A report on an extended treatment cycle for OCP the 9-12 day treatment cycle in the Upper Sassandra and Sankarani basins of South-Eastern Guinea: January-March 1986

I .t J: f; f it t p I A REPORT ON AN EXTENDED TREATI{ENT CYCLE FOR OCP The ?-12 day treatment cycle in Easins of South-Eastern 6uinea: the Upper Sagsandra and Sankar-ani January-l{arch 1986. A Report to: by: Chief VCU hlorld Health Organisation Onchocerciasis Control Programme B.P. 549 Ouagadougou I'leyer l'lSc Pleszak I'lSc I'li erzejewski PhD Bobo-Di oul asso['tarch 1986 R F K I SUI',ll',lARY An alternating 9-l? day treatment cycle was undertakerr sassanrdra and sankarani basins of south-eastern Guinea suitability for OtrP operational use. in to the upper assess its Between 4th January (week 1) and 27th February (week 9) a249.65 flight hours werE! used in prospecting and treating[ii I ornetres of ri ver. total of over 5335 Al I en;tomological r hydrological , and operational parameters werGr caref lrl I y moni tored. The control cycle appeared to work succegsfully, failing slightly onlyin week I in the Sankarani basin. Complete ccntrol was hindere,d by reduced susceptibility to Temephos in both basi"ns, making conclusionsdifficult to draw. Control operations wers! suspended prematurely and should have been allowed to continue for at leagt orre rnore 12 day cycle, in order to obtain comprehensive results regarding the limiting conditions of such an Extended cycle. It is recommended that further work should be undertaken without the constr,aints of operatiorral treatment requirements. INTRODI.JtrTION Currentfy trCP uses a 7 day treatment strategy to control the larval stage of Q+ damEosuE. The basis of this stategy lras been determinedfrom the lenqth of larval life which is known to vary throughout theyBarr aDd depend on rlany external factors such as water ternperature, water 'condi ti on and f ood avai I abi I i ty. HowevEr, during the cool pLariod of the year, and repopulation of breeding sites following The 7 dAX cycle has been adopted sinceit wels shtrrter than the minimum larval operationally efficient. The continuedproved it to be acceptable. Thus it seemed that there is treatment cycle with a lengthday cycle. the start of the Programme as development period, and was success. o{ the Frogram has breeding is often poor treatment slow. At such t i rnes larval developmunt may be retarded. Although little scientific work has been done on the length of l;rrva}lifer studie's by Agoua (1983) showed that the larval development time can be as long as 14 da1.s in areas of south-eastern Guinea. a potential for an altered between the present 7 day or extended cycle and a 74 An e,xt,ended treatment cycle woulcl result in a majorflight hours and insecticide costs. Additionally itburderq on the environment, reduce the pressure for resistance and simpli'fy logistic stock control and operational staff. I ITherefrore it was decided to undertake a feasibility reduction in would reduce the the developnent of workloads for study to as-sess the poLential of a 9-12 day extended treatment cycle for OCP operat-ional user and to try and determine the extei-nal factors whichinfluence the developrnent of larval life under natural conditions.Together with the experimental objectives the study would be responsible for larvicidal treatment of a large area. An alternating 9-12 day cycle was chosen because, taking into account a -3 day treatrnent period, it could still be fitted in w'i.th the OCP 7day cycle. while enabling weekends and l'londays to be kept free. AREA As the experiment had to be undertaken away {rom existing ocptreatments, the untreated Upper Sassandra and Sankarani basins of st:uth-eastern Guinea