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

JOINT COORDINATING COMMITTEE Onchocerciasis Control Programme in the Volta River Basin Area Ofice of the Independent Chqirrrut, c/o World Hcalth Organization l2ll Gcneva 27, Switzcrland Tcl. 3,t6061 Tcbx erllk 2TB2L J.C.C.-C.C.C. COMITE CONJOINT DE COORDINATION Programme de Lutte Contre I'Onchocercose dans la R6gion du Bassin de la Volta Bureau du Prdsident Indtpendant c/o Organisation Mondiale dc la Sant€ l21l Gentve 27, Suisse Tcl 346061 r6lcx &ftk 2782L JOINT COORDINATING COMMITTEE Fifth session Lom6, 5-8 December 1978 JCC5.3 25 September 1978 $ovisional agenda item 5 The Independent Chairman submits for the conslderation of the Joint coordinating committee, at its fifth session, the report of the seventh meetlng of the Scientific and Technical Advisory Committee. This document has been reviewed by the Steering Committee owf srtcfta.t ORIGINAI.: ENGLISH ONCHOCERCIASIS CONIB.OL PROGRAMI'{E IN THE VOLTA RIVER BASIN AREA SCIENTIFIC AND IECHNICAI ADVISORY COMMITTEE Report of the seventh meeEing Brazzavi-ll-e. 2L-2 5 August 1978 12 ocP fsr^cf78.t Page 2 List 11. Arrangements for the next meeting . . 12. Close of meeting Annex I - Agenda of the meeEing Annex II - Report of the SAP Working Group Annex III - Reconmendations CONTENTS of participants . . Opening of the meeting Progress report on activities . Extens ion Reinvasion studies . . OCP Evaluation Report . Long-term future of the Prograrrne . Screening and evaluation of insecticides - report Adulticiding. Health infrastructure in the OCP countries Chemotherapy and the Tamale centre Endemicity 1eve1s . . Report of Ecological Panel Other matters Progranrme staffing of SAP working group on Insecticides , 3-7 July 1978 3 4 5 6 7 8 9 10 Page 3 5 5 6 6 7 8 10 l0 L1 11 13 t4 L4 t4 L4 L4 15 t6 25 ocPf srAcfTB.L Page 3 LIST OF PARTICIPAI.ITS Members Dr E. G. Beauso1eil, Director of Medical Services, Ministry of Health, p.O. Box M. 44, Accra, Ghana Dr D. t{. Buttner, Head of Department of Helmlnthology, Scientific Director, Bernhard-NochtInstitute, Bernhard-Nocht-Strasse 74, 20OO Hanburg 4, Federal Republic of Germany Professor J. Diallo, Facult6 de M6decine, p.o. Box 6191, Dakar - Etoile, senegal Professor L. G. Goodwin, Director of Science, Zoological London N.W.1, United Kingdom Society of London, Regents park, Dr Peter llaske11, Director, Centre London W8 5SJ, United Kingdom for Overseas Pest Research, College House, Wrightrs Lane, Dr H. J. Knuttgen, Director, Institute of Tropical Medicine, University of TtJbingen, Tttbingen,Federal Republic of Germany Dr James Miles, Chief, Pesticides Branch, Vector Blology and Control Division, Bureau ofTropical Diseases, Department of Health, Education and Welfare, Center for Disease Control,Atlanta, Georgia 30333, United States of America Dr J. Mouchet, Inspecteur g6n6ra1 de Ia Recherche, office de 1a Recherche Scientifique etTechnique Outre-Mer, Services scientifiques centraux, 7O-71, Route drAulnay 93L4O, Bondv,France Dr L. E. Rozeboom, Professor Emeritus of Medical Ent.omology, Ihe Johns Hopkins University,3196, Laverne iircle, Harystead, Maryland zlo74, united staEes of Aoerica Joint Coordinating Cornmit tee Dr M. G. candau, rndependent chairman, cfo wHo headquarters, Geneva, World Bank Mr S. Denning, Division Chief, progranme I. United States of America World Health Organization Dr comlan A. A. Quenrmr, Director, Regional office for Africa, Mr Marc Ls. Bazin, Director, onchocerciasis control progranrne, Switzerland [Iestern Africa Region, World Bank, Washington D. C. BrazzaviLle , Congo Oua ou Upper Volta Dr J' Hamon, Director, Division of Vector Biology and Control, wHo headquarters, Geneva,Swi tzerland Dr J. A. Mahoney, Director, Disease control and Environmental Hearth, Regional office forAfrica, Btazzaville , Congo Dr B' o' L. Duke, Chief, Filarial rnfections, Division of Malaria and other parasitic Diseases,WHO headquarters, Geneva, Switzerland Mr R' Helmholz, chief, Administrative Services, onchocerciasis control progranne, ouagadougou,Upper Volta ocYf srrcfta.t page 4 Dr M. Baldassini, Regional Officer (Other Parasitic Diseases), Regional Office for Africa, Brazzavi 11e Congo Dr J. B. Davies, Entomologlst, Vector Control Ouagadougou, Upper Volta Unit, Onchocerciasis Control Prograrme, Dr V. Eyakuze, Regional Officer Africa, Brazzavi-]-Le, Congo (Research Promotion and Developrnent), Regional Office for Dr F. C. Grant, Regional 0fficer (Onchocerciasis Control), Regional Office for Africa, BrazzavtlLe , Congo Dr rba Gueye, Regional officer (Malaria), Regional office for Africa, zavi 1 1e CongoBraz Mr J. D. M. Marr, OCP Liaison Officer, WHO headquarters, Geneva, SwiEzerland Dr J. Odetoyinbo, Regional Officer (Vector Biology and Control), Regional Office Brazzavi,tl-e ., Congo Epidemiologist, Epidemiological Evaluation Unit, Onchocerciasis for Africa, Dr A. Prost, Prograrune, Contro 1 Ouagado ugou , Upper Volta Mr G. ZeEbo, Medical Entomologist, Vector Control UniE, onchocerciasis Control prograrme, Ouagadougou , Upper Volta ocvfsrrcfta.r page 5 1. OPENING OF l]IE MEETING 1.1 The seventh meeting of the Scientific and Technical Advisory Comittee (STAC) took place at the WIIO Regional Office for Africa, Brazzavi-lle, from 2L to 25 Augusr 1978. Itre meeting was opened by Dr Comlan A. A. Quenrm, WHO Regional Director. In welcoming t.he parEicipants, Dr Quenr-m expressed his appreciation to the corrmittee and t.hanked the members for their conscientious and sustained efforts to fulfil their terms of reference, which were reflected in the excellent report fot L977 to the Joint Coordinating Comittee (.fCC).1 L.2 Dr Quenr-m also welcomed Dr Candau, Independent Chairman of the Joint Coordinating Comittee, and Mr S. Denning of the World Bank who had been invited to at,tend the present meeting in view of the irylications for the future of certain items to be dlscussed, in Particular the draft OCP Evaluation Report which would be presented to the next session of the JCC. Dr Quentm drew attention to the pressing need for a drug Eo 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 Ehe Regional Director ca1led upon all concerned for increased efforts to enable the objecEives to be met. 1.3 In the absence of Professor P. Janssens, Chairm:n of STAC, who was attending the International Congress of Parasitolot, tl Warsa\d, Dr Peter Haskell chaired the meeting. 1.4 The Comittee was inforred that Dr A. Rougemont had recently been appointed Chief of the oCP Epideniological Evaluation Unit and therefore could no longer retain his STAC membership. Dr I. Lindsay rdas unable to attend due Eo a previous comitnent. 1.5 The agenda adopted for the meeting is appended as Annex 1. 2. PROGRESS REPORT ON ACTIVITTES 2.1 Mr Bazin reported on the acEivities of the Progranrrne in 1978 and on the action taken on the recomendations made by the Cormrittee at its sixth Eeeting in November L977. These recormendations had virt,ually all been inplemented. As proposed^by SIAC2 Programe 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 alternative insecticide.' The report of this Group which had been chai,red,bv Dr Miles, had been circulated to the Cornmittee as working documenr ocef srrcfl7.4 (ocPf silrcf 78.25). wittr regard to the suggestion for a working group to review the epidemiological evaluation techniquesr) an exchange of correspondence on this subject had taken place between certain STAC members and Prograrme personnel which had clarified the issue. 