Scientific and Technical Advisory Committee: report of the seventh meeting, Brazzaville, 21-25 August 1978

ocPfsr^cf78.r ORIGINAI.: ENGLISH ONCHOCERCIASIS CONIB,OL PROGRAMI'{E IN THE VOLTA RIVER BASIN AREA SCIENTIFIC AND IECHNICAL ADVISORY COMMITTEE Report of the seventh meeting BrazzavilLe, 2L-25 August 1978 ocYfsracfta 1 page 2 List 1. ) 3. 4. 6. 7. a o 10. CONTENTS of participants . . Opening of the meeting Progress report on activities . Extension Reinvasion studies . . OCP Evaluation Report . Long-term future of the Progranrne . . Screening and evaluation of insecticides - Adulriciding . Health infrastructure in the OCP countries Chemotherapy and the Tamale centre Endemicity levels . . Report of Ecological Panel 0ther matters . report of SAP working group Progranrme staffing 11. Arrangements for the next meeting . . 12. Close of meeting Annex 1 - Agenda of the meeting Annex II - Report of the SAP Working Group on Annex I11 - Recornmendations Ins ec ti c ide s aa July 1978 Page a) 5 5 6 6 7 8 10 10 11 11 13 L4 t4 14 L4 L4 15 L6 l) Members DrE.G Ghana ocPfsr^cf7B.L page 3 LIST OF PARTTCIPAI.ITS Beausoleil, Director of Medical Services, Ministry of Health, P.O. Box yI. 44, Accra, Dr D. W. BUt.tner, Head of Department of Helminthology, Scientific Dlrector, Bernhard-Nocht Institute, Bernhard-Nocht-Strasse 74, 2OO0 Hamburg 4, Federal Republic of Germany Professor J. Diallo, FaculE6 de M6decine, P.o. Box 6191, Dakar - Etoile, senegal Professor L. G. Goodwin, Director of Science, Zoological Society of London, Regents Park, London N.W.1, United Kingdom Dr PeEer Haskell, Director, CenEre for Overseas Pest Research, College House, Wrightrs Lane, London W8 5SJ, United Kingdom Dr H. J. Knuttgen, DirecEor, rnstitute of Tropical Medicine, university of Federal Republic of Germany Titbingen, Tllbingen, Dr James Miles, Chief, Pesticides Branch, Vector Biology and Control Division, Bureau ofTropical Diseases, DepartmenE of Health, Education and I'IeIfare, Center for Disease ControlAtlanta, Georgia 30333, United StaEes of America Dr J. Mouchet, Inspecteur g6n6ra1 de 1a Recherche, Office de la Recherche Scientifique etTechnique Outre-Mer, Services scientifiques centraux, 7O-71, Route dtAulnay g3L4O, Bondy, France Dr L. E. Rozeboom, Professor Emeritus of Medical Entomology, Ttre Johns Hopkins University,3196, Laverne iircle, Ha@stead, Maryland 2Lo74, united states of Aoerica Joint Coordinatine Comittee Dr M. G. Candau, Independent Chairman, cfo WHO headquarEers, Geneva, Swit.zerland World Bank , Mr S. Denning, Division Chief, prograrme I. United States of America Western Africa Region, hlorld Bank, Washi ton D. C World Health Orsaniza ti on Dr Com1an A. A. Quenum, Director, Regional Office for Africa, BrazzavilLe, Congo Mr Marc Ls. Bazin, Director, onchocerciasis control programe, 0uaga dougou Upper Volta Dr J. Hamon, Director, Division of Vector Biology and Control, wHO headquarters, Geneva, Swi tzerland Dr J. A. Mahoney, Director, Disease Africa, Brazzaville, Congo Control and Environmental Health, Regional Office for Dr B. O. L. Duke, Chief, Filarial Infections, WHO headquarters, Geneva, Switzerland Division of Malaria and Other parasitic Diseases, ., Mr R. Helmholz, Upper Volta chief, Administrative services, onchocerciasis control prograrrns, ouagadougou, ocP fsr^cf7B.r Page 4 Dr M. Baldassini, Regional Officer (Other Parasitic Diseases), Regional Office for Africa,Brazzavi 1 1e Congo Dr J. B. Davies, Entomologist, Vector Control Unit, Onchocerciasis Control prograurne, Ouagad ougou Upper Volta Dr V. Eyakuze, Regional Officer Africa, Brazzaville, Congo (Research Promotion and Deveropment), Regional office for Dr F. C. Grant, Regional Officer (Onchocerciasis Control), Regional 0ffice for Africa, Brazzavj-l-Le , Congo Dr rba Gueye, Regional Officer (Malaria), Regional office for Africa, Brazzavi 1 1e Congo Mr J. D. M. Ma Dr J. Odetoyin Brazzavi.LLe rr, ocP Liaison officer, wHo headquarters, Geneva, switzerland bo, Regional 0fficer (Vector Biology and Control), Regional Office for Africa, Congo Dr A. Prost, Epidemiologist, Epidemiological Evaluation Unit, onchocerciasis Control Prograrune, Ouagad ougou Upper Volta Mr G. zerbo, Medical Entomorogist, vector control uni-t, onchocerciasis Ouagadougou, Upper Volta Control Progranme, ocPfsr\cfTB.L Page 5 1. OPENING OF I'IIE MEETING 1.1 The seventh meeting of the Scientific and Technical Advisory Cormnittee (STAC) took place at the WIIO Regional Office for Africa, Brazzaville, from 2l to 25 August 1978. Ttre meeting was opened by Dr Ccmlan A. A. Quenrm, WHO Regional Director. In welcoming theparticipants, Dr Quenrm expressed his appreciation to the cornmittee and thanked the oembers for their conscientious and sustained efforts to fulfil their terms of reference, which were reflected in the excellent report for 1977 to the Joint Coordinating Comittee (.fCC).1 L.2 Dr Quenrm also welcomed Dr Candau, Independent Chairman of the JoinE Coordinating Comittee, and Mr S. Denning of the World Bank who had been invited to attend Ehe present meeting in view of the irylications for the future of certain items to be discussed, in Particular the draft OCP Evaluation Report which would be presented Eo the next session of the JCC. Dr Quentm drew aEtention to the pressing need for a drug to be used in mass caryaigns for the treatment of onchocerciasis. The importance of the Programe to the peoples of West Africa could not be over-emphasized, and the Regional Director called upon all concerned for increased efforts to enable the objectives to be met. 1.3 In the absence of Professor P. Janssens, Chairman of STAC, who was attending the International Congress of Parasitolor, tl Warsaw, Dr Peter Haskell chaired the meeting. L.4 The Cqnr.i gtee Iras informed that Dr A. Rougemont had recently been appointed Chief of the OCP Epidemiological Evaluation Unit and therefore could no longer retain his STAC membership. Dr I. Lindsay rdas unable to attend due to a previous conrnitment. 1.5 The agenda adopted for the meeting is appended as Annex l. 2. PROGRESS REPORT ON ACTIVITIES 2.L Mr Bazin reported on the activities of the Programe in 1978 and on the action taken on the recomendations made by the Comittee at lts sixth meeting in November L977. These recormendations had virtually all been implemented. As proposed^by STAC2 Prograume staff had attended the Special Working Group on Filariasis organized by TDRJ inJuly; also in July a Scientific Advisory Pane| Working Group had been called to consider the question of a suitable alternaEive insecticide.* The report of this Group which had been chai.red bv Dr Miles, had been circurated to the comittee as working docrmenr ocPf srAcf77.4 (ocpf fltcf7B.z5). wirtr regard to the suggestion for a working group to review the epidemiological evaluation techniques,J an exchange of correspondence on this subject had taken place between certain STAC members and Progranme personnel which had clarified the issue. 2.2 Ttre proposal for Dr Vajime, Programne cytotaxonomist, to visi-t Nigeria6 to collect material had not been iqlemented in view of the other MIO missions in connexion with a control campaign in that country. On the other hand, arrangeaents were under way for the visits of Dr Crosskey and Dr Petersen to the Prograrrme area/ in mid-October and a workshop was planned at the start of their visit, in Lama-Kara (Togo), on S. damnosum species^in hlesE Africa. Ttre proposal for a multidisciplinary group on integrated disease controlu activities had been discussed with other WHO divisions concerned; however, taking inEo account the Programers priorities in 1978, it had been agreed to postpone this until later. 1 oce/srec /tt.z.2 ocef srrcftt.l, paragraph 47. 3 *O Special Prograrnme for Research and Training in Tropical Diseases a ocYfstecf77.3, paragraph 69. 5 ocef srrcf 77,3, paragraph 39. 6 ocYf srrcf 77.3, paragraph 57. 7 ocef srrcf 7t .3, paragraph 56. 8 ocefstacf77.3, paragtaph 77. ocPfsr^cft8.r PaEe 6 2.3 Fina1ly, the WIIO Regional Office for the Americas had been invited to send an observer to the Present meetingl but although the response had been favourable participation was not possible at this meeting. Extension 2.4 RequesEs for an extension of rhe OCP activities to the Senegal River Basin area and the Nigerian part of the Niger River Basin had been made to the JCC at Kuwait in December 1977. The JCC accepted to fund feasibility studies in the Malian part of the Senegal River Basin area and suggested that other feasibility studies be provided for by WHO. In 1978, funds were allocated for that purpose by the Regional Director, AFRO (US$ 150 000) and the Director- General of wHo (us$ 30 ooo) in addition to other available resources. 