each having high populations ofE.qlaoagEum e{ere chosen in which to conduct the experiment. The advantaEe,of these two areas is that they offered two completeisolated river basins having different meteorologyr topography, andhydrologYr but resting adjacent to treated and untreated river systemsthat could act as control=. Hence, a comparative study of the twodifferent areas could be carried out with little difficulty. The experimrntal zone in south-eastern 6uinea candivided into 2 main arEas by their location. be conveniently 1) The Upper Sassandra basin, the more southerly and mountainou; containing the cooler easterly +lowing River Sassandra maintributaries (Boa, Bagbe, Bafing and their tributaries). 2, The Sankarani basin containing the sligtitly warrner northerlyflowin,l tributaries that cornbine to form the River Sankarani, atriputary crf the Niger. The most important of these are theSankarani , Di on, Gbarihal :r,, and Kourai . i The RiveF Hilo was used as the stretchedttir, Ivory Coast) of the weekly treated controls. untreated control and the the Boa, Bagbe, and Bafing I ower served as The area is described in detail by hlalsh i1?84) for the upperSassandra basin and by Baher (1944) {or the Sankarani basin area. T'IETHODOLO6Y Odienne was used as the operational base because of the targe size ofthe experimental area. Two helicopters Herl: reserved lar the experi- mentr one treatment machine and one prospection machine. It was decided at the start that two pilots should tl-y and stay withthe experiment for the first four treatment./prospection cycles in order to work with experirnental team until everyone was well acquainted with the area and the experimental procedures. In practice an experienced treatment pilot stayed with the {-rial for the duration o'f the trial whereas prospection pilots Here exchanged more or legs crn a weellly basis. ? Based on a three da*r. treatment circuit a chosen. This model leaves free weekends,for briefings and still fits in with the aerial operations. ?/LZ day treaL.ment cycle Has and allows Hondays to be used OtrP routine 7 day interval of The basis c:f the Hon hleek I week 2 hJeek 3 hleek 4 Week 5 l.leek 6 cycle is shown t{ed. Thu. xx x xx x in the following Fri. Sat. Sun tabl e Interval t2I =omE!prospecti on 9-12 day Tues. x Ix x x x x As can be seen the start of operations alternates between Tuesday andThursday with every third weelr being free of activities. This r esultsin B treatrnents clver a period of 12 weeks which gives a 33 per cent reduction in all activities and costs. For the purpose of this experiment the treatment of the experimental area actually required two days, one day for each river basin. In the experiment, each treatment was covGrred by a pre and a posttreatment prospection, one day before and one day after treatmeni.Frovision was allowed to retreat and reprospect if onsl or rnore gites along a stretch o{ river weiialeft with larvae following treatment, 'i-he start of the experinrent had initialy been planned tor thebeginning of Decernber 19El5. However it was delayed until the 4 Januaryl986 due to unforseen circumsf-antres. During the pre-treatmentprospection of the first cycle the Guinean borders were closecl and allflight Bctivities trancelled, thus the start of the experime,rt had tobe postpened until one we'ek later. FurthermorE!, for the rest of the month o{ January a Guinean national had to accompany the helicopter at all time=. This complicated and delayed work as he had to be collected{rom and"treturrned to Kankan during each cycle. several e.quipment problems and hericopter trreakdjwns caused serious derays which interrupted the planned treatment and schedul e. For the experirnent, a number of fuel and insecticide caches set up t:r restoclred. Tabre 1 shows the caches included in ment and tl-.