensively reviewed in this article. Africa In Mauritania, seroepidemiological studies point to the existence of a large focus of endemic syphilis (bejel) with some persistent transmission in population groups living along the Senegal River (14). In Senegal, Ridet found clinical and serological evidence of continued endemic syphilis (bejel) transmission in populations south of the Senegal River where 2.1% of the children under 15 years of age showed early clinical lesions of the disease and about 14% had serological evidence of treponema! infection - not less than 60% of these were hightitre reactors (>1:16); 70% of adults had serological evidence of past exposure to treponema! infection (15). The endemic area seemed to extend into the Rapp. trimest. statist. sa nit. mond., 45 I1992)
-229departments of Linguere and Kedougou in Eastern Senegal where a much lower disease activity was found. According to Graitcer (unpublished report, 1985) the health services identified 1 119 cases of endemic syphilis (1980) primarily in the districts of Longa, Thies and Eastern Senegal. 60% of cases occurred in children under 15 years of age. Yaws used to be meso- to hypoendemic in the Lower Casamance, an area adjacent to the Gambia and close to the Atlantic Ocean, but disease transmission in this focus may have ceased already (15). The very rare seropositivity in children could be TABLE 1.
attributed to congenital syphilis. However, yaws cases continued to be reported (Table 1) from different areas of the country and there is no explanation for the reported presence of yaws in the same area where endemic syphilis is found. In Guinea hypo- and mesoendemic areas were situated close to the borders with Liberia and Sierra Leone in the humid forest zone. After a mass treatment campaign no cases of yaws were reported until 1983, when a resurgence occurred, during which more than 1 600 active cases were reported. Since then yaws cases have continued to be detected
REPORTED CASES OF ENDEMIC TREPONEMATOSES, 1983-1990"
TABLEAU 1. ,CAS DECLARES DE TREPONEMATOSES ENDEMIQUES, 1983-1990" 1983 1984 1985 1986 1987 1988 1989 1990
Africa -
Afrique 70 3 895 781 117 8 041 732 203 18 235 3 327 485 102 9 226 674 629 1 644 16 109 283 91 246 9 160 1174 224 898 225 31 2 956 260 111 1 730 545 14 5030 1 025 2 173 161 10 468 580 103 4 425 1 236 88 100 5 166 1 404 533 213 127 10 6 594 415 1 687 286 18 2 404 89 3 425 1 553 269 18 790 2 064 187 614 208 2 280 927 265 380 5 639 48 22 234 20 476 17 738 2 428 583 1 503 94 4354
Angola ............................ Benin - Benin ...................... Burkina Faso Yaws- Pian Bejel - Bejel Burundi ............................ Cameroon - Cameroun ............... Central African RepublicbRepublique centrafricaineb ............ Chad- Tchad ....................... Congob Cote d'lvoire Yaws- Pian Bejel - Bejel Equatoria Guinea- Guinee equatoriale ... Ethiopia- Ethiopie .................. Gabonb Ghanab Guinea - Guinee Guinea-Bissau - Guinee-Bissau ......... Mali ............................... Niger .............................. Nigeriab- Nigeria ................... Rwandab ........................... Senegal - Senegal ................... Togob Uganda- Ouganda .................. Zaire- za·ire ........................ Zambia - Zambie .................... •• 0 ••••••• 0 0 •••••••• 0. ••••• 0 ••••••••• 0 0 •••• ••••• 0 0 0 0 0 ••••••• 0 •• 0 ••••• 0. •• 0 ••••• 0. 0 0 0 0 •••••••• ••••• 0 ••••••••• 0 0 •••• 0 •••••••• 0 •• 0 •••••••••••• 0 0. ••• 0 0 0 ••••••••••• 0 0 0 •••••••• •••••••••• 0 •••••••• 0 • 0 0 0 ••••••••••••• 0 0 ••••••••••
585 168 5 223 1 652 3 8 9 314 525 408 70 4 382 697 380
394 342 4 012c 161 4 95 0 1 154 19 3 5 719
210 3 534 59
704 875 189 21 5 729 H7
17c 2 899 4124
25
South-East Asia -
Asie du Sud-Est 588 7 302 422 15 931 339c 2 0 0 0 278
India -lnde ........................ Indonesia - lndonesie ................ Thailand- Tha'ilande .................
