The pathogenesis, diagnosis and control of Johne's disease.

Since 1962, when the control of Johne's disease was last reviewed by the BVA technical development committee there have been no dramatic advances in diagnostic methods for Johne's disease or in methods of control. However, there has been a slow, but steady increase in knowledge of the various aspects of the disease. This article attempts to set out what is known and, more important, not known about the subject.