=ir weekly usage during the experimr.-ntal period. had to be the experi- In each river a nut.tber of control gites were selected (Figs Za-c) supports werE marked. As the experiment continued, gites withoutbreeding were dropped and new gites selected. If a gite was foundpositive after treatment a more thorough prospection o{ t-he river stretch or the whole river was conducted. In this Hay prospection continuously adjusted to the existing entomological situation. and Has Dn rivers where either no water gauge existed or gauges had not been calibrated river discharge rneasurements werE! carried out before eachtreatment. Wherever possible measurements were conducted as close aspossible to the non-calibrated water gauges, in order to begin the cnnstruction of a calibration curve for future uE;e. The first measurements were done with a float and stop watch. Thereafter an Ott Hicro-moulinex current meter was used. l.lean ities were measured directly using the standard approximation Teknar was applied by the boom und nozzle spray system usingtwo BXSO wl.irljet nozzles with an applic;-r'tion rate of o.6 or two) 1.2 I /s. vel oc- that l'1ean Velocity = Velocity O 4O'/. of the River Depth. The discharge was calculated atrross the river as the sum of the velocities at intervals t v (No. of Revolutions/seconds) x k x Nidth x De6th Di scharge = Surn of Vt( - Propeller Constant) Together with each discharge ,nea=urement and/or prospection a number of river par-ameters were also recorded. These included water temperature (actual at the time of visit ar,d !"taxima and l"linima at sornEr sites). To mEasure these, minimumy'rnaximum thermometers hrere! anchoredperrnanently at gite B on the Dion, gite 5 on the Sankaranin gite 19 onthe Bagbe' and gite 14 on the Bafing. FH, conductivity, and Turl,id-ity were also measured. Larvae wElre collected continuously thror-rghout the experimental area and sent to the Western Extension laboratory atKoulouha for cytotaxonomic identification. The treatment circuit lr,as arranged so as to treat the Sankarani basinduring the first day of treatment and the Sassandra basin during the second. Occasionally, because of time constraints, the upper Gbanhala and Gbaroni rivers Here included in the second treatment day. Temephos 20 EC (Abate) was initiatly used as the only larvicide, at a rate of O. 1 rng ai/L./lO min. (O.31 product/cu m/s) for rivers having adischarge.less than 1O cu m/s and O.O67mg ai./l/l0min. (O.21 product lcu m/s) for rivers having a discharge, greater theln 1O cu m/s. However as nurnerouS treatment failures occured from the first treatment and complete control could not be achieved even after re-treatment (evenin multiple di:ses) rivers Eibanhala, Sankarani, and Kourai h,erE! switch- ed to TeJpar (E.t) treatments from week 6. The appliuation rate ofprodurct(diruted with 2o7, water) was 1.6mg product./l/to min. Aerial treatment and retreatment of whole ri\rers'*"= carried out by a he1 i copter f i tted wi th the newl y devel oped appl i cati on system. T,-eat- ment with this system had been chosen since ground tests had revealedthat it lras more accurate and reliable than the old systems. For rapid aPPlication of Abate a large Cribble nozzle the Solid StreaimVeejet (H L/2 U OO2OO) rrith stabi I izor jet ( no. 11S7O t/2 x t/?thaving an output of O.B L/s hau been installn-rd. For small applicat-iens the small dribble system with an output of O.3 L/s rcas used. Depending on the size of the river either nozzle was a complete band of insecticide across the river. selected to apply onE or-(for the The experirnent enabled