An evaluation of the gamma interferon test for detecting bovine tuberculosis in cattle 8 to 28 days after tuberculin skin testing

The gamma interferon (IFN-gamma) test was evaluated for its ability to diag nose bovine tuberculosis in cattle that 8 to 28 days previously had a posit ive caudal fold skin test. The sensitivity of the test was determined in a group of 163 Mycobacterium bovis-infected cattle from 21 herds. The specifi city was estimated in a group of 213 cattle which had reacted to a caudal f old test, but were from 82 herds that had no evidence of infection with M b ovis. The sensitivity and specificity of the IFN-gamma test was 85 and 93 p er cent respectively. No significant differences in the sensitivity and spe cificity of the test were observed between blood samples that were cultured on the day of collection and those cultured the day after collection. Thes e findings support the use of the IFN-gamma test as a practical serial test that can be used to complement the caudal fold skin test. (C) 2000 Harcour t Publishers Ltd.