07/26/2012 04:57 EDT | Updated 09/25/2012 05:12 EDT

Cook shellfish to avoid illness, says BC Centre for Disease Control

VANCOUVER - The BC Centre for Disease Control is reminding Canadians that eating raw or undercooked bivalve shellfish such as oysters, clams, mussels, scallops and cockles could lead to illness.

Shellfish may accumulate bacteria (Vibrio parahaemolyticus), viruses (norovirus, hepatitis A), and toxins (paralytic shellfish poisoning, diarrhetic shellfish poisoning) or other impurities present in the water, the agency said Thursday in a release. Thorough cooking destroys bacteria and viruses but does not destroy toxins.

Five cases of locally acquired Vibrio parahaemolyticus infection have been reported so far this year while 42 cases were reported in 2011. These illnesses have been linked to raw shellfish served in restaurants, bought in stores, or self-harvested throughout British Columbia, including in the communities of Gibsons, Sechelt, Powell River, Ladysmith, Qualicum, Ucluelet, Gabriola Island, Cortes Island and Parksville.

B.C. has also experienced outbreaks associated with shellfish. In 2010, an outbreak of norovirus from raw oysters affected more than 30 people, and in 2011 more than 60 people became ill after consuming cooked mussels contaminated with diarrhetic shellfish poisoning.

Anyone becoming ill with diarrhea and vomiting after eating shellfish should report their illness to their local public health office or primary care provider and see a doctor if symptoms persist or become severe.

Here are some tips from the BC Centre for Disease Control to reduce the risk of shellfish-related illness:

— Buy shellfish from approved sources. All bivalve shellfish sold in British Columbia, for example, must come from a federally approved source, and outlets and restaurants selling them must be able to provide a shellfish shipper's tag, which ensures federal inspection.

— Eat only cooked shellfish. Cooking will destroy viruses and bacteria and decrease the risk of gastrointestinal illness. When cooking shellfish at home, ensure shellfish are kept in a cold environment at all times, use drinking-quality water to rinse ready-to-eat shellfish, and ensure adequate cooking time. Test oysters with a meat thermometer and make sure the temperature reaches 90 C (195 F) for 90 seconds. This will kill the Vibrio bacteria and minimize the risk of other infections.

— Prevent cross-contamination by storing raw and cooked seafood separately, cleaning and sanitizing knives and cutting boards and working with clean hands.

— Obey posted warnings and bans when self-harvesting shellfish.