Informal meeting on the progress of entomological research by the Onchocerciasis Control Programme: Lama Kara, Togo, 26-28 August 1982

t bz A Pr-/ta/1 WORLD HEALTH ORGANIZATION ORGANISATION MONDIALE DE tA SANTE Infomal l{e€tin6 on the Progreos of DntornologioaJ- Beeearch by the Ooclrccerciasi's Coatrol Prograame Lana l(ara, Togo 26 - 2B Auguet, 1t82 s. &a'' R'P q \-,^,. 1 i I oAgenda: 26 AWust Gboho. C.. Son6. A.. 0u6ltrogo. J.. Almo}lua. 8..: General situation in the reinvasion areas in Togo and 3enln. Reeults in L981 and present sltuation. T. Report on studiee on the reinvasion W E:.j@g s.1. lnto the Eastern area of OCP and resuLts of erperimenta.L treatments of potential sources camied out by Ga:ms, Cheke and Kerner in 1!81. Renz 4.3 Report on the preliminary results and discussions on ttre on-going studies on reinvasion and the vectorial capaclty of S. goubrense in Northerrr Togo and Benin. Zerbo. Q.. Ravbogld. J.:ProltgtlmL studieg on the trangniseion of 0. vulus by the forest epeciee of the S. 4elonoeup coqller in Gtrana. Otrar, M.: Histochenical differentiation of filarial larrrae for:nd in S. damosum e.I. within the OCP area. Renz. A: Report on the transrlsgion of Onchocerciasis in the sarrarrna area, in Northem Cameroon. Agenda 2/ Augustr EeEE- A.: A nathenatical nodel of 0nchocerciasi Se .C-@r-R:rs Report on th,: ftight perfo:mance studies on fu[ry s.I camled out at Akosombo and 0ua6adoug:ou in 1981. Si-rmons. K.. Raybo-ul.d. J.: Iuprovements in colonising S. damroeum 8.1. in Amtrerst (USl,.) and Akosrrnbo. Kqrt.,rk. D..: llhe nonitor ing of susceptibility and the sittration of resistance in the OCP area. Kurtak. D.__-Ravbould. J.: Report on experinents on croga-brecdlng of temephos resistant S. soubrense of fvory Coast cnd susceptible S. soubrenee of Togo. MereS.ittr. S.: Esterase studies on E. demrosun eomplex speciesrparticularly on resistant and susceptible Erjoubrense populations. Ja,rrback. H.. Report on resuLts of SirnuLirr.n larvicide screening. M.. Renaud. P.3 , r/2 -2- 28 Au.eqgt._Jaonback. H.. 0cra M.. Renaqd P..: Dernorrstrati.on of closed circuit troughs in the Laboratory. Ocran. l{.. Baro Tele..: Demonstration of open-circuit (mini-gutter) troughs in the fie1d. Proceedi:1gs 26 Arrgust. I9B2: flee meeting was opened srd convened by Dr. J. Grrrnewald at 9. am. He welcomed the participants to the second OCP research neeting and elrLained that the aim is to revievr the reseerch done by both consulta.nts and staff members. The format of thc neeting was established, breaks for refreshment oceuring in the morning (B - t2) and afternoon (f5OO - 18OO). Dr. Philippon was r-urable to attend the meeting as he had to travel to Bouake and then Bandiagra, but sent his regards. Dr. Paugy was also rrnable to attend due to consultants from Bouake working rrith him in 0ua6adougou. ItIr. Adjorrnou welcomed the participants to Kara on behalf of the Sector and Sub-Seetor Staff. 1. Reinvegion of the E_astenn Zone (Dr. C. Gboho) Dr. Gboho erplained that the Sota, IvI6 and Kara River basins had been subject to reinvasion since L977. fn Benin the two captrrre points for monitorini; reinvasion are Gbasse ( 7 aays per week capture) and Beterou () a"y" per r+eek); in Togo, I{6 brid.ge and lranda Pozanda are J d.ays per week capture points for reinvasion. In 1981, experimentaL treatment of the river Mono to its confluence with the Arnou and of the Asukawkaw and Kpaza river systerns in the Volta Ilegion was staxted on 2Jrd Jr.rne for sir wceks. This treatoent was not successful on the Mono as lanrae were found throrrghout the period. Hor+ever, biting catches at Djodje on the tlawa river were reduced. After treafuent of Asukawkaw ferry, where forest species of S. dasrosum 8.1 are ueualLy present, savanna flies predominated and repopulation by forest speciee has taken some time. a r/, ,Dr. Alcpoboua said that in 1980, very few pale wing tufted flies were caught at