Badger cull may actually make TB spread worse, scientists warn

‘If you target certain pockets, you are disrupting the social network and making them move around lots, and this can spread the disease’

Culling badgers may help to spread TB further as it disrupts local populations and drives them into previously uninfected areas, a new study has found.

Scientists say unless strict rules are followed it may be better to carry out no culling at all rather than continuing an ineffective operation that makes things worse.

Campaigns to eliminate animals such as foxes, bats and wild boar to stop diseases spreading have been carried out on numerous occasions, with mixed results.

The badger cull conducted between 1998 and 2005 to protect British cattle from TB was one of the largest of its kind ever conducted, resulting in the death of 11,000 badgers.

While some locations saw infections drop, the trial also led to the disease spreading further into previously uninfected cattle and badger populations.

Despite these shortcomings, the government has proceeded with a new round of culling to bring the disease under control, leading to a further 30,000 badgers being killed.

The cull is highly controversial, with farmers and ministers often squaring off against campaigners who have called it “the biggest destruction of a protected species in living memory”.

Given the uncertainties surrounding it, researchers used mathematical models to predict the outcomes of different strategies and their impact on the spread of TB.

“Previously there wasn’t really an understanding of what affects the outcome of these culls,” Dr Naomi Fox, one of the study’s co-authors at Scotland’s Rural College, told The Independent.

She said a combination of factors including how much land people had access to for culling, how long the programme went on for and the number of animals targeted all impacted final success.

“If you don’t have access to too many fields and target certain pockets, you are disrupting the social network and making them move around lots, and this can spread the disease,” she said.

The team did not advocate a total end to the on-going operation, but said programmes should aim for a “Goldilocks zone” where culls are sufficiently intense without triggering local extinctions.

“We are also saying if the bit of culling you are doing is just going to make it worse, sometimes it’s better to just do nothing,” said Dr Fox.

She noted that the government’s stated goal of killing 70 per cent of all English badgers was broadly consistent with this.

The study was published in the Journal of the Royal Society Interface.

A review conducted by independent experts in November found the earlier cull had a “modest but real” impact on TB, but opponents maintained there was insufficient evidence for the current operation to justify the death toll.

Both groups agreed non-lethal methods like badger vaccinations and improved biosecurity measures by farmers were being overlooked while badgers were scapegoated.

Dominic Dyer, CEO of the Badger Trust, said the researchers were right to note the so-called “perturbation effect” by which animal movement helps spread disease.

“Despite the huge cost and cruelty involved, no reliable scientific evidence has been published to prove that badger culling is lowering bovine TB in or around the 31 cull zones across England,” he said.

A spokesperson for the Department for Environment, Food and Rural Affairs said: “Bovine TB remains one of the greatest animal health threats to the UK, causing devastation for hard-working farmers and rural communities.

"While the badger culls are a necessary part of the strategy, no one wants to be culling badgers forever.

“That is why we are pursuing a range of interventions to eradicate the disease by 2038, including tighter cattle movement controls, regular testing and vaccinations.”