Uncooked oysters from Canada’s Pacific Coast have been confirmed as the source of a norovirus outbreak. according to the British Columbia Center for Disease Control.

Oysters making people ill have been traced to a section of Effingham Inlet on Vancouver Island’s west coast.   The oysters were harvested between Sept. 7 and Sept. 21.

Because of the outbreak, the Canadian Food Inspection Agency (CFIA) issued an expanded warning about eating oysters. 

The public warning originally included Evening Cover Oysters Processing of Nanaimo, B.C.  It was expanded to include Albion Fisheries of Victoria, Albion Fisheries of Vancouver, Pacific Rim Shellfish of Vancouver and Sea World Fisheries of Vancouver.

BC’s Center for Disease Control reports that at least three clusters of norovirus in the Vancouver area are related to eating uncooked oysters from Effingham Inlet.

Canadian officials did not say how many people have come down with symptoms of the virus, which include nausea, vomiting, diarrhea and stomach cramps usually within 48 hours of consuming raw oysters and lasting for several days.

Oysters feed by filtering large amounts of water through their gills.  When the water is contaminated with norovirus, the virus can build up in the flesh of the oyster.

Norovirus–which can spread from person to person as well as through tainted food or in water contaminated by feces–is a common cause of gastroenteritis, but is rarely fatal. 

Cooking kills the virus.

Involved in the investigation, which continues, are: CFIA, Vancouver Coastal Health, the BC Center for Disease Control, the Public Health Agency of Canada, and Health Canada.