Scientific and Technical Advisory Committee: report of the fourth meeting, Geneva, 2-4 November 1976

ocefsrecft 6.2 Rev. I ENGLISH ONLY ONCHOCERCIASIS CONTROL PROGRAMME IN THE VOLTA RIVER BASIN AREA SCIENTIFIC AND TECHNICAL ADVISORY COMMITTEE Re rt of the fourth meetin Geneva 2-4 November 1976 2LIST OF PARTICIPANTS I'{embers of the Committee Dr Colvin Gibson, 3307 Harrell Street, Wheaton, Maryland 20906, United States of Amer ic a . Dr Peter Haskell, Director, Centre for Overseas Pest Research, College House, Wrights Lane, London W8 5SJ, United Kingdorn of Great Britain and Northern Ireland. Dr Pieter Janssens, VogelzanE, 12, 22321 s Gravenwezel, Belgium. Dr Hermann Knuttgen, Director, Institute of Tropical Medicine, University of TUbingen, TUbingen, Federal Republic of Germany. Dr Friedrich Kuhlow, Director, Department of EntomoLogy, Bernhard-Nocht-Strasse, Institute of I'laritime and Tropical Diseases, Bernhard-Nocht-Strasse 74, 2 Hamburg 4, Federal Republic of Germany. Dr Marshall Laird, Director, Research Unit on Vector Pathology, Memorial University of Newfoundland, St Johnts, Newfoundland, Canada AlC 557. Dr Christiaan Lucasse, Chief, Department of Microbiology, Institute of Tropical Hygiene, Mauritskade 57, Amsterdam, Netherlands. Dr James I'li1es, Chief , Pesticides Branch, Tropical Diseases, Department of Health, United States of America. Dr Jean Mouchet, lnspecteur g6n6ral de Recherche, 0ffice de 1a Recherche scientifique et technique outre-mer, Services scientifiques centraux, 7O-74, Route drAulnay, 93140 Bondy, Franc e. Dr George S. Nelsonr'k Director, and Tropical Medicine, KePPel Northern Ireland. Department of Medical HeLminthoLogy, London School of Hygiene Street, London WCIE 7HT, United Kingdom of Great Britain and Dr Letitia E. Obeng, (Director, lnstitute of Aquatic Biology, Ghana) c/o United Nations Environment Progranrne, P.O. Box 30552, Nairobi, Kenya' Dr Felix Serie, Directeur g6n6ra1 de 1a Sant6 publique, Ministbre de la Sant6 publique, Boite postale 8023, Cocody -Abidjan , Ivory Coast. Economic Development Adviso ry Panel (EDAP) Mr p. M. Henry, (Chairman), Development Centre, OrganizaLi:on for Economic Cooperation and DevelopmenL, 94, rue Chardon-Lagache, 75016 Paris Cedex, France. Mr W. de Souza, (Secretary), Development Centre, Organtzation for Economic Cooperation and DevelopmenL, 94, rue Chardon-Lagache, Ecological Panel (EP) Dr E. B. Worthington, International Biological Programme, Publications CournitEee, The Linnean Society, Burlington House, London w.1., united Kingdom of Great Britain and Northern Ireland. Temporary Adviser Dr R. Garms, Department of Entomology, Bernhard-Nocht-Strasse, Institute of Maritime and Tropical Diseases, Bernhard-Nocht-Strasse 74, 2 Hamburg 4, Federal Republic of Germany. WHO Secretati-at Vector Biology and Control Division, Bureau of Education and Welfare, Atlanta, Georgia 30333, 75016 Paris Cedex , France. Dr T. Lepes, Director, Division of Malaria and other Parasitic Diseases, Onchocerciasis Control Progranrne in headquarters, Geneva, Switzerland, meeting ) responsible for the(Secretary of the J,i Dr Nelson was unable to attend the meeting. 3WHO Secretariat (continued) Dr B. 0. L. Duke, Senior Medical Officer, Division of Malaria and other Parasitic Diseases, Headquarters, @, Switzerland. l'1r J. Duppenthaler, StatisE.ician, Onchocerciasis Control Progranrne, Headquarters, Geneva, Swiczerland. Dr P. Kramer, I"ledicaL OtftcerfEpidemiologist, Chief, Onchocerciasis Epidemiology and Public Health, Onchocerciasis Control Progranme, Ouagadougou Upper Volta. Dr R. Le Berre, Scientist/Entomologist, Chief, Vector Control Unit, Onchocerciasis ConErol Programme, Ouagadougou, Upper Vo1ta. Dr E. de Maar, Medical Officer, Special Progranrne for Research and Training in Tropical Diseases, Headquarters, Geneva, Switzerland. Mr J. D. M. l"Iarr, Entomologlst/niologist, Onchocerciasis Control Programme, Headquarters, Geneva, Switzerland. Dr E. Onori, Medical OtfrcerfEpidemiologist, Onchocerciasis Control Progranrne, Headquarters, 9=."*, Switzerland. Dr C. Pant, Entomologist, Ecology and Control of Vectors, Division of Vector Biology and Control, Headquarters, Geneva, Switzerland. Mr G. Quelennec, Entomologi-st/Chemist, Onchocerciasis Control Prograrmne, Headquarters, Geneva, Switzerland. Dr H. Ramamonjy-Ratrimo, Regional Adviser, Prevention and Control of Diseases, Regional 0ffice for Africa, BrazzaviLle , Congo. Mr F. Walsh, Entomologist, Onchocerciasis Control Prograrmne, Ouagadougou , Upper Vo1ta. 4A. OPENING OF THE MEETING l. The fourth meeting of rhe Scientific and Technical Advisory Cormnittee \^ras held in Geneva from 2 to 4 November L976. The meeting was opened by Dr T. Lepes who i.nformed the Cornmittee that Dr G. Nelson was unable to attend; Dr Lepes welcomed the representatives of the Economi-c Development Advisory Panel and the Ecological Panel. 2. Recent changes in the management structure of OCP were described. With the retirement of Dr Bellerive on 30 June 1976, the Director-General had appointed Dr Lepes as focal point for WHO headquarters support to the Programme. In line with the Organizationrs general policy for intercountry prograflmes, the overall responsibility for the Onchocerciasis Control Progranrne had been transferred to the WHO Regional Office for Africa , Brazzaville and, as a result, the support provided by WHO headquarters was being modified. A new Prograrmne Director, I"1r M. BazLn, (later introduced to the Conrnittee), would take over from Dr P. ZiegLer in December 1976. Dr Ziegler would takeup new responsibilities thereafter. As far as STAC and the other advisory bodies r^7ere concerned, meetings would be held more frequently in Africa which would afford greater opportunity for members to become acquainted with the activities and problems of the Prograrmne. 3. The Committee was also informed that a Scientiflc Advisory Panel (SAP) Working Group had met the previous week to consider the reinvasion problem. Dr P. Haskell who had chaired the Working Group would report to the meeting. B. ELECTION OF CHAIRMAN 4. Dr P. Janssens was elected Chairman of the meeting. appointed rapporteurs. Drs C. Gibson and F. Kuhlow were C. ADOPTION OF THE AGENDA 5. The provisional agenda (Annex I) was adopted with the addition of an item on'rResearch f undingrr. D. PROGRESS REPORT ON ENTOMOLOGICAL ACTIVITIES 6. WHO provided the Committee with a comprehensive report on the entomologi-cal activities carried out in 1976 as well as a review of the overall results obtained in Phases I and II since the beginning of insecticide treatment. The operarions had been generally successful except for a few sites where complete control was not always achieved. In such insEances action was taken inrnediately to avoid the vector becoming re-established. Accordingly, fly numbers had been reduced to a level where no transmission could be detected. In fact in some parts of Phase II no S. damnosum had been recorded at all. The Cormnittee was also informed that during the dry season the situation was such that treatment could be inter- rupted on certain stretches of rivers for varying periods, resulting in a substantial reduction in the amount of insecticide utilized. 7. At a site on the Black Volta river where the rtBillerr cytoEype predominated before control, treatment vras interrupted to determine whether this cytotype had been definitely eliminated from the area. This was confirmed when only the 'rSirbarr cytotypes became re-established. New breeding places found in a recently developed rice growing area near Bobo-Dioulasso had been the object of special study on the biology of the vector. It was found that S. damnosum decreased considerably without chemical control when subjected to intensive trapping. 