Location: Mosquito and Fly Research Unit
2013 Annual Report
Two genes (CO1and cytb genes) found in DNA taken from in the mosquito blood meals were amplified by PCR and sequences of purified amplicons queried in GenBank and Barcode of Life Database (BOLD) to identify blood meal sources. Seventy-three percent of the mosquitoes from Garissa were Aedes ochraceus and 23% Aedes mcintoshi, and both species preferentially fed on goats, cattle, sheep and humans. In Baringo, 38% of Mansonia uniformis had fed on sheep. Eight Rift Valley fever virus isolates were from Ae. ochraceus blood meals from human (1), cattle (1), sheep (4), goat (1) and unidentified host (1). Of these, mosquitoes with blood meals from sheep (3), goat (1) and unidentified host (1) had disseminated infection. The only RVFV positive Aedes mcintoshi (with disseminated infection) blood meal was from donkey. In Baringo all the 4 Mansonia uniformis that fed on sheep had disseminated infection. Ndumu virus (NDUV) was also isolated from blood meals of some mosquitoes in Garissa. Thirteen of the NDUV were from Ae. Ochraceus (7), Ae. mcintoshi (5) and Ae. sudanensis (1). No mixed infections in mosquitoes were detected although both viruses shared the same vectors. These data have shown that RVFV and NDUV were co-circulating during the outbreak. The observation that humans were hosts to RVFV vectors and were possibly involved in human-mosquito-human transmission of the virus is quite significant.