Vector control unit report of activities for the month of the June 1976

'ÿrr t *^\ /-f-S**+.(,I i*r,ORGANISIiTION MOIIDIÀIE DE I,A S PROGR/IMME DD IUTIE CONTRE t\ 2l lrellr wq - Basin of the Comoë : Ls last month, the rêsults were exeellent exceptln the region of the laraba Brid.ge (cf .5). I I ONCHOCDRCOSE - Sasin of the B1ack Volta VECTOR CONTROI IINÏT Report of Âctirities for the month of June - 1976 1. Aerial Operations Five cycles of treatment have been made in the ?hase f and II zones(ZZ to 26 for Phase I and 21 to 25 fot phase II). The rainy season was ful1y under vray in both operational ?hases though the rainfall wos general.ly Iight, especially in the Comoë antl Trower Black Volta valleys. Â11 major rivers have now receivecl some treatment though many tributaries renain d.ry, and by the end of the month the Sissili hacl ceaseè to f1ow. Ireatment was unâertaken by thBee heli- copters ancl one fixecl-winged, aeroplane (see nap). Owtng to the fluctuating water leve1s nost of the treatment helt- copters were accompanied by a VCU stâff member and a simultaneous pros-pection and treatment was und.ertaken. However, the efficacy of this tech- nlque 1s doubtfulr in qy opinion, and attenpts were mad.e to stanclard.ize treatments acôord.ing to fixed schedules, which greatly reduced the number of tlrops &ad.e. Thls was generally highly sueeessful on the Comoë, White Yo1ta, Kulpawn antl Red Vo1ta rlvers, In ad.clition to the standard treatment of the control zone five cycles of treatment vrere mad.e on experimental basis in the lower Sandama vaIley below Kossou Dam. Tables la and. 2a of the Aerial Operations report for June show the number of hours flown by each aircraft there bein6 a fifty percent lncrease over last month. The consr.rnption of Âbate is also shown. This ls a great tncrease over last month owing to the nôveuent into ful1 wet seasorr con-ditlons and the experirnental treatments. 2, Evaluation The problems of reinvasion are dealt w:ith in paragraph 1. 2.1 ?hase I - - Basin of the Sanifing : The situation in this difficult border region improved considerably, eight sites show'ing a reduction in fly den- sities, in several cases substantial, aird. onJ.y Kouo showing a clts- appointing increrne to 18 flies per day, ?atous rates vÿere high suggesting reinvasion. - Upper reaches : fhe situation ls quite satisfactory ( î ô -2- - Central reaches : Identical with the upper reaches - Sougouriba-Ba : Sone rrnd.etected local bree«1ing occureci in the flrst v'reek of the nontli but the situation vÿas generally satisfactory, onlyUabere and Batié lont reaching d.ouble figures. It seens certain that sone in::igrant- f lies are regularly reaching tl:is vaIIey. iling lengths show very 1itt1e variation suggesting a discrete singlô source. - lower reaci:es : nunbers renained 1975 levels. there ÿÿas a rise in f1y densities in the Bui area but reasonably satisfactory at less tnan 5û. of the June 2.2 }hase II June was not a particularly wet nonth and. f1y au:abers were generallysatisfactory. rn the ramale Sector f1y d.ensities ôn1y reactred doüb1e figüresat three points centred on Zongoiri rapid.s and the pàrous rate ind.icated. a1oca1 origin. [his upsurge of locaI breeding had been elinlnated by the nonth encl . rn the ouaga'dougou sector the season was not fuily underway, nhiriy-sevendays catching in the I,éo Sub-Sector yieldecl no fl-ies. in the ouàgad.ougoü and.[enlrodogo sub-sectors respectively o:r]y tv,ro and three sites averaged. norethan 1 f1y per day, in all tvrenty-five sites being coveretl. 5. fteinvasion .During the rronth the reinvasion of the Sandana and fleraba (lont Routierarea) vras in full swing with pattern of events renarkably sinilar to that of1975. ïnvestigations showed that at w:ith a fairly high infection ratc.