Recent Developments in Nonspecific Inflammatory Bowel Disease

Etiology and PathogenesisUlcerative colitis and Crohn's disease are probably heterogeneous disorders,195 , 196 each of which shares similar clinical, pathologic, and biologic features; their individual identification will ultimately depend on the recognition of common characteristics (e.g., distinctive pathologic features, immunologic patterns, or genetic traits). No accepted analogues of inflammatory bowel disease have been found in animals or reproduced experimentally,197 , 198 and there is no evidence that another species acts as a reservoir for any putative infectious agent or agents for these human diseases.199 Ulcerative colitis and Crohn's disease are more common in some countries (e.g., the United States, England, and Scandinavia, with . . .