Dynamics of malaria transmission near two permanent breeding sites in Baringo district, Kenya

Abstract

Entomological and malario-metric measurements were made near two permanent breeding sites in Baringo district, Kenya in order to determine the prevalence and seasonality of malaria and the relative importance of two local anopheline mosquitoes as malaria vectors. The breeding sites studied were the Perkerra irrigation scheme and the Loboi swamp, whereas the mosquito species involved were Anopheles gambiae Giles (sensu lato) and Anopheles funestus Giles. Malaria accounted for 54 per cent of annual clinic attendance in the district and transmission occurred throughout the year. Overall values of vector density, man biting rate and crude inoculation rates did not differ significantly between the two areas. However, there was a strong seasonal trend in the values of these parameters which varied between the two sites, resulting in peak transmission occurring at different times of the year, April-July in Lobio and August-October in Perkerra. Crude inoculation rates were about 5 times higher in An. gambiae than in An. funestus, indicating that the former was the more efficient and more important vector in the district.