The Minnesota Department of Health on Friday said at least 60 people became sick after eating contaminated food at two events at downtown Duluth’s Greysolon Plaza Ballroom on Dec. 3.

That report was up from 40 people as of Thursday.

Trisha Robinson, a senior epidemiologist with the health department, said it appears the culprit was norovirus, the most common food-related illness in Minnesota, which is often spread by food-handlers who don’t thoroughly wash their hands.

People who have been ill should also refrain from preparing food, commercially or for their own families, for an additional 72 hours after they recover, Robinson said. The virus, which moves from anal to oral contact, is not easily spread by casual contact but moves fast through contaminated food.

Greysolon Ballroom remains open and able to serve food, Robinson said, but Department of Health staff members have been on site to make sure the facility is taking proper precautions to prevent the problem from happening again.

About 250 people attended one event and 100 attended the other at the Greysolon, state officials said. One was a wedding and the other a private party.