Oyster Norovirus Outbreak Sickens at Least 328 in Canada

A large oyster norovirus outbreak has sickened at least 328 people in Canada as of April 8, 2022 (and at least 103 in the United States). Raw and undercooked oysters can contain pathogens such as norovirus that can make you sick.

The patient case count by province is: British Columbia (293), Alberta (3), Saskatchewan (1), Manitoba (15), and Ontario (16). Illness onset dates range fro mid-January and early April 2022. Not all cases hav been tested, but the presence of norovirus has been confirmed based on the tests of several patients.

The outbreak is linked to consumption of raw oysters from British Columbia. Some oyster harvest areas in British Columbia associated with this outbreak have been closed as a part of this investigation. Several food recalls have been issued in February, March, and April 2022.

Do not sell, use, eat, or serve the recalled oysters. And avoid eating raw or undercooked oysters to reduce your risk of foodborne illness. Always cook oysters to an internal temperature of 90°C (194°F) for a minimum of 90 seconds to kill norovirus and other pathogens. Note that steaming oysters until the shells open is usually not sufficient to kill pathogens.

Do not cook oysters or any other bivalve shellfish that stay open when raw, and discard these items that do not open when cooked. Keep raw and cooked oysters separate to avoid cross-contamination. Do not use the same plate or utensils for raw and cooked shellfish, and wash counters and utensils with soap and warm water after preparation.

Symptoms of a norovirus contamination include a fever, diarrhea, vomiting, nausea, stomach cramps, headache, chills, fatigue, and muscle aches. People usually start feeling sick 24 to 48 hours after exposure, but some people can get sick as quickly as 12 hours later.

If you have eaten raw or undercooked oysters harvested from British Columbia and have been ill with those symptoms, se your doctor. You may be part of this oyster norovirus outbreak.