A foodborne norovirus outbreak at a hospital and an attached long-term care facility

We investigated a foodborne norovirus outbreak in a hospital and an attached long-term care facility (LTCF). An at-risk group of 698 people was identified, which included staff, hospital patients, LTCF residents, and adult daycare users who shared consumption of food prepared in a central kitchen. Three different diets were prepared in three separate sections: a standard diet, a special diet, and a diet for residents at the LTCF. During the first 3 days of the outbreak, 47 (16%) of 285 staff members and 55 (13%) of 413 patients became symptomatic. Eating the standard diet was significantly associated with a risk of illness for staff members (relative risk [RR], 18.13; 95% confidence interval [CI], 5.76-57.03) and patients (RR, 2.12; 95% CI, 1.05-4.31). Some stool samples were positive for norovirus GII/4. The standard diet may have been contaminated while being prepared in the central kitchen.