On April 1, 2017, a community fundraiser was held in Freeport, Minnesota. The event was a spaghetti dinner and silent auction attended by approximately 700 people. Food at the event was prepared and served by volunteers.

On April 3, 2017, the Minnesota Department of Health (MDH) foodborne illness hotline received an email reporting illness in event attendees. Seventy-nine attendees were interviewed. Forty-three met the case definition. Ten stool specimens were tested. All were positive for norovirus GI.II. Two of the isolates were sequenced and had identical nucleic acid sequences (GII.P16-GII.2).

In a multivariate model, salad (adjusted OR, 4.5; 95% CI, 1.2 to 16.2; p=0.02) was independently associated with illness. The salad was obtained pre-cut and pre-washed in bags. The bags were emptied into a large bowl, and shredded carrots and cabbage were added. Glove use was reported during salad preparation.

A complete list of volunteers was not available. Nineteen of 41 individuals who were specifically asked about volunteering at the event helped with food or beverage service. None reported illness before the event. Eight were ill after the event with illness consistent with the illnesses reported by event attendees.

The source of contamination was not identified.