Asukawkaw. Before treatment, up to 200 flies/week were caughtr after the ertrlerimental treatmentl this dropped to 2 per week for six months. Ihe site has been repopulated b,y pale tufted. flies, rnainly S. squarnos-um. Before the treatment the proportion of cytotSrpes was; sa: da: 105: 18: 5, and after treatment this is; sa/sat sq: da: 6z 2z L. ft has talcen almost one year for the proportion of d.ark t4fted. flies to return to the pretreatnent level. ft was explained that the pale trrfted flies refemed to as savanna species also included pale tr:Jted. -,S. sqrranqsUq. rn 198r fewer flies were caught at Gbasse thar: in r9go, probabry due to the clinatic conditions. During the orperinental treatrnent the captures at Beterou and Kaboua wulre lower, but there was liLtle effect at Gbasse, inplying that the reinvasion of the Sota Basin is fron ttre East as well as the South. S. glpmosurn is irportant in the reinvad.ing population in Togo, but not Beni.n. Ihe 1982 studier of reinvasion ere in progress tJ:ough no experimental treattr'int will be carried out. fhere are, in general, Iower nrrmbers of fries, less than 20 per day at Gbasse, for exAmple, arrd the weekly treatnent at Landa Pozanda vrls etopped in March 1982 and only in the last week of Ar:gust have the fly nrrnbers risen. ff. Dr. Grrrnewald: es on the 10n J s.1 in_tq_Dqs_tern OCF and resuLts of e&erimen tal treafuents of potentlal ed out Cheke and Kerner in 1981. Dr. Grrrnewald sr.rnrmarised ttre reinvasion stud_i.es of Dr. Ga"r"ms, Cheke and Kemer. Tn L979 Ga:ms et aI for:nd differences in the reinvasion phenomena in ty-Tf Coast and the Eastern OCp parous ratcs being higher in the West. In the East biting differences wero found. betuecn catches at lvl6 Bridge and Landa Pozanda which are only 50 lss apart. At I!6 Bridge _S._sguenogllo is predoninartt, where as S. sirbanrrn S. d.a^mnosum are the na5.n species at Landa Pozanda. .,/4 - 4^ It r,ras assumed ths.t the reinvcding flies rrould not originate from verTr far and erperim:ntal treatnent of'-L_5W,g breeding sites within a rad.ius of 100 Kms. was proposed. ttris treatment in 1980 had little effect on biting catches or the il.,IP leve1s, so the I9B1 treatment etlcompassing larger areas South of the Programme wag proposed. Tkre treatrnent was also an experiment in how to treat the breeding sites in mountain areas. fhe treatment begun during hearryr rai.ns arrd. flooding. Rcsults were satisfactory in the Asr:karukaw, wawa and Kpaza systems although there were always problens in treatin. the mor:ntainous areas and ranrae werc arways present thus it is difficult to assess the productivity of these breeding sites. As Dr. Gboho mentioned, Mono treatmeats werc unsucessful d.ue to rrnder dosing and not reduced susceptibil.ity. The effect on the biting populations i.n the south hlest (Djodje) was satisfactory and th,: population does not seem to have recovered yet. [trere has been a change in species composition, species. S. -g1q:{Losl4r replacing sanctipauli as the doninant Uithin the OCP the biting densities r,rhich ha.d increased. during ltallr rere reduced during the experirncntal treatment but the results were stll1 not very satisfactory at M6 Bridge. fhe erpcLrinental treatnent had no effect on biting d.ensities in the South i..e. Ietetou, (ttono River). ftrere was a general d.iscussion about the repopulation of Asukawkaw bridge W S. sgUa.nosun. It was agreed. that It is difficult to say whether the speci.es conposition has changed. due to repopulation bfi one species, or whether the species uas arways present in low nunbers, and has remained wherr: as the predomi.nant species has been erirninated. fhis poses the probrems of bias d.uring gempling methods of quantifying lanral densities. rrl. Mr. Renz. prerUq+ngry_ g9eq1_!e.