Blood-meal analysis for anopheline mosquitoes sampled along the Kenyan coast

A total of 1,480 Anopheles gambiae sensu lato and 439 An. funestus, collected from 30 sites along the Kenyan coast, were tested by direct enzyme-linked immunosorbent assay (ELISA) for blood-meal identification. Overall, the enzyme-linked immunosorbent assay (ELISA) identified 92 and 87% of the samples tested in An. gambiae s.l. and An. funestus, respectively. Of these, human IgG was detected in 98.97% (n = 1,347) of An. gambiae s.l. and 99.48% (n = 379) of An. funestus. Only 14 (1.03%) of the An. gambiae s.l. had fed on other vertebrate hosts tested, which were bovines, chickens, and goats. Additionally, only 2 An. funestus had fed on goats. In all the 28 sites that had bloodfed mosquitoes, An. gambiae s.l. had a human blood index greater than 0.9. Twenty-five of these sites had a human blood index greater than 0.9 for An. funestus, while the other 3 sites had no bloodfed mosquitoes. The An. gambiae s.l. were tested by polymerase chain reaction (PCR) for species identification. A total of 338 were An. gambiae s.s., 79 were An. arabiensis, and 12 were An. merus. The human blood index was 0.96, 0.91, and 1.0 for An. gambiae s.s., An. arabiensis, and An. merus, respectively. The Plasmodium falciparum sporozoite infection rates were 6.2% for species in the An. gambiae complex and 3.7% for An. funestus. These results emphasize that An. funestus and members of the An. gambiae complex on the Kenyan coast are highly anthropophilic, with nearly all specimens feeding on humans during every blood meal. The results further demonstrated active transmission of P. falciparum sporozoites by the primary vector species. This study suggests that the use of insecticide-treated nets will be effective for controlling biting mosquitoes inside houses along the coast of Kenya.