8. To facilitaEe the entomological assessment, reference was made to sEudies in Cameroon and Ivory Coast where a hypoendemic situation r{as related to a potential transmi-ssion of less than 5OO infective stage larvae per year, mesoendemic to a transmission of 5OO-1OO0 larvae and a hyperendemic situation to a transmission of more than 1OOO. Using these criteria to 5determine transmission intensity, in 1975 Phase I had only three areas hrhererrhyperendemicrl levels of transmission were recordedl two of these were in the reinvasion zone. In L976, these same areas of reinfestation not only diminished in size but transmission was reduced to a rrmesoendemic" 1eve1. 9. On 14 January 1976 operations started in Phase II. Difficulties encountered during the rainy season due to the very large daily fluctuations in the discharge of the river necessitated adaptation of the system of treatment to ensure satisfactory control. pilots were accompanied on these treatment flights by technical staff so that on-the-spot decisions could be made on how to deal with each individual situation. 10. i"lith regard to Phase III, the Conmrittee was informed that spraying operations were due to commence in February L977. Adequate control of the western zone before the possible onset of reinvasion in the Phase I area may contribute to the elimination of potential sources of invading flies. In the eastern zone control would be restricted initially to the Oti and its tributaries until the tributaries of the Niger began to flow. 11. In order to determine whether the invading flies come from south of the progranrne area, an experimental treatment of the lower Bandama south of Kossou Dam was carried out during a six-week period. The local biting-fly population was effectively reduced from overlooo per day to less than 10, this 1evel being retained for several months after treatment stopped. However, in the reinvasion zone, t.he fly densities persisted at a high level inthe Leraba valley and on the Upper Bandama. L2. WHO informed the Conrnittee of the change in aerial contractor for the years and the logistic arrangements made for the transfer, and of the new hydrologicalbeing established to meet the needs of the Progrannne as it extends to phase III. L97 7 -197 9 stations E. REINVASION PROBLM4 AND REPORT OF SAP WORKING GROUP 13. Reinvasion problem: Dr R. Garms, WHO consultant, reviewed for the Committee the special . the Prograntrne area Ln 1976 on the reinvasion problem.investigations carried out in L4. Repeated and thorough prospecEions had not revealed S. damnosum breeding which could account for the high biting densities in the Bandama rna f,".uU. r"gion, although localfailures of treatment and residual pockets of breeding urere encountered on several occasions.It was therefore believed that regular, large-scale movement of flies (rrreinvasion") deepinEo the Programme area was taking place. 15. The general pattern of reinvasion in 1976 was similar to that of 1975: commencing atthe end of April it continued throughout the rainy season and affected the same areas, although biting densities in the Bandama valley were lower than the previous year. L6. The reinvasion was not constant, but exhibited considerable day-to-day variations: curves of biting densities at different catching stations showed similar trends with severalpeaks and troughs at the same time. Apparently, waves of flies came to bite synchronously at many places over a large area which suggested that the phenomenon was influenced by meteorological factors. rt r^/as highly probable that the flies were transported by wind sys t ems . 17. rn the Leraba va11ey, biti-ng fly populations were characterized by exEremely high parous rates (about lOO%) suggesting that the flies had taken a blood meal outside the controlled area. The occasional occurrenceof nulLiparous flies may indicate failure of treatment or undetected nearby breeding sites. 618. Inf ectivity rates of f lies r^rere high, reinvaded region (Leraba valley) suggesting the controlled area. even in completely uninhabited areas of the that the flies become infected before reaching L9. Cytotaxonomic identification of larvae reared from eggs of wild caught and comparative morphological studies of aduLts revealed that the migrating were composed mainly of savanna cytotypes Nile (=5. damnosum s.s.) and Sirba , engorged flies, popu La t ions(=S. sirbanum). of the start 20. The results of transmission experiments confirmed that both these cytotypes which are considered to be the main vectors of savanna strains of O. volvulus, were able to supportthe development of the loca1 o. volvulus of the L"..b.-Bandarna.egior. 21. FIy densities on the Bandama, while hi.gh, did not reach the same levels as in 1975.It is possible that the lower Bandama treatment (para. 11) may have contributed to [his, butthe fact that the majority of flies originating from the lower Bandama belong ro Lhe foresr cytotypes, while those found invading the controlled area were almost exclusively savanna cytotype, suggested that the lower Bandama could not be a main source of reinvasion. 22. It was not possi.ble to identify any areas of departure of che flies. Such source areas must be breeding sites of Nile and Sirba cytotypes, which are highly productive at the end of the dry and during the rainy season, and which are possi-bly located in regions hyperendemic for onchocerciasis. 23. Breeding sites of the Nile and Sirba cytotypes are known to the south, west and north-west of the controlled area. Some of the latter are located in phase II (West)Programme. Therefore the situation in the Leraba-Bandama region may improve with the of trearment of phase III (West) in 1971. 24. As no evidence of reinvasion was observed in phase \,Jere entering f rom the eas t. Working Group on the reinvasion probl in Geneva from 26 to 29 October L976. at a later date. The Group had cons results of experimental control operaj.nfluence of the meteorological condi study to elucidate the reinvasion pro laboratory colony of S. damnosum was II it is unlikely thar the flies 25- STAC endorsed the decision to cormence spraying in Phase III Wesr as early as possible tn L977 in order to evaluate its possi.ble influence on reinvasion. Should reinvasion recur, STAC recommended experimental treatment of all known breeding sices of the Nile and Sirba cytotypes adjacent to Phase I and phase III (West). 26. SAP Working Group: Dr P. Haskell, (Chairrnan) reported on the Scientific Advisory Fanel em and identification of research priorities, which met The report would be distributed to members of STAC idered various aspects of the biology of the vector, the .tions outside the Programme area and the overall tions. It then hlghlighted points requiring further blem. In this regard the importance of developing a stressed. STAC considered that the task was likely tobe a long-term one, demanding collaboration among a number of specialis[s. Due to thedifficulty of transporting live S. damnosum material, most of the work would have to be donein, or near, the Programme area. However, the possibility of the colonized strain derived under selection Pressure, differing from wild strains in important behavioural and other aspects should not be overlooked. 