A descriptive entomological survey of malaria vectors in busia county

Abstract

Malaria is a leading cause of sickness and deaths in globally especially among children and pregnant women with majority (90%) of cases being in Africa. The prevalence of Malaria in Kenya is 8% with the highest prevalence (28%) being in Lake Endemic region (KMIS 2015). Successful reduction of malaria burden in an area requires knowledge of vector species present. The main objective of this study was to determine the entomological indicators of malaria in Busia County which is within the Lake endemic zone. Three sub-counties of Busia (Bunyala, Teso South and Matayos) were sampled and mosquitos were collected using light traps, Pyrethrum spray catches, Aspiration and human landing catches in 28 houses in each sub-county. Collected mosquitos were identified using taxonomical keys and through PCR and also analyzed for blood meal and sporozoites through ELISA. Results showed that An.arabiensis was the predominant species followed by An.gambiae with a heterogeneous distribution, P <0.001 (x2 = 39.37, df = 6). The indoor resting density of anopheles mosquitoes was 9 mosquitoes/house/day while the human biting rate was 1 mosquito/person/day. The main source of blood meal was human (27%) and bovine (12%), p <0.001 (x2=47.656, df=9). The sporozoite rate was 7% and annual EIR, 13 infective bites/person/year meaning a person is likely to get 13 episodes of malaria in a year. The main breeding habitat for Anopheles was small water pools. In conclusion, the primary malaria vectors in Busia are An.arabiensis and An.gambiae s.s. The indoor resting density is high and reduction can be achieved through indoor residual spraying. The presence of sporozoite and Anopheles species fed on human blood underscore the malaria endemicity status of Busia County. The findings of this study provide important information for control of malaria in Busia County.