A Vermont restaurant linked to a norovirus outbreak that has sickened more than 50 people reopened Sunday as public health officials continued their investigation.

The Vermont Department of Health began the investigation this past Tuesday after numerous reports from sick people who had eaten at the Windjammer Restaurant and Upper Deck Pub in South Burlington, VT.

“If you dined at this restaurant between March 11 and March 23, please help us by taking the short survey below,” according to the state health department’s outbreak investigation page.

“The questionnaire takes less than 10 minutes to complete. Responses are anonymous. … Please complete the questionnaire whether you were sick or not.”

Health officials allowed Windjammer and Upper Deck operations to resume Sunday. The restaurant and pub were closed Friday and Saturday for cleaning and sanitizing. Norovirus is highly contagious, can live for long periods of time on surfaces such as tables, and can easily be transmitted via foods and beverages.

At least nine of the more than 50 people who reported becoming sick after eating at the Windjammer have been confirmed by laboratory testing to have been infected with norovirus. All of the sick people reported eating at the Windjammer of its affiliated Upper Deck Pub before becoming ill, according to the state health department.

Windjammer owner Tom O’Connell told the Burlington Free Press that there is no evidence the norovirus outbreak originated at restaurant, telling the newspaper it could have come in from a customer, employee or food vendor. “Norovirus travels in mysterious ways,” O’Connell said, according to the newspaper.

The U.S. Centers for Disease Control and Prevention report that norovirus is the most frequent cause of foodborne illness in the United States. It causes severe gastrointestinal symptoms including nausea, vomiting, diarrhea and stomach cramps. Symptoms of a norovirus infection typically begin 12 to 48 hours after being exposed.

The illness usually lasts one to three days in most people. Some people can become so dehydrated that they need special medical attention to receive IV fluids. There is no vaccine for norovirus and no course of treatment other than maintaining hydration.

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