Research carried out in Ireland indicates that, up to 2008, using a detailed post mortem and histological examination, 35-50% of badgers in high cattle TB prevalence areas were infected with TB compared with an infection rate of 14.9% in areas of low cattle TB prevalence areas thereby substantiating the link between the presence of TB in cattle and in badgers. However, more recent research has shown that the percentage of badgers now infected with TB in previously high cattle prevalence areas has halved since then. The reduction in the incidence of TB in badgers is welcome and indicates an improvement in the health of the badger population. It is to be hoped this will also have knock on benefits for any future badger vaccination programme.
With regard to the impact of TB in badgers for TB in cattle, a research paper published in 2010 summarises the evidence on the role of badgers in the spread of TB in cattle both in Ireland and the UK and concludes that “badgers are directly implicated in the transmission of infection to cattle” and “the ability to eradicate tuberculosis is severely constrained while infection continues to be spread from badgers” (Mycobacterium bovis Infection in the Eurasian Badger (Meles Meles): the Disease, Pathogenesis, Epidemiology and Control (Science Direct) ).
There is considerable evidence that the removal of badgers results in a reduction in the incidence of the disease in cattle. In summary, the first major research project into the impact of badgers on TB incidence in cattle in East Offaly found that the risk of herd breakdowns was found to be 14 times higher in the control area compared with the area from which the badgers were removed. A later study, the Four Area Project, involved the intensive and proactive removal of badgers in four “removal” areas and “reactive” culling of badgers in matched reference areas. The published results of this project also demonstrated that there was a significant reduction in TB levels in cattle following the removal of badgers. In view of this research and in order to limit the spread of TB from badgers to cattle, the Bovine TB eradication programme implemented by my Department contains a wildlife strategy involving the removal of badgers by culling when an epidemiological investigation associates a TB herd breakdown with the presence of badgers. This strategy is an important element of Ireland’s bovine TB eradication programme and has contributed to a significant reduction in the incidence of bovine tuberculosis in the cattle population in recent years. TB reactor numbers were 18,500 in 2011, the lowest recorded number in any year since the commencement of the eradication programme in the 1950s.
My Department is satisfied that the badger culling strategy has contributed to a reduction in the incidence of TB over the past number of years. However, it is my intention to replace badger culling with vaccination when research demonstrates that this is a practicable proposition. There are trials ongoing at present to determine if vaccination of badgers can provide an effective alternative to badger culling in the longer-term and to develop an efficient and effective vaccine delivery methodology.