Western Pacific -
Pacifique occidental 2 33 833 4 041 492 1 647 411 1 854 2 070 157 11 3063 4165 446 0 3 421 6 477
Fiji- Fidji .......................... Papua New GuineaPapouasie-Nouvelle-Guinee ........... Solomon Islands- lies Salomon ........ Vanuatu ............................ VietNam • 0 ••••••••• 0 ••••••••• 0 0 0 0.
9 664 29 1 927
Americas -
Amerique 16C 21 22 14 136 12 92 23 94 98 78 78 70
Colombia (yaws) - Colombie (pian) ...... Mexico (pinta) - Mexique (pinta) ........
a In general data are compiled from country reports to WHO, consultant and research surveys- En general, les donnees sont etablies envoyes !'OMS, d'enquetes de consultants et de resultats de recherches. b Infectious lesions only- Lesions infectieuses uniquement.
a
a partir de
rapports de pays
c
Provisional data- Donnees provisoires.
Wid hlth statist. quart., 45 ( 1992)
MAP 1. REPARTITION GEOGRAPHIOUE DES TREPONEMATOSES ENDEMIQUES AU DEBUT DES ANNEES 90
GEOGRAPHICAL DISTRIBUTION OF THE ENDEMIC TREPONEMATOSES IN THE EARLY 1990s
CARTE 1.
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~
"' 0: i· ,..
~Yaws- Pian • Endemic syphilis- Syphilis endemique WH092522
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:;·
"
~5.. 8i
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The designations employed and the presentation of material on this map do not imply the expression of any opinion whatsoever on the part of the secretariat of the WHO concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries - Les designations utilis&es sur cette carte et Ia presentation des donnees qui y figurent n'impliquent, de Ia part de !'Organisation mondiale de Ia Sante, aucune prise de position quant au statut juridique de tel ou tel pays, territoire, ville ou zone, ou de ses autorites, ni quant au trace de ses frontieres.
~
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-231-
(Table 1) indicating that yaws transmission is still present to some extent in the former endemic areas. In Liberia low-level yaws transmission was suspected to occur in areas close to the border with Cote d'lvoire, namely Nimba, Grand Bed and Maryland counties; the government considered intensifying anti-yaws activities but was unable to do so owing to lack of financial resources. The present epidemiological situation concerning yaws is unclear and the government is in favour of an epidemiological investigation. In Cote d'lvoire where active surveillance for the endemic treponematoses is being pursued, large numbers of cases of yaws and endemic syphilis are being reported to the Ministry of Public Health (Table 1) - about one-third are infectious lesions. One-third of the cases are reported from four rural provinces: Adzope, Gagnoa, Bondouku and Tissale. In 1991 mass treatment activities were implemented in two regions. In Ghana following the mass penicillin treatment campaign (1955-1965), static health care facilities could not control the spread of yaws in the affected populations. Consequently, active yaws cases increased 21-fold between 1969 and 1976 (16). The three southern regions - Ashanti, Eastern and Central - reported 80% of the yaws cases, with incidence rates between 400 a·nd 500 cases per 100 000 population. The government, in cooperation with the European Economic Community, WHO, UNICEF and USAID launched a yaws/yellow fever programme which also included BCG and tetanus vaccination activities (1981-1983). As a result, yaws was reduced to 62 cases per 100 000 population in the most affected areas. Economic problems in Ghana have limited the continuation of yaws control activities which may result in another resurgence of the disease, particularly in the most remote rural areas. The government is interested in reactivating intensified yaws control activities. Yaws appears to be still highly endemic in Togo (Table 1) where the endemic area is located in the southern region and along the borders with Ghana and Benin. Yaws prevalence rates of 2-3.5% were reported from the 5 most affected prefectures (lacs, Vo, Yoo, Kloto and Bassar).c In Benin yaws is endemic in the provinces of Mono, Atlantique and Oueme in the .south of the country. A survey in Oueme province found 1.7% of children suffering from infectious yaws lesions (17) and serareactor levels of 19%. About 3 000 yaws cases are detected annually (Table 1) indicating continued yaws transmission in the affected areas. Yaws control is limited to the activities of the fixed health care facilities which are often far away from the remote yaws endemic areas. An endemic syphilis (bejel) focus is suspected to exist in the north of the country. The yaws control programme in Nigeria is part of the federally operated sexually transmitted disease (STD) control programme which is now integrated with the AIDS control programme. Yaws cases continue to be reported from many areas of the country, including from those areas where the disease is
