Dáil Éireann Debate, Tuesday - 15 September 2020
897. Deputy Niall Collins asked the Minister for Agriculture, Food and the Marine the percentage of animals slaughtered under the tuberculosis eradication programme deemed to have the disease post-mortem. [23911/20]
View answerWhen cattle are slaughtered as reactors under the TB eradication programme, it is because they have tested positive for infection with TB. In the past 12 months, 20,993 cattle have been slaughtered as reactors under the TB eradication programme, as they are deemed to be infected with the TB disease agent. The test specificity is estimated at 99.98%, meaning the number of false positives to the skin test is estimated at 1 animal in 5,000 tested. However, the skin test has an estimated sensitivity of 80% which means that approximately 1 in 5 animals infected with TB will not be identified by the test, on average. This means that false negatives are much more problematic for the TB programme than false positives.
Visual inspection of reactor carcases at post-mortem finds that, on average, approximately 30% of such reactors have visible lesions of tuberculosis, meaning the infection has progressed to a stage where the disease process has caused such significant tissue damage that it can be seen with the naked eye. If a reactor does not have visible disease lesions, it does not mean it is not infected; visual inspection cannot detect the presence of microscopic lesions and bacteria within the tissues of such animals.
Separately from the slaughter of TB reactors, all non-Tb reactor cattle routinely slaughtered in Ireland are subjected to a post-mortem veterinary inspection which includes surveillance for lesions suspected to be caused by TB. Each year, approximately 3,600 such suspect lesions are identified and of these, approximately 45% are subsequently found by laboratory testing to have been caused by TB. The herds from which those animals came are then subjected to follow-up testing to identify any other undetected infected cattle.
