Joint Coordinating Committee sixth session, Geneva, 3-5 December 1979 : Scientific and Technical Advisory Committee report of the eighth meeting Geneva, 4-7 September 1979

tJOIN'I COORDINATING COMMITTEE Onchocerciasis Control Programme in the Volta River Basin Area Ofice of the Independent Chairman c/o World Health Organization l2l I Geneva 27, Switzerland TcI.346061 Tclcx lllffi 2782L J.C.C.-C.C.C. COMITE CONJOINT DE COORDINATION Programme de Lutte Contre I'Onchocercose dans la Rdgion du Bassin de la Volta Bureau du PrCstdent Indlpendant c/o Organisation Mondiale de la Santd l2ll Gendve 27, Suisse Tcl 3,t6061 Tttexg6i!3 2782L JCC6.3 15 October 1979 JOINI COORDINATING COMMITTEE Sixth session Geneva, 3-5 December 1979 Provisional agenda item 5 The Independent Chairman submits for the consideration of the Joint Coordinating Committee, at its sixth session, the report of the Scientific and Technical Advisory Committee. This document has been reviewed by the Steering Committee which has made the following comments: "The Steering Committee took particular note of the comments nade by STAC regarding insecticide testing and supported the recommendation that every effort should be made to intensify this work as soon as possi.ble. The Committee noted the recommendation to study the importance of the invasion of certain rivers by S. squamosum, supported the recommendations to continue and expand the entomological research programme on reinvasion and to strengthen the research component of the Vector Control Unit to enable greater liaison with collaborating institutions. The Committee suggested WHO take the necessary action to sponsor an international conference on tLre biology and behaviour of the vector as recommended by STAC. The recommendations for further chemotherapeutic studles in the OCP area, as weIl as those concerning changes in epidemiological evaluation techniques, were noted. Finally the Committee endorsed the recommendation that the post of statistician be filled as soon as possible." I Fr acr/:,\Act/79.J" JCC6.1 - Iàrgtlsh vt §f Errors and. cor[ien+"s l3.Le_6 pa::a 3 - line 6 1, typographical error : srrhseqtrent to 'll- . - '"jiSI--l pai.a 5 . J - ponultimate line delete $16? rvhich refers to sup5rlen,rntary hours, not flxed-nd-ng aircraft Iar;t li-ne : coutract figrrre should i"«rarl : tis .f5 6i -U-n:i--r S.'L : refelcnce to ,'iÀC/-l.iG ncmber cl'rnir.i;-,i; l').C. Pa.-c. rl _Lsi'il5.l0 - l.a;L l-i:le : 'L91,) kn i.s g;iven É-r'l.:rû .i.il .r)col.o,icl l'nlicl r-port but coni'lic Ls wit,h L I irr crf -,ictio:-. l.ric Jlird..;rt uiiri-ch 1;ives [J.t,00. VCU bel_ieve 4.00O _to be mj.nirntm and B.O()0 r..aximlm. I)41'3 5 .111 : rrunbor of subsectors : could he 25 if Bou3ouni corurted, as two; corrld be 21 lf extcnsion studles cxcludcd " rr la 5.11 - line 2 : t;.'pographical error : "Crouptt l:l;_-]. nrista]:c Lrr i5'.';y ilirnberini; : 5.1'/ does not exist. 12 f,rrla 7.4 - line I : typo;rapical error : rrhad establlshedtt { t f I i I ai i : o jt' ocvf srrcf to.t ORIGINAL: ENGLISH I ONCHOCERCIAS IS CONTROL PROGRAMME IN THE VOLTA RIVER BASIN AREA SCIENTIFIC AND TECHNICAL ADVISORY COMMITTEE Report of the eighth meeting Geneva, 4-7 September I979 Contents List of participants List of recommendations Opening of the meeting Report on Joint Coordinating Committee Report on the Independent Commission Adoption of the agenda Progress report on activj-ties Reinvasion studies I979 Entomologj.cal research - General General discussions on entomology Working Group on Taxonomy of S. damnosum complex IO. Insecticide testing 11. Epidemiological and chemotherapeutic research 12. General discussion on epidemiology and chemotherapy 13. Close of meeting Annex I - Agenda Annex I I Table I Comparison of fly catches 1975-1979, flies per man per day I 2 3 4 5 6 7 8 9 Pa ge 2 4 6 6 6 6 7 lo 11 t2 13 I4 I6 t7 t8 I9 20 ocvfsracfts.r page 2 LIST OF PARTICIPANTS Members Dr D. W. BUttner, Chref, Department of Helmrnthology, Bernhard-Nocht Institute, Bernhard- Nocht-Strasse 74, 2OOO Hamburg 4, Federal Republrc of Germany Dr Peter London Haskell, Director, Centre for Overseas Pest Research, College House, Wrrght's Lane, WB 5SJ, United Kingdon I Professor Pieter Janssens, Vogelzang 12, 2232 's Gravenwezel , Belgium (Chairman) Mr I' S. Lindsay, Earth Scrences Divrsron, Defence Research Establishment, Ottawa, Shirley Bay, Ottawa, Ontario, Canada K\A OZ4 Dr James Mrles, Chief, Pesticides Branch, Vector Biology and rlontrol Division, Bureau of Troprcal Drseases, Department of Heatth, Education and We1f,are, Center for Dlsease Control, 4tLanta, Georgia 3O333, United States of America Dr J. Mouchet, Inspecteur g6n6ral de Recherche, Office de Ia lRecherche scientifique et technique Outre-Mer, Services scientifrques centraux, 7O-71, route d'Aulnay, 93140 Bondy, France Dr L. E. Rozeboom, Professor Emeritus of Medical Entomology,'lhe Johns Hopkins University, 3I96, Laverne circre, lqmpstead, Maryland 21074, united states of America Temporary Adviser Dr R. Garms, Tropenrnstitut, Germany Bernhard-Nocht-Strasse 74, 2OOO I{amburg 4, Federal Repub)-ic of OCP Commrssron Dr H. Jamnback, Drrector, Science Services, University of the State of New york, New york State l\luseum and Scrence Service, AIbany, New York 12224, United States of America WorId Health Organrzatron Dr A. O, Lucas, Drrector, Specral Programme for Re-search and Traintng in Troptcal Diseases, WHO Ileadquarters, Geneva, Swrtzerland Dr O. Ba, Parasttologrst , Epidemrologrcal Evaluatron Unit, Onchocerclasis Control programme, Oua gadougou Dr J. B. Davies, Chief, Entomologrcal Evaluatron Vector Control Unit, Onchocerciasrs Control Programme, Ouagadougou Dr B. O. Gene va L. Duke, Chre f, FrlarlaI Infectrons, Parasitic Diseases Programme, WHO Headquarters, Dr F. K. Glokpor, Eprdemrologlst and Team Leader, Inter-Country ProJect for the feasibilitv Studres in the Senegal River Basin Area, Bamako Dr R. l-e Berre, Division of Vector Biology and Control, WHO Headquarters, Geneva Mr J. D. M. Marr, Lraison Offrcer, Onchocercrasis Controt Programme, Genel'a Dr A. Prost , Pa ras l-tologlst , Eprdemiologica l Oua ga dou gou Evaluatron Unit, Onchocerci-asrs Control Programne, ocvfsrecfzs . t page 3 Dr G. Qu6lennec, Entomologist/Chemist, Division of Vector Biology and Control, WHO Headquarters, Geneva Dr A. Salds, Epidemiologist, Onchocerciasis lVIr J. F . Walsh, Chief , Vector Control Unit , Obse rver Control Programme, Ouagadougou Onchocerciasis Control Programme, Ouagadougou Mr A. Renz, Tropenmedizinisches Institut, Republic of Germany University of Tiibingen, 74OO TUbingen 1, Federal ocvfsracfzs.r page 4 LIST OF RECOMMENDATIONS ENTOMOLOGY Re inva s ion STAC strongly recommended the continuation and if necessary, expansion ofIogical research programme on reinvasion over the whole operational area, bothpotential (paragraph 8.3). the entomo- actual and STAC recommended that the entomological and reinvasion of the treated zones of Marahou6 and evaluated. This study would determine whether at adapting the control- technique to forest and is found (paragraph 8.4). epidemiologrcal rmportance of the Bandama by S squamosum be careful ly to undertake a research programme aimed