SEASONAL DENSITY, SPOROZOITE RATES AND ENTOMOLOGICAL INOCULATION RATES OF ANOPHELES-GAMBIAE AND ANOPHELES FUNESTUS IN A HIGH-ALTITUDE SUGARCANE GROWING ZONE IN WESTERN KENYA

An entomological study was conducted on vectors of malaria and their r elative contribution to Plasmodium falciparum transmission in Mumias, a high-altitude site and large-scale sugarcane growing zone in Kakameg a district, western Kenya. Anopheles gambiae s.l., the predominant vec tor species, represented 84% (n = 2667) of the total Anopheles mosquit oes collected with AN. funestus comprising only 16%. Polymerase chain reaction (PCR) identified all 600 specimens of the An. gambiae complex tested as An. gambiae sensu stricto, an indication that it is the onl y sibling species represented in the high-altitude sites in western Ke nya. Plasmodium falciparum sporozoite rates of 6.3% (133/2118) for An. gambiae s.l. and 9.5% (38/402) for An. funestus by ELISA were obtaine d in Mumias. None of 1600 mosquitoes tested for P. malariae sporozoite s was positive. ELISA tests of mosquito blood meals indicated a high t endency of anthropophagy, a behaviour contributing significantly to ma laria transmission by the Vector species, with 95.9%, 4.86% and 0.2% h aving taken at least one blood meal on human, bovine and avian hosts, respectively Malaria transmission intensity was low as revealed by the low entomological inoculation rates (EIR) recorded. The EIR values fo r An. gambiae s.l. were 29.2 infective bites per person per year (ib/p /year) and 17.5 ib/p/year for An. funestus in Mumias. The highest inoc ulation rate for both vector species was 7.0 ib/p/month in July Plasmo dium falciparum parasite rate among asymptomatic children was 55.4% an d 44% in the wet (July-September) and dry (December-February) seasons, respectively. These results indicate that malaria transmission intens ity in the high-altitude site is low but perennial, with transmission being maintained by An. gambiae s.s. and An. funestus.