The Mecklenburg County Health Department believes norovirus is what caused customers and employees at Cowfish Sushi Bar and Grill to become sick.

Twenty-one employees and 34 customers reported flu-like symptoms, prompting the restaurant to close Saturday.

They have since sanitized and are back open.

The Health Department says it could have been passed on any number of ways.

“It could have been some contaminated object or presumably a contaminated food, but somebody had to have it to contaminate it in the first place,” said Dr. Stephen Keener, the medical director for Mecklenburg County.

The virus can live anywhere from days to weeks.