How do cattle contract tuberculosis from badgers?

Answer 1

British farmers and successive governments have long believed that bovine TB was being spread by badgers and infecting the national dairy herd, and since the 1970s badgers have been culled by gassing (now ceased) and shooting in attempts to prevent this spread. Tests carried out by the Ministry of Agriculture in the early 1970s showed that TB was more common in badgers than in other species. In the first Badger Act (1973), meant that licenses had to be issued for the killing of badgers. However, there are various other theories concerning the transmission of TB to cattle, and badger culling remains a contentious issue in the UK. Research into the specific mechanisms of how cattle contract bovine TB from badgers and into normal levels of transmission when culling is not practised is scanty.

Answer 2

They are infected through the droppings of cattle who have TB, when the droppings are near a badger's set. Dung flies lay their eggs on the droppings, and badgers look in the infected stools for the fly eggs, and eat them, infecting themselves with TB. Then the badgers, in turn, pass it on to other cattle who come near their sets.