The control of tuberculosis (TB) in British cattle is hindered by persistent infection of wild badger (Meles meles) populations. The Randomised Badger Culling Trial (RBCT), a large-scale field trial, demonstrated that widespread badger culling produced reductions in cattle TB incidence during culling, which were, to an extent, offset by elevated TB risks for cattle on adjoining lands. Once culling was halted, however, beneficial effects inside culling areas increased, while detrimental effects on adjoining lands disappeared. However, a full assessment of the utility of badger culling requires information on the duration of culling effects.
We have continued to monitor cattle TB incidence in and around RBCT areas after culling ceased. We have found evidence of an ongoing, but diminishing, benefit of proactive culling among herds inside the proactive culling trial areas continuing through at least 5 years following the final proactive culls. The effects observed outside trial areas have remained consistent with no ongoing effects of proactive culling in these areas.
At the time of abstract submission it is unclear whether Defra will proceed with licensing farmers to cull badgers using shooting of free-ranging badgers as well as cage-trapping and shooting. There are key differences between this proposed form of badger culling that undertaken within the RBCT so caution is required in extrapolating from RBCT results to what might be expected in areas subjected to this new form of badger culling.
Funding: The authors gratefully acknowledge the support of the United Kingdom Department of Environment, Food and Rural Affairs (Defra; http://www.defra.gov.uk/) for this work. CAD thanks the United Kingdom Medical Research Council (http://www.mrc.ac.uk/index.htm) for Centre funding.
Keywords: Incidence; M. bovis; Disease control; Badger culling
Biography: Christl Donnelly studied biostatistics at Harvard School of Public Health where she earnt an MSc and a DSc. In 1995 she joined the Wellcome Trust Centre for Epidemiology of Infectious Disease at the University of Oxford, headed by Roy Anderson, and built up a statistics unit, collaborating with a wide range of colleagues. Christl moved in 2000 with a group of like-minded colleagues to help form a new department, the Department of Infectious Disease Epidemiology at Imperial College London. Within the department, she is a PI in the MRC Centre for Outbreak Analysis and Modelling. She was the deputy chair of the Independent Scientific Group on Cattle TB (1998 to 2007) and played a key role in the design, analysis and interpretation of the Randomised Badger Culling Trial. She is currently PI of a Defra-funded grant undertaking further analyses of spatial and temporal trends in the RBCT data.