The Thunder Bay District Health Unit confirmed Friday that it was the Norovirus that caused an outbreak of gastrointestinal illness that affected dozens of people.

CBC News reports Maltese Grocery had shut down its catering operations temporarily after 85 people became sick after eating food at three events the company had catered the previous week. They’ve since resumed, but with additional precautions.

Senior Public Health Inspector Abby Mackie said clinical specimens submitted to a lab confirmed the Norovirus to be the source of the outbreak.

“It looks as if we’re looking at a food handler that may have inadvertently transmitted the illness through food,” Mackie said.

“People can be shedding Noro-like virus and not even know. So, it’s really important to be very stringent with hand-washing, glove use and other cleaning and disinfecting.”

Maltese Grocery is making some additional changes to its cleaning and hand-washing procedures, including the use of new chemicals and sanitizers.

The owners of the company released a statement apologizing for the outbreak.

“We are very sorry for everyone who has been affected and we take full responsibility, ” Lisa and Dave Maltese said, adding that they are “working with the Health Unit and have taken every precaution to ensure this does not happen again.”