Tuberculosis in cattle and badgers passes between members of the same species at least twice as often than between cow and badger, a study has found.
Researchers analysing genetic data from the bacteria that causes the disease also found that cattle are approximately ten times more likely to catch tuberculosis (TB) from badgers than badgers are to catch it from cattle.
Scientists say the findings of the research – which was conducted in Gloucestershire over a 15-year period – could improve control strategies, reduce disease transmission and cut associated costs.
Bovine TB is an infectious respiratory disease of cattle that is mainly spread through inhaling infectious particles in the air. It is caused by the bacterium Mycobacterium bovis, which can also infect and cause disease in other mammals, including humans, deer, goats, pigs, cats and dogs.
Using data from an undisturbed population of badgers in Woodchester Park in Gloucestershire and nearby cattle farms, this study provides the first direct evidence of transmission between badgers and cattle. It is an area where tuberculosis is known to occur frequently in both cattle and badgers.
The researchers analysed the entire genetic make-up of the bacteria from 230 badgers and 189 cattle, a process known as whole genome sequencing.
They combined this with detailed information on where the cattle and badgers lived, when they were infected, and whether they could have had contact with one another.
Scientists were then able to estimate how often the two species spread TB. They found that badgers play an important role in the maintenance of the disease in this area.
The work was led by experts from the University of Edinburgh, with collaborators from institutions including the Animal and Plant Health Agency, the University of Glasgow and University College Dublin.