mountainous situations where this specj.es Staffin of VCU The need for coordination of research between a1I interested bodies is certainlyincreasing and STAC, disturbed to learn of di.fficulties in this area because of the workIoad of the senior staff of the VCU, recommended that steps be taken immediately to strengthen this particular component of the Programme in such a way as to enable increasedliaison with scientists and institutions currently coffaborating in the different aspects of entomological research as wefl as those with a potentiat input (paragraph g.6). Biolosy and behaviour of the vector STAC, in view of the achievement of the Programme in advancing the understanding ofthe biofogy and behaviour of the vector, recommended that OCP sponsor an internatronal conference on this subiect. It felt that the tj-me was ripe to publicize the knowledge resulting from Programme activities and to stimulate further international scientifi-c interest and collaboration (paragraph 8.9). INSECTICIDE TESTING OCP facility for screening and evaluating candidate compounds The STAC recalled its previous recommendation on report of the seventh meeting (August 1978) which was and recommended that at1 other proposals submitted be(paragraph IO. L5). this subject in accordance (pa ra gra ph with its soon as 5.2) of the present v j-ews, possible CHEMOTHERAPY Trials of suramin STAC recommended that when the final results of the present trial are available, implemented as further trials should be undertaken to test even lower doses over Ionger such new triars should be done in the ocp area and should be repeated in transmlssion has not yet been interrupted (paragraph If.7). perrods of time, an area where E PI DEM I OLOGY Epidemiological evaluation techniques STAC recommended that for aII examinatlons of the second passage the techniques used should remain the same as for the first passage. Minor alterations which may be introduced(e.g. changes in the punch) should be indicated during subsequent evaluatron (paragraph 12.3) a I ocPfsrAcfTs.t page 5 As i-t was reported by the Epidemiological Evaluation Unit that, for the third passage, changes in the technology may be needed, STAC recommended that EPI first undertake itself or with the assistance of consultants or collaborating workers, such pilot trials of any new technique which is considered necessary for the third passage and that a report on proposed alternatives be made avaitable to the Expert Advisory Committee (paragraph 12,4). Staffing With regard to staffing, STAC recommended that the post of statistician be filled as soon as possi-bIe (paragraph 12.6) a ocvfsracfzs.r page 6 r, OPENING OF THE MEETING 1.1- The eighth meeting of the Scientific and Technical Advisory Committee (STAC) tookplace at WHO Headquarters, Geneva, from 4 to 7 September Ig79. The meeting was opened by the Chairman, Professor P. Janssens who welcomed the participants and read out a message from the Programme Director, Marc Ls. Bazin, who expressed his deep regret at belng unable to attend. Mr Bazin wished the Committee success during the dellberations of what wouldbe its Iast meeting. l-2 The Chairman also informed the Committee that a cable had been received from Dr E. Beausoleil to say he would be unable to attend the meeting due to illness. 2. REPORT ON JOINT COORDINATING COMMITTEE (JCC) 2.1 The Chairman invited Dr P. HaskeII, who, in the absence of professor Janssens,presented the STAC report to the Iast sesslon of the Joint Coordinating Committee inin December 1978, to comment on its reception. had Togo 2'2 Dr Haskell. said that the JCC had been impressed with the scientific achlevements of the Programme both in vector contror and epidemiology. The usual concern had been expressed about reinvasion and the JCC approved the continuation of research into this phenomenon and noted the need to study extensions into Ivory Coast, Togo, Benin and Ghana as a consequence. The Committee also supported the proposals for work on adulticldlng and on the screening and evaluation of insecticides. 2.3 The JCC fett that the programme for deveropment of chemotherapy to the transfer of the chemotherapeutic Research centre at ramale to work underway in connection with improving the efficacy of availabre noted. was iqportant and agreed the TDR- Programme. The drugs such as suramin was 2.4 The JCC had accepted the report of STAC on the evaluatlon and fr,rture of the programme, especially with regard to the extent to which some level of control and contj-nued surveillance, both epidemio)-ogical- and entomological, would be required beyond year 20.In this connection the JCC had been informed by the Director-General of WHO that an inde-pendent multi-discipJ-inary commission would be set up to review alternative technology and a pproa c hes . 2.5 FinaJ.ry, the JCC had given its approval, in principle, for a study mlssionfeaslbility of an onchocerciasis campaign in the Senegal River Basin Area. on the 3 . RE PORT ON TIIE INDE PENDENT COMI\I I SS I ON At the request of the Chairman, Dr Hugo Jamnback, representative of the Independent Commrssion, rnformed the Committee of the tasks before the Commission, its objectives and what had been achj.eved durrng the first meetings, in Ouagadougou, of the working groups on vector contror and extenslon. rt was not envisaged that the Commission's activities wouldduplicate or conflict in any way with those of STAC, or its successor, as its objectives were to plan a strategy for the Programme subsequent of I985. However, the Commission hoped to be able to cooperate closely with the other oCP bodres in obtalning information and developing r-ts rdeas. The chaj-rman extended the best wishes of the STAC to theCommission in the executron of its important task. 4. ADOPIION OF THE AGENDA 4.I The agenda adopted for the meeting is appended as Annex I wHo speciat Programme for Research and rraining in Tropicar Diseases1 ocefsrrcf zs. r page 7 5. PROGRESS REPORT ON ACTIVITIES 5.I The Committee was informed that on the basis of the Evaluation Report approved by STAC at its previous meeting, and as a result of two meetings of donors convened by the World Bank in January and May I979, contributions for the second financial phase already amounted to US$ 86 mitl-ion. Some major donors, while indicating readiness to continue support, were unable to indicate amounts, but from the financial point of view the continuation of the Programme was assured. 5.2 Anticipated 1979 expenditures are now estimated at US$ 1.2 million befow the amount approved by the JCC in December 1978. This had been taken j-nto consideration in preparing the l98O budget estimated at US$ 15 O27 tOO. The requirements for the period 1980-85 had alsobeen revised downwards to approximately US$ l-O7 miltion, mostly as a result of a lower cost for the aerial spraying contract than envisaged in the original calculations. 