Eight year prognosis of postinfectious irritable bowel syndrome following waterborne bacterial dysentery.

Although postinfectious irritable bowel syndrome (PI-IBS) is a well-recognised complication of acute gastroenteritis, its prognosis remains poorly defined. The natural history of PI-IBS was assessed among participants in the Walkerton Health Study (WHS), which has followed the long-term effects of a large outbreak of acute gastroenteritis related to municipal water contamination in May 2000. WHS participants were invited to return for annual assessment at a research clinic. Adult residents of Walkerton at the time of the outbreak who enrolled in 2002/2003 and returned for assessment in 2008 were eligible for a PI-IBS study cohort if they had no prior history of IBS or inflammatory bowel disease. A modified Bowel Disease Questionnaire was used to diagnose IBS by Rome I criteria and to identify IBS subtypes. Of 4561 WHS participants, 2451 returned for their 8 year assessment and 1166 were eligible for the PI-IBS study cohort (688 females, mean age 46.2 years). The prevalence of IBS among 742 eligible subjects who suffered acute gastroenteritis during the outbreak declined from 28.3% after 2-3 years to 15.4% after 8 years, but remained significantly increased compared with controls who did not have acute gastroenteritis (OR 3.12; 95% CI 1.99 to 5.04). Independent risk factors for PI-IBS at 8 years included female gender, younger age, prior anxiety/depression, and fever or weight loss during the acute enteric illness. IBS subtypes were not stable over time. Acute gastroenteritis can trigger IBS symptoms that persist for at least 8 years. Characteristics of the host and the acute enteric illness can predict the long-term risk of PI-IBS.