known not to exist, indicating the diminishing competence of medical staff to identify yaws cases. Small-scale epidemics continue to be reported from communities in the south of the country, in Bendel and Cross River States (M. 0. Alii, unpublished report, 1986) including a small outbreak close to Lagos (0. Ogunnowo, personal communication, 1988). where active surveillance is required to delineate and control a still simmering yaws endemicity. A bejel endemic area still exists in the department of Oudalan in the north of Burkina Faso; Oudalan is a semi-desert area of about 10 000 km 2 with a population of approximately 50 000. This area is adjacent to the bejel-endemic area of Gao in Mali (see below). Several studies found about 7% of children between 5 and 14 years of age with early bejel lesions; up to 22% of children and 41% of adults showed serological evidence of treponema! infection. Nomadic and semi-nomadic ethnic groups (e.g. Fulani, Tuaregs, Bellahs) were most affected by bejel. There has been little change in transmission levels over the past years (18). A yaws-endemic area is located in the south-west of the country, a savannah area with approximately 1.1 million inhabitants. An epidemiological investigation identified the area of Gaoua as the focus of yaws transmission, with 3.9% of children suffering from infectious yaws lesions and 11.6% showing serological evidence of treponema I infection (19). For most years no separate data are available for endemic syphilis (Table 1) since venereal and endemic syphilis (bejel) are reported as a single disease entity. The government sees the endemic treponematoses as a public health problem but lacks resources for their definite control. There are three distinct foci of endemic syphilis in the Sahel ian zone of Mali: a meso-endemic area is situated in the Senegal river basin in the west of the country; it includes 7 districts (1.5 million inhabitants) in the regions of Kays and to the north of Koulikoro, where 19% of children aged 5-9 years were found to be infected by the treponeme. Another focus of infection (0.6 million inhabitants) is associated with the Dogon tribe which lives on the cliffs of Bandiagara in the Mopti region in the centre of Mali (Ministry of public health, unpublished report, 1986). The most important bejel endemic area extends over 10 districts with 1.1 million inhabitants along the river Niger in the regions of Timbuktu and Gao. In preparation for a mass-treatment campaign, an epidemiological study (20) confirmed bejel to be hyperendemic in this area. More than one-fifth of the children between 5 and 14 years were found to be infected, and in more than half the infection was still active. A mass treatment campaign was implemented (1987-1988) in collaboration with Medecins sans frontieres. An attempt was made to evaluate different serological parameters for their efficacy in measuring the impact of mass treatment by a standard single-dose penicillin regimen on treponema! endemicity in the child population (5-15 years). A comparison· of two serum collections drawn randomly from the same population groups before therapy and 12 months later showed that the demonstration of the disappearance of treponema! lgM (present in active disease) by the solid-phase haemadsorption assay (SPHA) is the most sensitive indicator; but the test is complicated and costly.
'World Health Organization. Yaws and other endemic treponematoses. Report of a regional meeting, Brazzaville, 3-6 February 1986. (Unpublished document AFR/CD/58).
Wid hlth statist. quart., 45 (19921
-232However, a more practical indicator was shown to be a change in seroprevalence of high-titre VDRL reactors (>1.8, or better >1:16) among children who respond to the therapy by converting to a negative serological test (Table 2). Now, the government would like to continue and extend campaign activities. A yaws-endemic area used to exist in the districts of Bougouni and Sikasso in south-west Mali, an area bordering on Burkina Faso, Cote d'lvoire and Guinea. The Ministry of Public Health (unpublished report, 1986) believes that yaws transmission has ceased, as no clinical cases of yaws nor any serareactor could be detected among children under 10 yearsofage. Endemic syphilis (bejel) is found among the Tuareg and Bellah in the north of Niger: there are about 800 000 Tuaregs for whom the government conducts annual treatment clinics in several northern villages at