The fact that the differential diagnosis of inflammatory bowel disease includes intestinal infections has been a source of much interest and clinical concern for many years. Since the recognition of ulcerative colitis and Crohn's disease as clinical entities, numerous attempts have been made to identify a specific organism resulting in the clinical and pathologic picture of inflammatory bowel disease. The isolation, in 1984, of M.paratuberculosis initiated the current interest in and controversy about a mycobacterial etiology in Crohn's disease. The hypothesis that Crohn's disease is Johne's...