Experimental infection of Anopheles gambiae and Culex pipiens fatigans with Wuchereria bancrofti in coastal East Africa.

Abstract

Laboratory strains of Anopheles gambiae A and Culex pipiens fatigans from Tanzania, East Africa were experimentally infected with Wuchereria bancrofti to compare vector potential in the 2 species. Uptake of microfilariae, survival of the vector after an infective blood meal, number of filarial larvae reaching the infective stage and percentage of mosquitoes harboring infective larvae after 14 days were compared in the laboratory. C. p. fatigans ingested more than 3 times as many microfilariae when the 2 species were fed simultaneously on the same carrier. Fifty-four percent of the C. p. fatigans contained infective larvae after 14days compared to 9.0% of the A. gambiae. Feeding on a carrier with lower microfilaremia produced comparably lower values for each species. The mean number of infective larvae per positive mosquito was nearly twice as high in C. p. fatigans. A. gambiae showed a lower mortality rate than C. p. fatigans after an infective blood meal, but data indicated that the extremely low infection rates in A. gambiae nearly equated infected groups with controls. The extreme differences in Vector potential between the 2 species, in conjunction with the apparent role of A. gambiae as a vector in nature, suggest that strain rather than natural susceptibility may have been a major factor in the results of this study.