Written question asked by Andrew George (Liberal Democrat) on Thursday, 6 May 2004, in the House of Commons. It was due for an answer on Thursday, 20 May 2004. It was answered by Ben Bradshaw (Labour) on Thursday, 20 May 2004 on behalf of the Department for Environment, Food and Rural Affairs.

Dept for Environment Food and Rural Affairs

Question: To ask the Secretary of State for Environment, Food and Rural Affairs, what assessment she has made of combinations of specificity and sensitivity applied in countries which have a bovine TB problem, in their use of the Bovigam gamma interferon test. - Inc figures.

Answer: Andrew George: To ask the Secretary of State for Environment, Food and Rural Affairs what assessment she has made of combinations of specificity and sensitivity applied in countries which have a bovine TB problem, in their use of the Bovigam gamma interferon test. [172565] Mr. Bradshaw: The performance of the gamma interferon (g-IFN) test (Bovigam) has been assessed by many authors in trials carried out in several countries with bovine tuberculosis (TB) problems. This research has been carefully evaluated by Defra and scientists from the Veterinary Laboratories Agency. In these trials, the sensitivity of the test has ranged between 55.4 and 100 per cent. and the specificity between 70.0 and 99.6 per cent. However, these results are influenced by the characteristics of the cattle populations in which the studies were carried out, the prevalence of cross-reacting organisms, the cut-off point used to interpret the g-IFN test and the criteria used to establish the M. bovis infection status of the trial animals (often known as the "gold standard"). It is not, therefore, straight forward to extrapolate specificity and sensitivity estimates directly from one country to another. Ideally, the performance of a diagnostic test for TB should be evaluated under the conditions and in the geographical area in which the test will be used.

Secondary information