62.2 Itre proposal for Dr Vajime, Progranme cytotaxonomi.st, to visit Nigeria to collect at the start of their visit, in Lamr-Kara (Togo), on S. damnosum specie 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, arrangements were under way for the visits of Dr Crosskey and Dr Petersen to the Progranure area/ in rnid-October and a workshop was planned The proposal for a multidisciplinary group on integrated disease contro discussed with other L[lO divisions concerned; however, taking into acc priorities in 1978, it had been agreed to postpone this until later. 1 ocr/srec ftt.z.2 ocrf srrcftt .1, patagraph 47 . 3 WIIO Special Prograrrne for Research and Training in Tropical Diseases s in West Africa. 18 activities had been ount the Programets 4 ocYfsracfn.t, s ocef srrcf tt .t, 6 ocef srrcf tt .2, 7 ocefsracftt.s, 8 ocYf srrcf tt .2, paragraph 69. paragraph 39. paragraph 57. paragraph 56. paragraph 77. ocPfsrAcfTs.L Page 6 2.3 Final1y, the WIto Regional 0ffice for the Americas had been invited to send an observerto the Present meetingl but although the response had been favourable participation was notpossible at this meeting. Extension 2.4 Requests for an extension of the OCP activities to the Senegal River Basin area and the Nigerian part of the Niger River Basin had been made to the JCC at Kuhrait in December L977. Ihe JCC accepted to fund feasibility studies in the Malian part of the Senegal River Basin area and suggested that other feasibility sEudies be provided for by WIIO. In 1978, funds were allocated for that purpose by the Regional Direcror, AFRO (US$ 150 OOO) and t.he Director- General of I,IIIO (us$ 30 o0o) in addirion to orher available resources. 2.5 A preliminary analysis of the situation had been made in the savanna areas to the wesE of the Present Programe area, nErmely Guinea, Guinea-Bissau, Idali (western part), and Senegal and to the east of OCP in Nigeria. Subsequently, MIO staff visited all these countries(except Guinea-Bissau) to prepare couplementary field studies, discuss the need for additional river gauges for monitoring water flow, consider the need to develop national expertise, etc. The areas of these river basins where the onchocerciasis situation is best known are in Mali and Senegal; here the surveys on vector distribution will be coryleted by late 1978 through aerial surveys conducted during the rainy season. IIHO teams are being established to speed up the collectlon and analysis of information in Guinea and studies are being undertaken in the Senegal River Basin area to determine the possibility of onchocerciasls control. Studies are also being mad€r with WHO assistance, in Nigeria, and it seems probable that Nigeria will develop a national onchocerciasis control campaign in cooperation with WltO and other inter- national and bilateral instiEutions. 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 The reinvasion studies for 1978 were outlined by WHO. It was pointed out that these studies were still going on and that full results would not be available until the end of September 1978. 2.7 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 werq set up, six in "sourcetrareas and nine in theItarrivalrrarea. Ihirty-six vector collectors and nine chauffeurs were recruited Eemporarily to man these points. 2.8 l\so consulEants arrived on 1 May, and were joined by a third on 22 l(ay, to carry out detailed sEudies on the fIies. I\ro 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 technician at Seguela. Activities began in March. The wet season actually started six weeks earlier than in the previous three 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 Bandam4 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 it as a possible source river. Flow began on 25 April at which time 3O-5O tliesfnanfday were being caught ar Pont L6raba, 60-100 at Chauss6e Niakaramandougou and lOO-300 per day at a site on the River Bou. As in previous years, these were almost all parous savanna flies. 2.9 Ihe situation remained fairly consEant until 5 June when treatuents were extended to the rivers supporting savanna species in the Sassandra system as far south as Guessabo. Ttris led to about 50% reduction of flies on the Sassandra and Marahou6 ri.vers. Amongst flies caught hrere aPPreciable numbers of nulliparous, a situation which has always been associated with 1 ocr/srac ftl .2, paragraph 88. ocef srrcfta.r page 7 local breeding, so that the possibility remaing that some breeding sites or snall rivers were not being properly controlled. By Ehe end of June catches within the Prograrme area were 2O- 70 per day at Pont L6raba, 15-30 per day at Chauss6e Niakaramandougou, and 2O-5O per day at a site on the River Bou - a very great improvement on Ehe previous year. z.LO Prospection had showrr that at this time savanna flies were breeding on Ehe River Sassandra at Buyo further south than previously recorded, and heavy densities were found on a nearby Eributary, the River Nzo. Consideration was given to extending treaEmenEs to cover this area, but a prospection on 25 July found this river to be recently in flood. At the same time fIy densities at Pont L6raba and on the Bandama fell to less than 10 per day. It is not known whether these tr47o events were related. z.LL The studies have led to sme interesting developments in research. Subsector chiefs in the west have all been trained to distingui sh adult S. damnosuo of the savanna group and these are now being routinely recorded. A technique has been developed for measuri.ng adult flies which appears to show that S. damnosrm emerging froo pupae from certain rivers fall into discrete size disEributions, while one of the consultants is working on a pronising technique for deternining the ntmber of gonotrophic cycles undergone. 2.L2 In the discussions which followed this presentation WIIO was asked whether data were available on the distribution of S. damnosum species south of the extension 1lne in Togo, Benin and Ghana, and wheEher it could be assumed that forest species would not invade the Programe area and start breeding. Ttre Coumittee was informed that the distribution of S. damnosum species in the Ivory Coast Iilas no!, well docuoented; in Ghana savanna species existed as far south as the Akosombo Damn, and surveys were under rray 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 Prograrnme area, at Pont L6raba in 1976, and at Kankela on the River Banifing where one forest fly had been caught in 1978. The f1y at Pont L6raba had been identified from larvae reared from eggs produced by this specimen, while the Iknkela f1y had been identified from morpho- logical characters. IE would therefore seem t.o be a rare event. 2.I3 With regard to the possibility that forest species might become esrablished 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 rdere occupied, it was not siqly a mPtter of coryetition for attachment sites that linited the distribution of forest species, but a more ccryIex combination of ecology and physical and chemical properties of the rivers plus the apparent short flight range of forest female flies. 2.14 The Cormittee noted Irith satisfaction the work undertaken on the reinvasion. To assist Ehe Progranme to develop this work, STAC reco'nmended that a second SAP l^Iorking Group on Reinvasion be convened, which would also consider the implications of extension in this field. 3. OCP EVALUATION REPORT 3.1 Ttre Prograune Director explained that Ehis report was an up-to-date assessment of whatthe Programne had achieved. It had been prepared on a suggestion made by the SteeringConmittee in September 1977 and approved by the Jcc in December L977. part I was drafted by wHo and deart with the technical aspects of the Programe. part II concerned the economic development of the OCP area and was Ehe responsibility of the Bank. part I of the OCpEvaluation Report before the Cormittee had been amended according to the consensus of conrments received from various sources and the CotrmiEtee was invited to review its content. 