Infections which cause ileocolic disease in animals: Are they relevant to Crohn's disease?

Abstract

There has been a striking rise in incidence of Crohn’s disease in the last 20 yr, which is not simply due to increased recognition of the condition.’ In these circumstances there may be a major etiological factor operating in the environment, and one possibility, which has been considered, is an infectious agent. Possible infective agents have been identified in human studies, although their significance has not yet been established. A variety of acute and chronic infections affect the terminal ileum and colon of animals, and the pathology often resembles that seen in Crohn’s disease. Animal models of Crohn’s disease have received little attention although they may offer some guide to the etiology in humans. In some cases extensive efforts have been made to identify the causative agent because of economic implications in the food industry. Where such an agent has been identified, it has often been difficult to culture and in some cases is an intracellular bacterium. We do not suggest that these conditions in animals are Crohn’s disease, but in view of the similarity to ileocecal inflammatory bowel disease in humans, it would seem pertinent to review the current literature in the hope that one may identify useful areas for investigation. This may lead to some progress with this difficult problem.