Screening for the presence of microfillariae of dipetalonema streptocerca during onchocerciasis surveys in Ghana

+. -" trtt.\ J t'qd Lr lYOP,f-rD IIIJALTH ORGAI{IZ/IIION OI'IGIOCEBCIASIS COI\IT}?OI PNOGTN|]fl'IIE IN TEE VOIIA RIVI]B BAS]]{ AB]1\ Epid eroiological Evaluat ion Un'lt Iechnical Document ocP/EPIni.15 'F [J. Kc BRTNKIIA}TN SCHEENDfG IOR fI{E ?RES{SCE Otr'1"IICROFIL}'RIAE OF DURTNG ONCHOCERCIASIS SJR\THTS IN GHAI{A Ouagad.ougou, SePtembeY 1976 Dr, U. K. Brinlarann, Parasitologistr MtO,/OCt B.P. 54g, Ouag'd,ougo'. Upper-Vo1ta, ]i[est Africa \t) A scBEI$rrNGF13B-!14--&"Uffirigl*cq-Igqil-gf Ery ffi-wKrlr-6tmlri Introd.uction l,licrofilaria,e of-D._Etreptocerca were first d.escrj-bed in Ghanalans ar:'l' prevalence rates up to {Jib bave E-ffieportecl (ivfifl,rilP., 1975). Ilor,vever the 5co- lraphical distribution in Gha,a is not lvelr lmov,r:o. During the collectlon of baseh:re data for the Onchocerciasis Controlproject in the Volta }?iver Basin ,itur, i'b v'Ias therefore necessary to surve)' for thepresenceofthisspecj-esarrd.distingu:ishitfromn1crofi1ariaeof.oW vo1'nrl-lrs, fhe standarri. technique used to exarnine skln snj'ps d'oes not a'Ilovr the d.iffereirtiation. ir modifi-ed methorl h":Ld. to be develoBed to sereen at least a part of the population included. in the evaluations for the infection with D. strept-o- sg. Llaterials and l'[ethod.s To di-fferentiate the ur:icrofilariae of nr-ilt-reptorgqge ar:d o'-v9$ it is necessary to obtain stained specimen' In Tili (Rawlar District, Upper ilegion) blood a^nd skin ju-lces extrrli:rg from the wor.mds vrlrere the sicir: snips t od. uuup taken, 'nere collocted on 'nlcroscOpiC slides. After dryi:cs they vere stained. in Giemsa solution anc. exa'ra:j-ned' rmder the microscope at x50 magnificatj-on. In Danugu (sawtnr District, upper Reeion) ard. jrl Pasinkpe (cartuaga DlstrilJr liorthe-# i"efr"l in a part of the =sample fire stin was i-ncj-sed four ti-mes vrith the bIad.e of a vaccination stylus. ,Ihe incislong were usually about B m long and- ! nrm a,paIt. qr means of foreefll pinciring blood. aJld lynph vfas pressed. on micz\cs- copi-c slidus. The speclmen vrere again stained in Giemsa solution and exa'rrined r.urder the microscope" For another part of thc sanple in Danugu and PasirrJrpe as well as in all other .,,iir"e*" (""i-i"ure t ) sciuigLln's et ai. (lgla) tecrrnique_','ras used. skirr srrips taken from the rig]rt aJ1d left iliac crests by means of lYa1ser type corneal punch were subnerged in we}Is of rrlcrotitre plates in noznal saline for at least three hoqrs before a d.:rop of fo:oaaIln vras ad.ded. \'^/ith the aid of rwod'om nuuber tables a sample was picked. from the population in each rrillage' The fluid in the yrelIs thus iclentified rvas then presoed through r:allIipore filtres- (7fpo," lize] that'were subsequentry d'rled', stained' in hot Llayssts heanalum' cleared and exa- mined. r.rrr1 er the n:iczoscoPer As no reference specimen of nlcrofilariae of l" s=tr?etggglE? yer:e aTllable the microscopists were trainecl on lllustrations in iYItIJ,TilRrs (1975) book ard Buckrs (','ltto, 1974) monograpl4r on onchocerclasis' Resul-ts In fourteen clusters of ldorbhcrn Ghana speci-nen of 816 persons were exan:lncd' for the presence of microfilariac od D. s:-Ure-uLqcgEg', elsygg 1 .shovrs thelr geogr"aphical location. They represented. between l.TiL anfi' 66fr' of all persons seen in villa*es and e .6/,'rt