the time the nomads congregate. Over 9 000 bejel cases were reported in 1983; most were from the northern departments of Agadez, Arlit and Tchintabaraden. Financial limitations curtailed these treatment activities and reduced the number of reported bejel cases drastically (Table 1). In 1990 medical authorities resumed treatment activities at one gathering place of the Tuareg and expressed their interest in launching a bejel control programme among the nomadic groups in the desert area. There are anecdotal reports of numerous bejel cases in the northern part of Chad where war-like conditions have curtailed control activities. Several thousand yaws cases are reported annually from Cameroon (Table 1). The data were reviewed recently by Louis et al. (21). Most cases occurred in south-west Cameroon which is close to the Cross River State of Nigeria and may form a common yaws-endemic area. Another yaws-endemic area is located close to the border with Gabon, Congo and the Central African Republic where itinerant pygmy populations are heavily infected. Not less than 480 yaws cases were found among 653 pygmies examined (WHO/AFRO, unpublished report, 1992). Pygmy groups represent an important source of infection for the sedentary populations with which they come into contact. The health administration has no specific plan for the control of this infection. In Gabon yaws is endemic in the north (Woleu-Ntem Province) and is said to be primarily confined to itinerant pygmy groups which move freely across the border with Equatorial Guinea, Cameroon and the Congo. Reports on a recent increase of yaws in Ngounie Province have been investigated and results are awaited. Also in the Central African Republic yaws infections are predominantly found among the pygmies of the rain-forest area in the south of the country. In the course of treatment surveys carried out among pygmies in Sangha and Lobaye provinces, R. WidyWirski (unpublished report, 1986) identified active yaws lesions in 41% of 1 005 pygmies and more than 75% had serological evidence of active disease. An increase of reported yaws cases has been noted in recent years (Table 1). A health education campaign is currently being undertaken among pygmies. In Congo most yaws cases occur among the pygmies and are reported from the provinces of Likouala and Sanghia; and from the southern part of the country, Lekoumou and Kouilou. The first two areas are adjacent to the yaws-endemic areas in Cameroon, Gabon and the Central African Republic (Ministry of Public Health, unpublished report, 1985). Several surveys carried out in Likouala confirm very high rates of clinical yaws among pygmies (22). Plans have been drawn up for a yaws control programme in the north of the country. Yaws was thought to have been eliminated from Zaire since the early 1960s. However, the disruption of health care services and economic deprivation have made it difficult for the population to maintain personal hygiene and have led to an environment favourable to the transmission of the endemic treponematoses. Two recent surveys identified yawsendemic foci in Ubangi in the north-west of the country, not far from Bangui, Central African Republic, and in the lturi forest area in the north-east of Zaire (23, 24). In the former, focus cases with infectious yaws lesions were seen in 11% of the children under 15 years of age in this sedentary population. In lturi, yaws was found at a high rate among pygmies. WHO received a request to collaborate in the training of laboratory and other health personnel to be involved in planned yaws control activities. More than 200 yaws cases are reported annually from Rwanda (Table 1). Health authorities believe that the disease problem can be controlled by routine health service activities. In Sudan yaws is suspected to be still endemic in the southern regions of Equatoria, Bahr-ei-Ghazal and Upper Nile; but this area cannot be surveyed because of civil unrest. Some low-level endemicity
TABLE 2. VALUE OF DIFFERENT SEROLOGICAL TESTS IN EVALUATING THE IMPACT OF A MASS TREATMENT CAMPAIGN AGAINST ENDEMIC TREPONEMATOSES, IMBUKTU REGION, MALl TABLEAU 2. RESULTATS DE DIFFERENT$ TESTS SEROLOGIQUES UTILISES POUR EVALUER L'IMPACT D'UNE CAMPAGNE DE TRAITEMENT DE MASSE CONTRE LES TREPONEMATOSES ENDEMIQUES, REGION D'IMBUKTU, MALl 1987 1988
%
%
Ratio- Rapport 1987 1988
p
SPHA-IgM .................................... . Qualitative VORL- VORL qualitatif ................ . Quantitative VORL- VORL quantitatif {Titre~ 1:8) .... . Quantitative VORL- VORL quantitatif {Titre~ 1:16) ... . Quantitative TPHA- TPHA quantitatif {Titre~ 1:1280) .. Quantitative TPHA- TPHA quantitatif {Titre~ 1:10240) .