2.5 A preliminary analysis of the situation had been made in the savanna areas to the west of the present Progranme area, namely Guinea, Guinea-Bissau, Mali (western part), and Senegal and to the east of OCP in Nigeria. Subsequently, WHO staff visited all these countries(except Guinea-Bissau) to prepare complementary field studies, discuss the need for additional river gauges for monitoring water flow, consider the need to develop national experti-se, etc. The areas of Ehese river basins where the onchocerciasis situation is best known are in Mali and Senegal; here the surveys on vector distribution will be completed by late 1978 through aerial surveys conducted during the rainy season. WHO Eeams are being established to speed up the collection and analysis of information in Guinea and studies are being undertaken tn the Senegal River Basin area to determine the possibility of onchocerciasis control. Studies are also being mad€r with WI10 assistance, in Nigeria, and it seems probable that Nigeria will develop a national onchocerciasis control campaign in cooperation with WHO and other inter- national and bilateral institutions. Preliminary reports on the stage of development of these feasibility studies will be presented to the JCC session in Lom6, in December 1978. Reinvasion studies 2.6 Ttre reinvasion studies for 1978 were outlined by I,rtIO. It r{as pointed out that Ehese studies were stil1 going on and that fu1l results would noE be available until the end of September 1978. 2.1 To monitor the invasion this year a study centre had been opened at Seguela, Ivory Coast, the site of the new extension subsector. Fifteen everyday catching stations were set up, six in "source" areas and nine in the "arrival'r area. Thirty-six vector collectors and nine chauffeurs were recruited Eemporarily to man these points. 2.8 T\.ro consulcants arrived on 1 May, and were joined by a third on 22 Nlay, to carry out detailed studies on the flies. Tu/o automatic weather stations were installed at Pont L6raba and Seguela, and Johnson suction traps were set up at Danangoro, Pont L6raba and Madina Diassa Larval rearing equipment was installed with a trained Eechnician at Seguela. Activities began in March. The weE season actually started six weeks earlier than in the previous Ehree years. The first flies began to arrive at Pont L6raba during the first week of March and became well established by the third week, when they also appeared on the Bou and Bandama rivers. At that time the River Marahou6 was not flowing. It had been decided that the Marahou6 would be treated as soon as flow began in order to eliminate iE as a possible source river. Flow began oo 25 April at which time 3O-50 tbesfnanfday were being caught at Pont L6raba, 60-1oO atChauss6eNiakaramandougou and IOO-300 per day at a site on the River Bou. As in previous years, these were almost all parous savanna f1ies. 2.9 The situation remained fairly constant until 5 June when treatments r^rere extended to the rivers supporting savanna species in the Sassandra system as far south as Guessabo. This led to about 5O% reduction of flies on Ehe Sassandra and Marahou6 rivers. Amongst flies caught were aPpreciable numbers of nulliparous, a situaEion which has always been associated witfr I 1 oce f srecft J . 3, paragraph 88. ocPf sr^cf78.L page 7 local breeding, so that the possibility remains that sone breeding sites or small rivers were not being properly controlled. By the end of June catches within the Programme area were 20- 70 per day at Pont L6raba, 15-30 per day aE Chauss6e Niakaramandougou, and 20-50 per day at a site on the River Bou - a very great iuprovement on the previous year. 2.LO Prospection had shown that at this time savanna flies were breeding on the River Sassandra at Buyo further south than previously recorded, and heavy densities r^7ere found on a nearby Eributary, the River Nzo. Consideration was given to extending treatments to cover this area, but a prospection on 25 July found this river to be recently in flood. AE the same ti.me f1y densities at Pont L6raba and on the Bandama fel1 to less than l0 per day. It is not known whether these tr'/o events were related. 2.Ll the studies have Ied to scme interesting developments in research. Subsector chiefs in the west have all been trained to distingui sh adult S. damnosrm of the savanna group and these are now being routinely recorded. A technique has been developed for measuring adult flies which appears to show that S. damnosrm emerging from pupae from certain rivers fall into discrete size distributions, while one of the consultants is working on a promising technique for determining the number of gonotrophic cycles undergone. 2.L2 In the discussions which followed this presentation WHO was asked whether data were available on the distribution of S. damnosum species south of the extension llne in Togo, Benin and Ghana, and whether it could be assr-rmed that forest species would not invade the Programe area and start breeding. The Coumittee was inforned that the distrlbution of S. damnosr:m species in the Ivory Coast was nohr well documented; in Ghana savanna species existed as far south as the Akosombo Damn, and surveys were under qray to determine the ultimate southern limit in Ghana, Togo and Benin. As for invasions of forest species of flies into the savanna, this had only been observed along the southern periphery of the Programe area, at Pont L6raba in t976, and at Kankela on the River Banifing where one forest fly had been caught in 1978. The fly at Pont L6raba had been identified from larvae reared from eggs produced by this specimen, while the Kankela fly had been identified from morpho- logical characters. IE would therefore seem to be a rare event. 2.13 With regard to the possibility that forest speci.es might become established in northern rivers once savanna species were eliminated, it was thought that while even in the densest infestations of savanna species not all possible substrata rrere occupied, it was not siry1y a matter of coryetition for attachment sites that. linited the distribution of forest species, but a more cmplex combination of ecology and physical and chemical properties of the rivers plus the apparent short flight range of forest female flies. 2.14 The Co'rmittee noted with satisfaction the work undertaken on the reinvasion. To assist the Progranme to develop this work, STAC recomended that a second SAP Working Group on Reinvasion be convened, which would also consider the irylications of exEension in Ehis field. 3. OCP EVALUATION REPORT 3.1 The Prograrme Director explained that this report rdas an up-to-date assessment of what the Programe had achieved. It had been prepared on a suggestion made by the Steering Comittee in Sept.ember L977 and approved by the JCC in December 1977. part I was drafted by WIIO and dealt with the Eechnical aspects of the Programe. part II concerned the economic development of the OCP area and was the responsibility of the Bank. Part I of the OCp Evaluation RePort before the Corrnittee had been amended according to the consensus of co@ents received from various sources and the Cormittee was invited to review its content. 3.2 The ComitEee discussed at length problems concerned with the definition of the overall objectives of the Prograune, as given in the report. It felt that these should be more clearly defined, but as this matter vras intimately concerned wiEh the STAC consideration of the long-term future of the Progranrne, Ehe Cormitteers conclusions are reported under that heading below (Section 4). After this initial discussion the Cormittee reviewed the remainder of the rePort and felt Ehat it gave a useful overall picture of the considerable achievements of the Programe to date. However, the Corrrnittee made certain proposals for irnproving ghe conEent of the report. ocPfsrAcfTs.r page 8 3.3 With regard to training, the Comlittee was informed that this section would be expandedbecause of its importance in respect to the long-term future of the prograrmre. The prograumre confirmed that the research annex would include a list of all the research activities supported to date. The Corunittee proposed that further information be given on the roles ofthe Economic Development Unit and the public Health Adviser. 3-4 The Conrnittee felt that more attention should be given in the Evaluation Report to thelife expectancy of blind people. It was recognized that the PAG Mission had underestimated the nr.unber of blind people in the Prograrmre area; the findings of the Epidemiological Unit now suSSest the present figure to be in excess of 1OO OO0. Although no reliable data were available at present, evidence suggested that blind people may on average live only five or soyears after the onset of blindness. The Corunittee recorutrended that the implications of thisbe reflected in future evaluation reports. The Courmittee also recomnended that further databe collected to substantiate the conclusion and that Ehe Prograurne obtain the services of a consultant demographer to assist the Epidemiological Evaluation unit in this field. 