To ask the Secretary of State for Environment, Food and Rural Affairs how many of the cattle slaughtered during (a) 2009 and (b) 2010 as a result of bovine tuberculosis testing subsequently proved to be negative for the disease.
Number of cattle slaughtered as skin and interferon gamma test TB reactors in England:
All TB reactors are regarded as infected and European and national legislation require all such animals to be slaughtered. Those cattle are then subject to post mortem examination and a proportion of them will also be sampled for laboratory culture, but this is not to prove or disprove the disease status of the animal. The primary purpose of post mortem and bacteriological culture of TB test reactors is to assess the severity of infection and identify the strain of the causative bacterium—this is useful for epidemiological investigations and helps to support subsequent outbreak control efforts. TB is a chronic and insidious infectious disease with potentially long incubation periods. In the early stages of this disease it is often not possible to see lesions with the naked eye, and due to the fastidious nature of the TB bacterium (which may be present in low numbers in the affected organs) it is not always possible to culture it from tissue samples. It is therefore wrong to consider all TB reactors that fail to disclose evidence of infection in the slaughterhouse or in the laboratory as being ‘false positives’ or ‘negative for the disease’.