The specificity and sensitivity of the fluorescent antibody test for Mycobacterium johnei infection in abattoir and culled cattle.

In a series of 100 cattle in which there was no bacteriological or histopathological evidence of Mycobacterium johnei infection there were four positive reactions to the fluorescent antibody (FA) test with M johnei antigen and 20 to the complement fixation (CF) test. In a second series of 118 culled adult cattle M johnei infection was found in 26. The FA test was positive in 16 and the CF in 12 of those infected cattle. In 92 cattle with no evidence of M johnei infection the FA test was positive in seven and the CF test in 22.