-€lge:--eEgie-g Ifr. Renz said how this yearts stud.ies harl started with bad. luck as Dr. Ga.:ms could not come. .,/5 5- Dr. Cheke had broken his arrn and I{r Som6 had been sick. He outlined the ains of the stndy. Tktis Xeffir no experimental treatments are ptanned so the fulI extent of rei.nvasion can be obse:sred arrd conpaired with that of 1979. In particuler, it is of interest to see if no treatnent of the Asukawkaw and tributaries will affect the bitin.q catches. fhere is to br,' aquantitatlve otrr(y of vectorial capacity of S. soubrens To study the vectorial capacity, the species need to br: differentiated. Several keys have beer: developped by different groups who all Cisagree on the fj.ner points of differentiation. Which ever method is used, individual flies cannot be speclfically identified, but populations can be determined. ftre rains started earLy this year, but have not been very heatry and in bhe South thc lack of rain is very marked. The entomological situation reflects the hydrological one. Overall thcre is a ruauttion in the nr:nber of flies caught, this is particularly markcd at Djodje but it is inpossible to telt whether this is due to the lack of rain or to last yearrs treatmenl. lhe parous ratcs are lower this year in comparison with those of Vlestern areas of reinvasion. Lt lt6 Brid.ge paxous rates are J0 - g)%where ttrere is no locat breedi.ng, at Landa Pozanda 40 - 5U/o wherr-. local breeding occurs. The low paxous rates raise the question of what is the erplaination short fliatrt distance, a b rhavioural trait in S. squa^Eosun all owing it to travel lon.e distarrc() as a nullipar? The reinvasi.on phenornenon onLy affects certain river valleys in Togo and Benin and sites that supported breeding before treatnent. ftrere was a gencrel discussion aborrt possible erplanatlona for reinvasion concentrating on certain sitos including oviposition behaviour, biotopd profiles, bli.rod meal availabilit;,. llr Zerbo outlined sorne stud.ies in ljlali which indicate thet it is the b:cuding si'be itself that attracts the flies. IT. Zerbo. Studies or-r lhq _tgqns-pgp_igp. _o-l-Q.Jlg orl4e.il-gq{e?e.1'4e-sery}qis.-q@q-4.L.fl J-. ,./6 6A stud;r Ln L977 was initi:'l,ed "bo investigate tlee vectorial capacity of s. scrlg-lilgElir. as Dr. i.uir16v6r6 hc.d reirorted it to be a poor vector in the l/est. Asul(awkaw ferry was choson as it was predominantly !-rs-qrlglilglr1! flies were gorged on a blind. onchocercian from the Volta Region, kept for I da.rrs at Akosombo ancl then disected. High nortalities of the fries occured, probably during the trcnsportation. They were disectec after laying eggs and found to have high infections. Egg batches wer'a reared singly and the { lanrae resulting were aII id.entified. as s,saqct+lauri .by Dr. vajime. A mean of 9 infective Latrae/fLy (r - rg rarrae) was recorded from J fries. This shorued. that s. sa.nctipar[i could act as a vector. fts importance as a vector is clifficult to assess as the host preference of -Eggq-Bbrffig- and Essa49,!ipau1_i seens to differ in differcnt arees. fhere is little information on whcther S.-qg3Eosum._md !g)@s_e bite hosts other than marr. At Kintanrpo forest the lcvel of infection was lowen than other sites inptying -bhat Sr_s-quaqo-lsun was a poor vector. fheru- uas a general discussion obout transnission stud.ies and. high intakes of microfirarial resulting in high nortarities of flies. V. Dr._-.QqBr._.H-i-s-!g9he-mrc;[ _{r-tte--rSn!ial].o,g of $I. jgfgf- lery.?€.-louna g j:-4qg1-oS.glt.S-rf ._-g_ijtr!.rf _Lhe.o.cl:Seq. Dr. Omar sumraarised the work he did h J-977 - J! which is now published in'Propenmedizin rrrrd parasitologi.a. The his-r,ochemj.ca1 acid phospatase strain was used. to d.ifferentiate filarial larvae from female 6.d.amr_osrr-n s.1, within and outsid^e the OCp. rn lvlali, rvory coast and upper volta$out LCt6 of lrd sta6e ranrae LnLl.r% of !..da.qnosunl s.1. (savanna cyto species) could be separated. from those of 9.