Scientists track badger–cow encounters to understand cattle TB

From Nature:

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Pictures of badgers meeting cows are mostly staged, as face-to-face encounters are extremely rare.

Badgers and cows are scattered across the English countryside, yet the two species rarely meet face-to-face, a large study has revealed1. The finding is not merely incidental. It sheds light on how badgers transmit bovine tuberculosis (TB) to cows: a question which UK researchers have spent more than a decade studying.

Since 2013, the UK’s government has sanctioned the killing of hundreds of badgers (Meles meles) in controversial culls to try to dampen the spread of bovine TB. The disease, caused by the bacterium Mycobacterium bovis, cost the country an estimated £100 million ($131 million) in 2014 alone through compensation and control measures.

But the latest government-funded study — which involved fitting GPS collars and radio collars to track the whereabouts of hundreds of cows and scores of badgers — suggests that bovine TB is probably not passed by direct contact between species, but rather indirectly through contaminated pasture, says Rosie Woodroffe, a badger specialist at the Zoological Society of London who led the work. Despite recording thousands of nights of data, the team didn’t observe a single contact between badgers and cows. “This helps to explain why TB is so hard to control,” she says.

The findings suggest that badgers like to hang around earthworm-rich cattle pasture, but not the cattle themselves. Badger faeces and sputum — and cow pats from infected cattle — might be the carriers of M. bovis in farms, Woodroffe says. And in most cases, pasture and slurry from herds in which bovine TB has been detected is not treated as infectious, she adds.

The work backs up an earlier, smaller-scale study in Northern Ireland, which also suggested that badgers don’t often meet cows2. “To have corroboration from a different …

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