Epidemiology and vector biology of arboviruses in Kenya

The project will investigate the natural history of human arboviruses and their mosquito vectors in Kenya, which is endemic for several viruses of medical importance. Where appropriate medically important zoonotic arboviruses will also be examined in their animal reservoir. The project will be a multidisciplinary programme in both epidemiology and entomology, comprising a mixture of fieldwork, laboratory work and epidemiological analysis. In this setting, the burden arboviral infections is poorly quantified, making this work important for local policy development.

The primary viruses of interest in this project are proposed to be Rift Valley Fever Virus (RVFV) and West Nile Virus (WNV), both zoonotic. We will also use multiplex assays in a hospital setting to detect up to 15 other co-circulating viruses. RVFV has a domestic livestock reservoir, and WNV a reservoir in a variety of bird species. Previous work has focussed in semi-arid parts of Kenya, neglecting the wetter, tropical areas (around Lake Victoria), which are the focus of this project. The study will capitalise on a large-scale field activity (funded by the BBSRC) in western Kenya, and will enjoy the support of collaboration with a number of local institutions, namely the International Livestock Research Institute, which, with the University of Liverpool, operates a field laboratory in the study site.

The PhD will involve training in human virological diagnostics as well as entomological techniques, collection of mosquitos in Kenya, morphological and molecular identification of arbovirus vectors, isolation of RVFV and WNV and virus sequencing. We will field test a recently developed multiplex PCR-based field diagnostic for multiple viruses. In order to understand transmission and risk to humans, the project will involve the analysis, through serological tools, of blood samples from human patients presenting to health units (sourced from part of a larger study to which this project will be attached). All together, the project will provide important insights in to arbovirus epidemiology and transmission in this setting, and training in several different research methods. The student will form part of a highly interdisciplinary research team based in both the UK and Kenya, and will have full access to the resources of a large, multi-partner study.

Aim 1: Prevalence of exposure to RVFV and WNF in the human population. On-going studies of infection in the human population in the study site (funded by the BBSRC) will collect serum from a large number of febrile patients in treatment centres; this material will be available for serological screening for RVFV and WNV to make estimates to human exposure and disease burden.

Aim 2: Prevalence of RVFV and WNV in Culex mosquitoes. A viral sequencing-based approach will be used to detect both viruses in pools of collected mosquitos. This will include training in preparing material for sequencing and the analysis of sequence data.

Aim 3: Biology of Culex mosquitoes in the Lake Victoria ecosystem. Mosquito trapping techniques will be applied to quantify the distribution, biting behaviour and abundance of Culex mosquitoes in the study area. This will include training in entomology techniques, morphological and molecular identification. Blood meal analysis will be undertaken to understand the range of host species.

Aim 4: Prevalence in animal reservoirs and using data from the above aims, simple epidemiological modelling of transmission of arboviruses to humans from their animal reservoir through the vector mosquitoes.