To ask the Secretary of State for Environment, Food and Rural Affairs of those cattle slaughtered as reactors and inconclusives under the bovine tuberculosis eradication scheme, how many (a) were found to be free of tuberculosis through (i) visual inspections of lesions and (ii) culturing of tissue samples after death and (b) entered the human food chain in each of the last three years.
The following table shows the number of cattle slaughtered under bovine tuberculosis (TB) control measures in England in each of the last three years, and details the number of cattle where infection with Mycobacterium bovis ( M. bovis) was not confirmed at post mortem examination.
|Number of cattle slaughtered( 1)||Infection not confirmed at post-mortem examination|
|(1) Includes cattle slaughtered as skin and gamma-interferon (gIFN) test reactors, skin test inconclusive reactors and direct contacts. |
(2) 2006-07 figures are provisional, subject to change as more data become available.
Following a TB breakdown, we aim to carry out post-mortem inspections of all the slaughtered cattle. Tissue samples are taken from the reactor (or if several animals must be removed, from a representative subset of those), to attempt isolation and molecular typing of the causative organism in the laboratory. This is done to support epidemiological investigations and management of the incident, rather than to validate the ante-mortem test results.
Failure to detect lesions of TB by post-mortem examination, or to culture M. bovis in the laboratory, does not imply that a test reactor was not infected with bovine TB. With TB in cattle, it is frequently not possible to observe lesions during abattoir post-mortem examination and, due to the fastidious nature of this organism, it is very difficult to isolate it from tissue samples without visible lesions.
Meaningful confirmation proportions for TB test reactors cannot be provided, as substantial numbers of skin and gIFN positive animals are not subject to laboratory culture, for example, once infection has already been identified in other cattle from the same herd.
Responsibility for inspecting TB carcases and their associated offal rests with the Meat Hygiene Service (MHS). Under the EU Food Hygiene Regulations, all animals herds with no visible tuberculosis lesions, plus any cattle with visible tuberculosis lesions localised in one organ or one part of the carcase, will have been considered fit for human consumption by the MHS.