Routes for the potential transmission of bovine tuberculosis in the farmed environment

Pathogens which can infect wildlife, domestic species and humans can have serious health, welfare and economic implications around the world. Bovine tuberculosis (bTB), caused by Mycobacterium bovis, is a widespread disease that affects a wide variety of livestock, wild mammals and humans. In England bTB remains a substantial problem, despite long term management strategies. It is estimated to cost £120 million per year and in the year ending September 2020, 27,339 test-positive cattle were slaughtered. Mycobacterium bovis is proving difficult to manage, in part due to its generalist nature, infecting a broad variety of wild mammal species, and its ability to survive for extended periods of time in environmental substrates including water, soil and faeces. In this thesis, I explore two potential sources of M. bovis in the environment: water troughs, and the spreading of cattle manure and slurry onto the farming landscape. Using both camera traps and GPS collaring technology, I find that wild mammals do not regularly drink from water troughs, suggesting that the role of water troughs in interspecific transmission might be limited, although their potential role in intraspecific transmission warrants further investigation. By attaching GPS trackers to both muck spreaders and slurry tankers to monitor their movements, I find that slurry and manure spreading by farmers does not change in response to the detection of test-positive cattle on their farms, providing the opportunity for pathogen spread (both on and off the home farm). Whilst both water and cattle faeces management are covered in advisory guidance, their management to prevent infection risks is not enforceable. bTB provides an example of a disease with multiple possible routes of interspecific and intraspecific transmission, and for successful rapid disease control an understanding of all routes is necessary