A widespread badger cull is unlikely to stop the spread of bovine TB (bTB) across Britain, according to a new study.
But a targeted cull could help control infections in TB hotspots such as south-west England or south Wales, say researchers.
Peter Atkins, from Durham University's Institute of Hazard, Risk and Resilience, claimed the impact of badgers had been over-exaggerated.
Speaking to medical journal Epidemiology and Infection, Prof Atkins explained: "Badgers almost certainly play a part in spreading the disease, but my conclusion is that their impact over the decades has been far less than suggested.
"Very carefully arranging culling may have a part to play alongside other measures in areas of particular prevalence such as south-west England and south Wales, but my research suggests that extending the policy elsewhere may neither be justified nor particularly effective. It certainly won't be a panacea."
The government is determined to start a badger cull in two pilot areas this summer, after postponing it last year, to test whether the free shooting of badgers is "safe, humane and effective". If the trial is successful, the policy could be rolled out more widely before the end of 2014.
But Prof Atkins claimed other factors needed to be considered alongside a badger cull.
He said: "It is very probable that other animals did and do carry TB including badgers and deer, but cattle-to-cattle transfer is likely also to be an important factor.
"For example, only one out of nearly 400 badgers killed in road accidents in Cheshire over two decades tested for the disease turned out to be positive.
"This goes against received wisdom that bTB would have stayed in badgers which obviously weren't culled when the cattle were in previous decades and they then reinfected cattle stocks.
"But this interspecies transference seems unlikely to have occurred on the necessary scale."
Furthermore, no-one has yet proved definitively which direction the infection travels between species, he added.
"The Randomised Badger Culling Trial (RBCT), which ran from 1998-2006 indicated complex, interwoven patterns of infection and concluded badger culling was unlikely to be effective for the future control of bTB."
"If our analysis showing the lack of disease persistence in medium and low density badger populations is correct, the improvement of cattle controls including improved testing, tighter movement controls and, eventually, a useable vaccine should be enough to halt the spread."
Professor Peter Atkins, Durham University
Prof Atkins believes bovine TB in badgers is a spillover disease from cattle rather than an endemic condition and probably does not persist over lengthy periods.
He warned that a badger cull may "exacerbate the problem".
"When badgers are disturbed, they seem to perceive they are being attacked and move from their original area by a kilometre or more and join other badger groups, which spreads the disease," he said.
After the 2001 foot-and-mouth crisis, different parts of the country were restocked with cattle from the South West. And Prof Atkins said this could have spread bovine TB to other regions that previously had a low incidence of the disease.
A likely solution to the problem may lie in vaccination, but unfortunately inoculating cattle for TB is forbidden by EU rules as it would render testing for the disease ineffective, because all vaccinated cattle would test positive for it.
A cattle vaccine is unlikely to be commercially available for at least a decade.
Prof Atkins concluded the government should take a more comprehensive approach to controlling TB. He said: "The assumption that badgers are always responsible for this disease in cattle has to be reviewed.
"If our analysis showing the lack of disease persistence in medium and low density badger populations is correct, the improvement of cattle controls including improved testing, tighter movement controls and, eventually, a useable vaccine should be enough to halt the spread.
"We should continue to investigate, and cooperate with farmers over this problem."
A DEFRA spokesman said: "We have always been clear that a badger cull can make a meaningful contribution to reducing the spread of TB as part of a wider strategy to control the disease.
"Controlling the disease in wildlife is only one part of our approach to tackling TB. We have introduced tougher restrictions on the movement of cattle, a more comprehensive testing regime and we are encouraging farmers to improve their on-farm biosecurity to reduce the amount of contact between cattle and badgers. We are also continuing to invest in cattle and badger vaccines which could play a role in the longer term."
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Bovine TB and the badger cull
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