5.3 As the present aerial spraying contract would expire at the end of 1979, potential brdders for the next three-year contract had been aterted through advertisements in the world press, by direct notification and through aIl Permanent Missions to the lJN in Geneva. Thirty-seven replies had been received and, from these, 13 companies had been selected to bid. By the closing date four companies had submitted bids and the lowest bidder, whi,ch was the present contractor, was eventually awarded the contract. The rate per flight hour is US$ 385 and $ 369 for helicopter (Hughes 5OO C) and fixed-wing aircraft (Pilatus porter) respectively, the total contract cost being US$ 5 682 2OO. 5.4 The Committee was informed of the action which had been taken with regard to the establishment of the Independent Commission to look into the long-term future of the Onchocerci.asis Control Programme. Dr C. E. Gordon Smith, Dean of the London School of Hygiene and Tropical Medicine, had been appointed Chairman and eight members had been designated. Under its terms of reference the Commission would review alternative techno- logies , consj-der the role of chemotherapy, evaluate the possible influence of extending the operatrons beyond the present OCP area, determine to what extent the Programme could incor-porate the control of other diseases, recommend what research shoutd be undertaken J.eading to a more cost-effective approach and identify the type of structures, national and j-nter- national, that would be approprrate in future to carry on the Programme's activities. The Commrssion is operating through four working groups on vector control, extension, infra- structures for vector-borne diseases, and monitoring and evaluation. A draft report wouldbe submitted to wHO in June l-98O. The final report was to be completed by June Ig81 andpresented to the Joint Programme Committee in December I9g1. 5.5 The Committee was al-so informed that a new Memorandum of Agreement had been approvedprovrdrng for a change in the management structures of the Programme for the second financialphase, and detailing the general functions of the different bodies. The Joint Coordinating Committee would become the Joint Programme Committee (JPC), and the Steering Committee theCommrttee of Sponsoring Agencies (CSA). The National Onchocerciasis Committees would be maintarned. STAC' the Ecological PaneI and the Economic Development Advisory panel would cease to exist as separate entities and would be combined to form an Expert Advisory Committee, of which nine members would be concerned with scientific and technical matters, two with soclo-economics and one member with ecology. The latter would also chair a permanent ecological group. The annuar report of EAC wourd be presented to the Jpc. 5.6 The National Onchocerciasis Committees met jointly in Bamako from 24 to 26 April.Committees gave thel-r agreement to a formula for cost-sharing between their respectivegovernments for 1980-85' and also decided that in future each Participating Country would The assume responsibility for producing an activi-ti-es withln its State. annual report to the JCCfJpC on economic development 5.7 The posts of Personnel officer and Budget and Finance officer had become vacant andtogether wj-th the post of Statisticj-an had been widely advertised. Selection was expected short ly . a oCP/STACh9.1// page 8 5.8 The Programme had been involved in the drstribution of information, the organization of semi.nars and field visits for visiting scientists and dignatori-es, and interviews to press and radio. 5.9 Training continued to receive a high priority, being carried out in the units of the Programme, by arrangement with institutions in the area or by provision of fellowships for study elsewhere. 5.IO With regard to the actl.vities of the Vector Control Unit, the Ivory Coast southern extension. The total area rnvolved is rainy season up to 18 OOO km of river were treated each week but reduced to approximately 4 OOO km. the Programme about 764 OOO cove red In the thrs was now ,km- rn the dry season 5.11 The main change in operati-ons brought about by the Ivory Coast extenslon was a significant increase in the amount of insecticide used, from 75 281 litres to lO2 43O titres(36% increase) up to the end of Juty. At the same time there was an increase rn flight hours from 3 171 to 3 544.3 hours (I2% l-ncrease); this was made up of a 4g% increase rn fixed- wing time and onty a 7% increase in hel-icopter time. In view of the promising results obtained throughout the Programme area, helicopter flying time may be expected to decrease further as the control operati-ons progress towards the larger rivers in the south. 5.12 Entomological evaluation had been malntained at about the same level as in earlrer years. Six sectors are divided into 24 sub-sectors for this purpose and about 32O catching points are visited regularly. To maintain this effort and provide the ground back-up to the aerial operations, the Vector Control Unit employs 563 personnel of which fourteen are graduate entomologists, one is a cytotaxonomist and seven are operatlons managers and technical- officers. 5.13 During the first half of the year control reached its best level so far (see Table t, Annex II). Subsequently however, some dj-fficulty had been experienced in the Phase III east area where there was a fairly severe reinvasion problem exacerbated by extremely drffrcutt te rra in. 5.14 Reviewing the results for the last completed year (November 1977 - October 1978) rt was reported that control had essentially met the demands of the SAP Working Groupe on ICriteria in respect of Annual Biting Rates and AnnuaI Transmission Potentials, except in the peripheral zones. Results in the western flank this year were much more sati-sfactory, the extension of the control activities to the rivers in southern Ivory Coast havj-ng vrrtual11' reduced the reinvasion phenomenon to zero. 5.15 Wrth regard to the proposed extension to the south of the Programme area, the Commlttee was informed that studies had continued in the south of Ghana, Togo and Benrn. Through the mapplng of cytotypes the distrlbution of the constltuent members of the S. damnosum complex within the seven countries of the Programme was now well known. 5.I6 STAC was advised that the aquatic monitoring programme had continued as planned. A contract had been established wrth the University of Sal-ford, UK, for the processrng and analysis of aIl data coflected. A meeting of the hydrobiologists associ-ated with the OCP aquatlc monitoring programme would be held in Salford, at the end of September, to revlew the results in detail for the first time. This would be followed imrnediately by a meetrng of the Ecological Panel, Monitoring results indicate for Abate a possible 30% reduction in aquattc fauna but no effect on fish-productivrty. The Programme had provided a research trarning grant to enable a Ghanaian chemist to visit the Communicable Dlseases Center, Atlanta, USA, and other Iaboratories, to learn techniques applicable to chemical monitoring. It was planned that a consultant from Belgium would visit the laboratory in Akosombo, Ghana, in October to review the equipment. A meeting of representatives from institutions in West I OCPfSAPf77.1, report of meetlng ocvfsrecfto page 9 Africa who may be able to assist with hydrobiological activiti-es, would be held in Ouagadougou, in October, to plan national organisational structures for maintaining the monitoring programme in future. 