Microbial Exposure Assessment and Primary Production: Modelling Transmission Dynamics of E.coli O157 in Farm Animals Using Multi-Group Deterministic and Stochastic Models. J. T. Turner, R. G. Bowers, M. Begon, H. E. Clough, and N. P. French, University of Liverpool, UK
Reducing the prevalence and shedding of E.coli O157 in farm animals has been identified as a potentially effective risk reduction strategy in Quantitative Microbial Risk Assessments. Interventions in farm animals, such as improved hygiene, vaccination and nutritional changes, can be applied at both management group and herd level. A deterministic model of the transmission dynamics of E. coli O157 in a dairy herd was developed with the aim of understanding the criteria for invasion and persistence of the pathogen and the assessment of group and herd level control strategies. The model was based on a multi-group system of differential equations and was explored both analytically, using next generation matrices, and by the use of simulation studies. The deterministic model was extended to consider stochastic processes and the effect of control strategies on the probability and time to fade-out of infections. The results suggest that individual groups, particularly the ‘weaned’ group may be responsible for maintaining the basic reproduction ratio above 1.0 (the threshold criterion, Ro) and could be targeted for intervention. This work forms part of a much larger exposure assessment for food borne pathogens in dairy products in the UK.
Funded by DEFRA.
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