Infections and IBD.

An interaction between infection and IBD was identified soon after Crohn's disease and ulcerative colitis were first described. Since then it has become apparent that infectious agents are involved with both the etiopathogenesis and clinical course of IBD on several levels. Whilst our understanding of this interplay is incomplete, it is clear that infections can initiate both the onset and relapse of IBD. Furthermore, the disease process itself predisposes patients to certain infections, and many drugs used to treat IBD also increase the risk of infectious complications. Attempts to establish the relative infectious risks associated with the drugs used to treat IBD remain in an early stage; but it seems that the greatest risks relate to the combined use of immunomodulating agents rather than to individual drugs. The risk of infections in patients with IBD might also be exacerbated by underuse of, and perhaps substandard response to, vaccinations. It is axiomatic that physicians treating patients with IBD must be aware of these infectious risks and of strategies to minimize them. Meanwhile, intriguing advances in the use of parasitic agents as a treatment for ulcerative colitis and Crohn's disease have introduced a new angle to the interplay between infections and IBD.