---

Bovine Tuberculosis

Answer

The single intradermal comparative cervical tuberculin (SICCT) test, commonly known as the tuberculin ““skin test””, is the primary screening test for TB in cattle in Great Britain and other parts of the European Union (EU). The skin test, which is used throughout the world to screen cattle, other animals and people for TB, is the internationally accepted standard for surveillance for infection with mycobacterium bovis and is considered the best screening test currently available for detecting TB in live animals. No diagnostic test is 100 per cent accurate, but the current skin test is effective. Published research from studies around the world shows that skin testingwill detect approximately 80 per cent of all infected cattle (at standard interpretation). This is known as the test's sensitivity. Occasionally, reactions to the tuberculin test can be caused by exposure to other mycobacteria; when the skin test is applied to cattle without TB, there is a one in a 1,000 chance that a non-infected animal will be wrongly classified as a reactor. This is known as the test's false positive rate. An alternative way of defining this is to say that the skin test has a specificity¹ of 99.9 per cent. In October 2006, the Government extended the use of the gamma interferon blood test, alongside the skin test (as permitted by EU legislation), to improve the sensitivity of the testing regime for controlling disease in infected herds by identifying more infected animals more quickly. It is being applied mainly in herds disclosing TB infection in low risk areas to help ensure infection does not become established in cattle or wildlife. It will also continue to be available for use as a disease control tool in areas of higher incidence. In line with recommendations from the scientific community, Defra continues to fund further research into improved diagnostics for bovine TB. The cost to government of cattle testing in Great Britain for 2004-05 was £36:4 million and for 2005-06 it was £36.7 million. These costs include: tuberculin costs, arranging, assessing and monitoring tests, conducting investigations of incident herds and meeting the costs of private vets—local veterinary inspectors—who carry out most of the TB testing work. The cost to government of surveillance activity by the Veterinary Laboratories Agency, which includes tuberculin costs, was £4.9 million in 2004-05 and £7.5 million in 2005-06. We cannot provide an estimate of ““indirect costs””, which are difficult to define, although we certainly acknowledge that the farming industry also incurs costs to support the TB testing programme. Compensation paid for TB reactors and contact animals compulsorily slaughtered across Great Britain in the past four years is shown in the table below. Figures include salvage money received by the Government for those carcasses permitted to go into the food chain or eligible for the over 30-month scheme.

Year	2002-03	2003-04	2004-05	2005-06
Compensation paid (£ million)	31.9	34.4	35.0	40.4
¹ Specificity is the ability of a test correctly to identify non-infected animals identified as negative (the higher the specificity the lower the probability of false positives). Sensitivity is the proportion of infected animals detected as positive (the higher the sensitivity the lower the probability of false negatives).
No diagnostic test, including the tuberculin test, is totally accurate, ie 100 per cent sensitive and 100 per cent specific, as there is a trade-off between these two properties.

Secondary information

Type

Written question

Reference

3173; 691 c231-3WA

Session

2006-07

Subjects

Compensation Expenditure Testing Bovine tuberculosis

Contains statistics

Yes

Link

View this Written question on www.publications.parliament.uk