11.5 20.1 16.0 14.1 18.7 8.2
2.7 16.6 5.7 3.1 18.0 4.1
4.3 1.2 2.8 4.5 1.0 2.0
<0.0001 NS <0.001 <0.001 NS 0.035
Rapp. trimest. statist. san it. mond., 45 ( 1992)
-233of endemic syphilis exists in the Northern Region (Nuba mountains).d In Ethiopia an organized yaws campaign took place in the south and south-west of the country in the 1950s. No subsequent information on the epidemiological situation became available until a small survey of some villages in the Wellaga and lllubabor administrative regions in the south-west of the country was carried out in 1986 as part of a viral survey programme. Not less than 68% of 227 children tested showed serological evidence of treponema! infection, and infectious yaws lesions could be observed in 10 of 200 children in one area (25). This focus may well be a part of the yawsendemic area in Sudan. Although Angola was assumed to 'be free from yaws, it reported 70 cases of the disease in 1988 (Table 1).c A recent observation (26) of an unexplained positive syphilis serology in sera collected from 1 575 healthy black primary school children in Bloemfontein South Africa led the investigators to reflect on the possible existence of endemic syphilis in the population of the black township. Similar observations of what was believed to be endemic treponematosis had been made in black communities in Bloemfontein and the Cape Province. Two treponema! diseases which are similar to or identical with endemic syphilis and bejel existed in Bantu populations of Botswana (dichuchwa) and Zimbabwe (njovera). Dichuchwa may still be prevalent among the bushmen of the Kalahari desert, but njovera is no longer encountered (Latif, personal communication, 1992). Pakistan; 43 cases of infectious lesions were detected among 2 000 persons. Cases tested by VDRL were found to be reactive.
South-East Asia The present yaws situation in India is not entirely clear. An enquiry made into the extent of the yaws problem in Central India in 1985 showed that in at least 10 districts of 3 states (Andhra Pradesh, Orissa and Medhya Pradesh), low-level disease transmission was continuing. 1 349 yaws cases were reported from this area over a 2 1/2-year period (1983 to June 1985). Yaws endemicity appears to be associated with certain tribal groups and some degrees of inaccessibility. There may be some additional pockets of endemic treponematosis in Tamil Nadu, the North-East Frontier States and Gujarat (29). In Sri Lanka few yaws cases (2 cases in 1982; 9 cases in 1983) are reported from two areas of low socioeconomic status; the north-central plains and the adjacent lower part of the hill country and an area in the south of the country (30). The disease is being kept under surveillance by anti-malaria teams which are active in this area. Yaws appears to have been eliminated from Thailand, except for the occasional small outbreaks in the border area with Malaysia. Owing to rapid mop-up operations, these epidemics could be contained within a short period of time. By the early 1950s the estimated total number of yaws cases was about 12 million (i.e. mean prevalence 15%), making Indonesia the second largest focus of yaws in the world .(after Africa). A WHO/ UNICEF-sponsored national yaws control programme did not rely on a vertical approach and the use of mobile field teams but established 2 500 district teams to cover all 26 yaws-endemic provinces. Since its implementation yaws control activities were continued with varying intensity and changing control approaches. Yaws could be reduced to negligible levels indeed in 12 provinces including Java, Bali, major parts of Kalimantan and Sulawesi, but is still of considerable prevalence in the rural areas in the eastern and western parts of Kalimantan, the island of Sumatra, the Moluccas, Timor and in particular in Irian Jaya. In the latter area, yaws transmission is still quite intensive in the remote tribal areas, while among the new settlers originating from other parts of the country yaws is rarely observed. It may be estimated that since the onset of organized yaws control activities, the population living in yaws-endemic areas and therefore being exposed to yaws infection declined from 92 million to 35 million. The latest data available refer to 1984 when 15 931 infectious yaws cases were reported from 22 of the 27 provinces (31). There is little doubt that yaws still constitutes a major health problem in large parts of the population living in remote and economically depressed areas. A yaws control campaign was launched in 1991 in East Timor with support from UNICEF (Meheus, unpublished r~port, 1991).
Eastern Mediterranean d Yaws was reported (1955) from the lowlands between the Juba and Shabelle rivers in the south of Somalia, but no studies were undertaken to confirm the existence and extent of the disease. Bejel is suspected to occur among the Bedouin in the North. In the arid areas of Hijaz and Asir in Saudi Arabia, bejel was endemic among the nomatic and seminomadic Bedouin. Two recent studies (27, 28) found clinical and serological evidence of possibly no longer active foci of a nonvenereal treponematosis (bejel) in the north-west and south-west of the country. In the Syrian Arab Republic the disease has virtually disappeared after an eradication campaign in the 1950s in bejel-endemic north-eastern provinces of Deir-Ezzor, Hassaka and Ragga, and surveillance activities which continued for 8 years. A seroepidemiological survey carried out in Iraq on 102 children aged 7-14 years in the Amara region demonstrated that bejel transmission has ceased in this area for some time. Moreover, information on the situation regarding bejel in the western Euphrates valley and Mosul indicates that no bejel case had been seen for the last 20-30 years. A focus of endemic syphilis was discovered recently in a remote area in the north-western part of
Western Pacific d
World Health Organization. Regional meeting on endemic treponematoses, Amman, Jordan 20-23 October 1986. (Unpublished document EM/CD/36-E).