-v-ol@us - like larvae. fhe,:e was a d.istinct geographical distribution of these la:srae, the higtre$ percenta6es in the \Iorth West (lari) and the lowest percentages in the centre of the Progra.mre. rr Ghana and To6o all I ,l:\rae were nor?ho1o..-,ic.:lly anrJ enzlmatically similar to .9.-ro$-ggr. fhe specific identif ic:"'bion of this member of the qqehoccrc! Senus r:nlmown at present. flre techniques used. for this strain ,r/7 l- are sinple end casiLy transported; preparations of preservcd material on slides can be kept for years. Howcver as no differences havc. been obsenred b;,twe:n 0. -Eil-e-rE! ed -9.-vgI@E other m.-,thods are being investigated. r\ general discr.tssion about animel filariae folloned, and the problern of trarsporting filan'iae to Hamburi- for iCentification was discussed. Vf. Irtr Renz: Repgrt qn*t-tqgsm;is-s.i-o.q ot-o-n-c-!io-c_93:S3gs-rgrn--?.-aq{g4rg area oq@e.roog?. I'tr Renz '.lescribed his three yecr prograf,ure in Ca.neroon. The criteria of OCP were (/TTPTABR etc) vrere d.ravrn froni d.ata obLeinecl fron single vi11a6a i.n Ca.meroon. Mr Renz was fi:rther investigrting the rc.Iationship betreen transmission, woro loads and fly-man contact in hyporrneso and lffiler-enCemic villages to dc.tcneinc the rnost acceptable AtP IeveI. There were sone differences in mcthods of study e.g. fly catchee were frorn 6 am to IB.J0pn ancl two vector coLlectors worked. together. Catching sites uere siturted at difrerent distances frour breeding sites and the rlistribution of human novernent aror:nd l-.reeding sites was stud.ied. The calcul .tion of the AfF was made using ttre avera.ge number of lanra,e per fly (not the crude nr:mbcr). the AfP was correlated r.'ith thc level of infection in the hrrman population &n,-l it was concrud.,d the.t an A'rP of r0o is stitl too high for an accr:ptable level of trarrsnrissior]. A genr,ral cliscussion on the cha^ngcs in the epiderniological situation bcforc and. after the OCF started followed. r"ricte1i-zt-49ru* VIf. I'4r Renz: A ma Lical model of ts A mathernatical moclel of onchocerciasis d.oveloped. by Progessor Dietz of ftrbingen University was described. fhe mociel bries to dcscribe ntcrofilaria densi-tics, pr"evalencc of eye Lesions artd blindness in hum.:rn populatiofl o.nrL bhe avcrage nr.:-urber of infective larvae in bhe vector pop,rl.,tion as a function of a single variable describing vector nran contact. Data fron 5 villages in Cameroon (nenz, /a 8- Anderson, Fuglsang) and 4 villages in llest Africa (nfritippon, fhylfors, I'rost) were used to estim:t, bhe paranetcr vdues of the model. ftre criticel vec bo:-' density for a non zero enclemic level of diseasc cor?responcling to a net reproduction ratc of the filarial parasite of one is c.s'uirnr.ted fron these data. Tlris is an rtEil of 288 flies fr.rr a vector population showing the v'.ctorial capacity obse:rred for lrlest African villa6es and of J20 flies for the Ca.meroon vill,:6es. D;mami c pro jections of voctor cclntrol ef.L'ects by this nrodel indicatc that even 20 ycers of perfecb vector control would leave a s'.:-f.iicient rosidual parasite load for a neu approach to the original equilibriu.n after the vector deasity is re-established. ltris is ctue to the nodells asswrption of itrr oq)onential surrival fr:nction of the worm. VIII. Dr. Cooter: F1iehl-pgl{o;ggg:rce._g-lg{i.eg_q. l. qannostuo s. 1_. in I9Bl Ehe ain of this study ',ras to see if one could mecsure the different flight abilities of members of tLre comple:c. 'Ihe flight performance of thrce cyto specieg were t:sted r:nder controlled laboratory conditions. 'ltre flies wcre divided into three groupo: sucrose fecl; water-only-fed ( of both se'xes from laboratory emerged stock; and blood-fed, wild caught females. IIo real difference between ariy of the ttroups or cyto species was obse::red. fn general, sucrose-fed flies flew for the longest time and longest distances, although S. sirbanum nade fai rly long fli6hts when fed water onlyr males made proilr:essive.ly longer flights with a6e, but females could ncke long flights on any d.ay (be.tween 2 ancl 11). the record.ed maximr:rn f1igh t dr-rrations arrd distances were S. squqBosl.l4 - 262 minutes (.rf") 5.29 \<tt (female); -Sr_xo3_bllt!