Postinfectious irritable bowel syndrome after a food-borne outbreak of acute gastroenteritis attributed to a viral pathogen

Background & Aims: A large outbreak of acute gastroenteritis at the annual meeting of the Canadian Society of Gastroenterology Nurses and Associates (CSGNA) was attributed to food-borne norovirus. A prospective study was undertaken to determine the incidence and natural history of postinfectious irritable bowel syndrome (PI-IBS). Methods: Questionnaires addressing demographics, medical history, acute illness, prior bowel function, and current symptoms were mailed to all delegates within 1 month of the outbreak. Follow-up questionnaires were mailed at 3, 6, 12, and 24 months. The prevalence of new Rome I IBS among participants with and without acute enteric illness during the outbreak was calculated for each time point. Risk factors were assessed by multiple logistic regression. Results: Baseline surveys were returned by 139 of 197 delegates (70.6%; mean age, 48 +/- 6 years; 95.0% female), of whom 135 (97.1%), 133 (95.7%), 128 (92.1%), and 116 (83.4%) returned the 3-, 6-, 12-, and 24-month surveys, respectively. One hundred seven respondents (76.9%) reported an acute enteric illness during the outbreak. Eighteen subjects reported premorbid IBS. Among the remainder, 21 of 89 who experienced gastroenteritis (23.6%) reported symptoms consistent with PI-IBS at 3 months versus 1 of 29 (3.4%) who remained well (odds ratio, 6.9; 95% confidence interval, 1.0-48.7; P =.014). At 6, 12, and 24 months, the prevalence of IBS was similar among exposed versus nonexposed individuals. In multiple logistic regression, vomiting during the acute illness independently predicted risk of PI-IBS at 3 months (odds ratio, 10.5; 95% confidence interval, 1.3-85.5; P =.028). Conclusions: PI-IBS is common after presumptive viral gastroenteritis but might be more transient than after bacterial dysentery.