Understanding the Dynamics of Endemic and Epidemic Salmonella Infections in Cattle and Pigs: A Comparative Modelling Approach

The aims of this project are to:
<UL> <LI> Understand the processes that lead to the varying epidemiological patterns of endemic and epidemic strains of salmonella in livestock populations
<LI>Identify immunological tests that can be used to assess the role of cell mediated and humoral immunity in determining the dynamic behaviour of salmonella infections in livestock
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Both endemic and epidemic strains of salmonella have had a major impact on human and animal health and this organism remains one of the most important foodborne and direct-contact zoonoses. We aim to improve our understanding of the mechanisms that drive the epidemic behaviour of strains of Salmonella Typhimurium and lead to the fluctuating endemic behaviour of other salmonella serotypes. Such information will help to predict the nature of emerging strains and inform the development of control strategies.
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Mathematical models provide an ideal framework for assessing the complex role of factors, such as immunity, pathogenicity and persistence in the host and environment, as determinants of both the within and between herd dynamics of salmonella infection. We aim to explore and contrast the behaviour of both deterministic and stochastic models of endemic and epidemic strains. The models will be parameterised, where possible, from information gathered from a targeted systematic review of the literature and ongoing epidemiological studies. This process will inevitably help to identify gaps in our current knowledge and indicate areas for future research. Model building requires significant input from an interdisciplinary group of scientists. By combining the skills and resources of epidemiologists, mathematicians, microbiologists, molecular biologists and immunologists we aim to develop valid and well-informed models that will be of considerable value in decision making. The role of host immunity will be further considered by conducting detailed on-farm studies of natural infections in cattle. These studies will help to identify the most appropriate tests of cell mediated and humoral immune responses for use in population-based studies of salmonella in livestock.