British Columbia health authorities are reporting at least 64 people have fallen ill after consuming raw oysters from various restaurants and vendors in the southern part of the province.
The norovirus-like gastrointestinal illness was first reported Nov. 1, and additional reports have been made over the past month and a half in the Vancouver Coastal Health, Fraser Health, and Island Health regions, the BC Centre for Disease Control says in a Dec. 19 advisory.
Certain areas of the province, including portions of Baynes Sound to the west of Denman Island, have been closed to commercial shellfish harvesting by federal agencies while investigations are ongoing.
“Those affected have reported symptoms of diarrhea, vomiting, and/or stomach pain after eating raw oysters from restaurants and retail locations,” the advisory says. “While some individuals have visited emergency departments, there have been no hospital admissions reported.”
Norovirus frequently leads to gastrointestinal disorders and is particularly prevalent in the winter season.
Symptoms typically begin 12 to 48 hours after infection and last between 24 and 72 hours with the most common being nausea, vomiting, cramps, fever, and diarrhea, the agency says. Symptoms may be severe and can result in several bouts of vomiting within a brief timeframe potentially resulting in fluid loss or dehydration, which poses a significant risk for young children and the elderly.
Norovirus is easily spread from person to person and can also be contracted through the ingestion of contaminated food or water, the advisory says.
Food contaminated with noroviruses may look, smell, and taste normal, the agency notes, adding that oysters can become contaminated in the marine environment in which they are grown and harvested.
“The BC Centre for Disease Control and regional health authorities are reminding the public of risks associated with consuming raw or undercooked oysters, especially those who may be at higher risk of severe illness such as children, older adults or people who may be immunocompromised,” the agency says.
The BC CDC recommends consuming only cooked shellfish because the heat destroys viruses and bacteria, decreasing the risk of contracting a gastrointestinal illness. Shellfish should have a minimum internal temperature of 90°C for 90 seconds.
Thorough hand washing with soap and water prior to handling food, keeping cooking areas clean, separating raw and cooked seafood to prevent cross-contamination, and sanitizing knives and cutting boards are all important steps to avoiding food-related illnesses, the agency says.
Oysters that do not open while cooking should not be consumed, the agency notes. Oysters that do open should be eaten immediately after cooking with the leftovers refrigerated.