3.2 The Conmittee discussed at length problems concerned with the definition of the overall objectives of the Prograrme, as given in the report. It felt that these should be more clearly defined, but as this matter rTas intimately concerned with the STAC consideration ofthe long-term future of the Programne, the Conmitteers conclusions are reported under that heading below (Section 4). After this initial discussion the Conmittee reviewed the remainder of the rePort and felt that it gave a useful overall picture of the considerable achievements of the Prograrme to date. However, the Conrmittee made certain proposals for iryroving the content of the report. ocef srrcfta.r page 8 3.3 With regard to training, the Conrmittee was informed that this section would be expanded because of its importance in respect to the long-term future of the Programre. The programe confirmed that the research annex would include a list of all the research activities supported to date. The Comittee proposed that further information be given on the roles of the Economic Development Unit and the Pub1ic Health Adviser. 3.4 The Corrmittee felt that more attention should be given in the Evaluation Report to the life expectancy of blind people. It was recognized that the PAG Mission had underestirnated the nrmber of blind people in the Progranrme area; the findings of the Epidemiological Unitnow suggest the present figure to be in excess of 100 OOO. 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 Corrmittee recomnended that Ehe irylications of this be reflected in future evaluation reports. The Cornmittee also recornmended that further data be collected to substantiate the conclusion and that the Programne obtain the services of a consultant demographer to assist the Epidemiological Evaluation Unit in this field. 3.5 Fina1ly, the Comittee 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 Progranme. 4. LONG-TERM FUII'RE OF TIIE PROGRA},IME 4.L As indicated above, the Comit.tee considered the question of the overall long-term objectives of the Programe. The Cormittee endorsed the statement made in the 1977 STAC report @cvfsfacf77.2j that focuses on key public health and socioeconomic issues, that rhe PurPose of the onchocerciasis control operation is rrto reduce the impact of onchocerciasis t.o a sufficiently 1ow leve1 so that it no longer represents either a public health problem or an obstacle to soci.oeconomic development and also to Eaintain and adjusE control activities so as to stabilize the disease at a tolerable levelrr. Atttolerable Ievel" results when the biting density of Simulium damnosrm s.1. within the control area is reduced, if not to zero, at least to a 1eve1 at which transmission of O volvulus falls below the threshold at which serious lesions of ocular onchocerciasis develop. The tolerable 1eve1 in the West African savanna zone Iras recently considered by a SAP Working Groupl to be associated with a reduction of the Annual Transmission Potentia12 to less than 1OO, and the Annual Biting Rate3 Eo less than 1OOO. These definitions and figures had been accepted by STAC. Further observations on the parasitological parameEers associated with the tolerable leveI are given in paragraph 8.2. 4.2 lhe Onchocerciasis Control Programe was conceived and planned according to the best 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 Programe activities, as outlined below. The Comittee reco@ended that these findings be included in the Evaluation Report. It is, in particular, essential to Eake inEo account that: (a) the long-range acEive dispersion of s damnosr:m s. s. and S sirbanrm involves mostly parous females and thus has a greater epidemiological irnportance Ehan originally anticipated ; (b) the hr:man migration trends involve not only large population movements from the savanna zones to southern areas but also movements 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. damnosum complex is much better known; the breeding places of the savanna cytot)i?es s damnosum s.s. and S. sirbanurn stretch further south than or iginally anticipated. I ocef s*flt.t. The Biomedical criteria Onchocerciasis Control Programe area (OCP). Group, Geneva, 6-8 June 1977. 2 ATP 3 or* for Resettlement in the Volta Basin Report of a Scientific Advisory Panel hlorking ocPfsr^cf78 Page 9 4.3 During the discussion on the long-teru objectives of the Prograrme it became apparent that confusion had ari.sen due to use of the phrase 'reli-mination of the vectorrr in various Progranme docrments including the PAG Report.l In this connexion, STAC emphasized 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 Prograrrme area for the predicted 20 years. However, it \ras not possible to forecast now the precise level or nature of these acEivities, 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 daEa essential to forecast future developments. 4.5 As an example of the type of operational changes that will probably occur in Progranrme activities, the Cormrittee 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. Ttre degree to which this reduction in larviciding can be extended southwards and into the wet season can only be deterroined by careful experimentation to avoid jeopardizing levels of ATP. It would also be dependent on the effect of any southern and western extens i on. 4.6 It should be possible to make a reasonable estimate of the extent of these cuts in the Present area three years after the establishment of ful1 control operations in all three phases of that area, i.e. at Ehe end of 1980. Should the extensions now under consideration by the JCC be approved, a similar time-scale would apply in relation to Ehe additional cuts over the entire Prograrme 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 rei.nvasion phenomenon must have an iryact on the strategies of the Progrannne, STAC considered it essential that the research effort on this must be given the necessary priority. The data 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 situation in Ehe south-west will becone clearer in late 1979 when operations are extended to the breeding rivers in Ivory Coast as planned. Sinilarly, if larviciding were to be undertaken in the proposed southern extensions in Ghana, Togo and Benin, this would provide results to further clarify the extent of potential reinvasion sources. However, it was recognized that this informetion was unlikely to become available until at least one year after the irylemenEation of these extended operations. In the long term, any additional control schemes that rnay be introduced in the possible source areas outside OCP would be of benefit to the Prograume. 4.9 Another major factor in developing the most efficienE strategy for the OCP is the average reproductive life-span of the parasite in the hr-uran host. Ttre best available evidence indicates the maxiroum life-span of the adult worm to be between 11 and 16 years, and of the microfilariae approximately tl^ro years. Investigations i.n the transmj.ssion-free area of the Prograrrme show that the adult worms are still alive and fertile after more than three years. While more information will be available ln 1980, STAC confirmed that a further 10-15 years may be necessary to accurately deterxrine the life-span of the parasite. 