Diagnosis and control of bovine paratuberculosis (Johne's disease).

The literature on Johne's disease is quite extensive. The disease has been diagnosed throughout the world in a wide range of domestic and wild animals, but mainly ruminants. It is of economic importance only in cattle, sheep, and goats. A diagnostic test that is both sensitive and specific has not yet been found. This failure may be due either to the spectral nature of the immune response in an affected animal or to the impurities of the antigen preparations utilized in the various tests. Control and eradication of the disease is still in the research stage. Vaccination has been adopted mainly in Europe, with apparently satisfactory results. Vaccine evaluation has not always been correctly carried out. Several other control strategies have been attempted or suggested. None has been finally evaluated, and the disease is still a challenging problem.