At least 34 people statewide have contracted norovirus in the past few weeks in California after eating raw oysters harvested in British Columbia, Canada, state health officials said Saturday.

The state Department of Health issued a warning not to eat raw oysters imported from British Columbia where officials have closed multiple growing regions for sanitary contamination.

In California, people who ate oysters at nine restaurants throughout the state between March 11 and March 19 reported getting ill. Illnesses associated with oysters from British Columbia have also been reported in other U.S. states, the department said.

Despite issuing multiple recalls of oysters from British Columbia, the health department said it has continued receiving reports of people getting ill. It advised restaurants and retailers to check their inventory and shellfish tags to ensure that potentially contaminated raw oysters are not available for purchase, and to discard any leftover contaminated oysters.

Canada has reported more than 270 cases of gastrointestinal illness linked to the consumption of raw oysters.

Norovirus is contagious and causes inflammation of the stomach and intestines. Symptoms include vomiting, diarrhea and fever.