4.10 As already noted, a further couplication affecting the development of the Progranme is the considerable seasonal migration of hr.man population into the controlled area, some of whom will be infected with onchocerciasis. Ttre magnitude of this phenmenon rdas at present In the context of the PAG Report the wordrreliminatet'(Latinrreliminarert: to cast over the threshold) was used to mean destruction of the vector within the control area and its continued exclusion therefrom for a stated period of time. 1 I ow fsracfte.r page 10 unknown and the Cormnittee recormnended the continuation and expansion, if possible, of the present research effort. 4.LL While sorue of the above factors may adversely affect the early attainment of the over- all objectives of the Progranore, STAC recognized that there were others under consideration which, on balance, could improve the efficiency of the operations. These concern th.e development of new insecticides and their application, the possible introduction of adulticiding and the possible development of an effective chemotherapy programne. The Cormittee considered that after the 2O-year period, there will be a minimal requirement 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 INSECTICIDES - REPORT OF SAP I"IORKING GROUP 5.1 The Comrittee reviewed the Report of the SAP Working Group on Insecticides (Annex I1) and considered in detail the problem of identifying further chemicals for S damnosum larviciding. Chemical cornpani-es involved in pesticide production were very ready to cooperate in submitting new compounds and formulations for testing by the Prograrmne, provided that these could be rapidly screened and evaluated and Ehe resultant data fed back to the conpanies. The SAP Group Report emphasized that while some preliminary screening could be done on Simulir:m species other than damnosum, testing on S. damnosun must be introduced at the earliest possible stage of the evaluation procedure. Accordingly, 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 vi-ew of the present dependence of the Prograuune on a single compound. 5.2 The Comrnittee, noting that the river presently used for Eesting candidaEe conpounds will soon be subject to regular larviciding by OCP, strongly rsqe'rmended Ehat the Programme should take inmediate action to develop the necessary facility for screening and evaluating candidate conpounds. The requirements for this facility include: (a) a site within easy sizes; access of S. damnosum and S. sirbanum breeding ri-vers of varrious (b) suitable laboratory and housing accorunodation; (c) back-up support such as transPort and equipment; (d) provision of adequate staff, both professional 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 feasibility studies elsewhere. Adulriciding 5.4 Consequent to the STACTs previous recomnendation on this subject, it was reported that [he Prograrrne Vector Control Unit had monitored the effect of an application of various coupounds against riverine tsetse fly in the area on the adult S. damnosum population" 5.5 Trials were carried out on the Como6 River in Upper Volta by helicopter ULV1applicaEion of endosulfan, decamethrin and dieldrin; these applications were very successful against the tsetse and preliminary observations suggest that there was also an effect against 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 the river banks. 5,6 In view of these results, the Committee re-emphasized the irnportance of developing techniques for control of adult S. damnosum. This will require attention to two main points(a) discovery of resting sites of adults; and (b) work on the susceptibility of adult 1 Ultra 1ow volume ocPf srAcf78.L Simulir:o, particularly gravid females, because these are insec ticides. page 11 likely to be most tolerant to 5.7 lhe STAC, therefore, noting the reconrmendatlon on this point made by the SAP Working Group on InsecEicides, recormended an expansion of this work in view of its potential in controlling reinvading adult,s. 6. HEALIII INFRASIB.UCII'RE IN TI1E 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 i.n the participating countries do not adequately rneet theseneeds, and although the L97O-L977 statistlcs indicate an increasing expenditure, when the effect of inflation is considered the allocation to health has actually remained the same, or even decreased. Ttre measures adopted by the countries, incollaborati-on with MIO and other multilateral and bilateral agencies, to control and prevent endemic and epidemic diseases and to develop new strategies to meet their present and fut.ure needs, tilere outlined. 6.2 In relation to the intention to intensify chemotherapeutic research, it was noEed that an effective neEwork of basic health services would be essential for mrss treatment of infected Persons should a suitable drug becooe available. Every encouragement should therefore begiven to the participating counEries to develop the required basic health services. 6.3 It was also felt Ehat the National Onchocerciasis Comittees should be involved in prcmoting the health services in the seven countries. 6.4 It was suggested that there should be close collaboration wlth the Ministries of HeaIEh of the ParticipaEing countries, to investigate whether any OCP facilities could be utilized to augment local health services provided that Ehis did not interfere with Ehe operations. 6.5 Recognizing the importance of training in strengEhening the national services, STAC stressed the need for the esEablishment of permanent posts with careers in all the partlci- pating countries for those who will be tralned with OCp assi.stance. 6.6 STAC recormended that OCP should investigate the possibility of finding alr,ernative, siryler Eechniques, suitable for use at community level, which would facilitate Ehe transfer of responsibility for the continuation of operations, at the appropriate time. 7. CHEMOIT{ERAPY AND IHE TAI,IALE CENIR.E 7.L The Cormittee, in reviewing the future use of chemotherapy in the control of onchocer- ciasisr was aPPrised of the various constrai.nts. Ihe action being taken by the Special Programe for Research and Training in Tropical Diseases in promoting the development of new drugs was described. It was pointed out that the trilo drugs currently available , vj.z. suramin and diethylcarbamazine (ngC), w€r€developed in 1920 and 1943 respectively, therefore for 35years no nehT drug had been introduced. The development of a new drug for onchocerciasis is not easy and may take several years. About US$ 20 million was required to conduct a1l the tests to clear it with national comittees for trial in the field. After manufacture Ehedrug is often Pirat.ed by other countries which do not recognize patenE Iaws. Finally, the countries requiring the drug cannot afford to purchase it. 7.2 Under the auspices of MlO an approach was made Eo pharmaceutical coryanies in the United Kingdom, France, Ehe Federal Republic of Ge.rmany, Switzerland and Japan to discuss how progress night be made. For example, WHO could: (f) help with clinical trials; (2) assist with the screening and Eesting of coryounds available in companies; (3) contract research in coupaniesto help them investigate interesting groups of coryounds. 7.3 Sterming from TDR, several such contracEs had been established. A survey had been made of all drugs on the market for other diseases to identify those passed for hr:man and veterinary use of value against onchocerciasis - tesEing centres had been established. The main objective is to find a drug effective against the adult worms. ocP fsr^cf78.t Page 12 7.4 The Conunittee 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 minimum of 10 years with at least five years of clinical trials. However, some leads may be obtained from work done on veteri.nary anthelmintics over the past 10 years. Also, it is possible Ehat treatment possibilities with DEC and suramin could be improved. 