The epidemiology of Rift Valley Fever in northern Tanzania

Studentship strategic priority area: Food Security (Animal Health)
Keywords: Zoonoses, Rift Valley Fever, epidemiology

Rift Valley Fever (RVF) is an important anthropod zoonosis that can cause severe disease in both humans, ruminant livestock and wildlife. The disease typically occurs as large outbreaks in association with periods of heavy rainfall when mosquito vectors proliferate, with RVF virus (RVFV) persisting in dormant eggs of Aedes mosquitos in periods between epidemics. However, recent evidence indicates that RVF virus also circulates in mammalian hosts and mosquitoes between epidemics, and very little is known about patterns of circulation or mechanisms of during the inter-epidemic period. Furthermore, little is known about the socio-economic impacts of RVF in Tanzania during both epidemic and inter-epidemics period.

This project aims to investigate the epidemiology of RVF in multi-host ecosystems of northern Tanzania with the following objectives:

(a) to determine patterns of RVF virus infection in mosquitoes in relation to livestock density, livestock infection prevalence, rainfall and vegetation through longitudinal sampling and PCR analysis of mosquitoes collected from sites at wildlife-livestock interfaces;
(b) to investigate the relationship between infection patterns in mosquitoes, livestock and human infection and disease risk in areas surrounding wildlife-protected areas through linkage of mosquito PCR data with serological data from linked human and livestock populations;
(c) to determine risk factors for RVF seropositivity in livestock and human populations in areas surround wildlife-protected areas through analysis of human and livestock serological data collected from cross-sectional household surveys;
(d) to carry out RVF serological analyses of archived wildlife sera to investigate risk factors for infection for wildlife;
(e) to develop epidemiological models of RVFV in multi-host systems in order to explore potential strategies, such as livestock vaccination, to reduce the risk of major outbreaks.
(f) to determine the socio-economic impact of RVF in northern Tanzania through collection of data on livestock production losses during outbreaks (which are anticipated during the PhD study period).

The PhD project will be closely linked with two projects within the NNSRC Zoonoses and Emerging Livestock Systems (ZELS) scheme - "Social, Economic and Environmental Drivers of Zoonoses in Tanzania" (SEEDZ) and "Life on the Edge: Tackling human African Trypanosomiasis on the edge of wilderness areas"