Possible norovirus contamination of certain farmed oysters being sold and served in Ontario has prompted a recall by the Canada Food Inspection Agency.
The notice about potential for microbial contamination affects certain Taylor Shellfish Canada ULC brands including Cloudy Bay, Fanny Bay and Sunseeker oysters, the agency says.
Recalled products should be thrown out or returned to the location where they were purchased, the CFIA said on its website.
Food contaminated with noroviruses may look, smell and taste normal, the agency warned.
The recall was triggered after a CFIA investigation into a foodborne illness outbreak in B.C., where the oysters are also sold.
According to a the B.C. Centre for Disease Control, between Nov. 1 and Dec. 18, there were 64 cases of norovirus-like gastrointestinal illness reported in the Vancouver coastal region.
Those affected have reported symptoms of diarrhea, vomiting and/or stomach pain after eating raw oysters from restaurants and retail locations, the notice states.
While some individuals have visited emergency departments, there have been no hospital admissions reported, the B.C. agency said.
Norovirus is a common cause of gastrointestinal illness, especially during winter. Symptoms begin 12 to 48 hours after infection and can include nausea, vomiting, cramps, fever and diarrhea.
Symptoms can be intense and generally last between 24 and 72 hours, the B.C. agency said.
Dehydration can be a serious problem for those who are very young and older adults, officials warned.
Norovirus spreads easily from person to person but can also be caused by consuming food or water contaminated with the virus.
Oysters can become contaminated if the virus is present in the marine environment where they are grown and harvested.
The B.C. Centre for Disease Control noted there are risks associated with consuming raw or undercooked oysters, especially for young children, older adults or people who may be immunocompromised.
To kill norovirus, cook oysters thoroughly — to an internal temperature of 90 degrees C for 90 seconds — before eating, the centre said.
