Brucellosis in Kenya - understanding epidemiology and informing control at regional scales

点击翻译按钮获取中文摘要

Food security and livestock productivity are strategic objectives of the Government of Kenya. Brucellosis, one of the highest priority animal diseases in sub-Saharan Africa, is a major impediment to achieving these objectives as it reduces the fertility and milk production of multiple livestock species, including cattle, sheep, goats and camels. In Kenya, there is evidence of widespread exposure to Brucella in multiple livestock species and it is known to be an important cause of human illness. Vaccines against Brucella exist and targeted design and implementation of interventions have been shown to reduce the impacts of brucellosis in the poor communities most affected by this disease. However, brucellosis is caused by several different Brucella species, each of which has complex multi-host epidemiology and current vaccines are host and pathogen species specific. B. abortus is typically maintained in cattle and B. melitensis in sheep and goats, but in sub-Saharan Africa both B. abortus, B. melitensis have been reported in a variety of hosts including cattle, sheep and goats. Accurate understanding of who infects who, with what Brucella species is critical to inform the design of cost-effective programmes for the control of brucellosis but this remains a major knowledge gap in most low and middle income countries, including Kenya.One of the big challenges in achieving brucellosis control has been the inability of serological diagnostic tests to differentiate infections caused by different Brucella species and the scarcity of molecular or culture based diagnostic data that enable accurate identification of the infecting Brucella species. For Kenya, this means that we do not know whether cattle, camels, sheep or goats, are infected with B. melitensis, with B. abortus or with both. This project will exploit existing sample collections and serological data to address key knowledge gaps in our understanding of the multi host transmission dynamics of brucellosis. Specifically, we will:1) Establish qPCR assays to detect and species-type Brucella at KEMRI and apply this methodology to test an existing archive of Kenyan livestock samples. An archive of 200+ livestock and another 400+ camel samples will be tested using qPCR to identify the infecting Brucella species. 2) Model existing multi-species serological data to quantify transmission dynamics between host species and the spatial scales at which they occur. Bayesian latent process models will be developed and applied to reconstruct Brucella transmission dynamics using serology data obtained from a cross-sectional survey conducted in 2012-2013 in three distinct regions of Kenya. 3) Communicate research findings to stakeholders including policy makers to facilitate the design of brucellosis control strategies in Kenya. Through research meetings and a workshop the insights produced in this project will be shared with local partners to design national brucellosis control policy in Kenya.This project builds from and extends the RCUK and DFiD funded study The Molecular Epidemiology of Brucellosis in Northern Tanzania (BB/L018845/1). The results from this previous study indicate that B. melitensis, B. abortus and B. ovis are present in northern Tanzania, that B. melitensis is the predominant zoonotic Brucella species causing human brucellosis and that sheep & goats are the most likely animal source of Brucella exposure in both humans and cattle. By linking new combinations of data resources and analytical expertise, this project offers opportunities to extend molecular diagnostic and modelling approaches developed previously. Our project will fill critical knowledge gaps about brucellosis epidemiology in Kenya. Importantly, it will also enable application of common approaches to datasets from neighbouring Tanzania and Kenya, offering a mechanism to improve understanding of broader scale regional patterns and variation in Brucella epidemiology