After a vertical treatment campaign in the early 1960s, yaws was considered eradicated from
Wid hlth statist. quart., 45 ( 1992)
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Cambodia. Subsequently there were anecdotal reports of skin lesions believed to .b~ ya.ws bei.ng seen among Cambobian refugees arnvmg m Tha1land. In 1986 Cambodia reported 4 858 cases of clinical yaws. Considering the inadequacy of the health service infrastructure at that time and the limited diagnostic capabilities for this "end-of-the-road disease" it may be reasonably assumed that the number of reported cases does not reflect the true extent of the disease problem. During a consultation, R. Widy-Wirski (unpublished report, 1987) observed several villages with children having active yaws lesions. He also found high seroreactor rates in both children and adults, indicating a recent resurgence of yaws transmission in certain communities. Antiyaws activities were implemented in military secure areas of Kampong Speu, Kampong Chhang, and Siem Reap province between 1987 and 1991. During this period 1 935 yaws cases were treated. In Papua New Guinea yaws was deemed to be under control as a result of the nationwide total mass treatment campaign in the late 1950s and limited regional efforts in the late 1970s. However, various investigations since 1978 confirmed a resurgence of yaws infection in the North of the country (East & West Sepik, Karkar Island) and Papua (East New Britain, New Ireland, North Solomon) with isolated pockets of high clinical and serological prevalence being encountered often. 833 yaws cases were reported in 1984 (32). By 1989 the number of reported cases had quadrupled (Table 1). Of serious concern are observations from Papua New Guinea and the Solomon Islands of diminished response to treatment with repository penicillin and the persistence of yaws transmission despite intensive treatment of cases and contacts. The possible emergence of Treponema pertenue strains with reduced susceptibility to penicillin needs to be investigated. Yaws prevalence in the Solomon Islands was the highest among the Pacific Islands. Following the WHO/UNICEF-supported national yaws treatment campaign and subsequent surveillance activities (1956-1970), yaws was thought to have been eliminated and transmission interrupted. In 1981 many cases of skin lesions were observed in the Western Province. A serological investigation confirmed these lesions to be due to yaws. It was speculated that yaws had been reintroduced from a yaws-endemic area in Papua New Guinea. In 1984 a mass treatment campaign was launched which examined 29 135 people and identified 4 041 active yaws cases, predominantly in children. Subsequent to this campaign, yaws reappeared in the same area and led to a further yaws treatment campaign with the assistance of the New Zealand Army in 1987. 2 070 active yaws cases were detected among the 24 216 inhabitants of the yaws-endemic area (33). In response to a renewed yaws epidemic, another treatment campaign was carried out in 1991.
unpublished report, 1992) the infection may spread again from there to the rest of the population. Americas Until the first half of this century, yaws and pinta represented an important public health problem in several countries of Latin America and the Caribbean. In most of the endemic areas, yaws and pinta were eradicated through national mass treatment campaigns. Unfortunately, pockets of these two endemic treponematoses still exist in remote areas of some countries (S. Talhari, unpublished report, 1988). In Suriname yaws appears to be still endemic among the black populations living in the interior of the country, where over 10% of rural schoolchildren had a positive syphilis test in 1980. Few clinical yaws cases from the interior seek care in the capital city, and civil unrest in the interior prevented the implementation of control activities. Low-level yaws transmission persists in Guyana where between 1979 and 1984 the leprosy service identified 36 yaws cases. In Venezuela no yaws cases have been identified for the last 15 years. The disease is regarded as being eradicated. However, between 1983 and 1985, 24 pinta cases were reported, and pinta transmission is going on among Indian populations close to the border with Colombia. In Panama yaws cases have not been observed since 1980 and the disease can be regarded as having been eradicated, but the eradication of pinta is less certain. As recently as 1988 some foci of yaws were detected by R. Widy-Wirski (unpublished report, 1988) in the course of surveys for HIV infection among rural populations in Haiti. Two cases of early yaws reported in pregnant women in Martinique (35) give evidence of continued low-level endemicity of this treponematosis. In Mexico pinta was endemic predominantly in the states of Guerrero, Michoacan, Chiapas and Oaxaca. In the course of a national pinta campaign, which was deactivated in 1983, over 250 000 pinta cases were· traced and treated. In the state of Michoacan the disease is thought to have been eradicated. Active pinta surveillance is maintained in the state of Oaxaca only. While pinta does not represent a public health problem now, low-level disease transmission is continuing (Table 1) in the remote pinta-endemic areas which may offset some of the gains achieved by the control programme. Yaws is still endemic in communities along the Pacific coastal area of Colombia where an integrated active surveillance programme is operational. A disturbing increase in reported yaws cases has been noted in recent years (Table 1). In addition, yaws cases are reported from other endemic areas of the country. In Brazil no new yaws infections have been seen for several years. Pinta is now rarely seen among Indians in the Western Amazonas region and along the tributaries of the Rio Negro. Rapp. trimest. statist. sanit. mond., 45 (1992)
