t
RAPID EPIDEN{IOI,OGICAT, N,TAPPING OF ONCIIOC]E,RCIASIS (REN{O) rN r\,{ALAWT'
B.E.B. NWOI(8"
Cortsultant, Natiorral Orrchoccroiasis Corr trcl l,r'r'rgrarnlnc, N igeria School of Biological Sciences, lrno Statc [.lrrivcrsig, P.M.B 2000 Orverri, Nigcria.
P.r\.,J. TAMBALA
Natiorral Coolclirrator, NOCP N4itlarvi
P.O.Box 2273 Blanlyrc, IVlalarvi.
c. \\/ittc I
Courrhy Director, InterrrationaI liyc l;oundatiorr Malau,i ) P.O.Box 2273 Blantyte, I\4alarvi. t
Tlris study reccivcd Iinarrcial sul)l)or1 lkrrn WI-IO Atiican Progranrrrrc ltrr Orrclrocerciasis
Clorrtrol (APOC). OugacloLrgLro IJurliirra Iraso (OU/lCP/CTD/5041AP197104)
{< WHO tetttllot'alY Ath,iscl'ort I([lN'lO attil att{ltor lo rvltt'lttt corresl.tctrtclence should be
addresserl 2-
ARSTRACT
With the sponsorship of WIIO Al-r'ica Prograrrrrne for Orrclrocerciasis Control
(APOC), a nation-wicle Rapid Epiclcrniological Mapping of Orrchoccrciasis (I{EMO) was carlied out befween May arttl .lune I(r, 1997 in Malawi. In this exercise the lcvels of disease endertricity' were evaluatcil bi, Rallrtl Epiderniological Assessrnerrt (REA) - a village diagrostic lnethod based ott cxatnittatiorr oF onchocercal norhrles irr 50 resident ttrales pervillage agecl > 20 years. O[thc total 405 villages selectccl fi'orn tlre thrce Regiotrs in the couttttyfor this exercise, 357 (88 l5'2,) rvcrc actually exarrrirrecl rvhile tlre 48 others
( I 1.85%) were irraccessible at the (irne ol- the study. TIre rcsults slrowecl that
Oltclrocerciasis was ap;larerrtly absent in all the 130 villages exarnirrecl in tlre uortherrr regiott while only l2 (ll.zlnl,) out ol' the 107 exarrrinccl villages were positive for oltcltocercal rrodules in the central Region rnostly on the weslerl llorler with I i N{ozarnbique, alrcl southenr border Ntclreu District as well as tlre east celrh'al lrost of Dedza It District. Endernic otrchocerciasis was rccorclecl in. all tlre l0 soutlrerl Dish'icts wlrere 6l
(50.837") of tlre 120 exarnirted villages were positive for onclrocercal rroclules, especially ott tlte easterrt side of the Mularrje rnountain arrcl Thyolo-Clrikrvawa escatpnrent. On the rvltole, of'the total ,i57 viilages exaruincci rrr lhis study, 73 (20.45%) of tlrenr were carryirrg oncltocercal uodules. These epidcrniological results are rliscusscrl in tlre liglrt of prioritization arrcl successful irnplcrrrerrtatiorr oF Cornruurrity Directed Dish'ibution of lvermectitr (CDTI) control strategy irr N4alar.r,i. 1 _)
INTRODUCTTON
Flulnatt oltcltocerciasis was first forrnally l'eltorted ilr lr4alarvi by Gopsil (1939).
Later', Harvey (1967) tttade artotltet'r'cport. Tlrese earlier stuclies clcsctitrccl cases in'l'fiyolo
Dishict. The first systerrratic atternptto preserrt a nalion-rvicle prcvalelrce arrd geographical clish'ibutiort of oltcltocerciasis in Malawi was carlied out by Bcrr-Sira arrd his collcagues irr
1912. ht this shrcly only 3482 people \\/ere exarninccl in thc rvhole corurlry and rnost of tltetll cattte fi'orn Tlryolo District. Tlris lvas Ibllou,ed rrp subsctluently by other studies
(Rattrprett, 1976; Buclclelt, 1979; Bunrharn. 1988; l99l). All thcse later stuclies poiltted to -fhyolo the fhct that enderrtic oltcltocerciasis is far fiorrr beirrg resh'ictecl lo tlre Disttict as rvas p[eviotrsly thought. Etrtoltrological slurlics lrave also confinncrl tlris as vector flies
Itave beelt fourtd breeding arrd bitirrg in otlrer areas outsidc 1-lryolo (Berrrer & Can', 1954,
Lewis, 196 | , Davis, 1985; Tanrbala, 1988; Rol;e rts, 1990).