ÿÿas a dearth of sausage stages. Drinstar larwae fron flies caught at ninations so far have proveC to be leraba, alnost all flies were olcl pars i.lost infections were t}:ird stage and there Raybould lvas suceessful in rearing late ïreraba Sridge - all cytotaxononic deter- Itri1e/Sirba, -x Dr Qui1lévére has nade a najor break through in the identification ofthe adult females by cLassical tanoaonic raethodÀ, and ]ris work ha.s in general,been confirrled and elaborated. by Dr Garms. Experimental treatnent of the lotÿer Banclana had a spectacular effect on1ocal fIy nr"mbers. Biting rates of ,'from 5OO to 1OOO per day feI1 witirinthree weeks to less than 10 per rlay. iiovrever, at the iine oi vrriting no effectwas clsceinlble in the nlddlà Bandana and. r,era.ba where inmigration continuesunchecLred. Recent investigations ]:ave inclicated that most of the biting fLiesof the lower Bandama are of the rrBand.anarr cytotype and. this area is clearlynot responsible for the invasion at leraba lriagè. Judging bJ, the spectacularsuccess of the experinental control - loca11y, there cà.,rràt be much 1ocal rcovement of flies and. virtually no movement into the area - at 1east in theeâr1y rains. Tlius prospects for the control of large river forest fo:ms of§.*agtgsum would appear to be excel-Ient, tirough anànalous data from 1,iberiaand G'"rinea would heed to be consiclered, anci further carefully nonitored. erpe-rinents mad'e before concrete reco,,oend.ations could safely be ma6e. * The earrier report of a rrBandaman larrrae progeny of a f1y caught atleraba Brid'ge was the result of a cytotaxonomic nistar<e, a-1- I 4. Preparation of Phase III In the East, the trama Kara Sector became alnost fu1Iy operationald'uring the month. In the I,ama Kara Sub Sector fifteen sites vrere covered. and sirty-seven days catching und,ertaken, seven of the sites averagingover 1OO flies per day. Overall_ parous tate was 7g%. îen sites werè côveredin the Dapaon Sub-Sector, where probably owing to dry conditlons catches were generally 10w. The parous rate overall was 66/r. Twenty-two d.ays catching was und.ertairen in the Natitingou Sub-Sectorin the second half of tire month, the parous rate being aaoui |od". sone -survey n'ork was undertalren in the Kand.i Sub-Seôtor. Entomological woriçhas not yet coonenced. in the Niamey Sub-Sector. [here has been no significant entomological activity in phase III i{est, Conclusions J.F. Vfalsi: Ag. c:hLef /,{cll the pattern of entomologicai events in Phase I and II has been strikingl-ysimilar to 1-975.- Control has, if anything, been slightly better than in tg15.The reinvasion phenonenon has now been ruify authenticaied and. substantialprogress has been mad.e in our understanding of S.d.amnosun dlstribution and.behaviour. A major break through has been àcnieîeffiTËî taxononic separa-tion of female trBand.amartfromrtNile/sirbartrand. furtLer progress is nowpossible in linking cytotaxonomic sturlies with classical taxonomic studies.thanks to Dr J.N. Raybouldts success in rcaring Sinuliun damnosum 1arvae.Results of Dr Bennett's xFS studies ere eagerrÿ avGïlEEt - - The high parous rates found in the üacontrolled phase III East (espe-ciaIly the lama Kara district) ,ty suggest an invasion phenonenon siuilarto that now conYlncingly denonstrated for the leraba lriage by Dr R. Garms. È t; tll ÿr ,Ü rl q .J i ts 1 rt * # : ,R)'r j'l !é't :-1 l: '.t iIl \.. I :t t ,,) .$p il",t { r. I o tJ1 tn t -ÿ"* .J *rd I 3/t {-fi {: 3 r.*-l ffi _:} r irF {Ë Ut ("- f, Ï /ir\L', .+ üN, I I ttt ,t : 'Ja{ ] &{# #d{'i}Ë# æ, $ tÊ # in,, \51 til. I 'l ü #,, t.§; #h# "', ;' t §& i -- i1I t *§& i{rl f I I | "",, t I\ I .d*' # ,\{T t, f*} & fr ,: \ * ft §Bt' # * ,, g& . -*,*bi-ài TJ,TÈ' 'r*'s: lËt olt"/# Iffi # {} t: 't 1. 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