5.I8 With regard to the work of the Epidemrological Evaluation Unit, the Committee was informed that the parasitological and clinical reexamination of 6 559 persons from 41 viIlages, originally examined in ),974-75, had been undertaken after three years of vector control operations, 5.19 The actual- prevalence and density of microfilaria had not changed slgnificantly with the notable exception of the under-five children. In the zone where transmlssion appears to have been interrupted (25 villages with ATPs of 0-197) 798 chrldren under 5;-ears of age were examined in 1978-79 but no new case of infection with O. volvulus was found. This compares with a prevalence of 82 infections out of 8IO under-S's (fO.f%) examined in l-974-75. In the ar'ea with some residual transmission (15 villages wi-th ATPs of O-1O2) nine new infections were detected among 488 under-S's examined in f978-79 (i.e. 1.8%). Thrs compares with 9t lnfections among the 523 under-5's examined in 1974-75 (i.e. 17,3%). In the reinvasion zone (l village with an ATP of 488) the status quo had been maintained: two infections out of 29 under-S's examined in 1978-79 as compared with I infection out of 28 under-S's examined in 1974-75. In the 5-9 years age group a marked decrease of prevalence had been observed, especially in those villages where transmissi-on is thought to have been rnterrupted. 5.20 Ocular onchocerciasis was reviewed very carefully. In the area of apparently interrupted transmj-ssion the eye Iesions had stabilized and the rncidence of se!'ere IeslorE was Iow, while in the reinvasion zone evolutj-on of these lesions was more towards blindness than improvement. 5.21 The migrant populations resettling in the successful-ly controlled river valleys were examined yearly and among them no fresh infectron had been detected so far. 5.22 The longitudinal surveillance had now been programmed on a four year perlodrcrtl. However, it was recognized that this frequency may have to be reviewed rf the end-polnt of the absolute Iongevity of O. volvulus was to be assessed and, with a view to ol)tarnrng necessary information, one group of villages was to be reviewed yearly, and anothcr every two years. The current diagnostic techniques were unlikely to be sufficientl,v sensrtrve for parasrtological monitoring when the O. volvulus load had been drasttcalJ.y reduced and new approaches and technrques would become necessary. -c,23 The collagenase digestion technique had been set up in the unrt laborator)'and largc- scale use was now made of histochemical stalnlng of microf]-larlae. -c,24 The accumulated clrnrcal and parasitologrcal data, whtch were systematlcally stored and progressi-veIy analyzed had made it possible to draw some rmportant conclusrons. Fol' example, the drstrrbution of T. streptocerca had been establrshed over the area and its rolc as a possible source of diagnostlc error could be excluded. Transmj-ssion "rn utero" was present rn 4% of the children from parasitized mothers and remained present for six months The mrcrofilarurra was a good lndicator for a systemic infecti-on and correlated wrth the presence of serious ocular onchocerciasis. 5.25 The debilitating role of onchocerciasis woulcl be assessed by the relation we:ghtf height ancl eventual-ly by ergometl-c methods. A decrease of the rmmunogenrc potential in heavy O. volvul-us rnfections was under investigat]-on using vaccrnes and intradermoreactions, as well as the rmpact of the simultaneous infection with O. volvulus and with other parasltes. 5.26 The epidemiologtcal unrt was pursuing, with geographers, its lnvestigatlon of the relatronship between onchocerciasis and the settlements of rural populations and, with demographers, a study of the mortality of the blind. I ocvfsracfts t page lO 6. REINVASION STUDIES I979 6.I The Committee was informed of the various studies carried out on the reinvasionphenomenon. In 1979 the main field research on reinvasion had been divided into two sections. The first was a continuation at a reduced level of the studies in the south- western area, begun in 1975, and the second covered the eastern part of the programme inN' Togo and N. Benin. Thlrty-eight addr-tional vector collectors and tO drivers had been recrurted to cover I4 every-day catching stations. Four consultants had been recruitedduring the period May to JuIy, three being based at Lama Kara in Togo and the fourth at Hohoe in Ghana. Western area 6.2 In the west' activrties had been limited to monitoring the effect of extended rnsecticidal treatments by augmenting the normal evaluation network with every-day catching stations at L6raba Bridge, Chauss6e Niakaramandougou, and at Gl.te Mermis; other catching stations had been manned for 2-3 days per week. Entomological techniques were the same as in 1978. the extension of insectlcidal treatment i-n the rivers of Coast extension towards the south had been accompanied by damnosum s.1. over the period June-August at L6raba Bridge ramandougou, but not on the rivers Marahou6 or Sassandra 6.{ The treatments of t979 had been extended southwards to cover further breeding sites ofS, damnosum s.str. and S. sirbanum Thus, alI the Sassandra system and the Bandama-Marahou6 svstem south to Tiassali had been included in the routine Iarviciding programme which had begun on 6l\4arch 1979. 6.5 Through August 1979 fly catches in the previously reinvaded areas of the Bandama and Leraba rivers remained remarkably low. For example, at L6raba Bridge, the average daily catch during that month was less than six flies and the cumulative Monthly TransmissionPotentrars (IITP) attained a Ievel of only 34 for the first eight months of l97g compared wrthI 122 in 1976. \lonthty Biting Rates (MBR) were correspondingly low, being 962 for theperrod Februarv-August I979 compared with 14 832 in 1976. Catches at Chauss6e Niakara- mandougou had been even more dramatic, with an accumulated MBR of only 217 for the eight- 6.3 In I978 rn the Ivory brtrng by S. 6.6 .{long th(, extension, the S the Sassandra system reduced level-s of and Chauss6e Niaka- month perrod. Only one rnfective larva of O, volvulus had been found this year. These results had been paralleled by alI other catching stations in the Bandama-L6raba region Baoult. rlver valley of MaIi, which Ires due north of the Ivory Coast remained unchanged from previous _vears.da mnos um brting densities 6.7 In an attempt to rdentify further the S. damnosum s.l. populatrons remarni-ng on the RSassandra and [1. ]\larahouri, specrmens of adutt flles were collected by a consultant for electrophoretic ldentifrcation. Preli.minary data indicate that biting populattons at some sj'tes on the R- Banarorl, a trrbutary of the R. Marahou6, may include up to 42% S. squamosum This spectes drd not occur on the Rivers be composed entirely of the S. damnosum s Bandama and Li'raba where populations appeared to S . s irbanum group.str. 6.8 It seemed, therefore, that Sassandra, Marahou(, and Bandama flres rnvading the upper Bandama northwest of the Programme area, the extension of control to aIl known breeding sites systems had caused a dramatic reduction in the number and L('raba rivers, but