Vanuatu (the former New Hebrides) continued to report yaws cases (495 cases in 1985); most were from Tanna Islands and some from Espiritu Santo. With the help of the New Zealand Army, a mass examination and treatment programme was carried out on Tanna Island in 1989. Among 18 223 people examined 464 suspected yaws cases were found, of which 23% could be serologically confirmed, bringing the prevalence of clinical yaws cases to less than 1% (34). Two years later a considerable number of yaws cases were again reported from Tanna Island from villages which had refused to participate in the recent control programme (W.I. van der Meijden,
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The last foci of endemic syphilis were located in rural Bosnia and among Moslem Turkish farmers in Bulgaria. With the advent of penicillin therapy a mass treatment campaign was implemented in Bosnia in 1948. This campaign was the model for the epidemiological approaches applied in subsequent mass treatment campaigns against the endemic treponematoses all over the world. In surveys and resurveys 35 238 cases of endemic syphilis were treated. The campaign resulted in the eradication of the disease in 1951 (36).
The little known focus in Bulgaria was also successfully controlled by a case-treatment campaign (19581962). A follow-up study confirmed that complete interruption of treponema! transmission has been achieved (37). Acknowledgement
The authors wish to thank their colleagues in the Regional Offices for their collaboration in gatherall the information, and in particular ing Dr D. Barakamfitiye and Dr G. Petersen for providing detailed data.
SUMMARY The endemic treponematoses which comprise yaws, endemic syphilis (bejel) and pinta constitute a group of potentially disabling and disfiguring infections which primarily afflict children in tropical and subtropical areas. Foci where these diseases are now endemic have a patchy distribution and are typically confined to underprivileged communities living in remote rural areas, with little or no access to health services and removed from the mainstream of socioeconomic development. A drastic decline in the prevalence of these infections was brought about by the implementation of mass treatment campaigns with penicillin under the· technical guidance of WHO and with material sup.!ooo. port from UNICEF in the 1950s and 1960s. These worldwide campaigns against the endemic treponematoses halted disease transmission in many areas and held the promise of complete eradication if intensive surveillance could be continued for some time with the increasing involvement of the basic health services. National campaigns were so successful that relatively low priority was given to the preparation of the rural health services for this new task. The failure of many countries to integrate active control measures into the functions of the rural health services led to the gradual build-up and extension of treponema! reservoirs and the resurgence of foci of increased disease transmission particularly in communities where standards of hygiene and health care had remained low. In a number of former endemic foci only low-level transmission persisted; in a few areas disease prevalence increased dramatically to reach pre-campaign levels. The lack of technical and financial resources limited the success of renewed national control activities in the most affected areas. Today, with waning interest in these diseases confined to remote, and thus silent, population groups, and a decreasing ability of health staff to identify cases, data collected by countries need to be supplemented by information from other sources in order to arrive at a more valid assessment of the situation concerning the endemic treponematoses. Central and West Africa are most severely affected by the resurgence of the endemic treponematoses. In recent years a number of countries (e.g. Ghana, Cote d'lvoire and Mali) have launched renewed control efforts, often combining yaws or endemic syphilis control with other public health programmes. In Central Africa itinerant pygmy groups are still highly affected by yaws and are an important source of infection for the sedentary population with which they come into contact. In Chad, Sudan and Ethiopia, there is some evidence of persistent foci of endemic treponematoses; the epidemiological situation in Southern Africa is not well established. In the Eastern Mediterranean, bejel has been eliminated from most areas, but foci of infection have been reported in remote villages in Pakistan, and some endemic syphilis transmission might still prevail in nomadic people of the Arabian peninsula. Health officials in South-East Asia and the Pacific Islands have documented remaining foci of yaws in at least 7 Member States, including several outbreaks in the Solomon Islands. Indonesia has made dramatic progress in yaws control but widely dispersed foci of infection still persist, particularly in Irian Jaya, the Moluccas, Sumatra and Kalimantan. In the Americas, yaws incidence is very low with very small foci remaining in Suriname, Guyana, Colombia and some islands of the Caribbean. Pinta cases are still detected in Indian tribes of Mexico and the Amazon basin.