the new system to be fietd-tested {or the fi,:-gt time. Experience strowed it to perform excellently. The re-treatment of knapsack sprayer or single isolated gites was done eitt"rer by Hudson by an Azo compressed air operated sprayer {rom the ground, or from the air. After the occurance of treatment fa:ilures susceptibility tests were conducted by the a series of teams of Dr I aboratory Kurtak. RESULTS / DISCUSSION 1. ENTBHOLOEiICAL RESULTS The Daily Biting Rates are shown in Figures Sthat the DBRs were effectively reduced in allto those of the previous year when there was weekly control. The only capture point that did not exhibit improved DBRs followingthe initiation of the 9-12 day cycle ulas Tere on the Dion (see FigEe) r which registered extremely high DBRs throughout the experimentelperiod. The likely explanation of this result is becausEr some stretches of the Dion downstream of rere were untreated. a-E!- The f igures show river basins; comparable a succesful continuous Larval prospections at the beginning of the experiment revealedthere was heavy breeding in both of the river Basins, with mosting sites having heavy infestations of all stages of larvae. that breed- Although rnost larval stages grere controlled duringtreatfient, several gites continued to be nopulateJ(Refer to Frospection Data Sheets l-14: Figs 6a-n) several possibiIities were consi.dered for the Iack with legephos. the first after treatme,nt. of complete control 1. .Two Abate batches were used in the study, old product in whiteanuiqg, and newly delivered product in red drums. Both had beenlrsed on the sarne basin and a high mortality rate appeared to haveoccrrrred with old product, but less so with new p;-oduct. Thepossitrility that the new product was of reducer! activity wastested. Therefore in week s the rivers Ebanhala, sankarani, andKourai hrere r-etreated, harf sf each river with the nsrw product and half witri the old product (See fig.3b). Hosrever, these resultsshowed that there was nr: difference between the two products. (see merno of 30. 1.El6). 2- Thertg may have been reduced susceptibility to Temephos atthe standard operational dose (O. 1 mO ai/1./1O min). Theref ore, aseries of gites were treated at the experimental rates of o.l;o'2' o.4 and o.6 mg ai./l/lO min. on 24 January. However, the prospectinext day revealed that cornplete larval control had again not beenachieved, even at sixfold the normal dose (see ,"ro o+ SO. l.E6). 3. As there appeared to be resistance to Temephcs a laborat-ory susceptibility test was carried out at Bdienne. Although thedefinitive report by Dr Kurtak has not yet been issued, thereappeared to have been a reduced susceptibility but still withinnormal Temephos limits. However; ;rS a precaution the whole sf theSankarani basin (except the Dion) was changed over to B.t. treat- ments. Following the change to B.t. on the ulation was reduced drastically. Sankarani basin the larval pop- Post treatment prospections in week 7 revealed a reduced mortality inthe lower Bagbe on the Sassandra basin. A subsequent susceptibilitytest did not give any conclusive results as to whether thei larvalpopulation showed a reduced sensitivity to Temephos. I Durin{ week g. pre-treatment prospection on the Sankarani river revealed the presence of a small number of pupae. This was the firstindication, in an arEla where regular complete, Iarval control was takingplace; that a complete larval rtevelopment cycle had occured. From week 9 aIl treatments were suspended by VCU. ?. AERIAL trPERATIONS During the course of the were used in prospecting experirnent a total of 249.45 +light hours and treating over 5335 kms. of rive,-. Sankarani Sassandra total River Length