Modified intra-dermal test for the diagnosis of paratuberculosis in goats

Abstract

Efficacy of single intra – dermal Johnin test was compared against two modified intra – dermal Johnin tests for diagnosis of paratuberculosis in goats. One hundred and fifty adult goats were divided at random into three groups and each group was subjected to one of the intra - dermal tests. Group 1 being the single johnin intra – dermal (SID) Johnin test whereas in group 11 (modified intra – dermal test – MID – 1) and group 111 (modified intra – dermal test – MID – 11). The second injections were given after third and fifth days of first injection. Six animals giving positive results and two animals giving negative results were slaughtered from each group and confirmation of infection was ascertained by histopathology. Fecal samples and rectal pinch from all the animals were subjected to zeihl – Neelsen’s acid – fast staining for detection for M. paratuberculosis. Serum magnesium levels of all test positive animals and an equal number of test – negative animals from each group were compared. After 24 h MID – 1 was found to be superior to both SID and MID – 11 tests. The MID – 1 test had higher specificity (66.6 per cent against 58.33 per cent in SID and 40 per cent in MID – 11) and predictive value of positive results (83.3 against 55.5 in SID and 50 per cent in MID – 11). The MID – 1 and MID – 11 tests had 100 per cent sensitivity and predictive value of negative results as against 50 per cent and 33.3 per cent of SID. Examination of fecal sample and rectal pinch was found to be of little value in the diagnosis of early paratuberculosis in goats. Serum magnesium levels between test positive and test negative animals was found to be not significantly different in all three groups. The results of the present study indicate that MID – 1 test could be used as an efficient diagnostic test for detection of paratuberculosis among goats.