Zoonoses in Livestock in Kenya (ZooLINK)

The goal the Zoonoses in Livestock in Kenya project (ZooLinK) is to enable Kenya to develop an effective national surveillance programme for zoonoses (meaning infectious diseases acquired through contact with animals or their products). To achieve this goal we will work in close collaboration with Kenyan government departments to set up a project in western Kenya as a model for a national programme.

The rationale for ZooLinK is that the burden of disease caused by zoonoses is greatly underestimated - as we know from our own research in the study region. In one recent but relatively small-scale study, we found 14 different zoonoses circulating in humans and their livestock. In addition, we expect this burden to change in the future as a result of continuing changes to livestock production systems in Kenya and elsewhere in order to satisfy increased demand for livestock products - again, we have good evidence of this taking place. The most important changes are the commercialisation and intensification of what was previously subsistence farming, changes in trading patterns (e.g. the distances that livestock and their products are transported), and changes in favoured breeds. All of these affect the risk of zoonoses and other infectious diseases. For example, our work has indicated that genes from exotic dairy cattle are 'leaking' into local cattle populations and altering susceptibilities to specific infections.

There is therefore a pressing need for good surveillance of zoonoses in order to establish their true burden and how that is changing. Importantly, this does not have to be set up from scratch. Kenya already has veterinary surveillance for infectious diseases in place at livestock markets, slaughterhouses and butcheries and in the wider farming community. It also has clinics and hospitals reporting infectious diseases in people. So the systems exist and are manned by trained staff. What is needed, and will be provided by ZooLinK, is increased awareness of zoonoses, better diagnostic support, better ways to record, share, analyse and interpret data, and closer integration between the human and animal health sectors.

In order to convince potential funders of the value of a national programme, we need to provide evidence that an enhanced surveillance system can contribute to improving public health in a cost-effective manner. For this reason, during our project we will closely monitor our enhanced system's performance and compare it to the current situation, identifying which activities do (or do not) provide good value for money. ZooLinK will also provide a platform for Kenyan public and animal health workers to get hands-on training (e.g. in diagnostic methods or electronic data systems) and to become familiar with a 'One Health' approach to surveillance. Training will be coordinated by Kenyan partners and will generate a cadre of individuals with first-hand experience of this way of working - this should leave a very strong legacy in its own right.

In addition to addressing these practical issues, ZooLinK will also provide a unique scientific evidence base which will help us to understand and anticipate changes in zoonotic disease burdens and to recommend effective interventions. This will involve detailed study of economic, social, demographic, genetic, and epidemiological drivers and the way that these combine to produce an overall burden of disease and risk of disease outbreaks. In this context the unusually comprehensive nature of ZooLinK is a major advantage: there are obvious limitations to studying single diseases or drivers in isolation (e.g. changes that favour one disease may reduce the risk of another; or effects due to changes in one driver may be outweighed by changes in another). The high quality data to be collected by ZooLinK, supported by state-of-the-art, diagnostics, genetics, and economic, statistical and mathematical modelling, will allow us to tackle such questions.

We will establish an enhanced zoonotic disease surveillance system in an area of western Kenya where we have prior evidence of a substantial burden of zoonotic and food-borne diseases. This will involve the development of mobile phone-based data collection tools and training of staff in their use. At the same time we will assess the operation, performance and costs of existing surveillance activities.

We will deploy diagnostic tests for 14 different zoonotic pathogens, plus common coinfections, in both humans and livestock. We will also develop new multiplex systems using bead-based technologies and paper-based assays (as a longer term goal aimed at point-of-decision diagnosis).

We will screen 7500 livestock at markets and slaughterhouses, and 5000 humans reporting to health care facilities with suspected zoonotic disease, to obtain baseline epidemiological data on the prevalence/incidence of zoonotic infections in the study populations. We will identify risk factors in individuals and at specific locations. There will be more detailed studies of a subset of individuals (600 per species) in a case-control format; for humans this will include trace-back to residence. For cattle and pigs the subset will be genotyped using state-of-the-art SNP chips, primarily to establish ancestry and estimate levels of introgression.

We will develop a risk network model of zoonotic disease distribution in different species and locations, parameterised from and validated against the field data. The models will be used to test different ways of allocating resources to surveillance, by species and location, in order to maximise cost-effectiveness (as DALY-weighted numbers of cases detected).

We will develop projections of demographic and agricultural changes, particularly trends towards the commercialisation and intensification of livestock production, and use the risk network model to estimate consequent changes in zoonotic disease risk and economic burden.

Immediate impacts will include the provision of an enhanced, integrated human-animal health surveillance capacity serving 1.5M people in western Kenya and improved care for >6000 patients, together with new data on zoonotic disease burdens, including contamination of the food chain. Medium term impacts will include provision of a scientific evidence base, including cost-effectiveness data and operational experience to justify and facilitate the setting up of a national zoonoses surveillance system managed by the Kenya Zoonotic Disease Unit (ZDU). Long term impacts will ultimately depend on the link between evidence of the public health burden due to zoonotic diseases and future investment in appropriate control or prevention strategies. This will be facilitated by explicit comparison between the cost-effectiveness of currently operating surveillance systems and ZooLinK's enhanced, integrated system. One encouraging example from our previous work is the case of human African sleeping sickness, for which the Ugandan government introduced (within 5 years of publication of the scientific evidence) cattle market-based screening to prevent introduction of the disease into new areas.

Beyond the impacts listed above, we foresee multiple beneficiaries within the project's timeframe.
- Improved diagnostic systems could potentially benefit those exposed to the target zoonoses throughout Africa.
- Improved training of a cohort of animal health assistants will benefit veterinary public health throughout Kenya.
- The reduced risk of zoonotic diseases in livestock achieved through enhanced surveillance will improve the marketability of livestock products - nationally and internationally - across the entire study area; this will especially benefit those intending to farm commercially - at however small a scale - and all those involved in the value chain for livestock and livestock products.

Institutions benefiting will include Kenya's Ministry of Public Health and Sanitation and the Department of Veterinary Services within the Ministry of Livestock Development. ZDU is a joint initiative of the two Ministries with direct links to them, and is a key partner in ZooLinK. Importantly, the frameworks for surveillance and disease control are already in place (e.g. the ZDU "One Health" Operational Plan); ZooLinK will add in the operational capacity and evidence of cost-effectiveness. Other countries in the region may wish to learn from the Kenyan model, and we will support study visits by policy makers from elsewhere to see ZooLinK at first hand.

Other beneficiaries will be international organisations including WHO, FAO, OIE and AU-IBAR. All are concerned with improving surveillance and the capacity to detect and control zoonoses.

Targeting policy bodies serves the primary purpose of contributing to the livelihoods of poor livestock keepers in Kenya and the East African region. This project is built on the observation that subsistence farmers are intensifying production, but this transition is not an easy one, demanding an ability to compete in such markets. We know from our existing work that, in practice, zoonoses are a barrier to growth in this sector in the study region. For example, large numbers of potentially successful pig keepers are currently excluded from national pork value chains because a major meat processor (rightly) perceives the zoonotic disease risk (specifically for T. solium cysticercosis) in the Lake Victoria basin to be too high. Improving confidence in the quality of livestock products from this region will create significant marketing and trade opportunities. Consumer health will benefit directly.