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

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

Brucellosis reduces the fertility of multiple livestock species in Kenya, causing abortions or premature births and reduced milk production in livestock species including cattle, sheep, goats and camels. Brucellosis also causes considerable morbidity burdens in human populations and has nutritional impacts. Approximately 56% of the Kenyan population is food insecure and milk is the single most important livestock food product. Brucellosis is important because it impacts on both livestock reproduction and milk production, with consequence direct and indirect impacts on health, nutrition and socioeconomic wellbeing in people.

A key barrier to the implementation of cost-effective control measures for brucellosis is the current absence of the specific data required to determine both the burdens of brucellosis and the potential impact of different disease control measures. The research outputs of this project will add value to previous investments in regional brucellosis research projects and contribute to filling the knowledge gaps that currently hinder the development of targeted brucellosis control policy. These are an important steps in a larger and longer-term process. In addition to providing an evidence base for policy development, the effective communication of research findings at appropriate parts of the impact pathway is crucial to achieving the long-term goal: the development and implementation of a national brucellosis control policy in Kenya. Such a policy will serve the ultimate beneficiaries of this research project: livestock keepers and their families, milk consumers, butchers, abattoir and slaughterhouse workers, and veterinary professionals.

We have built a collaborative team and developed a study that is designed to ensure ongoing dialogue between researchers and policy makers and enable the onward communication of evidence provided through this study, to politicians in Kenya and policy drivers at other points in our impact pathway. Throughout this project we will work with stakeholders in Kenya to ensure that project research outputs are fed directly into ongoing processes for the development of brucellosis control policy in Kenya.

The project involves research and capacity strengthening for both laboratory diagnostics and data analyses. Through the projects direct connectivity with multiple stakeholders in Kenya and the wider region the availability of these tools for other researchers will be maximized. In Kenya, key partners for both the delivery and communication of the study include Dr Peninah Munyua based at CDC-Kenya, Dr's Mwatondo and at the Zoonotic Disease Unit, Dr Njeru and the Ministry of Health and Dr Bernard Bett at the International Livestock Research Institute. The University of Glasgow is a global partner in the Wellcome Trust funded African Institutes capacity strengthening consortium Afrique One ASPIRE, which also includes ILRI-BecA. The ASPIRE programme includes a thematic training programme on brucellosis. As well as providing direct training opportunities for students in this programme, research and policy initiatives resulting from this project will be fed into this network of African research institutions. The network spans six countries from both east and west Africa with interests in one-health, resulting in continental opportunities to disseminate findings and practice. Finally, there is an important opportunity to promote regional consistency in approaches to the assessment of brucellosis burden and its control through this project. Both Kenya and Tanzania are implementing the FAO coordinated USAID funded program "Supporting Global Health Security Agenda to address Zoonotic Disease and Animal Health in Africa". This project provides an opportunity to link research initiatives in Kenya with ongoing developments in Tanzania, and to share expertize and best-practice at a regional level.