had not affected the position on the of in the 6.9 Table I, Annex II of this report, shows the dramatic fall in fly catches, of flies per man per day, between 1975-1979, at several sites in the programme on the basis area. ocv/srac/zo. t page 1l Eastern area 6.1-O Intensified studies on the reinvasion phenomenon in Togo and Benin had been in progress since Aprit 1979. As in previous years large numbers of flies reappeared in the wet season atong the M6 and Kara rivers in Togo and on the main river valleys in Benin. Significantly increased parous rates, along with an absence of local breeding sj-tes at the beginning of the rainy season, suggested that the controlled area was being reinvaded by flies from sources outside the area. In Togo, this reinvasion did not seem to penetrate far beyond the boundaries of the Programme. The course of the reinvasion and the movements of the fly populations were monitored by a network of four every-day catching stations in Togo and frve in Benin. At most sites f1y densities steadily increased in May and reached high levels in June, with maximum peaks of more than 8OO flies at Zougou, Benin. The pattern of the reinvasion and the characters of the f1y populations differed at the M6 and the Kara Rrver, suggesting that the fties ori.ginated from different sources. 6.Lf i\lorphological studies to determine the nature of the invading populations (confirmed by the cytotaxonomical identification of larvae) revealed that S. damnosum s.str S. sirbanum and S. squamosum were involved. Almost aIt flies reinvading areas in Benin belonged to the savanna cytospecies, but catches in Togo were thought to contain a consi- derable proportion of S. squamosum. In JuIy flies collected inside and outside the controLled zone were preserved in liquj-d nitrogen for subsequent electrophoretic identi- frcation, which may provide more detailed information on the species composition and the movements of fly populations reinvading Togo and Benin, 6.12 Durrng the period of reinvasion, extensive surveys had been carried out south of the OCP area to study potentj-aI source areas and the di-stribution of breeding sites of the different cytospecies. About 65 larvaI collections had been made for cytotaxonomic rdentificatron and adults were bred out from the same sites for morphological studies, and for morphometric comparison with flies caught in the reinvaded areas. Data so far available indicated that S. damnosum s,str. was widely distrj-buted in different types of rivers throughout the area south of the controlled zone, that S. sirbanum was more common further east in southern Benin, while S. squamosum a ppeared to be more confined to the mountainous areas along the Ghana-Togo border. Breeding sites of s. soubrense and S. sanctipauli had also been recorded in southern Togo and Benin b. 1J Ri ve rs and S. The nearest possible source for the reinvasion of Togo were the Kpaza and the Anie where breedrng was taking place at the beginning of the wet season wj-th S. damnosum squamosum as the main species. selective experimentar insecticide treatment of some systems south of the OCP area may yj-eld valuable information on the general directions fIy movements, and the proportional contribution of these rivers to reinvasion. rlver of the 7. ENTOMOLOGICAL RESEARCH GENERAL 7.1 The research activities carrj-ed out by, or in association with, the Vector Control Unit were described to the Committee. 1 .2 l\latlng 1n the J-aboratory by S. soubrense caught in southern Ghana was confirmed. OnIy a small number of flies carrying spermatophores were obtained from rearing cages but the possibt-lity of selecting out a mating strain clearly exists. A strain of the S. damnosum complex probably capable of mating in captivity had aLso been observed in southern Togo. 7.3 The Committee was also i-nformed that laboratory reared S. adersi collected near Ouagadougou appeared to be mating in the emergence bags, but this needed confirmation by the observation of spermatophores. As the larvae of S. adersi are extremely catholic in tlterr choj-ce of habitat, being capable of livj-ng in a wide variety of water velocities and even 1n polluted waters, they should be relatively easy to rear in the laboratory. O. volvulus had been shown to develop in this species in the laboratory I ocvfsrtcfts.r page 12 7.4 A team at the unj.versity of Massachussetts, usA, had estabrishment a self-perpetuating supporting thecolony of S. decorum , now in its 14 month and 12th generation. OCp was maintenance of this colony for the next twelve months 7,5 Sampling methods, specifically developed by research workers of the Instj-tut deRecherches sur 1'Onchocercose (IRO), Bouak6, had permitted a systematic study to be undertaken of the resting sites of blackfly females in different stages of their development.First results obtained in Mari and Ivory Coast showed that they rest rargery in the vegetationbut the places vary according to the type of environment. S. damnosum as a vector of other Onchocerca species 7.6 In the past, hj.stochemical staining of infective larvae, morphol-ogically indistin-guishable from O. volvulus obtained from biting S. damnosum s.l. , had shown the presence oftwo types of larvae in the Programme area. T\rro consultants had been recruited to study thedevelopment in S. damnosum of Onchocerca ochengi, a parasite of cattle. The infective Iarvae of this species proved to be inseparable from those of O. volvulus, both morphologically andhistochemically, and therefore the second type of rarva stilr remained to be identifred.Studies were continuing in MaIi where this parasite is common, in an attempt to find what species are present. To date O. ochengi, O gutturosa and O armillata had been found in cattle 8. GENERAL DISCUSSIONS O}I ENTOMOLOGY 8.r STAC complimented the Vector Control Unit on the outstanding work it had on all that had been achieved in the operations during the past year. unde rt a ken and 8.2 It was agreed that the excellent control results obtained in l978-1g7g may be partly due to favourable climatic and hydrqlogical conditions. Therefore, STAC warned that rt must not be taken for granted that these exceptionally low fly densj-ties could be attained every year, and the consistent effort of the Programme must be sustained. 