Purpose: Describe foodborne norovirus outbreaks in the United States reported through NORS and characterize their attribution by setting, contributing factors, and implicated foods.
Methods: Data reported to the Centers for Disease Control and Prevention (CDC) through NORS for all suspected and confirmed foodborne norovirus outbreaks during 2009–2012 were extracted. Descriptive frequencies of outbreak characteristics were generated using standardized categorization schemes.
Results: During 2009–2012, 1,018 foodborne norovirus outbreaks were reported to CDC, resulting in 21,320 reported illnesses (median 12 illnesses/outbreak, range 2–303), 1,141 healthcare provider visits, 536 emergency department visits, 217 hospitalizations, and 2 deaths. Norovirus was laboratory confirmed as the etiology in 664 (65%) outbreaks; most (82%) were caused by genogroup II, specifically genotype GII.4 (53%). Restaurants were the most frequently reported setting of food preparation (60%), followed by catering or banquet facilities (18%) and private homes (7%). Among the 496 (49%) outbreaks in which factors contributing to contamination were reported, a food worker was implicated as the source of contamination in 373 (75%). At least one food was implicated in 380 (37%) outbreaks. Most implicated foods were consumed raw (70%) and considered ready-to-eat (57%); salads (23%) and sandwiches (7%) were implicated most frequently.
Significance: Foodborne norovirus outbreaks continue to occur with great frequency in the United States and result in substantial morbidity. Prevention efforts should target appropriate practices for handling of ready-to-eat foods and hygiene of food workers.
Disclaimer: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.