The herd-level incidence of Mycobacterium bovis has been increasing in the United Kingdom (UK) and Republic or Ireland (RoI) for the past thirty years, resulting in substantial economic and animal welfare issues. Failure to control this pathogen in cattle is in part due to European badgers (Meles meles), a wildlife reservoir that are responsible for a proportion of transmission of M. bovis to cattle. Monitoring infection in badger populations is currently limited due to the need to trap badgers, which requires highly trained field staff and is expensive. In addition, although contact with infected badger faeces is a potential transmission route to cattle, very little is known about the extent and variability of the environmental pool of M. bovis shed by badgers. In this project we evaluated the suitability of using environmental badger faeces and a quantitative PCR (qPCR) assay to diagnose and monitor M. bovis in badger populations and described the extent of this environmental pool of potential infection. The first study identified that intensive environmental faecal sampling and analysis with qPCR is at least, if not more, sensitive at diagnosing M. bovis in badger populations than the currently used immunoassays. This study also identified that even within a high prevalence population, the levels of shedding of M. bovis in faeces are highly variable between groups and between seasons, suggesting that there may be heterogeneity in transmission risk throughout the year. Using this non-invasive qPCR method to monitor the first field trial of oral BCG vaccination identified a trend of decreasing levels of M. bovis in faeces with increasing vaccination levels however, these results failed to reach statistical significance, highlighting the importance of adequate sample sizes when implementing this method. Finally, characterisation of the gut and faecal microbiota from animals shedding M. bovis in faeces confirmed that the source of faecal M. bovis is most likely sputum that has been expelled from the lungs, and not from colonisation of the gut. The work presented here suggests that this non-invasive monitoring method can be applied to examine the variable pool of M. bovis over periods of time and large areas, providing an epidemiological tool which has the potential to be implemented to monitor infection in badger populations and disease intervention strategies.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:682902 |
| Date | January 2015 |
| Creators | King, Hayley C. |
| Publisher | University of Warwick |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://wrap.warwick.ac.uk/77509/ |
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