Question to the Department for Environment, Food and Rural Affairs:

To ask the Secretary of State for Environment, Food and Rural Affairs, how many cattle slaughtered as a result of severe interpretation skin tests were subsequently found to be clear of bovine TB in each of the last three years.

It is not possible to conclude that any bovine animal which is positive to the tuberculin skin test, whether at normal or severe interpretation, is clear of the disease. It is very likely that those cattle are infected with bovine TB, even if no visible TB lesions are found at post-mortem meat inspection. This is because the skin test used in the UK and Ireland is very specific, meaning it is very unlikely to generate a false positive result. TB researchers have estimated this likelihood to be approximately one false positive result for every 5,000 TB-free cattle tested using the standard interpretation of the skin test, and one for every 1,200 using the severe interpretation. Reactors to the skin test may therefore not have any visible lesions because they are either in the early stages of the disease, or the lesions are too small to be detected by the naked eye.