If not badgers, then how is bTB spread?

Recycling infection in the herd through inaccurate testing:

  • The Government policy depends heavily on the skin test which Government scientists estimate to be only 50-80% accurate.  So up to half of the bTB-infected cattle go undetected & therefore remain in the herd.

  • Even where accurate, the skin test only detects infection at an advanced stage once antibodies have developed. By this time, the animal may well have spread infection.

  • Cattle identified as infected are not removed immediately; farmers have up to 10 working days to remove infected cattle, during which time they can spread the disease to other cattle.

  • Inaccurate testing leaves an undetected reservoir of infection in the herd, carrying a high risk of repeat outbreaks even after a herd has had the ‘all clear’. Infection can also be spread to unborn calves.

  • Cattle farmed intensively in stressful conditions in the close confines of a barn are thought to be more susceptible to disease.

 

Manure and slurry:

  • bTB can be spread through ingestion as well as via respiration.  Infected cows shed bacteria in their dung at a very high rate, with just 1 gram containing enough bTB organisms to infect another cow (Sibley)

  • Bacteria can survive for months in slurry which may be spread on pasture and can be washed into streams.

  • There is thus a high risk of infection spreading to:

    • cattle kept in barns.

    • cattle grazing on pastures on which slurry has been spread.

    • badgers eating earthworms, slugs, snails etc, infected by slurry.

  • Infection may also spread to neighbouring farms via transmission on slurry lorries or via the watercourse.

  • Fears have also been raised that hunts traversing farms may be spreading infection to previously bTB free farms. 

 

Cattle movements – bTB on tour:

  • The huge number of cattle movements every year within and between different risk areas (eg. over 1.7 million in 2016) risks new infections.

  • Live auctions bring together hundreds of cattle from a wide regional catchment. 

  • Risk-based trading, whereby purchasing decisions are informed by cattle and environmental data, is currently voluntary and poorly supported;

  • The same unreliable skin test is used for testing the vast number of annual cattle movements.  If only 50% of infected cattle are identified by the test, this leaves huge numbers of infected cattle moving from county to county.   Hence, the disease is spreading throughout the UK.  

 

Other players:

  • Badgers are not the only wildlife to carry bTB so it is possible that there is some risk of infection from deer and other wildlife.