JOHNES-DISEASE IN A HERD OF FARMED RED DEER

An outbreak of Johne's disease in a herd of farmed red deer was studie d for four years. Serological, histopathological and cultural techniqu es were used to monitor the progress of the disease, and delayed type hypersensitivity skin tests were also applied. The results of the sero logical tests showed that they were poor predictors of future clinical cases and did not consistently identify animals harbouring mycobacter ia. The histopathological methods provided a sensitive and specific me ans of confirming the infection. The skin tests had a low sensitivity and the results were poorly correlated with the serological results in seropositive animals. A vaccination policy was instituted which was a ccompanied by a change in the pattern of disease. la!though the histop athological evidence suggested that the infection was still occurring, there was a marked reduction in the incidence of clinical disease. Va ccinated animals showed a good response to the skin test.