In February 2011, public health investigators from the Hennepin County Human Health and Public Service Department (HSPHD) investigated an outbreak of norovirus among patrons who at dined at a restaurant located in Plymouth, Minnesota. The implicated meal date was February 6. Five outbreak associated cases were identified. No one was hospitalized and no one died. A stool specimen collected from one case tested positive for norovirus GII.

Illness histories and job duty information were obtained from the 16 restaurant employees. No
employees reported having had gastrointestinal illness previous to or on the implicated meal date. HSPHD sanitarians noted several critical violations when conducting an inspection of the restaurant. Critical violations included no employee illness log; no record of proper freezing of raw fish for parasite destruction; a container of crunchy topping used to coat sushi pieces was held at room temperature instead of being refrigerated; sushi rice was held out of temperature control for more than 4 hours; a metal bowl used to mix sushi rice was not properly washed, rinsed and sanitized; and plastic wrap used to cover some of the bamboo sushi mats was not changed at least every 4 hours.

Investigators concluded this was a foodborne outbreak of norovirus gastroenteritis associated with eating at a restaurant. The vehicle of transmission was not identified; however, most cases ate sushi. It is possible that the sushi chef who reported mild symptoms was the source of contamination. Reusing single-use gloves and improper sanitizing of bowls and utensils could have contributed to contamination of food.