3.5 Fina11y, the Corrnittee felt that budgetary provisions in the report should be as flexible as possible to facilitate changes up or down as dictated by the progress of the programe. 4. LONG-TERM FUTURE OF THE PROGRA}O'{E 4.L As indicated above, the Cormittee considered the question of the overall long-term objectives of the Prograrme. The Comittee endorsed the statement made in the 1977 STAC rePort (oCYfSfeCf77.2) that focuses on key public health and soci-oeconomic issues, rhat the Purpose of the onchocerciasis control operation is t'to reduce the impact of onchocerci-asis to a sufficiently low level so that it no longer represents either a public health problem or an obstacle to socioeconomic development and also to maintain and adjust control activities so as to stabilize the disease at a tolerable leveIr'. A "tolerable leve1" results when the biting density of Simulium damnosum s.1. within the control area is reduced, if not to zero, at least to a leve1 at which transmission of O. volvulus fa11s below the threshold at which seriou s lesions of ocular onchocerciasis develop. The tolerable level in the West African savanna zone was recently considered by a SAP Working Groupl to be associated with a reduction of the Annual Transmission PotentiaL2 to less than lOO, and the Annual Biting Rate3 to Less than 1Ooo. These definitions and figures had been accepted by STAC. Further observations on the parasitological parameters associated with the tolerable level are given in paragraph 8.2. 4.2 The Onchocerciasis Control Programrre was conceived and planned according to the besf information available in 1973 on the epidemiology of the disease and the biology of its vectors. Since then the knowledge on these subjects has noticeably increased, as a result of the Programle activities, as outlined be1ow. The Corrnittee recounended that these findings be included in the Evaluation Report. It is, in particular, essential to take into account that: (a) the long-range active dispersion of S. damnosum s.s. and sirbanum i-nvolves mostly parous females and thus has a greater epidemiological importance than originally anticipated ; (b) the human migration trends involve not only large populatiorr movements from the savanna zones to southern areas but also movements from the coastal and forest zones to the OCP area, thus introducing neuT volvulus carriers in this area; (c) the distribution bionomics and vectorial inportance of the various members of the S. damnosum c omplex is much better known; the breeding places of the savanna cytotypes S. damnosum s.s. and S sirbanum stretch further south than originally anticipated. L ocef s*ftt.t. The Biomedical Criteria s 0 Onchocerciasis Control Prograrmre area (OCp). Group, Geneva, 6-8 June 1977. 2 ATP 3 ou* for Resettlement in the Volta Basin Report of a Scientific Advisory Panel Working ocef srrcfta.t page 9 4.3 During the discussion on the long-teru objectives of the Progranme it became apparent that confusion had arisen due to use of the phrase rrelimination of the vectortt in various Programre docuoents including the PAG Report.l In this connexion, STAC erophasized that it had never been considered feasible to eradicate the vector for all time from the OCP area. 4.4 STAC therefore considered a nuober of basic questions relating to the long-term future of the Progranrme and concluded that on presently available knowledge and techniques there would have to be continuous operational activity in the Programe area for Ehe predicted 2O years. However, it \ras not possible to forecast now the precise 1evel or nature of these activities, because the Programe has been operaEional over the whole of the originally designated area for just over one year, a period insufficient to allow the collection of the basic data essential to forecast future developments. 4.5 As an example of the type of operational changes that will probably occur in Prograrme activities, the Comittee was pleased to note that OCP has been able to suspend systematic larviciding on some of the perennial rivers of the central part of the control zone in the dry season. the degree to which this reduction in larviciding can be extended southwards and into the hlet season can only be determined by careful experioentation Eo avoid jeopardizing levels of AIP. It would also be dependent on the effect of any southern and western extension. 4.6 It should be possible to make a reasonable estinate of the extent of these cuts in the present area three years afEer the establishment of fuIl control operations in all three phases of that area, i.e. at the end of 1980. Should the exEensions now under consideration by the JCC be approved, a similar time-scale would apply in relation to the additional cuts over the entire Progranrme area. 4.7 STAC considered that it would be dangerous to permit ABRs to increase as endemicity levels fe1I because this could lead to a decrease in the rate of decline of the disease. 4.8 As the reinvasion phenomenon must have an iryact on the strategies of the Prograume, STAC considered it essential that the research effort on this must be given the necessary priority. Itre daEa presently available suggest the possible sources to be eastern Guinea, north-east Liberia, southern Ivory Coast, Ghana, Togo, Benin and possibly Nigeria. STAC considered that the situatlon in the south-west will become clearer in late 1979 when operations are extended to the breeding rivers in Ivory Coast as planned. Similarly, if larviciding were to be undertaken in the proposed southern extensions in Ghana, Togo and Benin, this would provide results to further clarify the exEent of potential reinvasion sources. However, it was recogrrized that this information was unlikely to become available until at least one year after the iqlementation of these extended operations. In the long term, any additional control schemes that Eay be introduced in the possible source areas outside OCP would be of benefit t.o the Prograume. 4.9 Another major factor in developing the most efficient strategy for Ehe OCP is the average reproductive life-span of the parasite in the human host. Ttre besE available evidence indicates the mnximum life-span of the adult worm to be between 11 and 15 years, and of the microfilariae approximately tr{ro years. Investigations in the transmission-free area of the Progranme shop that the adult \rorms are still alive and fertile after more than Ehree years. While more information wlll be available in 1980, STAC confirmed that a further 10-15 years may be necessary to accurately determine the life-span of the parasite. 4.10 As already noted, a further corylication affect,ing the development of the Progranrne is the considerable seasonal migration of htrman population into the controlled area, some of whom will be infected with onchocerciasis. The magnitude of this phencmenon rras at present In the context of the PAG Report the word "eliminate" (Latin'reliminarerr: Eo cast over the threshold) was used to mean destruction of the vector within the control area and its continued exclusion therefrom for a staced period of time. 1 ocP fsrAcftB.Lpage 10 unknown and the Corunittee recommended the continuation and expansion, if possible, of the present research effort. 4.lL I^Ihile some of the above factors may adversely affect the early attainment of the over- all objectives of the Prograrmre, STAC recognized that there r47ere others under consideration which, on balance, could improve the efficiency of the operations. These concern Ehe development of new insecticides and their application, the possible introduction of adulticiding and the possible development of an effective chemotherapy programne. The Corrnittee considered that after the 2o-year period, there will be a minimal requiremenE for surveillance of vector and parasite, the tactical and localized application of larvicide and supportive chemotherapy. The magnitude of this maintenance operation and its duration will depend on the success of the present campaign and on the introduction of new technology. 5. SCREENING AND EVAIUATION OF INSECTTCIDES - REPORT OF SAP WORKING GROTIP 5.1 The Comrittee reviewed the Report of the SAP trtlorking Group on Insecticides (Annex II) and considered in detail the problem of identifying further chemicals for S damnosum larviciding. Chemical cornpanies involved in pesticide production were very ready to cooperate in submitting new compounds and formulations for testing by the Prograrune, provided that these could be rapidly screened and evaluated and the resultant data fed back to the conpanies. The SAP Group Report emphasized that while some preliminary screening could be done on Simulirm species other than damnosum, testing on S. damnosun must be introduced at the earliest possible sEage of the evaluation procedure. AccordinglL it is clear that the necessary facilities must be set up in Africa. The STAC reviewed and strongly endorsed this aspect of the SAP Report in view of the present dependence of the Prograrrne on a single conpound. 