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About bovine TB

Bovine tuberculosis (TB) is an infectious disease of cattle. It is caused by the bacterium Mycobacterium bovis (M. bovis). This can also infect and cause bovine TB in other animals, eg badgers, deer, goats, pigs, camelids (llamas and alpacas), dogs, cats, etc.

It is also a zoonotic disease, which means it can be transmitted from infected animals to people where it causes a condition very similar to human TB. However, the risk of people contracting bovine TB from cattle in Great Britain is currently considered very low.

History of the disease

The trend of cattle TB incidence in England has been rising for 25 years.  The area affected by TB has spread from isolated pockets in the late 1980s to cover large areas of the west and south west of England and Wales. The maps below show the extent of the problem in those areas:

TB extent maps (GB) for 1986 and 2009

 

Clinical signs and transmission

The clinical signs of bovine TB (eg weakness, coughing and loss of weight) are now rarely seen in GB cattle due to the slow progression of infection. The Government’s compulsory testing and slaughter programme ensures that most cattle herds are tested for bovine TB at least every four years. This identifies most infected cattle before the disease is apparent.

There is still some uncertainty surrounding bovine TB and the way it is transmitted, but it is mainly a respiratory disease, caught by breathing in the M. bovis bacteria that cause bovine TB. This usually happens when animals are in close contact with each other, so animal density is a major factor in the transmission of M. bovis. Bacteria released into the air through coughing and sneezing can spread the disease to uninfected animals.

Direct transmission can happen, eg through nose to nose contact. There is also evidence that indirect transmission is possible, eg through contact with saliva, urine, droppings, pus from abscesses, etc. We know bovine TB is transmitted from cattle to cattle; from badgers to cattle and cattle to badgers; and badger to badger.

Page published: 8 December 2011