Localised badger culling in response to bovine tuberculosis (TB) outbreaks increases the risk of infection in nearby herds, according to a new analysis.
The study, by researchers at the Medical Research Council Centre for Outbreak Analysis and Modelling at Imperial College London, is published today in the Royal Society journal Biology Letters.
The findings come as the Government prepares to decide whether to license farmers to organise the widespread culling of badgers over areas of 150 square kilometres or more in western England.
Bovine TB is a major animal health problem in Britain. In 2009, one in every 10 cattle herds tested showed evidence of bovine TB, leading to 35,000 cattle being slaughtered. In the last decade, the slaughter of infected cattle has cost around 500 million to the taxpayer.
Efforts to control the disease have been hampered by the persistence of Mycobacterium bovis, the bacterium that causes bovine TB, in the wild badger population, and transmission of the disease between species.
The new analysis found that the presence of any reactive culling activity in the previous year within one kilometre of a herd more than doubled the risk of bovine TB, even after adjusting for the number of confirmed outbreaks nearby. The number of badgers culled in the vicinity of the herd was also associated with increased bovine TB risk.
"These findings add to the evidence that localised reactive badger culling has a detrimental effect on tuberculosis risk for cattle," said Professor Christl Donnelly, from the MRC Centre for Outbreak Analysis and Modelling at Imperial College London, who led the study. "This may explain why culls in the past were ineffective at reducing the incidence of bovine TB."
The findings may be linked to the observation that surviving badgers in a partly-culled group wander over a larger area, increasing their contact with neighbouring cattle. This is kn
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Imperial College London