27 . STAC endorsed the following recommendations (a) that high priority be given to the development of a method for age-grading of flies for use in L977 and that a specialist be appointed for this purpose; (b) that cytotaxonomic studies be undertaken during the next dry season to demarcate the southern limits of the distribution of Nile and Sirba and the relative frequency of these two species in larval populations; in view of the importance of the identification of cytotypes more professional and technical personnel should be recruited and trained in the relevant techniques; 7(c) that deliberate temporary re-establishment of breeding at the Grechan site on the Leraba should be permitEed to enable studies to be carried out on the biology of the flies in t.he reinvaded zonel (d) in vi-ew of the promising results obtained so far, high priority should be given to conti.nuation of X-ray fluorescence spectroscopy investigations Eo identify the source of invading flies; material from potential sources in Guinea, Mali, Senegal, etc., should be included in these tests and used also for morphological and cytotaxonomic determinations; (e) other methods for trapping and location of resting places should be developed, for sEudies on the biology and movement of S. damnosum ; various traps, battery-powered aspirators, pyrethroid spraying and net should be evaluated; (f) high priority should be given Ln 1977 to the installation of Rothamsted-type suction traps at key positions during the reinvasion period to study the wind-assisted movements of flies and their relation to meteorology, for which a consultant acquainted with the technique should be recruited; (g) that development of suitable traps for catching the adults of the Nile and Sirba cytotypes of the S. damnosum complex be pursued; (h) that Ehe network of catching sites operated daily should be extended in order to obtain more accurate information on f1y densities; (i) with regard to the suction trap techniques to be used (see (f) above)) a prograrmne should be elaborated to correlate entomological and meteorological data to trace the source of the migrating flies; (j) to collect sufficient meteorological data, the number of synoptic observation stations in the OCP area should be increased and the cooperation of the World Meteorological Organization should be sought; the establishment of a small agro- meteorological station at the Leraba experimental site should receive high priority. F. REPORT ON ENTOMOLOGICAL RESEARCH AND PROPOSED PROGRA},IME FOR 1977 28. Entomological research in 1976: WHO reported on the progress made in the research carried out in L976 Lt vector ecology and environmental protection. 29. The problems encountered in transporting eggs from West Africa Eo the United States of Ameri-ca and Europe had hampered progress. Recently adults had been successfully reared from two batches of eggs at the Tropical Institute, Tubingen, Federal Republic of Germany, where also, a blood feeding system had been developed and two females induced to lay eggs but Ehese had proved sterile. 30. A Consultant, Dr Grunewald, had visited the Progranrne area to test the vnater quality associated with the different cytotypes of the S. damnosum complex. It was found that the cytotypes Bandama and Yah colonized sites of different water qualicy to those colonized by the cytotypes Nile, Bille and Soubre. As a result of this work, it became possible to identify potential sites for a rearing Iaboratory. Similar studies on water quality are being pursued at Bouak6. 31. A research entomologist was recruited and had been activeJ-y engaged together with ORSTOM entomologists in Bouak6, in rearing larvae, pupae and adults for taxonomic identifi- caEion, from eggs obtained from flies invading the controlled area. This same entomologist is in the process of establishing a rearing laboratory at Akosombo, Ghana. 832. With regard to research on the S. damnosum complex, considerable progress was reported in the studies carried out under an agreement with the OCCGE, Bouak6. Using a combination of antennal form and the number of teeth on the maxillae, i-t was found possible to idenrify the adults of the Nile/Sirba, Bandama/Soubre and BilLe/Yah cytotype groups. This technique has already been applied successfully in the research on the invading flies. Also, under an agreement with the Biosystematics Research Unit, Otta\^/a, Canada, it was found that the adulr females of the Sirba and Soubre cytotypes could be separated using a combination of characters different from those above. These studies on morphological characteristics should be continued. 33. The research cytotaxonomist on the Progranrne has continued to identify and plot the distribution of the different members of the complex inside and outside the OCP area. He is also attempting to find polytene chromosomes in adults which could be used for identi- fication. A research worker at the University of Canberra, Australia, supported by a smal1 grant, has found chromosomes in the Malpighian tubules of Australian species and consi-ders that the so-called C and G banding technique may produce specific features. He will shortly visit l^lest Af rica to try out his methods. 34. Under an agreement with the Liverpool School of Tropical Medicine, United Kingdom, studies are being undertaken on enzyme polynnorph isms in members of the S. damnosum complex. Ten enzymes are being examined and initial results indicate that the alcohol dehydrogenase bands differ in the Bandama, Bille, NiLe and Sirba cytotypes. 35. A seasonal variation in the composition of cytotypes predominating at differen't times of the year has been reported at two sites in Ivory Coast. At Danangoro on the Maraou6 river there was a change from 80% Soubre in November to 80% Nile in April; on the Cavally ri-ver the cytotypes changed from Bille in February and March to Yah later in the year. This point should be further investigated in view of numerous similar examples with other vectors characterized by species complex. 36. In order to review the progress already made in the study of the S. damnosum complex, to clarify nomenclature of the different cytotypes and to coordinate the future research progranme, a Working Group on vector complexes will meet i.n Geneva from 15 to 19 November L976. The report of this meeting wiLl be sent to STAC members in due course. 37. The main research on S. damnosum sampling has been carried out at Bouak6 under agreements with ORSTOM and the Leopold Institute, Antwerp. Two adult trapping devices have been tried: the windowpane trap suspended above the river to intercept the adults in flight, and the aluminium sheet laid flat at the side of che river, each coated with a sticky substance. Both devices trapped physiological stages different from those caught by vector collectors and can thus be used to provide further information on the biology of the fly. The r,rindowpane Lrap also has the advantage of indicating the height and direction of movement of the different stages along the river. 38. Trapping devices generally were considered by the SAP Working Group on the reinvasion problem. STAC felt that research in this field should be directed towards trying to improve trapping capacity by using attractants including pheromones. 39. With regard to the pre-imaginal stages, results so far indicate that thin plastic strips provide the best type of artificial substrate and using these, larvae and pupae were found at depths greater than three metres. Observation of pupation and hatching cycles showed similar patterns with one peak in early morning and another in late afternoon, thus confirming the findings of previous workers. 40. Studies are progressing on the rate of transition of food particles through the gut of the larvae, which has an important bearing on the development of some formulations of ins ec t ic ide. -9- 41. For these sampling studies to be pertinent to the needs of the Onchocerciasi-s Control Programme, it. is essential that the cytotypes being studied be clearly identified. A11 sampling devices must be suitable for the Sirba and Nile cytotypes. 