Blood-feeding patterns of Culex quinquefasciatus and other culicines and implications for disease transmission in Mwea rice scheme, Kenya.

Studies were conducted in Mwea Rice Scheme, Kenya during the period April 2005 and January 2007 to determine the host-feeding pattern of culicine mosquitoes. Mosquitoes were collected indoors and outdoors and tested for human, bovine, goat, and donkey blood meals by an Enzyme-Linked Immunosorbent Assay. A total of 1,714 blood-engorged samples comprising Culex quinquefasciatus Say (96.1%), Culex annulioris Theobald (1.8%), Culex poicilipes Theobald (0.9%), Aedes cuminsi Theobald (1.0%), Aedes taylori Edwards (0.1%), and Mansonia africana Theobald (0.1%) were tested. Except for A. taylori, in which the single blood meal tested was of bovine origin, the other species fed mostly on both bovine (range 73.3-100%) and goats (range 50-100%). Donkeys were also common hosts for all species (range 19.4-23.5%) except A. taylori and M. africana. C. quinquefasciatus was the only species containing human blood meals (0.04), and indoor collected populations of this species had significantly higher frequency of human blood meals (9.8%) compared with outdoor-collected populations (3.0%). Mixed blood feeding was dominant among culicine species comprising 50.0%, 73.3%, 73.5%, 80.6%, and 94.1% of the samples for M. africana, C. poicilipes, C. quinquefasciatus, C. annulioris, and A. cuminsi, respectively. Ten mixed blood meal combinations including a mixture of all the four hosts were observed in C. quinquefasciatus, compared to one blood meal combination for M. Africana, and two combinations for C. poicilipes, C. annulioris, and A. cuminsi. Mixed bovine and goat blood meal was the most common combination among the five culicine species followed by a mixture of donkey, bovine, and goat blood meals. We conclude that culicine species in Mwea are least likely to be vectors of lymphatic filariasis due to their high "preference" for livestock over human hosts, but they present an increased risk for arbovirus transmission particularly Rift Valley Fever virus, in which domestic animals serve as amplification hosts.