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 treatment of onchocerciasis paEients who come from infected villages within motoring distance of Tamale. 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. Ttre chemotherapy programne 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, administrative and financial responsibility for the chemotherapeutic centre had been handed over by the OCP to the LIttO Special Prograrmne for Research and Training in Tropical Diseases, where it will form part of the activities of the Filariasis Scientific lJorking Group and its Steering Comnittee. 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 complete, but also less I'vio1ent", than diethylcarbamazine citrate (OeC). The ful1 fol1ow-up results of the trials at Tamale are not yeE available. Preliminary results indicate that although the drug does temporarily reduce microfilarial concentrates, the acceptabiliEy of repeated doses by villagers is low 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 Taoale included attempts to quantify the l,TazzottL reaction to DEC and a study of the possible effects of Indomethacin in daruping 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 in human medicine and selected for trial by the Filariasis SWG of the Special Prograrune; (ii) transepidermal DEC; (iii) detailed study of the pharroacokinetics, metabolism and toxicity of DEC and of suramin, making use of C14-labe1led preparations of these drugs. lnrnunological and pathological support for the programme of chemotherapy is foreseen, so as to investi.gate and perhaps prevent the tissue-damaging reactions to microfilariae. Adequate ophthalmological support is also being sought. 7.lO After approval by the I^IHO committee on ethics, any promising leads for improved chemotherapy which come from the centrets work may be tested in pilot trials on a village scale within the OCP area with the help of the Progranune staff. The Conunittee noted that the Tamale centre was located in an area of interrupted 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 centre ouEside the control area. j.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 I ocPf sr{cf78.t Page 13 - recogniziog 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 those already affected by the disease, and as a supplementary means of control by reducing the parasite reservoir in man; - reconrnends that the Filariasis SWG should be encouraged to continue and expand its currenE programre 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-Eoxic macrofilaricidE; (iii) developing means to prevent Eissue-damaging reacti-ons to the death of micro- filariae in the human host. 8. EIIDH'{ICITY LEVELS 8.1 The Conmittee was informed of studies undertaken by Ehe Programe on the definition of endemicity leve1s of onchocerciasis. These studies concluded that the prevalence of onchocerciasis in a population, as defined by standardized rates for microfilariae carriers, is the simplest parameter for a survey team to measure rapidly in the field and does not require sophisticaEed technology. The correlations investigaEed 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 coumunity the situaEion is intolerable or is likely to become so in the short or long tenn; such conmunities are in an unstable state; this is hyperendemicity; (b) when onchocerciasi-s 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 between 35% and 60% of. cases, the degree of severity varies both from one group to anoEher and from one person in a group to another; this is mes oendemici ty. 8.3 These definitions, based on findings in the West African savanna zone, may not be appli- cable elsewhere. It 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, congraEulating the team on this excellent piece of work, noted that the sociodemographic studies were undertaken in only one part of the Progranrme area, and recom- mended that they should be complemented by similar sEudies in other river valleys with different ethnic groups and agricultural systems. First priority should be given ro 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 severi-ty of onchocerciasis is the result of the smal1 size of settlements or vice versa. 8.6 The results of such studies could provide useful guidelines for the long-term socioeconomic development of the presently underpopulaEed valleys in the OCP area. owf srrcf ta.t page 14 g.7 In discussions on the general epidemiological evaluation activities, STAC considered that the fundamental diagnostic survey techniques agreed at the beginning of OCP should not be changed. Supplementary techniques which might 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. g.g OCp being primarily, and essentially, an operational programme using mass techniques as diagnostic Eools, the limitations of these techniques should be borne in mind when analysing the data obtained from village surveys. g.? STAC recormrended that the Prograrmne should endeavour to collect information on the following subj ects: (a) the number of people at risk living in the reinvasion areas; (b) the life 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 regr ession of O. volvulus infections after interruption of and low-mesoendemi.ctransmission in children and young Persons particularly in hypoendemic viIlages. 9 . REPORT OF ECOLOGICA.L PANEL 9.1 The report of tl-re meeting of the Ecological Panel held in Rome on 29 and 3O May 1978 was presented to the Cournittee 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 acce-Pted by boLh Sroups are presented to the JCC. 10. OTIIER MATTERS Pro g rafitrne staffing lO.1 The Conrnittee expressed concern about the staffing of the entomological side of the programme, pointing out that there was 1itt1e margin to deal r+ith ernergency situations. lO.2 The Director agreed that this was a mattrer for concern and appealed to STAC to assist in the recruitment of staff, forwhich there was already budEletary provision and a mandate from rhe JCC for action. ]1, ARRANGWENTS FOR TT1E NEXT MEETTNG 11.1 It r,ras agreed that the date and place of the next meeting Director in relation to the prograrEne of meetings of the ocP, but at about the same time of the Year. L2. CLOSE OF MEETTNG should be determined bY the that it would be aPProPriate rhe chairman thanked the Regional Director for the hospitalitl' for the excellent services provided. The chairman al-so thanked staff, the interpreters and aI1 those who had contributed to t-he 12,l In closing the meeting extended to the Connnittee and the Prograrmne DirecLor and his success of the meeting. 