Modelled impacts of badger culling on cattle TB in a real area with geographic boundaries

As a part of bovine tuberculosis eradication strategy, the Welsh Government has proposed a badger cull in a defined area in and around North Pembrokeshire, and has published information on herd densities and incidence levels within and close to the area. In the present study, three sets of previously published data relating the impact of badger culling inside and around previous culling areas to distances from culling area boundaries have been used to model possible impacts of the proposed cull, taking account of three possible scenarios in which geographic boundaries reduce, to varying extents, adverse effects caused by increased badger movements. For the scenarios considered, the results predict average changes in confirmed herd incidences (CHIs) in the range –15.7 (–29.1 to 1.6 per cent) to –25.3 per cent (–52.2 to 46.1 per cent) over a period of 10 years, comprising average changes in the culling area in the range −26.1 (–34.8 to –14.8 per cent) to –32.6 per cent (–59.6 to 47.6 per cent), and average changes on adjoining land in the range 4.5 (–21.8 to 39.8 per cent) to 7.8 per cent (–16.1 to 38.5 per cent). The overall impacts equate to average reductions in the number of CHIs of between 122 (37 to 187) and 158 (–254 to 304).