Biosecurity in Canadian dairy farms: Unraveling the epidemiology of bovine infectious diseases and refining diagnostic strategies to improve their detection, prevention and control

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Biosecurity is a priority for Canadian dairy industry stakeholders and an important component of the Dairy Farmers of Canada ProAction Initiative. Biosecurity aims to limit the transmission of infectious diseases with an important negative impact on the Canadian economy, the environment, and human health. Biosecurity measures reduce the risk of introduction of emerging diseases into a population, decrease the prevalence of endemic diseases and prevent the risk of food contamination with infectious pathogens. Information on biosecurity measures is often collected through risk assessment questionnaires and, it has been suggested that they have the potential to predict Mycobacterium avium subsp. paratuberculosis (MAP) herd status. However, their analysis is not straightforward because of the high dimensionality of the datasets which have a high number of variables that are often correlated. Machine learning is therefore a suitable alternative to handle these complex data. Accurate diagnostic tests and screening strategies are crucial to precisely measure the impact of biosecurity measures and monitor disease prevalence but in practice, perfect reference tests are not often available. Thus, Bayesian latent class models are a suitable methodology to evaluate the diagnostic accuracy of imperfect tests. For this specific funding cycle, the objectives of my NSERC-Discovery research program are to: 1) estimate the prevalence of MAP, Salmonella Dublin and Bovine Leukemia Virus in Canadian dairy herds, 2) develop and validate a classification model to determine the status of dairy herds regarding these infectious diseases; 3) evaluate the accuracy of diagnostic tests and screening strategies to detect MAP and S. Dublin in dairy farms. In the long-term my research program aims the prevention and control of infectious diseases of high priority for the Canadian dairy industry stakeholders, to limit the economic losses associated with their introduction or presence in the farms and, ultimately, reduce their negative impact on animal health and welfare, public health, and the environment. My research program will advance the current knowledge in biosecurity, epidemiology, and animal health, and help dairy producers and veterinarians to reduce economic losses associated with production limiting diseases. Government agencies will use the newly generated data to design or update structured prevention and control programs. My research program is a first step towards the diagnostic and control strategies based on transmission routes rather than single pathogens. A framework that could be extended to other transmission routes such as airborne or vector-borne diseases to facilitate the implementation of control programs. Ultimately, Canadian consumers will benefit by having access to dairy products of the highest quality, produced by animals raised in outstanding welfare conditions with minimal use of antimicrobials.