The vectors of malaria and filariasis in Kilifi and Kwale districts of Kenya
Kubasu, Sammy Shimenga
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The species composition of malaria and filariasis mosquito vectors were determined at two sites in Kilifi and three in Kwale districts in Coast Province, Kenya using morphological features and polymerase chain reaction (PCR). The species recorded include Anopheles funestus Giles, An. gambiae s.s. Giles, An. arabiensis Patton, An. merus Donitz, Culex quinquefasciatus Say, Aedes aegypti LInnaeus and mansonia species. Significantly different numbers of these species occurred in different sites within the same locality and between different districts in the same area (2=12.2; df=5, P<0.001). The observed micro-habitat differences in vector abundance may have direct implications in disease transmission and endemicity. Using the enzyme linked immunosorbent assay (ELISA) technique, blood meals taken from mosquitoes were determined to establish the source of feeding. Human immunoglobulins (IgG) bovine IgG and goat IgG were analysed. Results indicated that An. gambiae s.s has the highest preference (93.75%) for human bloode meal followed closely by An. funestus (88.30%) and to a fair degree by Cx quinquefasciatus (66.70%) and An. arabiensis (60%). This tendency of anthropophily was important in malaria and filariasis transmission by the vectors in the study areas. Anopheles merus had the least (25%) of its members which had fed on human blood. The results also revealed mixed blood meal feeding (e.g. human and or bovine/goat IgG) by the vectors, especially so in An. arabiensis and An. merus. The tendency for these vectors to also feed readily on non-human hosts may reduce their efficiency to transmit human diseases. Indirect enzyme linked immunorsobent assay was used to determine infection rates of malaria parasites in mosquito vectors. Plamodium falciparum, P. malariae and P. ovale were detected in samples collected from Kilifi District. Plasmodium vivax was not detected in any of the analyzed mosquito samples. The Plasmodium species (P. vivax) seems to be absent from Kilifi and Kwale Districts, or if present, then it is very rare indeed. In the case of Kwale District, only P. falciparum was detected.