5.2 The Cormnittee, noting that the river presently used for testing candidate corpounds will soon be subject to regular larviciding by OCP, strongly recomended that the Programme should take innnediate action to develop the necessary facility for screening and evaluating candidate corpounds. Ihe requiremenEs for this facility include: (b) suitable laboratory and housing accorunodation; (c) back-up support such as transport and equipment; (d) provision of adequate staff, both professi-ona1 and ancillary. 5.3 Because of the potential difficulty of finding suitable river sites within the partici- pating countries of the Progranrne, the STAC recognized that the Director might have to carry out feasibili.ty studies elsewhere. Adul ri c id ing 5.4 Consequent to the STACTs previous recorunendation on this subject, it was reported that the Progranrne Vector Control Unit had monitored the effect of an application of various conpounds againsc riverine tsetse f1y in the area on the adult S. damnosum p opula ti on. 5.5 Trials were carried out on the Como6 River in Upper Volta by helicopter ULV1application of endosulfan, decamethrin and dieldrin; these applications were very successful against the tsetse and preliminary observations suggest thaE there was also an effect aga inst S. damnosum. However, it was limited to endosulfan and decamethrin and was only observed in the spray blocks which exceeded 5 km in length along Ehe river banks. 5.6 In view of these results, the Conunittee re-emphasized the irnportance of developing techniques for control of adult S damnosum. This t^ri11 require attention to two main points(a) discovery of resting sites of adults; and (b) work on the susceptibility of adult (a) a site within easy access sizes; of S. damnosum and S. sirbanum breedi ng rivers of various I Ultra low volume ocPf sr/lcf 7B.t Simulir.u, particularly gravid females, because these are insecticides. page 11 likeIy to be most tolerant to 5.7 the STAC, therefore, noting the recmendation on this point made by the SAP Working Group on lnsecEicides, recormended an expansion of this work in view of its potential in controlling reinvading adults. 6. HEALIII INFRASIRUCII'RE IN IIIE OCP COUNTRIES 6.1 In considering the above, STAC recognized that the health needs of the population benefiting from the OCP would have to be met. Ttre existing health care delivery systems in the participating countries do not adequately meet these needs, and although the L97O-1977 statistics indicate an increasing expenditure, when the effect of inflation is considered the allocation to health has actually remained the same, or even decreased. The measures adopted by the countries, incollaboration with WIIO and other multilateral and bilateral agencies, to control and prevent endemic and epidemic diseases and to develop new strategies to meet their present and future needs, were outlined. 6.2 In relation to the intention Eo intensify chemotherapeutic research, it was noEed Ehat an effective neEwork of basic health services would be essential for mass treatment of infected Persons should a suitable drug become available. Every encouragement should therefore begiven to the participating countries to develop the required basic health services. 6.3 It was also felt thaE the National Onchocerciasis Comittees should be involved in promoting the health services in the seven countries. 6.4 It ldas suggested that there should be close collaboration with the Ministries of Health of the participating countri.es, Eo investigate wheEher any OCP facilities could be utilized to augment local health services provided that this did not interfere with Ehe operations. 6.5 Recognizing the importance of training in strengEhening the national services, STAC stressed the need for the establishment of permanent posts with careers in all the partici- pating countries for those who will be trained with OCP assistance. 6.6 STAC reco'nmended t.hat OCP should investigate the possibility of finding alEernative, siryler techniques, suitable for use at conmuni.ty leve1 , which would facilitate the transfer of responsibility for Ehe continuation of operations, at the appropriate time. 7. CHEMOIHERAPY AND I'tlIE TAI',IALE CENIRE 7.L The Comittee, i.n reviewing the future use of chemotherapy in the control of onchocer- ciasis, was aPPrised of the various constraints. Ihe action being taken by the Special Programe for Redearch and Training in Tropical Diseases in promoting the development of new drugs was described. It was pointed out that the Ewo drugs currently available , viz. suramin and diethylcarbamazine (OfC)r w€E€developed in 1920 and 1943 respectively, therefore for 35years no new drug had been inEroduced. The development of a new drug for onchocerciasis is not easy and may t.ake several years. About US$ 20 nillion was required to conduct all the tests to clear it vrith national cormittees for trial in the field. After manufacture thedrug is often pirated by other countries which do not recognize patent laws. Finally, the countries requiring the drug cannot afford to purchase it. 7 .2 Under the auspices of trllIO an approach was made to pharmaceutical coqanies in the United Kingdom, France, the Federal Republic of Ge.rmany, Switzerland and Japan Eo discuss how progress might be made. For exarople, WHO could: (1) help with clinical trials; (2) assist ,ith th. screening and testing of coqounds available in coupanies; (3) contracE research in companies to help them investigate interesting groups of coryounds. 7.3 Steruning from TDR, several such conEracts had been established. A survey had been made of all drugs on Ehe market for other diseases to identify those passed for htman and veterinary use of value against onchocerciasis - testing centres had been established. The main objective is to find a drug effeccive against the adult \^rorms ocP fsrAcfTs.t Page 12 7.4 The Conrrittee felt strongly that it must be clearly understood that the time required to produce a new drug could not be predicted. An absolutely new coryound could take a minimug of 10 years with at least five years of clinical trials. However, some leads may be obtained from work done on veterinary anthelminti.cs over the past 10 years. Also, it is possible that Ereatment possibilities with DEc and suramin could be irrproved. 7.5 The Chemotherapeutic Research Centre at Tamale has now received most of its necessary equipment, and the junior staff are adequately trained. A 23-bed ward is available for treatmenE of onchocerciasis patients who come from infected villages within motoring distance of Tarnale. Medical and nursing supervision is available to the patients on a 24-hour basis and, with Patients staying in hospital for three to six weeks on average, annual through-put of some 2OO patients is foreseen. Ihe chemotherapy prograrme is run in conjunction with the University of Liverpool, which provides regular consultant support (four visits per year), and extensive back-up facilities from the School of Tropical Medicine and the Department of Clinical Pharmacology. 7.6 As of July 1978, the scientific, administraEive and financial responsibility for the chemotherapeutic centre had been handed over by the OCP to the WttO Special Programne for Research and Training in Tropical Diseases, where it will form part of the activities of the Filariasis Scientific Working Group and its Steering Corrnittee. 7.7 Most of the work to date had been on Metrifonate which had been shown to have a micro- filaricidal action that is less corylete, but also less rrviolent", than diethylcarbamazine citrate (OgC). The fu11 follow-up results of the trials at Tamale are not yet available. Preliminary results indicate that although the drug does temporarily reduce microfilarial concentrates, the acceptability of repeated doses by villagers is 1ow and interest in this form of therapy appears to lapse rapidly even though the reactions to treatment are less than with DEC. 7.8 Other recent investigations at Tamale included attempts to quantify the l(azzottj- reaction to DEC and a study of the possible effects of Indomethacin in darying down these reactions. In July 1978 a study began to evaluate the microfilaricidal properties of Furazolidone. 7.9 Clinical trials envisaged in the coming year include (i) other drugs approved for use i-n human medicine and selected for trial by the Filariasis SWG of the Special Prograrune; (ii) transepidermal DEC; (iii) detailed study of the pharmacokinetics, metabolism and toxicity of DEC and suramin, making use of C14-labelled preparations of these drugs. of Irmnunological and pathological support for the programme of chemotherapy is foreseen, so as to investigate and perhaps prevent the tissue-damaging reactions to microfilariae. Adequate ophthalmological support is also being sought. 