12.2 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. ocPfsrAcfTs.r Page 15 ANNEX I AGENDA Opening of the meeEing Election of chairman Adoption of the agenda Progress report on activities Review of draft OCP Evaluation Report Long-Eerm future of the Prograrrue Report on SAP Working Group on InsecEicides, 3-7 July 1978 Report on meeting of Ecological Panel, 29-30 May 1978 Health infrastructure in the OCP countries and action against other cormunicable diseases Chemotherapy and the Tamale centre Definition of endemicity levels Annual report of STAC Other matters Review and adoption of the report of the meeting Arrangements for the next meeting Close of meeting ocPfsrAcfTB.r Page 16 ANNEX II REPORT oF THE SAP WORKING GROUP oN INSEcficIDES, 3-7 JULY 1978 A. Introduction 1. The meeting was opened by Mr Marc Ls. Bazin, Director of the 0nchocerciasis Control Programme who after welcoming the participants (Appendix 1), explained that the working group had been convened on the reccmendation of the Scientific and Technical Advisory Conmittee which had repeatedly expressed its concern at the persistent tack 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 20 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$ 6O million budget for the first six years of the Programre had gone towards the cosE of insecticide and indications were that the international financial cormunity would be maintaining its interest in the Programne in the future. In addition, studies being undertakenin Guinea, Guinea-Bissau, Senegal, Nigeria, Sudan, Tanzania and elsewhere to plan onchocercia- sis control operations signalled the need for ever-increasing quantities of larvicides. TheDirector said that the Prograrnrne was ready to give seri-ous consideration to any alternati-ves 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 efffecti-veness, biodegradability and minimrm effect on the non-target fauna necessary. Chairman Dr J. W. Miles was appointed Chairnan and Dr J. Mouchet invited to be Vice-Chairnan. AdopEion 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 the chemical coryanies of the urgency of the problem and provide them r^rith all the information , thefirst part of the meeting was occupied with the presentation of a series of technical papers identifying the nature of the problem and characEeristics of the target. A review was made of the bionomics of the target species and how these relate Eo the control methodology with 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 sections of the rivers. Eggs and pupae had low susceptibility to insecticides but the larvae, attached co substrates and filtering their food from flowing water, hrere the most appropriate target. 6. Details l^7ere presented of the characteristics required from the insecticide formulaEions used in blackfly control. Among other things, they must have a high effectiveness against the blackfly larvae, good carry and rapid biodegradability, good dispersibility in water when applied from aircraft, moderate to high content of active ingredient and innocuity for non- target organisms. 7. The threat of developing resistance \47as always present. A suitable method for testing susceptibility had been developed and to date there was no indication of resisEance developing towards Abate. However, in rivers where DDT had been used for agricultural purposes B 2 C 3 D available to enable them to develop larvicides appropriate to the control of Simulium S. damnosum larvae v/ere reported to show resistance to this product. ocPf sr^cf t8.L Page 17 Annex II 8. Consideration was given to the problem 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 treaFment. Ttre Ecological Panel of the Programe had considered this acceptable as long as the productivity of the river rilas not reduced. 9. Due attent,lon must be paid to the toxicity of the insecticide to man and animals especially as, for Simulito control, the product had to be applied regularly to waterways. 10. Whatever product was used must be stable in the rather extreme conditions found in troPical Africa. Not only must the containers be sufficiently robust to Irithstand the hazards of transport over bad roads, but the formulation must be sufficiently stable when stored in the oPen air, often without shade, where terrperatures may reach 55"C. For logistical reasons it was often necessary to store drr.ms 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 Ehe results. Others had proved useful for preliminary screening but often the results obtained had not been comparable with riverine application. Trough tests had certainly shown greatest 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 means, 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 tests had to be carried out to determine the carry of the product, followed subsequently by a larger-scale trial of longer duration Eo check its effect on t.arget 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 optimto action on the larvae. These requirements included a density slightly less than one and emulsion ProPcrties when the formulation is mixed with water which allow it to be effective at lo\d concentrations. Further refinement of these requirements rras haryered by lack of understanding of how the foruulations act on the larvae in the river at. sites distant from the point of application. 13. In Ehe discussions which fo1lowed, several company representatives asked what were the chances of OCP using an alternative formulation to Abate should one be developed. It was explained that, in so far as it was technically feasible, and Eaking into consideration its effectiveness on the target organisms, its biodegradability, its level of effect on non-targeE organisms and cost, the Prograrme would be willing to change to another product. When more than one product became available MIO would be obliged to purchase it on the basis of inter- national tender. However, i.t was stressed that poEential markets for new products could be foreseen outside the present Onchocerciasis Control Prograrnme. L4. Some concern was e:<pressed at the lack of understanding as to why different formulations of Abate work or not and it was felt that while Abate seemed Eo be most effective as an emulsifiable concentrate, this type of formulation rnay noE be what is required for this. It was also felt that some distinction should be drawn berween screening of the basic cornpound and the evaluation of the product presented by the cornpanies. 15. Some clarification was requested on what policy would be followed if resistance to Abate developed. It was accepted that different approaches were possible 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. ocPf srAcf 7B.L PaSe 18 Annex II E. Reconmendations 16. Four working groups considered: (a) what industry would require to help it respond to the needs of OCP in providing alternative products; (b) ttre methods of testing the effect of new products on the t.arget organism; (c) the evaluation methods against non-Earget organisms; and (d) the operational constraints; and put forward the following reconrmendatj.ons 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 carri-ed compounds/products to cover the following phases: out should be used for evaluation of novel sma1l-scale screening agains t S. damnosum in hlest Africa including positive and blank standards, which is sufficiently flexible to accept technical compounds or experimental formulations ; trough evaluations as currentl y carried out to include observaEions on target and non- target organisms in comparison with a standard; river tests to establish effects against target and non-target organisms in comparison with a standard; large- s cale semi-operational evaluaEions in comparison with a standard. Results of these should be submitted pronptly after completion of testing. 19. Research should be undertaken on the physical characEeristics 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 traihed teams and regular sumtaries of their findings should be rapidly disseminated so that early signs of resistance of operational 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 condit.ions and field testing for stability. 