Testing for Bovine TB more effective than badger culls at controlling the disease

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Modelling produced by researchers at Queen Mary University of London (QMUL) has found that the only effective potential Bovine Tuberculosis (TB) control strategies are badger culling, cattle testing, controlling cattle movement, and ceasing the practice of housing farm cattle together during winter.

Modelling found that in a region containing about 1.5m cows of which 3000 to 15,000 might have TB, badger culling could account for a reduction of 12 in the number of infected cattle. While reducing the testing interval by one month could reduce the number of those infected by 193.

The model showed that regular and frequent testing of cattle could eventually lead to the eradication of the disease, whether or not badgers were culled and despite the current test being at most 80% accurate. Badger culling alone, however did not lead to TB eradication in the study and is therefore unlikely to be a successful control strategy.

The model also suggested that housing cattle in large sheds over winter could potentially double the number of infected animals in a herd, as under such conditions there is a much greater chance of TB being passed between cows.

This is the first large-scale model of TB in cattle and badgers that included the possibility of the infection being passed in both directions between the two species. The model successfully mimicked the changing patterns of TB in the UK, including the changes seen after TB controls were reduced during the foot-and-mouth epidemic of 2002.

Researchers Dr Aristides Moustakas and Professor Matthew Evans, of QMUL’s School of Biological and Chemical Sciences, used state-of-the-art computer modelling to understand how the interaction of different factors impacted on infection rates. Such factors included the movement and life-cycles of badgers and cattle; how cattle are moved and housed; how frequently cattle are tested, different types of badger culling; and the infection rates between animals.

The research is published online in Stochastic Environmental Research and Risk Assessment.

Professor Matthew Evans, Professor of Ecology at QMUL, said “Of the available Bovine Tuberculosis control strategies we believe that how frequently cattle are tested and whether or not farms utilise winter housing have the most significant effect on the number of infected cattle.

“TB is a complex disease and modelling it is difficult but we’ve successfully used our model to replicate real world situations and are confident that it can be used to predict the effects of various changes in the way we tackle the disease.

“Our modelling provides compelling evidence, for those charged with controlling Bovine TB, that investment in increasing the frequency of cattle testing is a far more effective strategy than badger culling.”

Responding to the findings Dominic Dyer of the Badger Trust and Care for the Wild said: “This research is large-scale, objective, and takes into full account the possibility of badgers being responsible for bTB infections in cattle – yet still it concludes that the answer to beating this disease is to focus on the cattle.

“This is the message we at Care for the Wild and the Badger Trust, and many others, have been hammering home over the last couple of years, so maybe now the government will feel the need to actually listen.

“The role badgers play in spreading this disease has been massively exaggerated, and the impact of culling them has been completely misunderstood. The fact that keeping large numbers of cows in winter sheds can lead to a doubling in the number of infected animals shows again the simple truth that bTB is caused by cattle spreading it to other cattle. The impact of more frequent testing simply highlights the issue that many infected cows are currently being missed, and are thus spreading the disease without anyone realising. Find the infection, you’ll beat the disease.

“DEFRA will no doubt dismiss this as irrelevant, because it doesn’t fit with their political strategy. The NFU are trying to claim that the cull has already reduced rates of TB in the area, but there’s no way they can be claiming that. bTB rates are dropping across the whole of the south west – of which the cull zones are an utterly tiny part – and the reason for it can only be the increased testing and better cattle control measures brought in, reluctantly, by the government two years ago.”

New figures from the Welsh badger vaccination programme also highlights just how exaggerated the impact of badgers has been.

* In 2014, 1316 badgers were vaccinated and all were returned to the wild in good health. None needed veterinary treatment in view of poor condition, none were found to have visible TB lesions

* After three years of the five year vaccination project, over 3,500 badgers have been vaccinated so far. None have been found to have visible TB lesions, no badgers have been removed and euthanised as a result, all have been returned to the wild

* Between June 2013 and April 2014 the Welsh Government undertook a road kill survey of badgers in the Intensive Action Area (ie high risk TB area where vaccination is taking place). 30 badgers were collected and tested for TB, only two were found to have TB (early stage, no visible TB lesions) which is 7% of the total number of badgers tested

Mr Dyer added: “A poll in the Gloucester Post showed this week that two out of three people are against the badger cull being rolled out across the rest of the country.

“But this figure would be much higher if people weren’t being given the impression that huge numbers of badgers are infected, and weren’t told that culling them is vital to beating the disease. Huge numbers of badgers are not sick, and as we’ve been saying, and as this new research tells us, culling them is not vital, and in fact is not even useful.

“Wales has improved testing and cut the number of animals slaughtered for bTB by 50% - the answer is staring us in the face.”