Befol'e the last trvo clccades or so, ,\irtttrlitrttt ttcut,cicornltlex was tlrc preclonrinant vectol' of lttttttatt ottcltocerciasis in Malarvi, cspecially on the Thyolo lrighlarrcls, the nrain i i loci of the clisease irr tlre coulrhy (De N4cillon, l9-i0; Lcwis, With r.altid I I9(rl) tlre t lloptrlation glowth altcl tnovelttertt of ;reoplc irr tlrc 1960s alrd 1970s irr Malarvi (Colernatr,
1974), altd restrltattt wiclesllread rlcforcstaliorr as rvell as otlrcr envirorrrneltal
rrrodificatiolts, S clutrttto:;ttm cornlllex otrlcornllcted ancl dis;tlaced thc less aggressive ,\1, ttrtt:vai as tlte lnairt clisease vector'(Burrrharn, I99l) Furllrer, Bulllrarn (1991) lrotecl tlrat tlre llrevaleltce of ,\. dutnno,srrrt has increascrl steadily sirrce tlrc l9-50s rvlren Berler.aucl
Carr'(1954) obselvecl tlrat .\1, dottrnos'trtt, was harclly noticealllc. l'lris irrcrease of ,\'. tlttrrtttrt,strrtt was to tlre extelrl that irr 198(r-87. <-wet'99.9"/n of tlre 100,000 ,\irtttrlitrrtt flies 4 catrght bitirrg tttalt ilt tlte coturtry were ,t tkrntro:;tln conrltlcx (llobcrts. 1990).
Frotn the alreacly kltorut biorrornics of ,\. dtwtrrosutn s. 1.. e.spccially thc flight l'ange
attd vectol'ial capacity as well as tlre corrtirrued nrovernent ol'inhabitants in tlre coturtry, tlre
extertt to wlrich oltcltocel'ciasis is endernic has rernainccl undefincrl. This lras create fttltclattretttal qtrestiorts altd difficulty to lrealth planners irrvolvccl in olcftocclciasis corrtrol -fhe 1o tlpel':ttionally defirte ettdernic Dish'icts/arcas. dcfirritions of' cndcrnic areas and lleollle at risk of irrfectiolt irt Malarvi is cslleciirlly irnptorlarrt lrorv that APOC is cletelltirrecl lo cotth'ol this debilitatirrg disease irr Af ica to strch a Ievcl that it rvill no lorrgcr bc a ptrtrlic lrealth ploblertr or obstacle to socioecorrornic develolllnerrt irr the corrtilrent. The APOC rrrairr ob.iective is to establish witlrirr a periocl of lZ years efl-ective anrl self-sustainatlle \ colttttlttltity-tlased lverrttectitt h'eahtteltt throughout cnclclnic areas. Alrl to atlaip a lealistic lorrg-tetrtr pl'o-iection of elirnination of the clisease, an overall covcrage ol-10Y"of the target ;roprrlatiolt ilr atty ettclentic are shoulcl llc aclrievcd (Dadzie, 1997) ip AII'ica. T6is tlrercfore calls for cotnltl'eltensive iltforrnation on the locatiorr arrcl llopulation size of all high-fisk cottttltttttities/r,illages that neecl to be tteatcd irr cnrlclnic arcas irr Atl'ica. lnlorrned by the APOC itrterest to sullport eltdentic Africarr counh'ies, inclrrrlins I\4alarvi. to contlol clttchocet'ciasis, ancl tlre absertce of a teliablc nalion-rvicle epi r N{ATERIALS AND M ETTIODS ST[ID)' AREA: Tlte study area for tlris exelcise was Malawi, a larrdlocl Af ican courthy of ch'arrtatic highlarrcis and exterrsive lakcs.'fhe Republic of Malawi with a ctttlettt estitnatecl population of 12 nrillion occupies a nAn'ow, curving sh'i1; of land along tlte east Afi'ican Great Rift Valley sh'etclring about 837krn fi'orn north to soutlr, it has a rvith valying fi'otrt Skrtr to t60krn. It is borclered by Tanzania to the rrorth, Mozarntriclue to tlte east and soutlt, ancl southwest, and Zarnbia to the west. Its total of I 18,484 sq. krn irrclrrcles solne 24,208 sq. krn of irrlarrd water arens of Lake Malornbc, Clrihva. Clriuta, anil l-al The lna.iol' ch'airrage systern is that of Lake Malawi. lt is fe l-l