22. With a view to finding an additional tool, studies should be carried out on the relevantbiology 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 have to be made; the application would 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; (b) - the development of methods of application for selected cornpounds. Target organi-sms 23. In general, coupounds showing appropriate mosquito larvicide or equivalent activity should be select.ed for evaluation against Simulium. These cornpounds should also have low acute and chronic toxicity to mannnals. Currently, there are several laboratory, semi-fie1d ocYf wrcfta.r page 19 Annex II and field evaluation techniques which can yield useful information on activity of larvicides against Simulito. It was urgent that these techniques and research prograrrmes 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 potential value to future research: a determination of whether the results obtained from evaluaEing larvicides againstpaleartic and neartic Simulium species are relevant in a control context to Simulir.ro d€mnosr.rm; - an evaluation in North America of larvicides and Africa; forroulations already tested in htest - a comParison in Africa of the effects of larvicides on Slmulium damnosum and on otherAfrican (Ethiopian) Simu r-um species 25. the An evaluation should be made in the laboratory and,for the field of the mode of action oflarvicide emulsion at the site of action. (c) Non-tar Eor ].SInS 26- Ttre chemical couPounds which had been shown effective on the target organism are expectedto have been tested for m:'nmalian toxicity.. The amount of toxicity information required will depend upon the scale of the test or use but the following criteria should be kept in nind: - 1ow manmalian toxicity of the formulation; - rapid metabolism of the active ingredient by marmals; and - biodegradability in the environment and not excessively accr:oulated in aquatic organisms such as fish which serve as hurnan food. Demonstrated non-ttmtorigenicity in standard long-term feeding studies should be obtained beforethe larvicide is introduced on a large operational scale so that their mamalian safety can be assessed with sufficient accuracy. 27. Compounds Eo be Eested on aquatic non-target organisos in the area of operation should already have been shown to be effective on the targeE Simulitm and have been tested on aquatic vertebratesr e.8. fish and arphibians, and also o.r plarrktorri" organisms. Evaluation tests inthe area should include: qu tter tests for inrnediate effects on invertebrates to ident.ify sensitive and relativelyinsensitive taxa; breedi siEe tests under operational conditions to de temine the short-term effecEs oninvertebrates. This would be done by saryling with fine and coarse drift nets 24 hourspre- and 24 hours post-treatment and by qualitative assessment of changes in Ehe composition of benthic fauna. 28. Large-scale or oPerational evaluaEion trials should be made in comparison with a non-treated area, which could be in the same river system, and should include: - invertebrate drift sampling with both fine and coast neEs during both the pre- and post- sunset periods; to determine the qualitative fate of the taxa and to make aquantitative assessment ; ocPf srAcf 7B.r Page 20 Annex II sampling by a method selected according to the habitat, to indicate quanEitative changes in the benthos; recording from visual observation of mortalities of the vertebrates. 29. After the coryound has been cleared for short-term and irmnediate 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 in use for the current application of temephos ln the Onchocerciasi-s Control Progranme may be used but, in addition, attention should be paid to the primary producers, phytoplankton and p eriphyton. 30. Chemical analysis of water, uud and important organisms such as fish, crustacea and molluscs should be carried out to monitor the fate of the coryound and assist interpretation of the non-target organism results. (d) Operations 31. While it was noted that specifications for temephos EC for Simulir.m larvae control were to be published, investigation should be conti-nued to refine the requirements not only for temephos but. also for new larvicides that might be developed. ConsideraEion should be given to physical/chenical, biological and other characteristics as they affecr rhe target organism, the environment and the operations. Underlying many of these was the need to have informa- tion on the mode of action of the larvicide emulsion at the larval sites. 32. T\uo conditions for carrying out large-scale field or operational trials were 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 conditioris(such as the appearance of resistance to temephos) should be tested in previously treated rivers with only the manpower 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 Ehe time needed to obtain sufficient data on the effects on target and non-target organi-sms. Evalua- tion of the effects on the non-target organi-sms should be made as prescribed in paragraph 28. 33. There were constraints in carrying out large-scale or operational field trials. Trials within or irsnediately outside the OCP area did not seem possible in the near future, especially if proposed extensions to the area were irnplemented. Thus another test area outside the OCP operati-ons would have to be found. While appreciating that responsibility for carrying out the work was beyond the capability of the Vector Control Unit 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 practicability of moni-toring the effects of new products on non- target organi sms either in non-S. damnosum ri-vers or in untreated tributaries of the treated rivers; FocPfsrAcfTB.r Page 21 Annex II - the developoent of flolring erater laboratory tests or other methods for determiningtoxicity of the new ccryounds to fish, which are of economic iryortance. Conclusions 35. rt was generally agreed to be unlikely that coffiiercial coryanies would devote resourcesto production of new coryounds for Simulirn control in the fut.ure but, given the existence of a field evaluation scheme on the lines suggested 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 to strengthen and expand thefacilities for testing available in Africa. Also nethods already in use elsewhere should beintroduced into Africa, as appropriate, especially for testing insect growEh regulators. 37. The view ltas exPressed that selection of a candidate product should be based at this stage on the results of tests on the target organi.sm, i.e. s. damnostm s.1. 38. The development of a more liberal exchange of information and results of research was called for. In this resPect, the coryany representatives, in particular, felt the meeting tobe especially helpful and considered it would be beneficial to have a follow-up meeting in approximately two yearsr time. ocP fsrAcftB .L page 22 Annex II Appendix 1 LIST OF PARTICIPANTS Dr A. N. Alekseev, Martinsinovskij Institute of Medical Parasitology and Tropical Medicine, I'loscow, USSR Dr C. Dejoux, ORSTOM Hydrobiology Laboratory, Bouak6, Ivory Coast Dr V. P. Dremova, Research Institute of Disinfection and Sterilization, @9y, USSR Dr P. Gui1Iet, Onchocerciasis Research Institute, Bouak6, Ivory Coast Dr P. Haskell, Centre for Overseas Pest Research, London, United Kingdom Dr H. Jamnback, University of the State of New York, Albany, New York, United States of America Dr J. l'liles, Center for Disease Control, Atlanta, Georgia, United States of America Dr J. Mouchet, ORSTOM, Bondy, France Dr M. MulIa, University of California, Riverside, California, United States of America Dr M. A. Odei, Institute of Aquatic Biology, Achimota, Accra, Ghana Dr B. Statzner, Zooological Institute of the University of Kiel, Kiel, Federal Republic of Germany Dr M. Yasuno, National Institute for Environmental Studies, @[i, Japan Dr A. N. Clements, Shell, United Kingdom Mr C. R. Dash, Dow, Switzerland Mr Delabarre, Roussel Uc1af, France Dr A. C. Grosscurt, Philips-Duphar, Netherlands Dr H. J. Holtmann, Celamerck, Federal Republic of Germany I"1r S. Kawasaki, Sr:mitomo Chemical Coropany, Japan lllr L. Lazare, Zoecon, United States of America Dr J. McCalh:m-Deighton, tClfYlant Protection, United Kingdom Dr H. J. Niessen, Bayer, Federal Republic of Germany Dr K. Schotz, Bayer, Federal Republic of Germany Dr G. W. Smith, Dow, United Kingdom Dr J. C. Wickham, l,Iellcome, United Kingdom Dr R. Wyniger, Ciba-Geigy, Switzerland Mr Marc Ls. Bazin, Director, Onchocerciasis Control Progranrme, WHO, Dr J. D. Briggs, VGB/VBC, WHO, Geneva, Switzerland Dr R. Le Berre, ECvfwC, WHO, Geneva, Switzerland Mr J. D. M. Marr, Liaison Officer, OCP, WHO, Geneva, Switzerland Dr G. Qu6lennec, PDS/VBC, WlI0, Geneva, Switzerland Dr A. R. Stiles , PDSfwC, LIIO, Geneva, Switzerland Dr M. Vandekar, PDS/VBC, wHO, 1@, Switzerland 0uagadougou Upper Volta Mr J. F. waIsh, Chief vcufocP, I^Jrlo, Ouagadougou , Upper Volta 1. , 3. 