Norovirus outbreaks on three college campuses - California, Michigan, and Wisconsin, 2008.

Noroviruses are the most common cause of outbreaks of acute gastroenteritis worldwide. Norovirus outbreaks affect persons of all ages and occur in a wide variety of settings (e.g., nursing homes, hospitals, restaurants, communities, schools, day care centers, military barracks, and cruise ships). During fall 2008, three norovirus outbreaks occurring on college campuses in California, Michigan, and Wisconsin were reported to CDC. Public health investigations led by the respective state and local health departments were conducted to characterize the extent of the outbreaks and implement appropriate control measures. This report summarizes the investigations of these outbreaks, which resulted in a total of approximately 1,000 cases of reported illness, including at least 10 hospitalizations, and prompted closure of one of the three campuses. Median duration of the three outbreaks was 19 days (range: 16-20 days), and the attack rates ranged from 1.5% to 12.9%. Because of the potential for widespread infection and rapid transmission on college campuses, efforts to prevent and control norovirus outbreaks in these settings should focus on promoting hand hygiene, environmental disinfection, and exclusion of ill food workers.