RESUME Les treponematoses endemiques: pas encore d'eradication Les treponematoses endemiques qui comprennent le pian, le bejel (syphilis endemique) et Ia pinta constituent un groupe d'infections potentiellement invaliWid hlth statist. quart., 45 (1992)
dantes ou defigurantes qui frappent avant tout !'enfant dans les regions tropicales et subtropicales. Les foyers actuels d'endemie sont repartis irreguliere-
-236ment et se limitent gemeralement aux communautes detavorisees vivant dans des zones rurales reculees a l'ecart du developpement socio-economique et dans lesquelles l'acces aux services de sante est difficile ou inexistant. Les campagnes de traitement de masse menees au moyen de Ia penicilline avec l'appui materiel de I'UNICEF au cours des annees 50 et 60 ont entraine un declin spectaculaire de Ia prevalence de ces infections. Les campagnes mondiales contre les treponematoses endemiques ont permis d'interrompre Ia transmission dans de nombreuses regions et laisse entrevoir Ia possibilite d'une eradication complete si une surveillance intensive pouvait etre maintenue assez longtemps avec Ia participation croissante des services de sante de base. Les campagnes nationales ont connu un tel succes que Ia preparation des services de sante ruraux a cette nouvelle tache est apparue comme mains prioritaire. Beaucoup de pays n'ayant pas integre de mesures de lutte actives aux services de sante ruraux, on a assiste a une extension et a un renforcement progressifs des reservoirs a treponemes ainsi qu'a Ia resurgence de foyers de transmission accrue, notamment dans les communautes ou les normes d'hygiene et de soins de sante restent peu developpees. Dans plusieurs anciens foyers d'endemie, on n'observe qu'une persistance de Ia transmission a un faible niveau, mais parfois Ia prevalence a augmente de fa~on spectaculaire pour se retrouver au niveau d'avant les campagnes. Le manque de ressources techniques et financieres a limite le succes des nouvelles activites nationales de lutte dans Ia plupart des regions touchees. Aujourd'hui, ces maladies qui se limitent a des zones reculees et a des groupes incapables de faire entendre leur voix suscitent mains d'interet et les agents de sante savent de mains en mains les reconnaitre. Les donnees reunies par les pays doivent done etre completees par des informations emanant d'autres sources pour permettre une evaluation plus precise de Ia situation des treponematoses endemiques. Les regions les plus touchees par Ia resurgence sont I' Afrique centrale et occidentale. Ces dernieres annees, plusieurs pays, par exemple le Ghana, Ia Cote d'lvoire et le Mali, ont lance de nouveaux efforts de lutte en rattachant souvent Ia lutte contre le pian ou Ia syphilis endemique a d'autres programmes de sante publique. En Afrique centrale, les groupes itinerants de pygmees sont encore tres touches par le pian et constituent une importante source d'infection pour Ia population sedentaire avec laquelle ils entrent en contact. Au Tchad, au Soudan et en Ethiopie, certaines indications temoignent de Ia persistance de foyers de treponematoses endemiques; Ia situation epidemiologique en Afrique australe n'est pas connue avec precision. En Mediterranee orientale, le bejel a ete elimine dans Ia plupart des zones, mais des foyers d'infection ont ete signales dans des villages recules du Pakistan, et il. est possible que Ia transmission de Ia syphilis endemique subsiste chez les nomades de Ia peninsule arabique. Les responsables de Ia sante en Asie du Sud-Est et dans les lies du Pacifique ont fait etat de foyers de pian qui se maintiennent dans 7 Etats Membres au mains, plusieurs poussees ayant ete notamment observees aux lies Salomon. L'lndonesie a fait des progres spectaculaires dans Ia lutte contre le pian, mais des foyers d'infection tres disperses subsistent notamment en Irian Jaya, dans les Moluques, a Sumatra et a Kalimantan. Dans les Ameriques, !'incidence du pian est tres faible et seuls des foyers reduits subsistent au Suriname, en Guyana, en Colombie et dans certaines lies des Cara"ibes. On observe encore des cas de pinta chez des populations indiennes du Mexique et d'Amazonie.
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