ti."" rir6rc-:l"tients inclucled i:r the basic erialuation i:: Ghama. In rnore than a thid of aI] clusters i:r ffirana parts of the oor)uLation have been e:ra.nined for mictof,ilariae of D. sLregLqgerca. The p'u'oi"it"e of oncho- cercj-asisinthe14c1uste"",*,g"atro,nT.ffi.i]5-vliththenrajorityabove 6q'. i. IIa none of the s'pecimen Table 1 summarizes the Discussi-on -2- mj-crcfj-lariao of P. strept_ocelca r,vere identified. results. D. streptocerca'.rsua}\r occrrs in rainforest areas, i.e. outsj.d.e the area of the Onchocerciasis Control Project, Accoztling to GIBSON & l,TItlFIE (tgZf) itis fairly easy to di-stingr"r:iskr raicrofils.riae of 0. volvr-rlus and D. streptocerca. rt ls not prnbabte that they could have ue*n riiE--laffi-u;. tnffiffi. Hovrever the negative result of the investigation does not entirely nrJ.e out thepossi.bility of D. streptoc.erca being preseni. For a]-]. clusters statisticaliderence ai:d sampling theory i-nrplies that even thor.gh zero prevalence was founl ,the tnre rates could have been as high as 5i( arid missed. by chance. Scarifj.ca-tion nethods that r,nrere used i-n three rrillnges have been shown not to be very sensj-tive 1n the d.etection of ndcrofilariae (nnmrc,imni D76), In futlre eva}ua-tions the search for rricrofilariae of D. stregtocerca r',ril1 therefore have to be continued., especially jJr villages necr the soufnern timtts of the OnchoccrciasisControl Project bordering on forest cor;ntry. Though time end. nar.povrer available will fina1l;; dete:rr-tne the sample size, a rar:d.om sample of about 1u;/, in each chster appears to be su_fficient as D. stle-plppqrca prevalence retes exceedingJii wou:.d. be detected with gl;. profaUffi- a' i- Rcferences BRII I{r[,tNN, U.K. (lSle) i\ eourpa.rison of sktn scarification and. skin biopsies in the diagnosis oi onchocerciasis, 'ilHo/OcP/lfechni-ca1 Docr.ment 76,11 GIBSON, D.Y[o & NEr\FIE, R.C. (lSl>) Ctassificati-on arul diagnosis of onchocercia- sls (unpublistred doclment ) olrciio /vw/lS.z+ MIJILER, R, (lllS) vforms anl dj-scase l,Vi1liam Hej:eeman Medical Books ltd., london, 'l 1O-1 'l 1 . scIIrtrIBER, p., BFiUN-II]NZINGDne R.A, & SOUTHGT\TE, B.A. (gle) A nevr technique for the d.ete:m:ination of microfilarial denslties in onchocerciasis'(r.rnpublished. d.ocument ) mto/oucBo/7 6.1 19 " ifoRID IIEi.lfH ORG/'lTIz.\[1oN (lSl+) lrOnchocercose, symptonatologie, anatomopatho- logie, diagnostic" ed. i\. A. Buclr, Genbve. EXJTIIIINATIONS FOR INFECTI0NS WITH p. STREPT0CERC,X BY ITfLLAGE VILLNGE NAME GE0GRrlPflIC,r,.L COORDI}IATES PERSOIIS EX},}.IINED PREVILENCE ONCHOCERCTASIS fi METHOD USED TO SCREEN FOR D. STREPTOCERCJ. N nI TOT.lL FOR D. STREP. 6 oF Tor.'n TILI 100531 0o34 r 285 ,t: 66.0 81 .1 Scarlfication DANIIGU 10044. 00141 650 37 91 19.7 64.6 ScarificatLon Flltration P].SU.]KPE 100261 10031 360 49 36 4.6 74.2 Scarification Flltration s0G0 go51l 0o58 r 194 N 10.3 75.0 Filtratlon DIru 1 0030 t 0059 ? 1',l5 25.1 75.3 Flltration SAB0N-GIDrl 8c 181 0017' 330 102 30.9 43.5 FiLtratlon SISTTI 90171 001618 291 114 39.2 68.1 Filtration ZAI\IDUA 1001 2l 0017t 313 6 1.9 7.5 FiLtratiou TI'MBO 1 00c4 I co 1g rE 423 1 1.7 36.3 FiLtration YAPiJA 9oo4 I 0011 I 191 10 5.2 D.',] tr'lltration B,}I,E 9006 t P36l 259 15 5.8 66.t Flltration BU/rNFO go56r P32t 240 17 7.1 70. r Flltration BUI-/LI{A}ILIF'IOM Bo16l F16l 168 11 6.s 60.7 Filtration BAWKU-EO SPITJTL 110031 0015 I 69 6g 100.0 1 8.9 Filtration 3948 816 N.7 t* ! I