42. With regard to environnental protection, the aquatic monitoring progranrne continued under agreements with the Institute of Aquatic Biology, Ghana, and the ORSTOM Hydlobiological Unit, Bouak6, Ivory Coast. Separate st.udies to observe and catalogue the different species of fish in certain rivers are being undertaken by an ichthyologist in Ouagadougou under an agreement with OCP. The data, which are forwarded to Geneva for computer storage, have indicated so far that the weekly treatments of the rivers with Abate have had little effect on the aquatic fauna. Great importance is being given to the collection of extensive baseline dat.a from the Bago6 and Oti rivers before Phase III control commences. 43. An independent review of the results from January to August L976 was prepared by a Consultant who atEended the six-monthly coordinating meetings of the different groups involved in this work. The review was presenEed to the Ecological Panel whose role is to evaluate and conrnent on the aquatic monitoring activities associated with the Onchocerciasis Control Programme. 44. Proposed research programne for L977: Most of this entomological research will be carried out at the Leraba site in Phase I of the Prograrmne area and will require, aparE from appropriate j-nstrumentation and back-up services, extra professional and technical staff and transport. 45. In early January L977 an experiment on the dry season dispersal of S. damnosum will be carried out at a discrete focus. This experiment will include temporary interruption of treatment of the Grechan site to allow the re-establishment of breeding and the trapping of flies. It is hoped that research workers from the Institut de Recherches sur ltOnchocercose,(f.n.O.), Bouak6, Ivory Coast will assist in this work. At Pont Routier, searches will be made for invading flies in order to investigate their physiological state and possible infections. A chain of daily catching stations will be seE up along the Leraba up to its confluence with the Como6. 46. As in 1976, Dr R. Garms will be appointed to assist the reinvasion study to be carried out from April to August. Dr Garms will be based at Bobo-Dioulasso. A second consultant entomologist will be based at Korhogo for the first two or three months. A network of about 20 daily catching stations will be established in the vrestern zone of the Programme area. Meteorological and hydrological data will be recorded dai1y. 47. To support these studies,25 additi-onal vector collectors and 6 drivers will be required as well as 6 Land Rovers, and equipment. Supplement.ary catching stations at selected sites in breeding areas of the Nile and Sirba cytotypes in the south and nest of the Prograrmne area would also require L2 vector collectors, 2 vehicles and 2 drivers. 48. Should i-nvasion recur despite timely treatment of Phase III (West), it is planned to treat experimenEally breeding sites to the south-west of the Programme area in Ivory Coast as already reconrnended (paragraph 25). The loca1 evaluation of this particular control could be undertaken by the I.R.0. Bouak6, Ivory Coast. G. WAYS AND MEANS OF PROMOTING THE DEVELOPMEM OF NEW INSECTICIDES AND FORMULATIONS 49. WHO reviewed the attempts made so far to find replacement blackfly larvicides. The active ingredient, while having a drastic effect on Simulium larvae, must have a low toxicity for man, marmnals and non-target aquatic organisms. fte a.failed specificatj.on of the formulation r{7as important as indicated by the comparison of the Procida formulation of Abate with other Abate formulations which, although prepared to the same specification, produced different results. Research is therefore being continued on specifications and on the biological mode of action of vari-ous formulations. Studies have been made of the nutrition of larvae with regard to particle size and time of ingestion. 10 50. Correlation of the results of laboratory tests with the performance of the compounds in field conditions is not yet possible. Accordingly, it is necessary to conduct large- scale field trials of promising formulations in order to determine their length of carry, efficacy and acceptance for operational use. As an intermediate stage, a "troughrrsystem has been developed in which a number of compounds are currently being tested. 51. The insecticide most advanced in the evaluation process is Chlorphoxim with which it is planned to carry out a large-scale field trial on one river ia L977. Preliminary trials are being undertaken with Abate WDP 50%, Abate 5OO EC, OMS-1825, Dimilin, Altosid, Reldan and fenitrothion. 52. A report was presented by Dr Miles, STAC member, on studies carried out, at Ehe Center for Disease Control, AElanEa, on the Eransfer of Abate from waEer to mud parE,icles. Under laboratory conditions most of the Abate became adsorbed on to these particles within a very shorE time, and only a sma1l concentration remained in the aqueous phase. This important finding could explain some of the anomalies in earlier stream tests which showed that Abate EC is not always effective immediately do\^rnstream from the point of application. 53. The Committee expressed interest in the work belng done on micro-capsules and, noting that this type of formulation could be more selective, reconrmended that firms be encouraged to provide other insecticides formulated in this way. It was emphasized that due considera- tion should be given to the Eype and size of capsule to ensure Ehat it would be readily ingested by all larval stages. 54. Having considered the progress achieved and the difficulties encountered, the Conmittee reconrnended that the highest priority be given to the evaluation of new compounds and new formulations, includi-ng micro-encapsulated formulations. 55. Noting Ehe advances made towards the development of selective biological methods for blackfly control, the Committee suggested that relevant mass cultivation studies, health and environmental safety investigations, laboratory and field trials be pursued. H. PROGRESS REPORT ON EPIDB,IIOLOGICAL ACTIVITIES 56. The epidemiological evaluation activities were presenEed by WHO. The two diagnostic methods that have been applied in the Programme were reviewed, i.e. the OCP standard method consisting of incubation of snips in distilled water and reading after 30 minutes, plus control of negatives in saline and reading after three hours or more using microtiEration plates, and the microtitration plate method used a1one. 57. Experience had revealed that, although the latter method produced the same prevalence figures with a higher yield of microfilariae, there was a risk of error in identificati.on and manipulation under field conditions which made it unreliable. 58. 0n the basis of the reports furnished, the Committee concluded that the microEitration plate method used alone should not be adopted at this stage because of the difficulties encountered in general field use. 0n the other hand trials should proceed Eo eliminate the sources of error of the microtitration plaEe method as welI as to develop other more sensitive methods. The aim of these trials should be to develop a more refined method for use by the Epidemiological Evaluation team j-n situations where a low prevalence and intensity of infection could be anticipated. 59. At a later date, when the prevalence and intensity of infection has declined, this more sensitive method may be generalized and adopted as the new standard method. This change, however, should take place in such a way as to avoid adverse effects on the comparability of data, as any mathematical adjustments will not alleviate compLetely the difference in methodo 1ogy. 11 I. REPORT ON },IEDICAL RESEARCH AND PROPOSED PROGRA]'{ME FOR 1977 60. Epidemiology: The Cormnittee was informed of the progress made in the studies on the dynamics of onchocerciasis transmission and on the pathogenesis of the disease in a savanna area of Northern Cameroon in agreement with the Medicat Research Council, United Kingdom, and the Institute of Tropical l"ledicine, Tubingen. 