Rift Valley fever RVF is a mosquito-borne viral zoonotic disease that causes significant economic and public health impacts in Kenya. Currently there is inadequate information on rainfall patterns and mosquito diversity including the dominant species in Nyandarua.
this study aimed to determine the rainfall patterns relative abundance and diversity of mosquito species that can transmit the RVF virus RVFV in Nyandarua.
Mosquitoes were purposively collected from all the homesteads with suspect RVF cases in 10 villages using the CDC light trap during the dry January 2021 long July 2020 and short November 2021 rainy seasons. Rainfall data was derived from the Climate-SERV satellite database. The mosquitoes were identified morphologically using a dissecting microscope and their identities as well as genetic diversity were determined using sequencing and phylogenetic analysis of the CO1 gene. A total of 97 328 and 366 mosquitoes were trapped during the dry long and short rainy seasons respectively.
There was variation in the average daily rainfall between 2015 and 2021 during the three seasons. Of the mosquitoes trapped 71 9 were males while 720 91 were females with 26 4 mosquitoes being blood-fed. During the three seasons various species of mosquitoes including Culex pipiens 58 Culex theileri 16 Culex vansomereni 3 Culex rima 2 and Culex perexiguus 3 were identified Simpson index 0.4. Culex pipiens was the most dominant species in this ecosystem Shannon index 1.2.
This study presents evidence of the abundance diversity and distribution of possible RVFV mosquito vectors attributable to variation in rainfall. Differences in mosquito diversity and distribution of mosquitoes are correlated with dry long and short rainy seasons. This variation in rainfall could have contributed to the observed difference in distribution abundance and diversity of potential mosquito vectors for RVFV in Nyandarua County.The data collected will help in the initiation of mitigation measures for the prevention control and risk prediction of RVF disease in Nyandarua.