The incidence of the inflammatory bowel diseases (IBDs), ulcerative colitis and Crohn’s disease has markedly increased in industrialised countries during the past few decades. In contrast to these countries, where helminthosis is rare, IBD is still uncommon in global areas where most people carry worms.1 2 Thus lack of exposure to parasites may critically contribute to the risk of IBD. In an article in Gut, Summers et al3 demonstrated efficacy of treatment with Trichuris suis in active Crohn’s disease (Gut 2005;54:87–90). T suis was additionally shown to be effective in ulcerative colitis in a randomised trial carried out by the same group.4 However, neither study addressed the mechanisms of action. Here we present a real-life scenario, which supports the impact of helminths in the prevention of IBD, and provide a rationale for the mechanisms of action.

A 12-year-old girl was admitted to our hospital with pasty and sporadically bloody stools. Outpatient rectal treatment with mesalazine …