61. Information was provided on the study being carried out by the Institute of Histology and Pathological Anatomy, Rome, on hisEopathological changes in early skin lesions due to onchocercias is. 62. The Cormnittee was told that, in line with the recommendation made at its third meeting, possible transplacental infection in onchocerciasis had been investigated by the Epidemiological Evaluation team. Preliminary results indicate that 'rin uterorr transmission of O. volvulus microfilariae may occur. 63. Epidemiological studies in the Farako area of the Sikasso region of MaLi, where control operations had been carried out without interruption since 1966, had revealed that trans- mission, when present, was minimal. The prevalence of the disease had declined and the risk of blindness had been greatly reduced. 64. Following tests by the Epidemiological Evaluation Unit, the Sjogren hand rest for measuring visual acuity in an illiterate population had replaced the E-test in the epidemio- logical surveys 65. Examination of selected villages in Northern Ghana had so far failed to idenlify Persons infected with Dipetalonema streptoc erca or Wuchereria bancrofti. 66. In accordance with a STAC recormnendation at its second meeting, an agreement had been established with the National Museum of Natural History, Paris to study the distribution of animal onchocerciasis in the Prograrnre area and identify the infective filariaL larvae in adults of the S. damnosum c ompl ex. 67. The Conrnittee was informed that the Epidemiological Evaluation Unit, in collaboration with the National Institute of Hygiene, Lom6, Togo, planned to study the histochemical staining Pattern of 0. volvulus microfilariae and to determine whether microfilariae of the forest strain can be differentiated from a savanna strain on the basi-s of the specific distribution of their acid phosphatase activity. This will complement studies, already undertaken by the Bernhard-Nocht-Institut for Maritime and Tropical Diseases, Hamburg, Federal Republic of Germany, which have shown clear differences between the Guatemalan strain, the forest strain in Liberia and the savanna strain from the OCP area. These studies have atso revealed that microfilariae from the uterus of adult worms have different staini-ngproperties of acid phosphatase activity as compared with those from the skin. The Committee recoirnnended that this type of study be extended to include the developing filarial stages found in Simulium vectors. 68. Under another agreement, nodules and skin snips are being sent from the programrne area to the Johns Hopkins University, Baltimore, Unrted States of America for the in vitro culture of microfilariae. 69. Immunology The conrnittee was informed that in the field of inrnunology, progress had been made at the Minerva Institute for Medical Research, Helsinki, in the isolation of twopurified O. volvulus ant igens which had already been tested with promising results in Enzyme Linked Immunosorbant Assay (ELISA). An assessment of a fluorescent antibody test at the Center for Disease Control, Atlanta, was nonconclusive so far but is being continued. T2 10. WHO reviewed for the Committee the ELISA technique which is being applied to many parasitic diseases. This technique has a potential for field use in onchocerciasis if specific antigens can be prepared for sero-epidemiological purposes. Research on the development of methods for detecEing circulating antigens, useful for early diagnosis of onchocerciasis, should be encouraged. STAC recommended that studies be inLensified towards evolving a highLy sensitive ELISA technique for mass diagnosis applicable in tropical field conditions. OCP personnel expressed interest in testing the applicability of this technique in the Programme area if suitable training could be provided. 7I. Chemotherapy: In the field of chemotherapy WHO reported that a thorough search and review of the literature on the pharmacodynamics and toxicity of DEC and suramin had been completed and would soon be published. 72. Preliminary results of chemotherapeutic trials carried out at OCCGE Centre Muraz, Bobo-Dioulasso, with DEC and with levamisoLe indicated that, at the dosage used, levamisole had no effect on the O. volvulus microfilariae, nor on the ocular lesions. The addition of levamisole to DEC seems to have no extra effect either on the microfilarial densities or on the incidence and intensity of side reactions. 73. Two agreements were concluded with the Unit6 drEnseignement et de Recherche de M6decine at Sant6 Tropicale, Marseille, for studies on the effect of 1ow-total-dose courses of suramin in rabbits and in onchocerciasis patients. 74. Recent trials carried out in Cameroon under the agreement with the }4edical Research Council, London, United Kingdom, indicate that metrifonate has a microfilaricidal action similar to DEC but with less side effects. 75. WHO will soon enter into an agreement wich the Government of Ghana and the Liverpool School of Tropical Medicine, United Kingdom, for establishment of a chemotherapeutic research centre at Tamale, Ghana. The first drug trial is tentatively planned for January 1977. 16. In reply to a question as to whether STAC shouLd take a position regarding the use of human subjects in chemotherapeutic studies, it was pointed out that WHO has a special comittee which reviews all such projects to ensure that the ethical requirements of the Vienna Convention, the Helsinki Declaration and the Charter on Human Rights are observed in programrnes supported by WHO. 77. Studies are in progress at CDC, Atlanta, United States of America, to find a new animal model by infecting jirds (I,ler iones unguiculatus) with Onchocerca cervicalis, using Culicoides varii ennis as a source of infective material 78. Nodulectomy: STAC was informed that negotiations are under way with the Bernhard-Nocht- Institute, Hamburg, and the Government of Upper Volta, for a pilot nodulectomy study on 3OO-4OO patients. This study would be carried out annually over a four to five year period in two hyperendemic villages where entomological findings indicate that transmission of onchocerciasis has been interrupted or reduced to a minimal level. The aims of this trial are (a) to assess the impact of denodulizatLol on the reservoir of the infection where the subjects are no longer exposed to reinfection, and (b) to evaluate the effect that this therapy may have on ocular pathology. 79. Some STAC members expressed reservations about a nodulectomy Progranrne, noting the difficulty in finding and removing deep or nonpalpable nodules in the field, and the possible need for highLy trained staff. On the other hand, the positive psychological value of providing visible treatment for affected persons in the OCP area was recognized and STAC recommended that the agreement r.rith the Bernhard-Nocht-Institute for Maritime and Tropical Diseases, Hamburg, be concluded. -13 80. To complement this research, STAC reconunended that where Lransmission of Onchocerca volvulus has been interrupted in the OCp area, on the possible effects of nodulectomy. a more detailed investigation be carried out (i) in accelerating the anticipated natural decline in microfilarial loads; (ii) in preventing the further development of eye lesions and the onset of blindness in persons already infected. 81. It r^/as proposed to study this problem in a group of persons living in those "epidemiological evaluation" villages where detailed clinical, parasitological and ophthal- mological examinations have already been carried out on the whole population. In this regard detailed clinical data on nearly 8000 patients in these villages has been computerized. 