Culling Badgers Probably Increases Transmission Of Tuberculosis, Study Finds

A cattle farmer's nightmare. Coatesy/Shutterstock

There’s an infectious disease going around and the authorities are undecided whether to vaccinate or exterminate infected individuals. In the UK, countryside-dwellers have been given the green light to kill any disease-carriers seen straying onto their land, although a new study reveals that this approach could actually lead to more transmissions than before.

Thankfully this rule doesn’t apply to humans, but is directed at badgers that carry Mycobacterium bovis, the causative agent of bovine tuberculosis (TB). In an effort to reduce badger-to-cattle transmissions, a badger cull was introduced in rural Britain in 2011, but the latest data shows that this initiative may well have backfired.

Publishing their findings in the Journal of Applied Ecology, a team of researchers used GPS collars to track and compare the movements of badgers in areas with and without farmer-led culling between 2013 and 2017.

As badger numbers fell in regions affected by the cull, survivors were observed roaming over much greater areas, covering an average of 61 percent more ground and visiting 45 percent more fields each month than they had done before the cull. They were also found to be 20 times more likely to trespass onto a neighboring group’s territory each night once the cull began.

This shift in behavior occurred as the removal of these little woodland critters opened up territories to other individuals who previously wouldn’t have dared step on another group’s turf.

As a result, badgers who managed to evade the cull were able to spread their urine and poop over a much wider area, increasing the likelihood of it coming into contact with cattle.

Study co-author Rosie Woodroffe explained in a statement that “as badger-to-cattle transmission is likely to occur through contamination of their shared environment, and TB bacteria can remain viable for long periods of time in the environment, the effects of increases in ranging behavior could create a source of infection for several months.”

The study also found that, as competition for food dropped once badgers started being killed, survivors were able to gather their nightly sustenance much faster than before, resulting in badgers spending about 90 minutes less out of their sett each night. This then made it much harder for farmers to kill them, suggesting that, ironically, the cull may actually be protecting the badgers and increasing their chances of infecting nearby cattle with TB.

Based on these findings, the researchers – along with most animal rights groups – point out that vaccination may offer a more effective and more humane approach to curbing badger-to-cattle TB transmissions.

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