final report - ARCHIVE: Defra

Environment and epidemiology
assess the risk that environmental Mb poses to cattle. In addition, should the development of a PCRbased
environmental screening tool prove feasible, research will be required into the development of
optimal sampling regimes in order to minimize the cost of screening potentially very large numbers
of sites.
4.6 Role of wildlife other than badgers
4.6.1 Two major Defra-funded investigations into the prevalence of bTB in wildlife other than badgers
have recently been undertaken. The first of these (SE3029, University of Oxford; see Mathews et al.,
2006) involved culture of Mb from faeces, urine and tracheal aspirates taken from live animals (mostly
rodents). The second (SE3010, CSL; see Delahay et al., 2007) involved culture of Mb from tissue
samples taken from carcasses of a wider variety of species including rodents, sciurids, carnivores and
ungulates. The second study also involved a semiquantitative risk assessment taking into account not
only the prevalence of TB in the wildlife species in question but also ecological factors affecting the
potential for transmission of infection to cattle. Both studies suggest that the only wildlife species posing
a potential risk to cattle, other than badgers, are deer, especially fallow deer Dama dama. Subsequent
Defra-funded field, laboratory and modelling work (SE3036, CSL; SE3037, Risk Solutions) suggests
that although red and fallow deer are likely to excrete Mb into the environment, there is at present
only a low risk that they transmit bTB to cattle. Nevertheless, wild deer do pose a significant risk to
cattle in other countries, especially when the deer in question occur at high densities (for references see
Wilsmore & Taylor, 2008).
4.6.2 Although it is widely believed that deer are becoming more numerous and more widespread in the
UK, the source of this perception is unclear since systematic data on nationwide population trends
in most species of deer are lacking. Relevant information seems especially sparse in the case of fallow
deer (Battersby, 2005). We therefore recommend that Defra liaise with relevant bodies, such as Natural
England and the Tracking Mammals Partnership, to ensure that adequate monitoring systems are in
place to provide reliable information about the distribution and numbers of deer, especially fallow
deer, now and in the future.
4.7 Modelling
There will be an increasing need to use models to represent multiple causal links within the ‘system’ to
help explain and predict many aspects of bTB. This necessary development was highlighted in the recent
review by Pfeiffer (2007). To be more effective, there should be increased coordination of the different projects
investigating all aspects of this disease. Of four modelling projects reviewed, only SE3026 generated any data,
while the others (SE3117, SE3229, SE4202) all relied on pre-existing data. However, as highlighted above,
there is a perceived need for improved summary data for bTB in cattle so some effort should be extended to
generate such a resource.
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