8.3 STAC congratulated the Progranme on the entomological research results and particularly the further knowledge gained on the reinvasi-on problem. It recognized that aIl had directpractical application in control. Nevertheless it was felt necessary to reinforce the point made by VCU scj,enti.sts themselves, that knowledge was still very far from complete with regard to fly distribution and movement. A good knowledge of what happens over a large part of the area is now available but these phenomena are still not fully understood. Accor-dingly, wj-thout further research, it would not always be possibte to explain future unexpected upsurges in Simulium bi-ting densities, nor would it be possible to improve thc existing forecasting system for the distributron of the various species of Simulrum rn the operational area. This latter would be most important in relation to the study of new low- cost vector control techniques by the OCP Commission, For these reasons, therefore, the STAC strongly recommended the continuation and , if necessary, expansion of the entomologica I research programrne on rej-nvasion over the whole operational area, both actual and potential 4 STAC recommended that the entomo logica I and epidemiological importance of the retnvasion8. of the treated zones of Marahou6 and Bandama by S. squamosum be carefully evaluated study would determine whether to undertake a research programrne aimed at adapting the techniques to forest and mountainous situations where this species is found. This control 8.5 The Committee, in reviewi.ng the achievements of the VCU, observed that there had been an evolution during the years of the Programme's operations in respect of the structures and organization of entomological- research. It is now recognized that, owing to the biology and behaviour of the vector, as wel.I as the Iack of continuous culture, it was necessary for ahigh proportion of research to be carried out in the Programme area. This implied greater use of consultants, as well as the need for Programme field personnel to work closely with staff from collaborating laboratories. ocefs'rncf ze page I3 8.6 The need of coordination of research between all interested bodj-es i-s certainly increasing and STAC, drsturbed to learn of difficultj-es in thj,s area because of the work Ioad of the senior staff of the VCU, recommended that steps be taken immediately to strengthen this partj-cular component of the Programme ln such a way as to enable increased llaison with scientists and institutions currently collaborating in the drfferent aspects of entomological research, as well as those with a potential input 8.7 The Committee expressed satisfaction at the prospect of culture of a species of the S. damnosum complex, or S. adersi as of great importance, and hoped this would be afforded every by the Programme. 8.8 As regards further developments in entomology, the Commlttee re-affrrmed the importance of continuation of the studres on resting sites of adult flres a9 an essentral pre-cursor to the develDpment of adultrcrdrng techniques. 8.9 STAC, in view of the achi.evements of the Programme i.n advancing the understanding of 1 development of a continuous work considered previously assistance and encouragement the biology and behaviour of the vector, reconmended that OCP sponsor an lnternational conference on this subject. It felt that the time was ripe to publj-cize the knowledge stimulate further internatronal screntificresulting from Programme activities and to interest and collaboration. 9. WORKING GROUP ON TAXONOT\IY OF S. DAMNOSUM COMPIJX 9.1 The Committee was informed of a meeting of taxonomists convened in Lama Kara from 16 to 21 October J,978, the report of which had been circulated to aIl STAC members. Participants had j-ncluded members of OCP staff at both the professj-onal and technical levels. The ob3ectrve of the meeting was to determine: (a) the possibility of identifying adult female species or species groups in the complex and degree of accuracy this could be done; and S, damnosum s.1 to discuss how . to the level of and with rvhat (b) what methods could be used for field identificatron. FreId trips were made by road and by helicopter to collect samples for group examrnation. 9.2 The meeting made several recommendations as folfows (a ) Larvae not intended for cytological identification should be rdentrfred morpholo- glcally whenever possible, at least to the species pa1r, rn order to rmprove knowledge of species di-stribution (especrally in areas that are potcntral sources of re invading f I res ) . (b ) (c) (d) (e) Further work to characterrze Larvae to specres level should be encouraged Further studr-es rn chromosomic polymorphrsm should be undertaken to determrne whether they are correlated with morphologrcal, ecologrcal and other factors. J Studres should continue to perfect the morphological taxonomy at the crltical research level and practical freld leveI. A be a search for simple and reliable characters for use in the Where practical, females caught bitrng in the OCP area shoul,d colour of the stem veln tufts, scutellar hairs, post cranral antennal form. of the complex both ma.lor obJectrve should freId. be scored for the halrs, and for (f) Noting the serrous lack of Simulium cytotaxonornrsts and cytotaxonomrc determlnations in Africa, the recrultment two suitable candidates should be undertaken immedtately the increasing demand for ancl trarning of at least ocv/sracfzs.r page 14 to. r A contract had been sig-ned with the Institut de Recherchefor screening of compounds which might be sultable for spraying whrle suitable compounds can probabry be found qui-te quickly the deverop:,ng a contror technique remains the elucldation of adult unrikely that adurticlding could be usefur and economicar unress determined. (g) Recognizing the vital necessity of obtaining associated material of alI stages the same egg batch, Iaboratory rearing should be encouraged and intensified as source of identified material for morphofogical investigati-on. f rom a 9.3 STAC, recognizing the importance of this work, fu1ly supported the recommendations ofthe Working Group. IO. INSECTICIDE TESTING Adulticrdin sur 1 'Onchocercose , Bouak6 , operations agatnst adults. limiting factor in resting sites, it being a precrse target is Review of insectrcide screening and evaluation lO.2 A short-term consultant had been recruited programme and the results obtalned to date. His Director, and would subsequently be circufated to The Committee was informed that it is intended to field, in the Programme itself, and to develop a : rnrtially in southern Togo. to review the present insecttcide testing report had been submitted to the programme interested members of STAC and WHO staff. upgrade the scale of activities in this mobile Iaboratory facility probably located 1o.3 The consultant would also carry out tests on susceptibility to di.fferent insecticidesin the Programme area. DDT resistance had been reported previously from several sites inWest Africa but many of these had since received regular Abate treatment over a period of several years. Accordingly, Iocal populations of to considerabl-e selection pressure, and it is impo out on a reEtrlar basis. S. damnosum s.I. must ha ve been sub3ected tests be carried ro.4 were the the rtant that susceptibilrty During the period under review, 5 oOO litres of Abate, 20% EC (Cyanamid Formulation 23) received for testing. An operational trial of this material had been scheduled near end of the rarny season when the most favourable conditions woufd exist for evaluation of results. This formulation had already been shown to be satisfactory in stage v tests. Testing outslde the Programme 10.5 The Commlttee recerved a report on the activitres of the pesticide Development and SafeUse Unit (PDS) of the Vector Biology and Control Division, WHO, with respect to research onSrmulrum Iarvicides. Io.6 The Committee was rnformed of the small number of companies which had provided specialformulations of larvlcides for brackfry control slnce the SAp working