[Helminths and inflammatory bowel diseases]. / Helminthes et maladies inflammatoires chroniques intestinales.

The current etiologic model of inflammatory bowel diseases proposes a genetically predisposed host responding to a variety of environmental triggers by exhibiting an abnormal immune response to normal luminal flora. Crohn's disease is common in highly industrialized western countries where helminths are rare and uncommon in less developed areas of the world where most people carry worms. From this observation grew the hygiene hypothesis, which states that our failure to be exposed to previously common infectious agents alters the immune repertoire established in childhood. Helminths diminish immune responsiveness in naturally colonised humans and reduce inflammation in experimental colitis. Crohn's disease involves over reactive T-helper (Th1) pathways, and helminths blunt Th1 responses, inducing production of Th2 cytokines. Helminths also induce regulatory T cells to maintain host mucosal homeostasis. Thus, there is an immunological basis to expect that exposure to helminths such as Trichuris suis will prove beneficial in Crohn's disease. Exposure to helminths may be effective in treating inflammatory bowel diseases and was well tolerated, according to the results of few studies. Its long-term safety remains unknown.