7.10 After approval by the ITIHO committee on ethics, any promising leads for improved chemotherapy which come from the centrers work may be tested in pilot trials on a village scale within the OCP area with the help of the Prograrmne staff. The Conunittee noted that the Tamale centre was located in an area of i-nterrupted transmission so that drug trials will be carried out on patients with an aging worm load. Accordingly, it recognized the future need to open a new testing cenEre outside the control area. 7.LL The STAC approving the handover of the scientific, administrative and financial responsibility for the onchocerciasis chemotherapy research programme at Tamale to the Steering Conrnittee of the Filariasis Scientific Working Group of the WHO Special Programme for Research and Training in Tropical Diseases; ocP fsr/icfT B.t PaSe 13 - recomlzl ng the great potential benefits to the OCP thaE could stem from improved chemotherapy for onchocerciasis, both for the prevention and cure of eye and skln lesions in those already affected by the disease, and as a supplementary means of control by reducing the parasiEe reservoir in manl reconnnends that the Filariasis SWG should be encouraged to continue and expand its current PrograllEne of chemotherapeutic research on onchocerciasis, by all necessary means, with the objectives of: (i) improving the use of current filaricides; (ii) finding and developing a practical, effective and non-toxic macrofilaricide; (iii) developing means to prevent tissue-damaging reacEions to Ehe death of micro- filariae in the hr:man host. 8. ENDE.,IICITY LEVELS 8.1 The Conrmittee was informed of studies undertaken by the Progra'nme on the definition of endemicity leve1s of onchocerciasis. Ttrese studies concluded thaE Ehe prevalence of onchocerciasis in a population, as defined by standardized rates for microfilariae carriers, is the simplest Parameter for a survey EeaE to measure rapidly in the field and does not require soPhisEicated technology. The correlations investigated show that the severity of the disease is always related to the degree of its spread in the conurunity. The prevalence rate is therefore a suitable means for defining levels of endemicity in onchocerciasis. 8.2 It follows from the investigation that (a) when onchocerciasis affects 60% or more of the people in a community the situation is intolerable or is likely to become so in the short or long term; such cormrunities are in an unstable state; this is hyperendemicity; (b) when onchocerciasis affects less than 35% of persons, the effects of the disease are limited and it is socially inapparent; this is hypoendemicity; (c) where there are beEween 35% ar,d,60% of cases, the degree of severity varies both from one group to another and from one person in a group to another; this is mesoendemici Ey. 8.3 These definitions, based on findings in the West African savanna zone, may not be appli- cable elsewhere. 1t is felt, however, that onchocerciasis is found in this region in its most severe form and there is little chance that studies made in other ecosystems will lower the two threshold vaiues defined. 8.4 The Cormnittee, congratulating the team on this excellent piece of work, noted that the sociodemographic studies were undertaken in only one part of the Progranrne area, and recom- mended that they should be complemented by similar studies in other river valleys with different ethnic groups and agricultural systems. First priority should be given to valleys situated in the savanna belt of the Progranrne while subsequent studies could be carried out in the forest zone. 8.5 It is important to determine if the severity of onchocerciasis is Ehe result of the smal1 size of seEtlements or vice versa. 8.6 The results of such studies could provide useful guidelines for Ehe long-term socioeconomic development of the presently underpopulat.ed valleys in the OCP area. ocP fsr\cfTs.r Page 14 g.7 Irr discussions on the general epidemiolcgical evaluation activities, STAC considered that the fundamental diagnostic survey techniques agreed at the beginning of ocP should not be changed. Supplementary techniques which,night have to be introduced should not replace the basic techniques, andmust not preclude the comparability of the initial basic survey results with data from subsequent surveys. 8.8 OCP being Primarily, and essentially, an oPerational Programme usinS mass techniques as diagnostic tools, the limitations of these techniques should be borne in mind when analysing the data obtained from village surveys. g.9 STAC recormrended that the Progranune should endeavour to collect information on the following subjects: (a) the number of people at risk living in the reinvasion areas; (b) the Iife expectancy of blind persons beyond the onset of blindness from onchocerciasis; (c) preferential mortality, if any, of persons blind from onchocerciasis in relation to Persons blind from other etiologies; (d) the distribution and regression of O. volvulus infections after interruPtion of transmission in children and young p...o.ri particularly in hypoendemic and low-mesoendemic vi11ages. 9. REPORT OF ECOLOGICAI PANEL 9.1 The reporr of the meeting of the Ecological Panel held in Rome on 29 and 30 May 1978 was presented to the conrnittee for information. It was felt that, since there are several matters of interest to both the Ecological Panel and STAC, ParticuLarly relating to Larvicides and their application, some way should be found to ensure that views accepted by boLh Sroups are presented to the JCC. IO, OTHER MATTERS Progranrne staffing lO. I The Cormnittee expressed concern about the staffing of the entomological side of the progranmre, pointing out that there was little margin to deal with ernergency situations' 10.2 The Director agreed that this was a matter for concern and appealed to STAC to assist in che recruitment of staff, forwhich there was already budgetary provision and a mandate from the JCC for action. 11, ARRAN'GM4ENTS FOR THE NEXT MEETTNG 1l.I It was agreed that the date and place of the Direclor in relation to the Programne of meetings of at about the same time of the Year. 12. CLOSE OF MEET]NG L2.L In closing the meeting extended to the Cormnittee and the Prograrmne Director and his success of the meeting. next meeting should be determined bv the the OCP, but that it would be appropriate the chairman thanked the Regional Director for the hospitalitl' for the excellent services provided. The chairman also thanked staff, the interpreters and all Lhose who had contributed to the 12.Z On behalf of the Cormnittee Dr Goodwin congratulated the Chairman on the comPetent manner in which he had guided the discussions of the group' 1. ) 3. 4. 5. 6. 7. 8. 9. 10. 11. L2. 13. L4. 15. 16. ocPfsrAcfTB.L Page 15 ANNEX I AGENDA Opening of the meeting Election of chairman Adoption of the agenda Progress report on acEivities Review of draft OCP Evaluation Report Long-term future of the Prograrme Report on SAP Working Group on Insecticides, 3-7 July 1978 Report on meeting of Ecological Panel, 29-30 May 1978 Health infrastructure in the OCP countries and acti.on against other cormunicable diseases Chemotherapy and the Tamale centre Definition of endemicity levels Annual report of STAC Other matEers Review and adoption of the report of the meeting Arrangements for the next meeting Close of meeting oce fsrecfta .r page 16 ANNEX II REPORT OF THE SAp I^IORKING GROUP ON INSECTICIDES, 3-7 JULY 1g7g A. lntroduction 1. The meeting was opened by Mr I'larc Ls. Bazin, Director of the Onchocerciasis Control Programrte who after welcoming the participants (Appendix 1), explained that the working group had been convened on the reco.r'mendation of the Scientific and Technical Advisory Conrmittee which had repeatedly expressed its concern at the persistent lack of a standby insecticide for the control of the vector. As, in the absence of a suitable medicament to treat the disease, it was anticipated that effective vector control would have to be maintained over a period of 2O years, the need for an alternative to Abate was obvious if only to guarantee the continuity of the operations to a successful conclusion. It was pointed out that approximately 12% of the US$ 60 nillion budget for the first six years of the Prograrme had gone towards the cost of insecticide and indications were that the international financial comnunity would be maintaining its interest in the Progranme in the fuEure. In addition, studies being undertaken in Gui-nea, Guinea-Bissau, Senegal, Nigeria, Sudan, Tanzania and elsewhere to plan onchocercia- sis cont,rol operations signalled the need for ever-increasing quantities of larvicides. Ihe Director said that the Progreme was ready to give serious considerati-on to any alternatives to the insecticide now being used, provided they were comparable in effectiveness, safety and cost. So far only the Abate formulation in the current operations had the combined qualities of efffectiveness, biodegradability and minimr:m effect on the non-target fauna necessary. Chairman Dr J. W. Miles was appointed Chairman and Dr J. Mouchet invited to be Vice-Chairman. Adoption of Agenda The Agenda (Appendix 2) was adopted. General information 4. One of the main purposes of the meeting being to appraise the representatives of Ehe chemical coryanies of the urgency of the problem and provide them with all the information available to enable them to develop larvicides appropriate Eo the control of Simulir.un, the first part of the meeting was occupied with the presentation of a series of Eechnical papers identifying the nature of the problem and characteristics of the target. A review was made of the bionomics of the target species and how these relate to the control methodology wiEh particular emphasis on the control operations. 