Ulster Unionist MLA, Robin Swann, has revealed through a series of Assembly Questions that over the last three years there have been 1,468 herds which had TB reactors but which the disease was not later confirmed either by post-mortem or laboratory testing.
These farms were then closed for an average of 149 days each.
Mr Swann, who sits on Stormont’s Agriculture Committee, said: “TB is a blight on our local industry.
“The discovery of a reactor can have a seriously detrimental impact on the operation of any farm business. Cattle in restricted herds may not be moved to other herds or to markets, and instead are only permitted to be brought to an abattoir. Such rules restrict cash flow as cattle can’t be sold and very literally they start eating into the marginal profits that should have made on the animal.
“Movement of any cattle from a closed herd is prohibited until a full series of TB tests is first carried out. I fully appreciate that once a reactor has been found in a herd both the farmer and the Department need to react swiftly in order to control the risk of the disease spreading.
“I was shocked however when it was recently revealed to me by the Agriculture Minister that there have been nearly 1,500 herds closed over the last three years alone for false TB readings. On average these farms, where the tests were later found to be negative, their herds were closed on average for 149 days. Many will wonder why, even after no trace of TB was found, it was still necessary for their herds to be close for almost five months.
“I accept that the vast majority of tests are accurate, however that will be little comfort to those farmers who have been so severely restricted when ultimately the disease may not be present at all.”
In response a department spokesperson said: “The Single Comparative Intra-dermal Tuberculin Test (SCITT or skin test) is the surveillance test for bovine TB required by the EU in Bovine TB eradication programmes. It is a biological test with a high “specificity” calculated to be about 99.98% when standard test interpretation is used. With this high specificity false reactors (animals which are skin test reactors but which are genuinely not infected) will be very much in the minority.
“The nearly 1500 herds mentioned did not have false TB readings. To put this in perspective we would only expect about one false TB reactor per five thousand disease-free animals tested. Therefore, finding a reactor in a herd is very likely to mean that the animal is infected. Finding two reactors in a herd means that TB infection in these reactors is extremely likely, whether or not this is confirmed at post mortem examination.
“TB lesions may be very small and localised in a carcase and hard to detect, particularly in the early stages of infection. Whilst TB is regularly confirmed in reactors after slaughter it should be noted that a TB reactor is never subsequently proven not to have had TB,” the spokesperson concluded.