Risk factors for sporadic shigellosis, FoodNet 2005.

Abstract Background: An estimated 450,000 cases of shigellosis occur annually in the United States. Outbreaks have been associated with food, water, child daycare centers, and men who have sex with men. However, for sporadic infections, which account for the majority of cases, risk exposures are poorly characterized. Methods: Foodborne Diseases Active Surveillance Network (FoodNet) conducts active, laboratory-based shigellosis surveillance in 10 US sites. We interviewed cases with illness onset during 2005 about exposures during the week before symptom onset using a standardized questionnaire. The proportion of patients who denied nonfood risks was used to estimate the burden attributable to foodborne transmission. Results: Overall, 1494 cases were identified. The approximate incidence was 3.9/100,000, with the highest rates among children aged 1–4 years (16.4) and Hispanics (8.4). Of the 929 cases interviewed, 223 (24%) reported international travel in the week before symptom onset. Of the 626 nontraveli...