82. A group of 200-3OO persons should be selected from perhaps IOOO of those who are especially 'rat risk'r of developing severe eye lesions or of becoming blind. A similar(or larger) control group should be retained. Selection of patients for boEh groups shouldbe based on one or more of the following criteria, which are the main I'risk signsrrforblindness listed by the WHO Expert Conrnittee on the Epidemiology of Onchocerciasis: (i) Presence of a head nodule; (ii) more than 50 microfilariae in one cornea;(iii) more than 20 microfilariae in one anterior chamber; (iv) more than lo (or possibfy 5) microfilariae in a skin snip from the outer canthus; (v) history of night blindness.or evidence of severely reduced visual fields; (vi) presence of a dangerous onchocercal eye viz. earLy sclerosing keratitis, active iritis, choroido-retinitis or papillitis and(vii) very heavy infection in the skin. 83. From the test grouP of patients all detectable nodules would be removed surgically by a team working in the villages. (as a refinement, the effect.s of removing head nodules only might also be investigated in a sub-group of patients.) 84. The evaluation of the effects of nodulectomy on microfilarial loads and on the evolution of eye lesions would probably take three to five years and would be carried out when the epidemiological evaluation teams visit the villages to make their routine re-examinations. No extra work would be entailed for the epidemiological evaluation teams, and the only extra cost, in terms of money and professional labour, would be that involved in assuring the excision of nodules. 85- It is felt that when it is explained to them, the populations of the villages selectedfor detailed examanination will appreciate the fact that something both spectacular and safe(nodulectomy) is being done for (some of) those who are especially at risk of going blind.This is likely to Promote goodwill and may be expected, in turn, to increase attendance rates at the subsequent routine detailed examinaEions to be made by the epidemiological evaluation teams. 86. The selection of Patients from among the populations of the villages concerned will be made with due consideration to logistical problems and to the sratistical validity of the sample. J. DRUG DEVELOPMENT 87. WHO reported the action taken to implement recortrnendations made by STAC at its previous meetings regarding the pressing need to improve chemotherapeutic treatment for onchocerciasispatients. Three approaches are being followed: (a) improvement in Ehe use of existingdrugs; (b) tests on the usefulness in onchocerciasis of other drugs already released for usein human medicine; and (c) establishment of a screening progranrne for new filaricides. Progress in the first of these approaches is reported above (paras 7L-74). _L4_ 88. WHO informed STAC of the steps taken to test the possible action against O. volvulus of several anthelminthic and trypanocidal compounds considered safe for human use. Possible candidate compounds include levamisole, mebendazole, metrifonate, nifurtimox and Berenil, as well as various combinations of these drugs with or without diethylcarbamazine. Trials on these drugs are included in the current programnes of OCCGE at Centre Mtraz in Bobo-Dioulasso, Upper Vo1ta, and of the British Medical Research Council team in Cameroon. Additional trials will soon be started at the Chemotherapeutic Research Centre in Tamale, Ghana. 89. WHO outlined a screening programme for filaricides. This long-term research project involves considerable work in the few laboratories where facilicies exist, and requires the cooperation of the pharmaceutical industry, of synthetic chemists, and perhaps of biochemists. Financial support on a small scale is already being given through the WHO Division of Malaria and Other Parasitic Diseases to some laboratories engaged in this work. Greater supPort is envisaged from the WHO Special Progrannne for Research and Training in Tropical Diseases. 90. Under the Filariasis Section of the latter Prograrmne, plans for which were drawn up in close consultation with OCP, ttre following courses of action have been proposed. (a) Additional support will be given to a number of academic centres where primary and secondary filaricidal screening is already in progress. (b) Efforts will be continued to obtain a large variety of selected compounds. from pharmaceutical companies, the United States Army bank of compounds synthesized in the search for antimalarials, and synthesis of new compounds based on knowledge of the biochemistry of filarial parasites. (c) A tertiary screening centre will be set up wherein new potential filaricides revealed by the primary and secondary screening can be investigated for action against O. gibsoni and O. gutturosa in cattLe. 91. In discussing this proposal, STAC emphasized the need for WHO to encourage pharmaceutical companies to become involved as the finding of suitable drugs could lead to mass chemotherapy programmes for filarial diseases, and to explore all possible avenues of finding for this work. Bearing in mind the proposals of the World Bank as reported to its third meeting, STAC recommended that it would be desirable to again bring this subject to the attention of the Joint Coordinating Committee. 92. Suggesti.ons were rnade regarding the possible use of deer, dwarf cattle and other animals suscep tible to Onchocerca infection, in the screening programme. It was pointed out that the inclusion of nifurtimox among the potential drugs to be tested was based on f ragmentary evidence of its macrofilaricidal activity against Litomosoides carinii and 0nchocerca volvulus, and it \ras suggested that another trypanocidal compound, Radanil, chemically similar to nifurtimox, should also be tested. K. DATA COLLECTION AND STORAGE 93. WHO reported on progress made in the collection and storage of data from OCP activities. The automated data checking and updating system for epidemiologicaL data was now oPerational for the simple evaluation, while the complicated system corresponding to the detailed epidemiological evaluation was under development and would be operational early tn 1977. Possible refinements, such as the use of microfilms for transmission of data, were being investigat ed. 94. Standardized forms have been adopted for recording and transmitting entomological data; monthly sunrnaries of f1y catching and dissection records were now being stored in the computer data bank. In addition, a map indicating areas of treatment, amounts of insecticide used, fixed wing and helicopter routes and dates, river discharge rates and positive pupal surveys was being sent to Geneva for storage at the end of each larviciding cycle. Nearly 15- all back data have been integrated into the sEorage system and sEeps were being taken to reconciLe, as far as possible, the data collected on earlier forms with the standard form now in use. 95. Standardized forms for recording and transmitting data from the aquatic monitoring programme have been in use for four months and, as for the vector control data, earlier reports would be reconciled, as far as possible, with the current standardized forms. 96. In discussing the report on data collection, STAC recommended that the data collected in the individual conrnunities by the epidemiological unit should be analysed with regard to the correlations of prevalence rates, microfilarial density figures and the prevalence of blindness in the communities. This kind of analysis would provide valuable information on the order of magnitude of criEical levels indicating risks of eye lesions, blindness and,for chronic skin diseases under the conditions prevailing in the community examined. It was suggested that, as discussed at the third STAC meeting, OCP should collect basic information on the different exposure of males and females in the various age groups to the bites of Simuli-um, particularly as related to behavioural differences of these population groups. 