Veterinary and Biomedical Sciences, Department of


Date of this Version



Published in Annual Review of Microbiology 58 (October 2004), pp. 329–363; doi: 10.1146/annurev.micro.58.030603.123726 Copyright © 2004 Annual Reviews. Used by permission.


Johne’s disease is a chronic diarrhea affecting all ruminants. Mycobacterium avium subsp. paratuberculosis (MAP), a slowly growing mycobacteria, is the etiologic agent. There is also a concern that MAP might be a causative agent of some cases of inflammatory bowel disease in humans, especially Crohn’s disease. Food products including pasteurized bovine milk have been suggested as potential sources of human infection. This review addresses microbial factors that may contribute to its pathogenicity. In addition, the experimental evidence defining MAP as the cause of Johne’s disease and the issues and controversies surrounding its potential pathogenic role in humans are discussed.