Badgers have always been blamed for the spread of bovine TB, but recent evidence indicates that their role may be less important than previously thought. A major study published last year found that while badgers favour grazing land for their sets, they actively avoid contact with cattle herds. In addition, analysis of TB incidence in the wake of the Foot and Mouth crisis suggests that cattle may be responsible for infecting badgers, not the other way around.
Just as badger droppings and urine are blamed for infecting cattle with TB, slurry is also a suspected carrier of the disease. Indeed, some evidence suggests that cattle themselves can act as disease vectors without showing symptoms. The skin test currently used is said by Department officials to be 99.5% accurate, which would mean just one in 10,000 infected cattle would not show symptoms. But wildlife groups arguing against badger culls say that TB tests can be as little as 80% reliable. Certainly some infected cattle are not detected. This leaves a gap on our side.
Ireland has recently shown a willingness to be flexible in its approach to TB control, by vaccinating remaining badgers in areas which have already experienced culls, after acknowledging that badger culls lose their impact after a certain time. The effectiveness of vaccination is still under review and many are sceptical that it will work. Certainly the culling which has been carried on since the 1960s has reduced overall incidence of TB, but even Department officials have realised that after a period of incidence reduction, badger culling alone is not enough.
Reduced culls have not been welcomed by farmers, who want to see badger eradication stepped up in TB areas, but what if a significant number of TB infections are coming from cattle herds themselves? In the UK this seems to have been the case. For example, TB was eradicated in Cheshire prior to Foot and Mouth in 2001, but after culled herds had been restocked using cattle from the south-east, incidences of TB suddenly grew. Professor Peter Atkins of Durham University believes that cattle were responsible for re-introducing TB: “Almost certainly a proportion of the increase in bovine tuberculosis after 2001 is the result of that restocking after foot-and-mouth disease.”
John Krebs, a zoologist at the University of Oxford, agrees. He led a nine-year study into the effectiveness of badger culls finding that by culling around 70% of badgers authorities could reduce bovine TB by about 16%. For Krebs this end does not justify the means. He says, “the much bigger issue is cattle-to-cattle transmission within and between herds.” Both of these academics have come out against badger culls, based on their belief that these policies have outlived their usefulness. They want the UK to look towards policies that have been successful in other countries.
For example, Switzerland has managed to eradicate bovine TB altogether through increased controls on cattle movement, more frequent tests and by culling entire herds where the disease is detected. In Ireland we only remove reactors, but we know that not all carriers of the disease show up in tests. If we are serious about eradicating TB, then we need to cull entire herds where reactors are found. Nobody wants to lose their valuable herd, built up over years of careful breeding, but disease eradication comes at a price. We are willing to wipe out badger sets, we must also offer something if this program is to be a success.
Increased biosecurity by farmers and reduced transfers of animals between herds also seem to have real potential to minimise incidences of TB infection. Use of badger-proof water troughs and barriers to keep them out of feeding areas in farmyards will help. But before we blame the badger for all our TB woes, we ought to be sure we have minimised the risk factors on our side. Only by culling entire herds will we actually follow other countries towards a successful TB eradication. Anything short of this and we will be struggling with the issue for generations to come.