97. With regard to the evaluation of aquatic monitoring data, it was pointed out that while the principal responsibility lies with the Ecological Pane1, STAC also has an interest in, and expertise for, such evaluations. STAC was informed that the PaneL r,/as concerned by the lack of data on fluctuations in the fauna of drift organisms throughout the 24-hour night-day cyc1e. Some members of STAC expressed a wish for more precise Eaxonomic .identi- fication of the aquatic fauna being monitored. It was reported that cormnunication had been greatly strengthened between the vector control operations staff and scientific workers from Bouak6 and Tamale engaged in the aquatic monitoring and that these groups held meetings several times a year. L. RESEARCH FI]NDING 98. STAC considered the future development and funding of the research activities of the Prograrmne and pointed out that it was essential to maintain a research programne large enough to cover the following three requirements: (a) provide the necessary basis for the efficient implementation of the present Programne; (b) provide the answer to problems thrown up by the present progranEner e.g. reinvasion, new insecticides; (c) lay the basis for new developments, more efficient techniques and new prograrnmes for the future. 99. The present STAC meeting and other meetings (e.g. SAP Working Group) had proposed research programmes beyond the capacity of the present budget and available manpower. For example, the present entomological sLaff are stretched to the limit and cannot rea11y carry out the further research deemed essenti-al. The SAP Working Group identified the need for more entomological personnel but the sErme was true for the Epidemiological Evaluation Unit and the aquatic monitoring programfle. 1OO. Another aspect to be considered in the long term concerned other diseases endemic in the OCP area, such as schistosomiasis and Erypanosomiasis. Although this was not the concern of STAC at Present it would seem likely that consideration would have to be given to a joint attack on the major diseases since some of the facilities utilized for oncho- cerciasis control were applicable to the control of other diseases. For example, aerial techniques could be used against tse-tse and even for the application of molluscicides and it would be wasteful to increase personnel in all areas when readjustment of the programne would enable some of the extra work to be carried out with a saving in overall cost. 16- lol. STAC felt that this matter should be brought to the attenrion of the JCC and urged that consideration be given to ways of obtaining the extra-budgetary funds that would be needed. M. ECOLOGICAL PANEL LO2. The Ecological Panel representative, Dr E. B. Worthington, explained that the report of the Panelts last meeting had not yet been finalized and would be distributed to STAC members at a later date. Dr Worthington briefly described the main role of the Panel which is concerned with the overall ecological impact of the scheme and not only the effect of insecticide application. The Panel had reviewed the aquatic monitoring progranme and was satisfied to learn that the groups involved had followed closely the protocol agreed by the Panel at previous meetings and that regular consultation occurred between them. The Panel had stressed the need for environmental manipulation where applicable and this was discussed by STAC in reLation to water management projects. 0n the human side, the Panel was concerned with the problems related to resettlement, not least exposure to other diseases, notably, schistosomiasis and trypanosomiasis. 103. The Committee, proposing that the latter item be placed on the agenda of the next combined STAC/EP meeting in Ouagadougou in March L977 , was informed by WHO of the possibility of the team leaders of the schistosomj-asis and trypanosomiasi-s research projects in the area attending the meeting. The hydrobiologists on the aquatic monitoring progranrme couLd also be invited. N. ECONOMIC DEVELOPMENT ADVISORY PANEL (EDAP) LO4. Mr Paul-Marc Henry, Chairman, reported on the second meeting of the Economic Development Advisory Panel, the minutes of which would be circulated to STAC members at a later date. Particular attention had been paid to resettlement and migration problems associated with the question of land tenure; the health, educati-onal and other infra- structures required; the potential of different types of land areas with regard to agri- culture and industry; the changing interest of people to settle a\ray from towns; the non- availability of energy and the role of women. The Connnittee was informed of the possible advantage of considering the development of the onchocerciasis controlled areas within the context of the larger Sahel prograrnme. O. OTHER MATTERS 1O5. Training: WHO informed the Committee that two WHO fe11ows, a health superintendent from Nigeria and a doctor from MaIi, were being trained by the Programme in the medical aspects of onchocerciasis. 106. STAC reviewed the important problem of the utilization of African scientific personnel in the Onchocerciasis Control Progranrne. It recalled this as being one of the original objectives of the Programme, but felt that little progress had been made. LO7 . The short- and long-term requirements were considered. As regards short-term needs, it was apparent that almost all sections of the Programme \"7ere understaffed. For Laboratory and field work it would be possible to overcome this by employing national graduates who could receive valuable "in-service'r training while facilitating the implementation of the expanded research programne proposed elsewhere in this report. As regards the long-term needs, it was agreed that it \ras essential to build up in the participating countries a cadre of personnel experienced in alL aspects of onchocerciasis conErol and research, to assist in the planning and execution of the national prograurnes which would have increasing importance for the whole control operation in the future. -t7 lO8. There was no shortage of qualified and enthusiastic national graduates suitable for such work, and i,t was likely that funds could be obtained to provide fellowships for training them in specific disciplines. However, STAC emphasized that the lack of a career structure in the public health services of many of the participating countries to absorb and employ those graduates after their training was a serious problem which could hamper the future development, not only of the Onchocerciasis Control Prograrnrne icself, but of the related economic development activities. The latter would require a number of scientists experienced in all aspects of the problem, both for the continued survei-llance of onchocerciasis and the subsequent development of essential connnunity health services. 109. STAC recommended that this matter be brought to the attention of the Joint Coordinating Committee at its meeting in Decernber. To overcome this problem, STAC proposed the establish- ment of an International Trust Fund for Onchocerciasis Training, with contributions from Participating Governments, the OCP training budget, WHO regional training funds and bilateraldonors. This fund would provide for the employment in the Programme of a number of African Research Fellows from the participating countries. When these scientists had completed their training with OCP, they would return to their own country to work on the onchocerciasisproblem, and would be supported from the Trust Fund until absorbed into the career structure of the relevant national organization; the maximum period for such support from the Trust Fund would be two years. 