*lge,4"JipAu1_i - 282 ninutes (mafe), 6.15 hn (rnale): !.:--psAQp4gg - 185 ninuLes (fenafe), 5.27 lm (female). All th,,.se were sucrose-fed f1ies. This year the total flightcapacity r,riII be investigateC by stintrlating the flies to exhaustion. i.:lit,ht under dif|crent htrmidities will be ocamined o.nC the Iipi,l conteni: of the fl.{.es will be measured. "/9 -9- Fron initial stuclies there is already evidence that thc tipid content i.s 1or.r.-:r in ncwly emerged flies. The dif.ficulties in extrapolating laboratory infomation to the ficld situa.tion were discusse.l. IX. Mr Simnons ,and Dr. Raybould: lnlgo--v-e.nlctntS-U1-colq1+g1g..S-.-339!99 s. f . i.D -.t1{te.f.q-tr..qg{-r$95:p-q@. l.Ir Sirunons described the rearing apparatus and his results obtained in 1!81 in rearing the 'rBeffa' forre (laUoratory colonization of uhe hrrmarroncIrocerciasisvectors@comp1ex(oiptera:sfumr1iidae) usin;: an encLosed, gravity trough rearing system. Journal of ltedical Entomolory VoI. 19 No. 2 tI? - L26 I9B2). 'Ihe four egg batches sent in 1981 and 1982 were rusuccessfully rcored.. Dr. llaybould described his studies on the effect of iit-breeding and concluded tha.t the pec..rliar sex ratios obtained by Sirnnons and Edmon were not a result of in-breeding. Althou6h the rBeffar form mates very readily iL is verX'difi.'icu1t to blood feed and this is the roain problem ln establishing a colony. fnvestigations of different mating techniques and di-tferent ovipositing methods were investigated at Akosombo. A saooeeaful crosir:3 hetueen --S,-gq19-eg4 fenrales fron Boti faIls and Beffa males from Tetetou rvas carriecl. out. A si.ngle egg batch tratched. and l.rrvae and aduLts were obtained. fhe larrrae exantned cytologicall5t were typical o.t hybrids between tuo spccies althou,$r the ad,.rlt males all posessed the Beffa forrn scutal pattern. Dr. P.ayborrld suggested that it wo,:ld bc interestin,'5- for some one 'bo carzy on with this work to i.nvestigate the relationship s betwoen the memb+rs of the S. damnosum complex. l-. lir. I(urtak: i.ionitorinl: of susceBtibiliff and the acLUa-I Sitt4elfo4 of resistance Dr. Kr:rtak explained that i t j.s difiicrrlt to detect resistance until it is rell established as often the first sign is a treatment faiL.re. ,. ho r!Co In April, 1980 resistance to temephos was confirmed at Chutes Gauthier on the Banda.ma river. By the qdddle of 19BI resistance was fairly wide sprcad. in Ivory Coast, but confined. to ttre -9. qoubrensc/sarrct di gxoupo Chlorphoxim was the only insecticide v&ich had gone through the entire testing procedure and could be used instead of Abate. In 0ctoberr 1981 :-.osistance to chlorphoxim was cletected at Chutes Ciauthier and the spread ol"' resistance follovred a sirailar patte::n to that of temephos. B. t. Ii 14 is bein..; used in resistant areas, but bhe problems of application a.nd for:rr.:lation mean that it is very difficult to use B. t. H-I4 during tJee reainy sea.son. Dr. I(urtak briefly described the techniques used to study insecticide \ susceptibility. Stud.ies on l-,he teroephos resistant soublg&F-eA!$cUlpq&1:t group have shown cross-resistance to a wide range of other organophosphates includinal pirinifos-methyl and chlorpyrifos-methyl which had shown promise as replacement insecticides. Ihe effect of s;mergists was examined and althou6;h synergism can tre demonstrated it is not a practic:.I alternative. Since resistartce appeared, -L_S_p_qbJgghes not been recorded from arry sites that it had not been founC at before, antd there is no evidence of reduced susoeptibility to temeplio s in S. da^rrtosum or sj.rbanlam. 