A study of DNA analysis has shown for the first time that tuberculosis (TB) can spread between cattle and badgers living near farms.
Researchers found outbreaks of the disease were linked between the animals by monitoring changes in the bacteria's DNA during a spread of bovine TB in Northern Ireland.
They mapped the genetic blueprints, or genomes, of bacteria isolated from 26 cows and four badgers while the disease spread.
The findings, published in the online journal Public Library of Science Pathogens, could not prove whether the disease was spreading from badgers to cattle or in reverse.
But the evidence is likely to prove significant in the debate over controversial Government plans for a mass badger cull in England, which was recently postponed amid widespread protests.