FIight. Hours: ( km) Prospecti on Treatment Fuel llsed (l) Insecti ci dr: Used ( I ) Abate Teknar For a detailed analysis nf(Figs. Saik) and the aerial The following period of the the treatments see the weekly treatment operation data sheets (Figs.4a-b). alae r) .t -)-, 103. Os 47.3 302.1 633.6 22o0 59. A5 39.45 543.3 o 5335 162.90 86.73 L3292 847 .4 633.6 ,naPs OnIy thp river Seremou (a' tributary of the Dion) s.ras withdrawnthe treptrnent cycle during the course of the experimentr as it ceased to flow. {rom had aerial operation problrms were9-l? day experiment. encguntereid during the Hel i copter Frobl em Delay (hrs)5:: {I 3 I 2SZU SZU SZU szv SZU TZS Radio failure Transf er pulr'lp f ailure Low power Change engine Change damper Transport of nelt engine for SZU Reduced engine power Change darnper 2 4 4 6 7 24 24 2 o No time was lost due to meteorologucal condtions evendays the visibility was very poor due to Harmattan and sorne Ecattered light rain occured. though on BomE! occasi on.rl I y 7 3. HYDROLOCItrAL RESULTS A co.npl ete record hras mai ntai ne,d of al I the hydrol ogi calpararneters that Here expected to influence the development oflarval E.dgooosgO . Hence, weekly rerords HerG! taken of pHr maximumand minimum c,rater temperatures, conductivity, turbidity and dischargerate. Figure 7 sel ected shows the change of some of these factors eachgite for each river.The following obgervations week on acan be made. fH: This remained constant throughout the whole experimentalperiod in the range 7.o-7.2 tor the sartrarani basin and 7. L-7.4for the upper Sassandra basin. Llater temperature! This increased fronrJanuary to a maximum of SOoc in J,larch.basin tended to be l- 2 oc warmer than i, 3. Conductivity: This increased infalling river levels. both river basins in relation to Turbidity: The t-urbidity reduced in both river basins over theperiodr especially where the river ran slowly over sandy beds. E .J Di scharge: AI I ri ver I evel s and hence di scharoes dropped. trlherecal i brati ons wFe undertaken i n prox i rni ty to ex i sti ng uncal .-ibrated water gauges (Diamaradou, Kodiana, sanankorJ, andEbel eba) a prel iminai'-y discharge curve was plotted (Figs. Ba-s:) . colJCLUSloNsr DrscussroNS and REC0HI'TENDATIoNS The e>l per i rn ,)everywnere, However itthe expenim The exptsriment appeared to breakdown on the Sankarani basin by week gfollowing a 12 day cycle when a few pupae wElre found on 5,ome gites onthe Sankarani river. The nupae founct on the Bagbe river during thatcycle probably developed frnm the larvae which had surviverj theprevious cycle's treatment. rt is there{ore not known if theyrepresent a trreakdown in the cycle. any firm conclusionsbasins could be drawn.further 12 day cycle I a 4 o a minimum of L7 c inGienerally the Sankarani the Sassandra basin. ent worked well with good larval control being achieveddespite problerns with resistance in both river basins.is felt that rnore information would have been obtained i+ent had started 4-6 weeks earlier. Unfortunately the experiment was stopped beforereqardihg larval development periods in the twoIt is considered that a minimum of at least oneshould have been conducted. As the resistance to Temephos was suspected intended to overshadow the experimental results"ment and work directed to this problem took upof time and effort. Furtherrnore, it interferedpretation of results. rt is sruggested that further work shourd be carried outthese findingsr and concentrate on the criticar periodi-e- just the' rz day periods. rn addition, operationarshould not be arlowed to interfere with the experiment. I I both river basins itReprospection, retreat- a considerable amount with the clear inter- to confirm of