Relationship between malaria and filariasis transmission indices in an endemic area along the Kenyan Coast

Abstract

Background & objectives: An entomological survey was conducted to determine the relationshipbetween malaria and lymphatic filariasis transmission by Anopheles gambiae s.l. and An. funestus intwo inland villages along the Kenyan coast.Methods: Mosquitoes were sampled inside houses by pyrethrum spray sheet collection (PSC). In thelaboratory, the mosquitoes were sorted to species, dissected for examination of filarial infection andthe anophelines later tested for Plasmodium falciparum circumsporozoite proteins by an enzymelinkedimmunosorbent assay (ELISA).Results: From a total of 2,032 female mosquitoes collected indoors, An. gambiae s.l constituted 94.4%while the remaining 5.6% comprised of An. funestus and Culex quinquefasciatus. None of the Cx.quinquefasciatus was positive for filarial worms. P. falciparum sporozoite rate for An. gambiae s.l.from both villages was significantly higher than Wuchereria bancrofti infectivity rate. Similarly, theentomological inoculation rate for An. gambiae s.l. was significantly higher than the corresponding W.bancrofti infective biting rate and transmission potential for both the villages. Mass treatment of peoplewith filaricidal drugs in Shakahola in the ongoing global elimination of lymphatic filariasis campaignseemed to have reduced the indices of filariasis transmission but had no effect on malaria transmission.Interpretation & conclusion: These results indicate the intensity of malaria transmission by anophelinesto be much higher than that of lymphatic filariasis in areas where both diseases co-exist and re-emphasisethe need to integrate the control of the two diseases in such areas.

Keywords

• An. funestus
• An. gambiae s.l.
• Kenyan coast
• Plasmodium falciparum
• transmission
• Wuchereria bancrofti