Badgers and cows share TB strain, Defra study finds

A Defra study has confirmed that badgers share the same strain of Mycobacterium bovis (M. bovis), the bacterium responsible for bovine TB, with local cattle populations.

This reinforces findings from previous research in 2022, which involved post-mortem examinations by the Animal and Plant Health Agency (Apha) of badger carcasses collected from two cull regions, Wiltshire and Gloucestershire.

If M. bovis was detected, the samples were subjected to Whole Genome Sequencing (WGS) analysis.

See also: New rapid bovine TB test to be developed

In Wiltshire, 10.6% of badgers tested positive for M. bovis, with two genetic groups called “clades” (B6-11 and B6-91) identified that matched local cattle cases.

In Gloucestershire, the prevalence was 14.5%, with five clades detected, again consistent with local cattle breakdowns.

Defra said establishing the direction of transmission between host species requires more M. bovis isolates from positive cattle and badgers, and further analysis of the WGS data.

Expert reaction

While Professor James Wood, an expert on bovine TB from Cambridge University, acknowledged that the data suggests potential transmission between badgers and cattle, he said that most TB transmission occurs within species (ie cattle to cattle, or badger to badger).

But ecologist Tom Langton said this new data does not shed any light on the transmission of disease between species.

Mr Langton, an outspoken critic of badger culling, also raised concerns that intensive culling of badgers has not significantly reduced TB levels among them, questioning the effectiveness of current strategies aimed at achieving healthy cattle alongside healthy wildlife.

“How does this fit with the original aspiration to create healthy cattle alongside healthy badgers?” he asked.

Defra response

A Defra spokesperson said: “Bovine tuberculosis has devastated British farmers and wildlife for far too long. It has placed dreadful hardship and stress on farmers who continue to suffer the loss of valued herds and has taken a terrible toll on our badger populations.  

“That is why are working at pace in rolling out a TB eradication package to stop the spread of this horrific disease.”