Group on Insectrcidel tn Geneva in 1978. The reason for thrs lr.mlted lnterest on the part of the companies is attributable, among other things, to the lack of guidelines which could be put at the disposal of the manufacturers for the preparation of formulations, as wel-I as rhe toxicity of many rarvicides to non-target organisms. rt is proposed to request the Ecological panel to suggest tolerable toxicity levels for non-target organisms and to stimulate research onformulations. tocvfswcfze 25 ocvfsrecfts.t page 15 IO.7 At the present time PDS has contracts wlth four laboratories conducting research on new pesticides. To date 2I formulations of seven insecticides had been provided to the four laboratories for testing. In addition to chemical pesticides, a biological agent, BaciIIus thuri-ngiensiS var, israelensis, had been provided to collaborating laboratories for testing, Physj-o-chemical and biological tests of the chemical and biologrcal products are in prcgress. IO.8 Preliminary results on one compound, decamethrj-n, showed havj-ng kilted larvae up to 10 km when applied at only O.OO7 mgfl results with Bacillus thurigiensis var. israelensis also seemed it to be hlghly ef fecti.ve, for 10 minutes, Ear1y promising; O.2 ppm applied a for 1O minutes caused detachment of the larvae downstream from the point of application. Future developments lO.9 STAC, after considering the above reports, and in view of the importance of the rnsectrcide aspects of the Programme, appointed a sub-committee to discuss possible future developments rn this field and the relationship of the OCP work to that of other bodies. l-O.10 The sub-commlttee again noted with concern that there had been a severe reduction rn the senior staff component of the Programme connected with vector research and control and that this, allied with the increase in the Programme area and the need for further lnsectrcide development and testrng work made it imperative to strengthen the Vector Control Unrt rn these areas (see also paragraph 8. 6). 1O.I1 STAC welcomed news of the intention to set up an insecticide screening and evaluation group in VCU and unanj-mously supported this proposal. It was felt that this group should carry out work on the evaluatron of new formulations and should develop a programme of susceptibility testing throughout the Progranure area. Routine testing of insecticides batches recerved for operational use should be undertaken as well as testing of batches stored for long perrods under tropical conditions. Such a group must also develop liaj-son wlth other interested groups, particularly VBCI, the OCP Independent Commission and laboratories external to the Prograrnrne, such as IRO, Bouak6. 10.12 In relation to such liarson, it was agreed that while VCU could contact industrial firms directly for advlce and assistance in their work, VBC should be kept informed of such contacts and any formal agreement with industry shoutd be the responsibility of VBC. The sub-commrttee pointed out that the new VCU group would have an important role in assistinq the vcctor control working group of the OCP Commrssion and probabty in implementing the Commrssion's recommendati-ons related to operational aspects. Dr Jamnback, on behalf of the Commission, welcomed the proposal to set up such a group and agreed that it would be of assrstance to the Commission. 10.13 It was poi-nted out that there was an urgent need to coordinate relevant aspects of envrronmental monitoring, which had suffered by being treated as a separate entity, wrth the insecticrde work. The sub-committee therefore considered that the appointment of a hvdroblologrst to this new group was important. 10.I'1 The sub-commlttee noted that rt was the task of VBC to commission more fundamental studles on new rnsectlctdes, such as B. thuringiensis , and on new formulations and approaches, and that the;ob of the new VCU group should be restricted, in general, to screening and e'valuation of i.nsecticides, riverine lests of selected compounds and formulations of operatr,onal importance, and tasks such as susceptibiLity testlng relevant to the development of now controL technrques. the WHO Division of Vector Biology and ControlI ocvf srrcf zs.r page 16 tO.t5 The STAC recalled its report of the seventh meeting, and recommended that alI other previous recommendation on this subject (paragraph 5.2 August 1978) which was in accordance with its present proposals above be of the views, implemented as soon as possible II. EPIDEMIOLOGICAL AND CHEMOTI{ERAPEUTIC RESEARCH l-1.1 The Committee \vas informed of an epidemiologlcal study undertaken of progress made in the development of new drugs. in Ivory Coast and ll'.2 Surveys carried out ln Ivory Coast confirmed the contrast between the severity of the signs and symptoms of onchocerciasis in the "savanna" zone and their more benign nature in the "forest" zone, an epidemi.ological pattern already suggested in earller surveys and described in Cameroon and Nigeria. If.3 Four-thousand individuals were examlned i-n 17 hyperendemic villages in eight different regions and located in the five main river basins. The examinatj-on was done according to the standard protocol, including ophthalmological and microfilaruria examination in the forest villages only. 11.4 No significant difference was found between the various clusters in savanna and forest in respect of parasite prevalence, microfilarial density or cyst carriers rate, but the c1i-nica1 pattern of forest onchocerciasis is less severe in Ivory Coast. IL5 The frequency of ocular lesions underlines the contrast between the geographical areas. For a virtually equal level of ocular parasitism (35-50%), severe and rrreversible ocular onchocerciasis is present in less than 4% of men and l% of women in the forest, whereas the corresponding figures j-n the savanna are up to 30% and 1O%. The severrty of the disease is much less in the forest zone, where fewer thran 4% of persons are affected with severe ocular lesions even in a very j-ntense focus of infection. Forest onchocercrasrs is apparently better toferated than savanna onchocerciasis. The forest epidemiological pattern seems to be found wherever the transmission of the disease is not due to S. damnosum s.str. or S. sirbanum 11.6 Further investigations on the parasites in the different geographical zones, by differential staininB, by cross-infection, etc. wiII have to be done over a sufficient pertod of time before it will be possible to assess the possibi-lity of stralns adapting to new vector species, to assess the inffuence of ecosystems and living conditions on the pattern of disease, and to assess the risks involved in the casual introduction of forest strarns to savanna areas where transmission has been interrupted. Chemotherapy ll.7 With a view to improving the use of an existing filaricide for J-arge-scale chemo- therapy of onchocerciasis, the Programme carried out controlled trials of low-total-dosage schedules of suramin, both inside and outside the OCP area. In six ascending weekly doses(O.2, O.4, 0.6, O.8, I,O, I.Og) up to a maximum total of 49, suramin is better tolerated than under the classical protocol (i.e. a test