5. With the wide dispersal of the adults and the present lack of knowledge of their resting sites, the attack had to be restricted to the larvae located in clearly defined secEions of the rivers. Eggs and pupae had low susceptibility to insecticides but the larvae, attached to substrates and filtering their foofl from flowing hrater, I^7ere the most appropriate targeE. 6. Details r^7ere presented of the characteristics required from the insecticide formulations used in blackfly control. Among other things, they must have a high effecEiveness against the blackfly larvae, good carry and rapid biodegradability, good dispersibility in water when applied from aircraft, moderate to high content of acEive ingredient and innocuity for non- target organisms. 7. The threat of developing resistance r^ras ahrays present. A suitable method for testing susceptibility had been developed and to date there was no indication of resistance developing towards Abate. However, in rivers where DDT had been used for agricultural purposes S. damnosum larvae rdere reported to show resistance to this product. B 2 c 3 D ocPf sr/lcf 78.r Page 17 Annex II 8. Consideration was given to the problen of non-target organisms and environmental contami- nation. The Onchocerciasis Control Programe had developed a protocol for monitoring the aquatic fauna and analysis of the data collected from a series of rivers indicated a general reduction in the bimass of approxinately 30% as a result of the Abate trear-ment. Ttre Ecological Panel of the Programe had considered this acceptable as long as the productivity of the river was not reduced. 9. Due attention must be paid to the toxicity of the insecticide to man and ani.mals especially as, for Simulium control, the product had to be applied regularly to rilaterways. 10. Whatever product was used must be stable in the rather extrene conditions found intropical Africa. Not only must the containers be sufficiently robust to withstand the hazards of transport over bad roads, but the formulation must be sufficiently stable when stored in the open air, often rsithout shade, where texlperatures may reach 55"C. For logistical reasonsit was often necessary to store drrms in these conditions for six months and more. 11. A critical review was made of the procedures followed in the screening and evaluation of insecticides against target and non-targeE organisms. Many laboratory methods devised had not been entirely satisfactory because of the inconsistency of the results. Others had proved useful for preliminary screening but often the results obtained had not been comparable with riverine applicati.on. Trough tests had certainly shown greatesE potential. Most OCp screening had been done using floating cages which were useful for studying effects on both target and non-target organisms, and, by this Eeans, it had been possible to cope to date with all products so far provided. Before a product could be considered for potential operational use, riverine t,ests had to be carried out to determine the carry of the product, followed subsequently by a larger-scale trial of longer duration to check its effect on target and non- target organisms in different seasonal conditions. 12. In conjunction with field screening, chemical laboratory tests had been carried out to develop specifications which defined the properties of the emulsion concentrate required for optimum action on the larvae. These requirements included a density slightly less than one and emulsion ProPcrties when the formulation is oixed with water which a1low it to be effective at low concentrations. Further refinement of these requirements rras haryered by lack of understanding of how the formulations act on the larvae in the river at sites distant from the point of application. 13. In the discussions which fol1owed, several company representaEives asked what were the chances of OCP using an alternative formulation to Abate should one be developed. It was explained Ehat, in so far as it was technically feasible, and taking into consideration its effectiveness on the target organisms, its biodegradability, its tevel of effect on non-target organisms and cost, the Progra@e would be willing Eo change to another producE. When more than one product becaue available WHO would be obliged to purchase it on Ehe basis of inter- national tender. However, it was stressed that potential markets for new products could be foreseen outside the present Onchocerciasis Control Prograrrme. 14. Some concern was expressed at the lack of understanding as to why different formulations of Abate work or not and it was felt that while Abate seemed to be most effecEive as an emulsifiable concentrate, this t5pe of formulation may not be what is required for this. It was also felt that some distinction should be drawn between screening of the basic compound and the evaluation of the product presented by the companies. 15. Some clarification ldas requested on what policy would be followed if resistance to Abate developed. It was accepted that different approaches were possi.ble and the best advice would be sought when required but, at present, no possible programne or policy could be considered in the absence of alternative products. ocef srrcfta.r page 18 Annex II E. Recomrendations 16. Four working groups considered: (a) what industry would require to help it respond to the needs of OCP in providing alternative products; (b) the methods of testing the effect of new products on the target organism; (c) the evaluation methods against non-target organisms; and (d) the operati-onal constraints; and put forward the following recomendations which were adopted Jointly by the participants. (a) Industry L7. A list of products cleared for operational use and safe for the purpose should be published and kept up to date. 18. Suitable sites where treatment is not carried out should be used for evaluation of novel compounds/pro<lucts to cover the following phases: - sma11-scale screening against S. damnosrm in l,Jest Africa, including positive and blank standards, which is sufficiently flexible to accept technical compounds or experimental formulations ; trough evaluati-ons as currentl y carried out to include observaEi-ons on target and non- target organisms in conrparison with a standard; river tests to establish effects against targeE and non-target organisms in comparison with a standard; large-scale semi-operat.ional evaluations in comparison with a sEandard. Results of these should be submitted prorptly afEer completion of testing. 19. Research should be undertaken on the physical characteristics important for a long carry downstream from the point of application, i.e. the emulsion at the site. 20. Methods which had been developed to determine susceptibility should be used by trained teams and regdlar sumrari,es of their findings should be rapidly disseminated so that early signs of resistance of operaEional significance can be seen. 21. Means should be considered by which field storage conditions for the formulation could be improved; information should be provided on actual storage conditions and field testing for stability. 