Badger project shows TB disrupts social groups

Scientists have demonstrated that the social lives of badgers change if they become infected with TB.

TB-infected badgers are more likely to be shunned by their own social groups than uninfected badgers, a study by researchers from the University of Exeter shows.

They found infected badgers, a significant reservoir for tuberculosis infection in cattle, were less likely to spread the disease within their own groups, but more likely to spread infection across groups.

This is because infected badgers, shunned by their social groups, were more likely to roam into other groups and facilitate the spread of disease across setts.

“In wild animals, just as in humans, social networks are very important for disease transmission,” said Robbie McDonald of the University of Exeter.

For the study, 51 badgers were fitted with electronic proximity collars that automatically tracked their social contacts.

PhD student Nicola Weber, from the university’s Centre for Ecology and Conservation, built a network of eight different social groups across the population and analysed the patterns of infection over a year.

She found TB-infected badgers were less well connected to their own social groups than uninfected badgers – but at the same time infected animals formed important links for the flow of infection between groups.

The work, funded by DEFRA, was conducted at the Animal Health and Veterinary Laboratories Agency’s National Wildlife Management Centre at Woodchester Park, Gloucestershire.

Commenting on the findings of the research, Prof McDonald said: “Social stability is thought to mitigate disease spread, perhaps by maintaining the distinctive position of these individuals.

“Culling badgers perturbs social structures and we think our findings may help understanding of so-called ‘perturbation’, where culling has been linked to increases in TB in badgers.

“Curbing TB infection in wildlife remains a challenge. Vaccination has the potential to disrupt disease flow, without perturbing social network structures.”

About 38,000 cattle were slaughtered in the UK in 2012 due to tuberculosis infection, costing the taxpayer an estimated £100m.

A pilot cull of badgers is under way in two counties in the South West as part of government control measures to eradicate the disease.

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