Inflammatory Bowel Disease: Historical Perspective, Epidemiology, and Risk Factors.

Inflammatory bowel disease (IBD) describes a group of closely related yet heterogeneous predominantly intestinal disease processes that are a result of an uncontrolled immune mediated inflammatory response. It is estimated that approximately one and a half million persons in North America have IBD. Pathogenesis of IBD involves an uncontrolled immune mediated inflammatory response in genetically predisposed individuals to a still unknown environmental trigger that interacts with the intestinal flora. There continues to be an enormous amount of information emanating from epidemiological studies providing expanded insight into the occurrence, distribution, determinants, and mechanisms of inflammatory bowel disease.