4. 5. 6. 7. 8. ocPfsr\cfTB.r PaBe 23 Annex II Appe ndix 2 AGENDA Opening Election of the chairman Adoption of Ehe agenda Appointment of the rapporteurs Nature of the problem and characteristics of the target 5.1 Bionomics of the EarSet species and relation to control, with special emphasis on OCP operations 5.2 Conflicting characteristics required from i-nsecticide formulations for blackfly control 5.3 The problem of resistance to insecticides 5.4 Ttre problem of non-target organisms and environmental contapination 5.5 The problem of the safety of insecticides to people 5.6 The operational problems Critical review of the procedures followed by the screening and evaluaEion of insecticides against target and non-Earget organisms and results to date 6.1 rntroduction: Generalities of the methodology followed in Africa 6.2 Laboratory tests, including simulation of field conditions 6.3 Field evaluation at small and medium scale 6.4 Large-scale field evaluaEion 6.5 General discussion Problems of insecticide screening and formulation developoent related to specifications 7.L Physical and chemical properties 7.2 Biological properties related to Earget organisms 7 .3 Biological properties related to non-target organisms - including man 7.4 Formulation development and specificaEion problems 7 .5 General discussion Intensification of research and development of insecticides for blackfly control 8.1 Prospects for new chemical and biological insecticides 8.1.1 Present trends in chemical insecticide research for public health ocPf sr^cf 7B.r Page 24 Annex II Appendix 2 8.L.2 Potential of some new insecticides, including pyrethroids and insect growth regulators 8.1.3 Potential of biological i-nsecricides 8.2 Prospects for new and iuproved formulations 8.3 ProspecEs for iryroved evaluation procedures 8.3.1 Laboratory and simulated field tests 8.3.2 Smal1- and meditm-scale field tests 8.3.3 Operational evaluation 8.4 Discussion 9. Presentation, discussion and finalization of the report 10. Closure of the meeting aocPf srllcf 7B.L Page 25 AI.INEX III RECOMMENDATIONS Relnvasion STAC recmended that 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 blind people AlEhough 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 Corrmittee recmended that the irylications of this be reflected in future evaluation reports. The Comittee also recornmended that further data be collected to substantiate the conclusi.on and that the Programe obtain the services of a demographer consultant to assist the Epidemiologi- cal Unit in this field (paragraph 3.4). Lo4g-teqq future of the Prograrnme Ttre Onchocerciasis Control Prograrme was conceived and planned according to the best information on the epidemiology of the disease and the biology of its vectors available in L973. Since then the knowledge on these subjecEs has noticeably increased, as a resulE of the Prograrme activities, as outlined below. Ihe Comittee recomended that these f indings be included in the Evaluation Report. IE is, in particular, essential to take into account that: (a) the long-range active dispersion of s. damnosum s.s. and g. siil4nrrm involves mostly parous females and thus has a greater epidemiological iryortance than originally anticipated; (b) the hr-oan migration trends involve not only large population movements from the savanna zoneg to southern areas but also oovements from the coastal and forest zones to the OCP area, thus introducing new O. volvulus carriers in this area (c) the distribution bionmics and vectorial iryortance of the varj.ous members of the s damnosuo corylex is much better known; the breeding places of the savanna cytotypes S. damnosrm s.str. and S. sirbanum stretch further south than originally anticipated(paragraph 4.2). Insecticides The Conrnittee, noting that the river presently used for testing candidate compounds will soon be subject to regular larviciding by OCP, strongly recorunended that the Prograume should take irmediate action to develop the necessary facility for screening and evaluating candidate compounds. The requirements for this facility include: (a) a site within easy sizes; access of S. damnosrm and S. sirbanum breed ing rivers of vari-ous (b) suitable laboratory and housing accorrmodation; (c) back-up support such as transport and equipment; (d) prowision of adequate staff, both professional and ancillary (paragraph 5.2). I ocef srrcfta.r page 26 Annex III Adul tic iding The Corrmittee re-emphasized the iryortance of developing techniques for control of adultS. damnosum. Ihis will require aEtention to two mnin points: (a) discovery of resting sites of adults; and (b) work on the susceptibility of adult Simulium, particularly gravid females, because these are 1ike1y to be most tolerant to insecticides. STAC, noting the recormendation 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 recomnended that OCP should investigate the possibility of finding alternative, sirnpler techniques, suitable for use at comunity 1evel, which would facilitate the transfer of responsibility for Ehe continuation of operations at the appropriat.e time (paragraph 6.6). Chemotherapy The STAC: - approving the handover of the scientific, administrative and financial responsibility for the onchocerciasis chemotherapy research prograqme at Tamale to the Steering Comittee of the Filariasis Scientific Working Group of the WHO Special programe for Research and Training in Tropical Diseases; - recognizing the great potential benefits to the OCP that could stem fron iryroved chemotherapy for onchocerci-asis, both for the prevenEion and cure of eye and skin lesions in those already affected by the disease, and as a supplementary means of control by reducing the parasite reservoir in mpn; - recormends that the Filariasis SLIG should be encouraged to continue and expand its current progranrme of chemotherapeutic research on onchocerciasis, by all necessary means, with the objectives of: (i) iuproving 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 the hr:man host (paragraph 7.11). Endemicity Ieve1s The Corrrnittee, noting that sociodemographic studies were undertaken in only one part of the Progranune area, recorrunended that they should be cornplemented by similar studies in other river valleys with different ethnic groups and agricultural systems. First priority shouldbe given to valleys situated in the savanna belt of the Prograuune while subsequent studies could be carried out in the forest zone (paragraph 8.4). idemiol ical evaluaEion STAC reconrnended that following subjects: the Progranrne should endeavour to collect information on the (a) the number of people at risk living in the reinvasion areas; I ocPf sr^cf7B.t Page 27 Annex III (b) the life er<pectancy of blind persons beyond the onset of blindness from onchocerci.asis ; (c) preferential 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 interruption of transmission in children and young persons particularly in hlryoendemic and 1ow- mesoendemic villages (paragraph 8.9). (