22. with a view to finding an additional too1, studies should be carried out on the relevant biology of adult flies with a view to examining control methods applicable to other adult Diptera. In order to consider the introduction of adulticide control in addition to larvicide control, the following research was required: a study of the relevant biology of the adults to determine where the application would have to be made; the development of methods for the field on S. damnosum adult testing candidate adulticides in the laboratory and in females and on non-target organisms; the development of methods of application for selected cornpounds. (b) Tarset organi sms 23. In general, coupounds showing appropriate mosquito larvicide or equivalent activiEy should be selected for evaluation against Simulium. These cornpounds should also have 1ow acute and chronic toxicity to manrnals. Currently, there are several laboratory, semi-field ocPfsrAcfTs.L Page 19 Annex II and field evaluation techniques which can yield useful infornation on acti.vity of larvicides against Sirnulir-m. It was urgent that these techniques and research programnes should be expanded to respond to the short-term and long-term needs of the OCP (perhaps along the lines proposed in paragraph 18). 24. In addition, the following investigations could provide information of potenEial value to future research: - a determination of whether the results obtained from evaluating larvicides againsE Paleartic and neartic Simuliurn species are relevant in a control context to Simulir-rm demnosum; an evaluation in North America of larvicides and formulations Africa; already tested in WesE a corparison in Africa of the effects African (Ethiopian) Simulium species. of larvicides on Simulir:m d46n6srrm and on other 25. the An evaluation should be made in the laboratory andfor the field of the mode of action oflarvicide emulsion at the site of action. (c ) Non- tar Eor slns 26. Ttre chemical coqounds which had been shown effective on the target organism are expectedto have been tested for ma'rmalian toxicity. Ihe amount of toxicity information required will depend upon the scale of the test or use but the following criteria should be kept in rnind: low manmalian toxicity of the formulation; - rapid metabolism of the active ingredient by marmals; and biodegradability in the environment and not excessively accr:mulated in aquatic organisms such as fish which serve as hr:man food. DeDonstrated non-ttutorigenicity in standard long-term feeding studies should be obtained beforethe larvicide is introduced on a large operational scale so that their manrmalian safety can be assessed with sufficient accuracy. 27 - Corrpounds to be tested on aquatic non-target organisms in the area of operation should already have been shown to be effective on the target Simulito and have been iested on aquatic vertebratesr €.8. fish and anphibians, and also on plarktorric-organisms. Evaluation tests inthe area should include: sutter tests for innnediate effects on invertebrates to identify sensitive and relativelyinsensitive taxa; - PreedinF site tests under operational conditions to determine the short-term effects oninvertebrates. This would be done by saryling with fine and coarse drift nets 24 hourspre- and 24 hours Post-EreaEment and by qualitative assessment of changes in the composition of benthic fauna. 28. Large-scale or oPerational evaluation trials should be made in comparison with a non-treated area, which could be in Ehe same river system, and should include: invertebraEe drift sampling with both fine and coast nets during both the pre- and post- sunset periods; to determine the qualitaEive fate of the taxa and to rnake aquanti Eative assessment ; ocP fsr^cf7B .t page 20 Annex II sampling by a method selected according to the habitat, to i.ndicate quantitative changes in the benthos; - recording from visual observation of mortalities of the vertebrates. 29. After the coqound has been cleared for short-term and inrnediat.e effects on the non- target organisms, monitoring of long-term effects should be carried out during regular application of the larvicide to assess the productivity of the ecosystem. The methodology ln use for the current application of temephos in the Onchocerciasis Control Progranure may be used but, in addition, attention should be paid to the primary producers, phytoplankton and p eriphyton. 30. Chemical analysis of water, mud and important organisms such as fish, crustacea and molluscs should be carried out to monitor the fate of the cornpound and assist interpretation of the non-target organism results. (d) 0perations 31. While it was noted that specifications for temephos EC for Simulium larvae control were to be published, investigation should be continued to refine the requirements not only for temephos but. also for new larvicides that might be developed. Consideration should be given to physical/chemical, biological and other characteristics as they affect the target organism, the environment and the operations. Underlying many of these was the need to have inforaa- tion on the mode of acti-on of the larvicide emulsion at the larval sites. 32. Ttvo conditions for carrying out large-scale field or operational trials r^7ere recognized: larvicides which have equivalent or iryroved performance over temephos should be tested in previously untreated rivers but the constraint noted in paragraph 33 would have to be taken into account; larvicides acceptable for use in place of temephos in urgent or emergency conditions(such as the appearance of resistance to temephos) should be tesLed in previously treated rivers with only the mrnpower constraint noted in paragraph 33 to be taken into account. In either case the timing of the trials should preferably cover the period from the middle of one rainy season into the following dry season, the actual duration depending upon the time needed to obtain sufficient data on the effects on target and non-target organisms. Evalua- tion of Ehe effects on the non-target organisms should be made as prescribed in paragraph 28. 33. Ihere were constraints in carrying out large-scale or operational field trials. Trials within or imnediately outside the OCP area did not seem possible in the near future, especially if proposed extensions to the area were irnplemented. Ihus another test area outside the OCP operations would have to be found. While appreciating that responsibility for carrying out the work was beyond the capability of the Vector Control UniE it was emphasized that it would require close supervision by OCP to ensure that the trial would simulate the present operations. In addition, sufficient staff and equipment, e.g. helicopters, would have to be provided. 34. In view of the foregoing, the problem of large-scale trials should be examined with particular reference to the following: the intensification of research on the development of environmental test methods including the possible use of additional smal1-scale techniques; the applicability and pracEicability of moni-toring the effects of new products on non- target organisms either in non-S. damnosum rivers or in untreated tributaries of the treated rivers; FocPfsr^cf78.l PaBe 2l Annex II - the development of flowlng ltater laboratory tests or other methods for deterriningtoxicity of the ne!, cqounds to fish, which are of economic iryortance. Conclusions 35. rt was generally agreed to be unlikely that conrmercial corryanies would devote resourcesto production of new coryounds for Simulir.rm control in the future but, given the existence ofa field evaluation scheme on the lines suggesEed above, industry would be prepared to submit samples of coryounds/formulations for testing and, where indicated, further development. 36. The variety of screening and evaluation methods developed seemed to be satisfactory.However, there was a need to do further research on these and Eo strengthen and expand thefacilities for testing available in Africa. Also methods already in use elsewhere should beintroduced into Africa, as appropriate, especially for testing insecE growth regulaEors. 37. The view was exPressed that selection of a candidate product should be based aE this stage on the results of tests on the target organism, i.e. s. damnostm s.1. 