Review of the Food-borne Zoonoses Research ... - ARCHIVE: Defra

Project code: OZ0318
Project title: Understanding the dynamics of endemic and
epidemic Salmonella infections in cattle: A
comparative modelling approach
Start date (dd/mm/yy): 01/01/03
End date (dd/mm/yy): 30/04/06
£399,343.00
Total cost:
Affiliation: University of Liverpool
Sub-contractor(s): Veterinary Laboratories Agency
University of Lancaster
Abstract of research
There were four interrelated aspects to this study of endemic and epidemic Salmonella
infections in dairy cattle, as follows:
1. Mathematical modeling. Considered both within herd and between herd transmission.
Focused on teasing out features underlying the variation in the infection dynamics of
different serotypes.
2. Immunological studies and quantitative microbiology. Began with the objective of
developing methods for measuring immunological responses to Salmonella infections in
cattle. Concerns arose over validity in very young animals and suitability for determining
long-term immunity. Alternative approach then taken (2a), involving on-farm longitudinal
studies and experimental Salmonella survival studies.
3. Space-time statistical analysis. Largely concerned with investigating the evidence for
clustering, as this could provide evidence relating to the transmissibility of infection (or its
origin in localised environmental processes). 4. Systematic literature review.
Review Summary
It was felt it should be useful to develop a model for salmonella in cattle. Although the
mathematics behind the modelling is complex and difficult to understand, the researchers
had done a good job of presenting their approach openly and clearly, including an openaccess
web page. The model had only been developed for cattle because of time
restraints and it may be worth considering whether it could be applied to pigs.
There was concern that the model would not be satisfactory if it did not take account of
the carrier state associated with S. Dublin, which is what makes S. Dublin so difficult to
control in the British population. There was also uncertainty about how the model had
been developed—it started as a generic salmonella model, which was then applied to
Salmonella Typhimurium, Salmonella Agama, and Salmonella Dublin, and then labels of
endemic and epidemic were applied, with no account taken of the carrier state.
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