bovine TB (bTB) and badgers

What is bovine TB?

Bovine tuberculosis (bTB), as the name suggests, is a strain of TB which mainly affects cattle and is caused by Mycobacterium bovis (M. bovis). Unfortunately this strain of the disease also causes TB in badgers, as well as other wildlife and domestic animals, and causes ~0.5% of the human TB cases in the UK.

A brief history of bovine TB and government policy:

1930’s: At least 40% of UK cattle are infected with bTB
1935: Government start cattle bTB testing and slaughter policies
1966: Only 1% of UK herds now showing positive for bTB
1971: First bTB found in badgers in Gloucestershire
1973: Badger Act enacted to protect badgers (but not from government culls)
1975-82: Ministry of Agriculture gas badgers in ~4500 setts in bTB hotspots using hydrogen cyanide at concentrations far too low to humanely kill badgers
1989-94: Irish ‘East Ofaly Project’ a trial cull of badgers using snares
1998-2002: Four Areas Badger Cull in Ireland
1998-2005: Randomised Badger Culling Trial in England
2009: Welsh Assembly Governmaent announce a plan to cull badgers in Wales – delayed by Badger Trust judicial review but 2nd plan announced in 2011
2010: English government announce plans for English badger cull including the possibility of allowing farmers to shoot free running badgers!

BCG Vaccine

Bacillus Calmette-Guérin (BCG) is an attenuated strain on M. Bovis which is widely used around the world as a vaccine against human TB. It protects mainly against severe childhood forms of TB. Recent study and field trials published by Mark A Chambers et al. 2010 demonstrated that intramuscular BCG vaccination of badgers reduced the severity and progression of bTB infections. It concluded “…BCG vaccine… could provide a new and important component of a comprehensive programme of bovine TB control for cattle in UK and Ireland. Several more trials have started up, by DEFRA, the National Trust, the Gloucestershire Wildlife Trust and others.

bTB Statistics

Cattle slaughtered as a result of bTB testing:

Graph below clearly shows that the rises suffered started with the almost complete lack of cattle TB testing and slaughter during the 2001 foot and mouth outbreak.

DEFRA bTB pages: www.defra.gov.uk
Badger Trust: www.badger.org.uk