38. The develoPment of a more liberal exchange of information and results of research wascal1ed for. In this resPecE, the coryany representatives, in particular, felt the meeting tobe especially helpful and considered it would be beneficial to have a folIow-up meeting in approximately two years I time. ocP fsrAcfTB.L Page 22 Annex II Appendix 1 LIST OF PARTICIPANTS Dr A. N. Alekseev, Martinsinovskij Institute of I'ledical Parasitology and Tropical Medicine, 4qsletr, USSR Dr C. Dejoux, ORSTOM Hydrobiology Laboratory, Bouakri, Ivory Coast Dr V. P. Dremova, Research Institute of Disinfection and Sterilization, Moscow, USSR Dr P. Guil1et, Onchocerciasis Research Institute, Bouak6, Ivory Coast Dr P. Haskel1, Centre for Overseas Pest Research, London, United Kingdom Dr H. Jamnback, University of the State of New York, Albany, New York, United States of Aurerica Dr J. Miles, Center for Disease Control, Atlanta, Georgia, UniEed States of America Dr J. Mouchet, ORSTOM, Bondy, France Dr M. Mulla, University of California, Riverside, California, United States of America Dr !1. A. Odei, InsEitute of Aquatic Biology, Achimota, Accra, Ghana Dr B. Statzner, Zooological Institute of the University of Kie1, Kiel, Federal Republic of Germany Dr M. Yasuno, National Institute for Environmental Studies, Ibaraki, Japan Dr A. N. ClemenEs, Shell, United Kingdom Mr C. R. Dash, Dow, Switzerland Mr Delabarre, Roussel Uclaf, France Dr A. C. Grosscurt, Philips-Duphar, Netherlands Dr H. J. Holtmann, Celamerck, Federal Republic of Germany Mr S. Kawasaki, Sumitomo Chemical Coropany, Japan lfrr L. Lazare, Zoecon, United States of America Dr J. McCallun-Deighton, rCI/P1ant Protection, United Kingdom Dr H. J. Niessen, Bayer, Federal Republic of Germany Dr K. Scholz, Bayer, Federal Republic of Germany Dr G. W. Smith, Dow, United Kingdom Dr J. C. I'Iickham, i,Ie1lcome, United Kingdom Dr R. Wyniger, Ciba-Geigy, Switzerland Mr Marc Ls. Bazin, Director, Onchocerciasis Control Progranrme, WHO, Dr J. D. Briggs, vGBfvBC, [fHO, Geneva, SwiEzerland Dr R. Le Berre, ECvfvBC, WHO, Geneva, Switzerland l'1r J. D. M. I"Iarr, Liaison Officer, OCP, WHO, Geneva, Switzerland Dr G. Qu6lennec, PDS/VBC, IrIHO, Geneva, Switzerland Dr A. R. Stiles, PDS/VBC, IIHO, Geneva, Switzerland Dr M. Vandekar, PDS/VBC, wHO, Geneva, Switzerland 0uaga douggu Upper Volta Mr J. F. Llalsh, Chief vcufocP, I4IIIo, Ouagadougou , Upper Volta oef sracfta.r page 23 Annex II i-x2 AGENDA 1. Opening 2. Election of the chairnan 3. Adoption of the agenda 4. Appointment of the rapporteurs 5. Nature of the problem and characteristics of the target 5.1 Bionomics of the target species and relation to control, with special emphasis on OCP operations 5.2 Conflicting characteristics required from insecticlde formulations for blackfly control 5.3 The problem of resistance to insecticides 5.4 Ttre problem of non-target organisms and environmental contaminatlon 5.5 The problem of the safety of insecticides to people 5.6 The operational problems 6. Critical review of the procedures followed by the screening and evaluation of insecticides against Earget and non-target organisms and results to date 6.1 Introduction: Generalities of the methodology followed in Africa 6.2 Laboratory tests, including simulation of field conditions 6.3 Field evaluation at small and medirm scale 6.4 Large-sca1e field evaluation 6.5 General discussion 7 - Problems of insecticide screening and formulation development related to specifications 7.1 Physical and chemical properties 7.2 Biological properties related to target organisms 7 -3 Biological ProPerties related to non-target organisms - including man 7.4 Formulation development and specification problems 7 .5 General discussion 8. Intensification of research and development of insecticides for blackfly conErol 8.1 Prospects for new chemical and biological insecticides 8.1.1 Present trends in chemical insecticide research for public health ocef sracf te.r page 24 Annex I1 Appendix 2 9 10 8.L.2 Potential of some new insecticides, including pyrethroids and insect growth regulators 8.1.3 Potential of biological insecticides 8.2 Prospects for new and iryroved formulations 8.3 Prospects for iryroved evaluation procedures 8.3.1 Laboratory and simulated field tests 8.3.2 Small- and medium-scale field tests 8.3.3 Operational evaluation 8.4 Discussion Presentation, discussion and finalization of the report Closure of the meeting ocvf srrcfta.r page 25 ANNEX III RECOMMENDATIONS Reinvasion STAC recormended thaE a second SAP Working Group on Reinvasion be convened which would also consider the irylications of extension in this field (paragraph 2.L4). Life expectancy of bl1nd people Although no reliable data are available at present, evidence suggests that blind people may on average live only five or so years after the onset of blindness. The Conrmittee recotmended that the irrylications of this be reflected in future evaluation reports. Ttre Contrnittee also recorrmended that further data be collected to substantiate the conclusion and that the Progran'me obEain the servlces of a demographer consultant to assist the Epidemiologi- ca1 Unit in this field (paragraph 3.4). Long-term future of the Programe Ttre Onchocerciasis Control Prograrme was conceived and planned according Eo the best inform"tion on the epidemiology of the disease and the biology of its vectors available in 1973. Since then the knowledge on these subjects has noEiceably increased, as a result of the Progrrme activities, as outlined below. The Comittee recomended that these findings be included in the EvaluaEi-on Report. It is, in particular, essential to take into account that: (a) the long-range active dispersion of S. damnosum s.s. and S. sirba num involves mostly parous feoales and thus has a greater epidemiological iryortance than originally anticipated; (b) Ehe hrnan migration trends involve not only large population movements from the savanna zones to southern areas but also Dovements from the coastal and forest zones to the OCP area, thus introducing new O. volvulus carriers in this area (c) the distribution bionomics and vectorial iryortance of the various members of the S. damnosr:m cory1ex is much betEer known; the breeding places of the savanna cytotypes S. damnosum s.str. and S. sirbanr.o stretch further south E.han originally anticipated(paragraph 4.2). Insec t icide s Ihe Conmittee, noting that the river presently used for testing candidate compounds will soon be subject to regular larviciding by OCP, strongly recomended that the Prograuune should take irmediate action to develop the necessary facility for screening and evaluaEing candidate coryounds. The requirements for this facility include: (a) a site within easy access of sizes; S. damnosr:m and S sirbanum breed ing rivers of various (b) suitable laborat.ory and housing accomodation; (c) back-up support such as transport and equipment; (d) prowision of adequaEe staff, both professional and ancillary (paragraph 5.2). ocPfsr[cfTs.r Page 26 Annex III Adul ticiding The Comittee re-enPhasized the iryortance of developing techniques for control of adultS. damnosr:m of adults; because the .. Ihis will require attention to two mpin points: (a) discovery of resting sites and (b) work on the susceptibility of adult Simulirm, particularly gravid females, se are llkely to be most tolerant to insecticides. STAC, noting the recomendation on this point made by the SAP Working Group on Insecticides, recolmended an expansion of this work in view of its potential in controlling reinvading adults (paragraphs 5.6, 5.7). Health infrastructure in OCP countries STAC recorunended that OCP should investigate the possibility of finding alternative, siryler techniques, suitable for use at comunity 1eve1, which would facilitate the transfer of responsibility for the continuation of operations at Ehe appropriate time (paragraph 6.6) Chemotherapy The STAC: approving the handover of the scientific, administrative and financial responsibility for the onchocerciasis chemotherapy research progranme at Tamale to Ehe Steering Corrnittee of the Filariasis Scientific l.Iorking Group of the WHO Special prograrnme for Research and Training in Tropical Diseases; recogni.zing the great potential benefits to the OCP that could stem from improved chemotherapy for onchocerciasis, both for the prevention and cure of eye and skin lesions in Ehose already affected by the disease, and as a supplenentary means of control by reducing the parasite reservoir in mrn; - reco'nnends that Ehe Filariasis SWG should be eniouraged to continue and expand its current Progra[me of chemotherapeutic research on onchocerciasis, by all necessary means, with Ehe objectives of: (i) improving the use of current filaricides; (ii) finding and developing a pracEical, effective and non-toxic macrofilaricide; (iii) developing means to prevent tissue-damaging reactions to the death of micro- filariae in Ehe htruran host (paragraph 7.Il). Endemicity leveIs The Conrnittee, noting Ehat sociodemographic studies were undertaken in only one parE of the Prograrnme area, recommended that they should be cornplemented by similar studies in other river valleys with different ethnic groups and agricultural systems. First priority should be given to valleys situated in the savanna belt of the Prograrmre while subsequent studies could be carried out in the forest zone (paragraph 8.4). Epidemioloeical eva luation STAC reconunended that the Prograrrne should endeavour to collect information on the following subjects: (a) the nr:mber of people at risk living in the reinvasion areas; ocef sracfta.r page 27 Annex III (b) the life expectancy of blind persons beyond the onset of blindness from onchocerciasis; (c) preferenEial mortality, if any, of persons blind frm onchocerciasis in relation to persons blind from other etiologies; (d) the distribution and regression of O volvulus infections after interr uption of transmission in chlldren and young persons particularly in hypoendemic and low- mesoendemi.c villages (paragraph 8.9). I