the cycle constrai nts q Further work should therefore be conducted using only the 12 day treatment intervals. It should be undertaken on a srnaller scale using a smaller nurnber of gites whiclr could be monitored regularly during the larval development period. Treatrnent could be done manually. Such arl approach would reduce costs and adopt a more scientific approach. An experiment could include di{ferent rivers, havinq dil4er- ent experirnental conditions and being in an untreated al-ea. Untreated gites ehoLrld be in close proximity as the object would be to evaltrater a treatrnent period and not the control of an area. Re-invading flies repopulating the gite would be considered an experirnental pre- requisite and not an indication of experimental failurE!. .,t ,t 3 "lr, t^ o -? q d $u ll ll d E x ( .J, c0 Ro-coeLt a7 goBo NoT tNLLuod,/) ( FtG,t) P'. P.oe pc.Iiort T-- i7cai,''s6Y WreruY UsE,loe Pen Clcne (r-'z aj c'pet'1*g"v) 9 Tsl- 2 o a 5q r60 lss -Lo__ !3s 1@_ 1'l_o__ 9o Wsrr I 2 5 I S b 1 ts O DIENN E F'ugu Auatc BK, P :I 780 '7 00 rsf 7 L+3 l+10 - +io- -loo 930 eq't 2e_9 300 252 too tog 9o lo9 GaELEBA Fureu i'* - --_--_r --Abole Bt z+o 1qo _ t o3{ 22o t+l o___- rt8 {5 11{ 7'1o .3q6- '38., 'L*{ -16i Z-t tP DAr.^Ap.o Fr.rU u Auate Bt lPlr ?80 iso 5o lb0 tL0 lEo I 2_o -zi_ _- Ito L{_-5f__ NlA1v10T0u FuEu ?, 1' b.a e P,,I 180 lgo EqrraIo BrYrrn itlIT[:ue r Abat c P"L go 2oo to( I - *- --- Xoot33 -_L7.___ 9o :s( BauAu R (5obo./o*",,) l=,.8 r I! l,Le i P T A[.,o i. BT +S( -b.11 _2Lo 2+0t{r 2oo I0( 3'l s 5o 30r tr3o 1o -lottBr) F r)F_L r PI- Abaie l.L Fuau Abal e P,t P I Lto( t':io <( !1.) 100 2g_o- qo 3rftco il0 8t niltnvrrtn loo I Kft{Ka, I [--ueu ipT v bi\l t e ,20 I 5 I 2*15 An:t FrtLL PT e bt I it.O tlo !_?? t1g 2oo 3-? O zso j+s tto /ouu Aun FuEu -P T _AGit-- t-. I I I tq2 g3 BoottDtfr L t Fueu PT t1t t7g r3't Irro Auote Bt Maoiaru I Fucu ? I ,13_ iq( ss Ab"t-e- Bt :_. -lo'ifr t-s Af,ale -Bt oo o -o 6q{ <) 2865 ?qe+._ sl52 .tb{ o a o 21_q ato -8r(_L?9 9__o ?IEsrt I€ 3Eq?(iP l.+" FuEu I 020 -o "-- t 02A 9oo o 90o 3l bo t1t91 15r q5r o 2.s-st- r 41?. r.-+l(.. t bvt r srf o 3,,9o +o3? l5 l5 2AoS ! I i I tgo (-, +oJr i I "'1 ,$ {.}- o Locolion of Confol Grtas For )'ll dog c.yp.r,,nco+ , l+ 0oN tl + o oC\ tl rr,7Io Y Jo(, to v + Loe,o OA a E + 9t, Brr lrl B w Ftct.za B^r,t GITE N3 LOCATIOiJ OF COIITII.OL GiTIS ITOR 9 - 12 DAY EXPETTII.II]]17 RI\NXT CO-ORDI]IAIES 1 2 ) A .t 5 6 7 (J c) 10 11 12 71 t4 14n t5 16 t7 uB 1B 19 20 20B 2t 22 )7 .AL.t 25 o< 27 2B 2g 1o 3t )z \g 3.t 35 3b Gbanhala Gboroni Gba.nhala S anllarani Koural Dion 080810 oeo955 0810 50 081150 080800 082210 o82655 08r940 085100 084000 oB46io o751io 075t4o o75840 0802 50 081ir0 08100 5 0812r_5 080810 092120 N 091720 N 091000 N o9t155 rr 095740 N 095945 N 09i540 N 091640 r{ 094870 Ir 0912 50 ri 095440 t't 084710 Ir 080120 N 080120 1{ 080220 i,l 0B01J0 r,r 080420 N 082840 rr 0 e2940 Ir ll I.,IAP Damaro ll n BeyJ-a Touba il Touba ll Xeyla ll il ll It ll il n Damaro Touba Damaro Damaro lou!2q ll ll ll tl lI !I !I 1{ r.t l,J }I U }I U 1,I u lil I,I 1{ 1,r l.I 1{ 1,I It n il ll ll ll ll il It il ,f 1l Boa Bafin5 ll ll BoSho Gouan 13a;;be BeyLa/Touba J3ey1a Beyla/Toubail ll il 3oa It Gbc (Basbe) It 075700 !r 08J000 N oT1tio v 0c4610 N 0801ro tr 0845i0 1{ 080i45 lf 08l2l0 N 081145 rr 084100 r( osi5io vr os,4ro N 0821_10 1.r 0sl2o5 N 085900 lf 0s5800 N 08j520 1r os511o r{ 091500 1,r 094500 1I oB222O tr 091500 II o747t5 w 0B2Bl5 N ogotr+5ql - o138Oo N oB )lzO4 ' on $r3o N O -? +b+ovJ - o8 2g+o tl O-7++f,$o w OSZ(.2 30 r{ o-l+3goi^J .- Ogl33o r.t o?+7OOt^r - ogztqrN O'l qf,f0t^t - OgZSlO r.l D j ilenba nasbe iiil o Suess ou ITil o Kou::aI Bagbe Gbanhalq Dio o Bq.r b i\) t, tl rl It ttc{ LB - ll ll