1lo. STAC pointed out that this would not only assist in rhe implementation of the Onchocerciasis Control Progranune on the expanded level which could be foreseen, but wouldprovide the participating countries with a method of reinforcing their health services with experienced personnel at reduced cost. II1. Membershi rt was noted that the mandate of the present committee members expired at the end of 1976. With regard to the selection of new members, WHO was reminded of the need to maintain a balance as far as different specialities were concerned. STAC felt that an apPointment for a period of two years was too short for members to become fu1ly productive and in order to maintain contj-nuity in the activities of the Cormnittee due considerati-on should be given to the possibility of extending the membership of at ieast some of the present members. P. DATE OF NEXT MEETING LL2. Some members of the Committee expressed the view that in spite of intensive discussionsthe time allowed for the meeting was too short to reach conclusj-ons leading to firm recom- mendations in respect of further scientific/technical activities of the progranrne. The Committee had requested on previous occasions that the working papers be distributed one month in advance of a meeti-ng, which regretfully had not always been complied with. However, even i-f all working papers were submitted well in advance in future, the number and magnitude of the problems to be discussed required more time than allowed so far. As a result the Committee had been unable to devote sufficient time to establishing clear priorities fordifferent asPects of research. The Committee requested one additional day of meeting forfuture sessions. 113. It was proposed that the fifth meeting of STAC be held in OuagadougouL977. A tentative date for the sixth meeting was given as 6 to 9 September to be decided later. fromlto4March L977 at a place a. ADOPTION OF THE REPoRT Ll4- The Committee revi-ewed and adopted the draft report with certain modifications. R. CLOSURE OF THE MEETING 115. In closing the meeting the Chairman thanked all participants and the secretariat forthe assistance he had received in carrying out his functions and for the contributions whichhad resulted in the meeting being so successful. 1B ANNEX I I 2 3 4 Onchocerciasis Control Programme in the Volta River Basin area SCIENTIFIC AND TECHNICAL ADVISORY COMMITTEE (STAC) Fourth Meeting Geneva 2-4 November L976 AGENDA Opening of the meeting Election of Chairman Adoption of the agenda En b omo Io gy (a) Progress report on entomological activities (b) Reinvasion problem and report of SAp working group (c) Report on entomological research and proposed prograrnme for 1977 (d) Ways and means of promoting the deveLopment of new insecticides and tormuLalions Epidemig logy (a) Progress report on epidemiologicaL act,ivities (b) Report on medical research and proposed prograrmne for L977 (c) Drug- development Data collection and storage Research funding Report on Ecological Panel meeting Report on Economic Development Advisory Panel meeting Other matters Date of next meeting Adoption of the report Closure of the meeting 5 6. 7. 8. 9. 10. 11. L2. 1' , 19- ANNEX II ST]MMARY OF RECOMMENDATIONS INCLUDED IN THIS REPORT Entomo logy I. Should reinvasion recur after implementation of control in Phase III (West), all known breeding sites of the Nile and Sirba cytotypes adjacent to the Phase I and Phase III (West) areas should be treated experimentally (paragraph 25). 2. High priority should be given to the development of a method for age-grading of flies for use ia L977 and a specialist should be appointed for this purpose (paragraph 27(a)). 3. Cytotaxonomic studies should be undertaken during the next dry season to demarcate the southern limits of the distribution of Nile and Sirba cytotypes and their relative frequency in larval populations; in view of the importance of the identification of the cytotypes, more professional and technical personnel should be recruited and trained in the relevant Eechniques (paragraph 27 (b)). 4. A deliberate temporary re-establishment of breeding at the Grechan site on the Leraba should be permitted in order to undertake studies on the biology of the flies in Ehe reinvaded zone (paragraph 27(c)). 5. High priority should be given to continuing the investigations using X-ray fluorescence sPectroscoPy to identify the source of invading flies and material from potential sources in Ghana, Mali, Senegal, etc., should be included in these tests and used also for morphological and cytotaxonomic determinations (paragraph 27 (d)). 6. Alternative methods for trapping and location of resting places should be developed for studying the biology and movernent of S. damnosum (paragraph 27 (e)). 7. High priority should be given to the installation of Rothamsted-type suction traps at key positions during the reinvasion period to study the wind-assisted movements of flies and their relation to meteorology, with the assistance of a Consultant acquainted with this technique (paragraph 27 (t)). 8. Research should continue towards the development of suitable traps for catching the adults of the Nile and Sirba cytotypes of the S. damnosum complex (paragraph Zl(il). 9. The network of catching sites operated daily should be extended to obtain more accurate information on fly densities throughout the reinvasj-on area (paragraph 27(h)). 10. To secure the collection of sufficient meteorological data, the number of synoptic observation stations in Ehe OCP area should be upgraded and high priority should be given to the establishment of a smal1 agrometeorological staEion at the Leraba experimental site(paragraph 27 (j)). 11. High priority should be given to the evaluation of new insecticides and new formulations and encouragement given to firms to provide different insecEicides in micro-encapsulaEed formulations (paragraphs 53 and 54). Epidemiology L2. The study of the staining properties of acid phosphatase activity in the microfilariae ofO volvulus should be extended to include the developing filarial stages found in Simulium vectors (paragraph 66) 20 Annex II Immuno logy 13. Studies should be intensified towards making a highly sensitive ELISA technique for mass diagnosis applicable in tropical field conditions (paragraph 69). No du lec tomy L4. An agreement should be established with the Bernard-Nocht Institute for Maritime and Tropical Diseases, Hamburg, for a nodulectomy study on 3OO-4OO patients, to be carried out annually over a 4-5 year period in two hyperendemic villages (paragraph 78). 15. To complement the above study (icem L4), a more detailed investigation should be carried out in an OCP area where transmission of 0. volvulus has been interrupted on the possi-b1e effects of nodulectomy. (i) in accelerating the anticipated natural decline in microfilarial 1oads, and and the onset of blindness in(ii) in preventing further development of eye lesions persons already infected (paragraph 79). Data collection and storage I6. The evaluation of the data collected in individual cormnunities by the Epidemiological Evaluation Unit should be analysed with regard to the correlation of prevalence rates, micro- filarial density figures and the prevalence of blindness in connnunities (paragraph 96). -2L- : ANNEX III MATTERS TO BE BROUGHT TO THE ATTENTION OF THE JOINT COORDINATING COMMITTEE 1. STAC reconuuended that the question of funds for drug development be again brought to the attention of the JCC (paragraph 9I). 2. STAC felt that research funding should be brought to the attention of the JCC and urged that consideration be given as to how to provide the extra-budgetary funds that would be required (paragraph 101). 3. STAC recomnended that the problem of training and subsequent employment of national personnel in their own countries should be brought to the attention of the JCC to determine whether a solution could be found (paragraph lO9).