'ihere is a discordence at some sites bebween the hi6h nurnbers of lartrae present and the low number of biting flies. It appears tha'b in some areas the resistant ij. soubrense is hir$fly zoophilic and does not pose an e1:ideroiological problem. At Gauthier the resistance to Abate and chlorphoxim has remai.ned fixed, indicating a trigh degree of isoLation of the populatio:r. l\t more peripheral sites there has bcen a reduction of chlorphoxim resistance since treatment stopped. At the Comoe the chlorphoxim curve has shifted back towards a nomal cullve, and at Janangoro bhe cunre now falls weII within the range of nornal susceptibility. Dr K-'.Lrbak described the attenp t to cross resistant S. ea.Ectipaqli. from the i,Iono river. Only J lanrae were successfully reared. (Lantae reared. from individual femaLes o.f resistant gq4gtipgqli/soqUrensg and .. /LL -11 - tested for susceptibilit',r shor+ed the same profile as a total population, individuals having a lot of variation in resr)onse to the insecticid.e). XI. Dr. llered.ith: Este-g1ge-_s-tLgd.i.e-s -o:r tkte S.d.amrosr:n conpleI, particularly g ;gegij?t-qn! .9g5!_sSe99g[ib,!9- popul--qtio4. .Dr. I{eredith explained the backgror.:nc to the work and that studies on nosquitoes arrd organophosphate resistance have sitown a sorrelation betrreen resist,?.nce and esterase erlzryrnes. liogqu-ito work has been camied. out rnainlli on laboiatory population 6.ncl extrapolating the r+qrk to the field i.s tenousr md to ttre S. dan:nqsllp complex even more so. ftrere are tr.ro possibilitiee (a) a difference in ban<iing pattern and. (U) " d.ifference in enzlnne aebivity. Stud.ies have sho',rn that rcsistant flies f'rom Ivory Coast -have a consistantLy hi..rher level of esterase activity than susceptible flies of the sarne species, but even susceptible populations shor* a broad rarrge of enzlme activity levels. Difl'erences in banding patterns were also observed. betvraen the Ivory Coast and Togo Sol{bfe_r}S-e--Aag[i!94} but this is most tikely to be a vcctorial polSrmozphism. Althoui.;h the activities differences exist, the;,r are not as clear cut.as the results from nosquito rrork. *r1. -Ds.- J@*E:.-Re"g!--on ggs3[-t-s-g{ .s-r-g+1r,:g--Laqligdg-i-qrsolE&. Dr. Ja^mnback stressed ho,"r tiee neerl for al teznative insecticid.es had boen well established. ancl how i rporta^nt for tl:e success of OCP it is. The laboratory has heen set up to test new insecticides which have been selected b5r Geneva on the basis of being 1:ood mosquito lanricides. He deseribed the tlro methods of testing, first in closed system troughs in the laboratory- and then in open system troug,lis irr the fierd. Temephos is used as the starrdard. Carbenatese pyrethroids, organophosphates and non- conventional insecticides are being Bcreened, and at Leas'b one insecticide from each sroup shows promise and ar'r-. available for fierd testin.;. ../L2 a t_L1 _ Eqqq4{ey--?_B^-,!t4tqt-:- Dr.. Ja.rnriback atd l4r Renaud demorrstrated the testing of azamethiphos in the close-system trou.ths in the l.rboratory. llr 0c::an then explainecl the open-system troughs (m-ini-gutters) out in th,' ,ield at landa Pozartda. Dr. Grunewald thaLiked the spc!{(eTs and pa.rticipants arrd the meeting 'Le:minated at 10. ]0 a,ra. s!.v-Dl ,.. I O LIS'I 0F I-I3.TICII'AI,TTS A. Akpoboua, VCU (tarale) T. Barro YCU (tam" Kara) R. Cooter, COFR Lond.on (AtosomUo) M. Denke, fnstitute of Fublic i{eaIth, Lome. C. Gboho, VCU (Oua4adougou) J. Gnrrewalde VCU (Oua3ad.orr61ou) H. Ja.rsrback, VCU (La^ma-Iiara) D. Krrtak, VCU (Oua6aaougou) S. lleredith, VCU (Ouagadougou) M. Ocranr VCU (ta^ura-I(ara) M. 0mar, Ha.urbulg (La.rna-I(aza) J. 0u6draogo, VCU (earakou) J. Raybould, VCU (At<osonrUo) F. Renaud., VCU (tama-tcara) A. Renzr tropical iled.icine Tibingen (ta.ura-fara) K. Simons, Mass. University, Anherst (USl)(,ttcosomUo) C. Adjorrnou, VCU (Lama-Kara) Ya.meogo, (Larna-Kara) Q. Zerbo, VCU (Ouagadougou cc: Prog:ramme Dircctor Dr. t'hilipponr Chief, VCU EIF. l4r. J.D. illarr, OCP Liaisor:, iIQ.