dose of O.I g followed by l.O g weekly for 5-7 weeks). The incj-dence of adverse effects especi-a1ly in the skin and eyes (rrrtis and optic atrophy) have been carefully evaluated. Although relatively mild they were still sufficiently severe to demand medical supervision of the treatment. In the OCP area three months after the end of treatment the efficacy was marked on the microfilarrae and on the embryogenesis in the female worms. The viability or death of the adult O. volvulus still has to be assessed after 8 months and one year. STAC recommended that when the frnal results of the present trj-aI are available, further trj-als should be undertaken to test even lower doses over longer period of time. Such new trials should be done in the OCP area and a should be repeated in an area where transmission has not yet been interrupted. { ocvfsracfts I page 17 1I.8 In compliance with the continuing need for close cooperation between TDR and OCP, a report was presented on the current efforts of the Special Programme towards improved treatment. In the Tamale Chemotherapeutic Centre a method for quantifying the Mazzotti reaction has been developed and trials of drugs that might control the reaction (indomethacin, sodj-um cromoglycate) are in progress. Up to now no one compound has been very helpful. I1.9 Trichlorfon (metrifonate), a presumed milder microfilaricide than DEC, has been tested in a number of dosage schedules. In fact it has proved to be a less certain microfilaricide than DEC, and in addition to producing all the usual side-effects, it also has an anti- cholinesterase action. In the OCP area trichlorofon has a very low acceptability, and as a result, it will not play a useful role in controlling onchocercj-asis there. II.IO Other drug trials are in progress with furazolidone, nitrofurantoin, IevamrsoleT" mebendazole, flubendazole, and 2-nitroimidazole derivates. Some of these drugs possess macrofilalicidal or an embryostactic action on filarial worms. Macrocyclrc lactones of avermectin group, being active against 4th stage larvae, might be useful as clrnical prophylactics. I1. Ll O. grbsoni in Australian cattle a the of changes in adult filarj-aI worms may Onchocerca worms. has become a very useful screeninB model for detection Studies of the folate and methronine metabol-i-sm of for specially-designed selective rnhr-brtors,produce new targets 12. GENERAL DISCUSSION ON EPIDEMIOLOGY AND CHEMOTHERAPY 12.l STAC welcomed the promisj-ng results of the second passage of eprdemroLogi('al evaluation which are particularly important because they indicate, for the first trme, both parasitologically and ophthalmologically, that the Onchocercrasi.s Control Programme rs having the intended effect on the parasite in man and on the drsease whrch 1t causes. 12.2 The Commrttee suggested that a short report should be prepared by the Eprdemrological Evaluation Unit at the time of the second passage on the fate of those blind people who were registered and examined during the first passage. 12,3 STAC repeated its previous recommendation that for all examinations during the second passage the techniques used should remain the same as for the fi-rst passage. llltnor alterations which may be introduced (e.g. changes in the punch) should be rndicated drrring subsequent eva luat ion . the Epidemiological Evaluation Unit that, for the thrrd passage, fi-rst undertakebe needed, STAC recommended that EPI should assistance of consultants or col-laborating workers) pilot trials of any new techniques which are considered necessary for the third passage, and that a report on proposed alternatives should be made available to the Expert Advisory Commrttee 12.5 Discussing the need for a more sensitive diagnostic technique for llght infection, STAC suggested that the use of the \lazzotti test in children should be carefull,y evaluated. Serologrcal techniques may become more specific, sensitive and reli-abIe. If stage specrfic antigens can be prepared, it may be possible to design simple serological tests to detect rnfect 1on . L2.6 With regard to staffing, fiIled as soon as possible. STAC again recommended that the post of statrstir:ran lre 12.7 In the fr,eld of chemotherapeutic research, the OCP should contrnue to cooperate with TDR, especially in regard to the activities of the TamaIc Chemotherapeutrc Centre. 12.4 As it was reported by changes 1n the technology may 1(either by itself o. *i I ( , ocvfsrrcf zs.r page 18 12'8 STAC recalled that during its seventh meeting tn Brazzavi.lle, in r9zg, because of theinsufficlency of scientific facts then available, it was unabre to give a definite answerto a question from the world Bank on the tong-term future of the programme. During the JCCin t'omi^, in December 1978, the srAC representative had stressed this point. 5TAC was stlllcompretely satisfied with the progress of the Programme but adhered to its r97g statement.Despite the progress made in 1g79, it was stirl too early to make a definite statement onthe long-term future based on the scientific facts avaitabre. T3. CLOSE OF MEETING 13'l rhe meetrng was closed by Dr s. Flache, Assistant Director-Generar, who warmlythanked the committee for the exemplary manner i.n which it had carried out its mandatenot onry at its eighth session, but since its first meeting in 1g24. The organizatiorhad appreciated the constructlve manner in which it had assisted the programme since itsincept ion. r2 0 to the to the The chairman thanked Dr Frache for hrs kind remarks and arso expressed h1s thanksProgramme Director and Ills staff, the interpreters and arr those who had contrlbuted success of all the meetings of STAC. t , II , 3 4 AGENDA Opening of the meeting Adoption of the agenda Progress report on activities Entomological research - reinvasion - S. damnosum as a vector of rother species of onchocerca Insecticide testing Report of Working Group on Taxonomy of S. damnosum complex Eprdemiological evaluation - parasitological and ophthalmological aspects of second passage - forest onchocerciasis in south Ivory Coast and south Benin AppI ied research a) eprdemrologr-cal: - debilitating effects of onchocerciasis in hyperendemic populations ocP/srACf 7s.), page 19 ANNEX I (re lat i onship I 5 6 7 with blindness and other ocular defects; b ) chemotherapy: - prelimi.nary results of therapeutical trial Other matters Review and adoption of the report of the meeting CIose of meeting weight/si.ze relationship ) at Bonga (Ti6b616) Upper VoIta q 10. Il. I a\ 8 ocefsracfze.t page 20 ANNEX II TABLE I COI''IPARISON OF FLY CATCHES - I975-I9?9 FLIES PER MAN PER DAY L6raba River - Pont Routier r 975 1 976 t977 I 978 1 979 May June July Augus t Septembe r 92 14r 26 50 2 r15 129 t34 39 6 151 105 60 33 4 1r4 86 6 2 4 69 54 I 1 Bandama River - Bema r975 1 976 1977 r 978 197I 57 56 6 33 94 68 82 18 t82 40 t2 7 1l 116 34 , <I 35 I4 2 I Bou River - Gite 3 I975 t97 6 1977 I 978 r 979 153 2t9 48 108 270 r70 256 33 344 103 58 2l 5 tt2 I5 1I 66 t7 32 Como6 River - Kafoto r975 1976 L977 1 978 t97 I I5 6 J 4t 8 32 15 1I 11 <1 34 7 D 10 <l 2 4 <I Marahou6 River - Gite Mermis r97 6 r977 L978 1979 341 280 I8 3r6 325 315 I 33r t2r 224 IO 27r 25 88 5 343 61 44 I I I ,