Drinking-water under a "One Health" lens: quantifying microbial contamination pathways between livestock and drinking-water

Diarrhoeal disease and lack of access to safe water remain significant public health issues in developing countries. There is also growing concern about the potential for disease, including diarrhoeal infections, to be transmitted from livestock to humans. This project addresses the potential drinking-water contamination risks to human health in rural sub-Saharan Africa, where people and livestock often live in close proximity. Preliminary fieldwork will be carried out in rural Kenya, building on an ongoing study that is simultaneously recording human and livestock disease in ten villages. The fieldwork will test different techniques to identify contamination hazards from livestock, alongside water quality testing and recording of diarrhoea in children. These techniques will include the use of GPS collars to track cattle movements, maps of hazardous areas created by the communities themselves, and also checklists for recording signs of livestock hazards at water sources and around water stored in the home. We will look at how feasible it is to record hazards using these techniques. We will also statistically assess whether we find greater water contamination and greater diarrhoea in children where there are more recorded hazards.

Since measurement of water contamination used in such areas is based on bacteria found in both livestock and humans, the project will also work on affordable ways of testing for micro-organisms that are specifically found in livestock faeces versus those found in human faeces. If successful, such techniques could be used to investigate the importance of different sources of faecal contamination of drinking-water. This in turn could help manage the safety of rural water sources like wells and rainwater and better protect drinking-water stored in the home from contamination through livestock.

Because this complex problem requires a wide range of expertise, during the project we will strength our academic team to include more disciplines, particularly specialists in child health and social sciences. The tools for identifying hazards from livestock will be made widely available at the end of the project and UK expertise in the microbiological laboratory techniques will be shared with Kenyan collaborators. The experience gained will be used to build up contacts and develop a plan and team for a larger-scale study of livestock hazards, water contamination, and diarrhoeal disease risk in several countries.

Background: Diarrhoeal disease risk remains the fourth leading cause of years of life lost globally, but the role of livestock in contributing to this burden remains unclear.
Objective: To develop and validate livestock-related hazard assessment protocols including affordable microbial source-tracking methods, deliver preliminary evidence regarding drinking-water contamination by livestock and its implications for human health, and develop a related multi-country research plan for a future, follow-up longitudinal survey component.
Study design: Water quality and livestock hazard module embedded in ongoing longitudinal health and demographic surveillance system.
Participants: Household members aged 6 months of over from 200 rural households in Siaya County, Kenya.
Outcomes: Source and point-of-consumption drinking-water contamination with E. coli and cryptosporidium; Fortnightly prospective prevalence of reported diarrhoea.
Planned analysis: Multinomial logistic regression of E. coli and cryptosporidium counts in drinking-water in relation to livestock ownership, sanitary risk inspection scores, and hazard maps, controlling for confounders; log linear model of prospective 2-day diarrhoea prevalence in those aged >5 months in relation to E. coli and cryptosporidium in stored water, controlling for confounders.
Immediate outputs: validated livestock hazard assessment tools; preliminary evidence on livestock, water contamination and diarrhoea risks; local capacity-building, particularly in microbial source tracking methods
Long-term research plan: Development of a multi-country protocol and research network for a water quality and livestock hazard module, to be embedded in longitudinal health and demographic surveillance systems such as INDEPTH surveys

The project's ultimate beneficiaries are rural households in LMICs (but particularly Kenya), particularly young children, using non-piped water and potentially exposed to faecal contamination from close contact with livestock, with the planned benefit being reduced child diarrhoea and disrupted zoonotic disease transmission in such households, balanced against economic benefits of livestock ownership. According to WHO/UNICEF, 26% of Kenya's 34,800,000 rural population currently use wells or rainwater. In the long-term (10 years after project), this group should benefit through improved water safety planning of rural water sources (e.g. wells; rainwater) and of stored water in the home via hazard identification and scientific understanding of livestock-related contamination risks generated. This project will provide the evidence required to develop effective interventions to reduce livestock-drinking-water transmission pathways (e.g. through source protection and safer storage of water in the home), with potential application in many water-insecure areas. This can ensure livestock continue to provide nutritional and financial benefits to the rural poor, while protecting drinking-water supplies and improving human health. During the project, 200 households in 10 villages in Siaya County participating in the study should benefit directly through contact with the project team, who should raise awareness about livestock-related hazards both to drinking-water stored in the home and at water sources, as will schoolchildren in this area via related education campaigns.

Direct intermediate beneficiaries include water sector NGOs, the Siaya County government, and community-based managers of rural point water sources, via development of microbial source tracking techniques, improved sanitary risk inspection protocols, and potentially also via hazard mapping exercise in the project's final 6 months and 3 years afterwards. The Kenya Vision 2030 policy strategy document highlights lack of capacity in water resources monitoring, better water quality, and catchments management as among eight key national challenges for the water sector. With its development of affordable microbial source tracking technology and hazard identification tools, the project should therefore address 3 key strategic challenges identified by the Kenyan government. In the final project year and 3 years following the project, the World Health Organization, with its remit to disseminate good practice in drinking-water management, could also benefit through the project's development of tools relevant to rural water safety planning. In the 3 years after the project, the scientific insights into livestock movements and related hazards could inform integrated water catchment management, e.g. by the Lake Basin Development Authority. The Zoonotic Disease Unit are a further intermediate beneficiary, who may benefit from development of livestock hazard identification tools and evidence on water-borne disease transmission.

The commercial benefits of the study are limited, but in the three years following the project, its findings could indirectly benefit makers of livestock GPS collars and microbiological companies (e.g. Idexx) via the development of new applications and markets for their products and the associated publicity from the project. During the project, MSc students in Kenya working with the Kenya Medical Research Institute will benefit from the project via capacity-building and training, particularly in the use of microbial source tracking techniques, with the future employers of these students (including government and NGOs as above) and project staff being the ultimate beneficiaries in the five years following the project. Finally, there are also obvious benefits to the academic team delivering the project, through skills development, collaboration network enhancement, and research profile development during and in the 3 years after the project.