Public health officials in the United States are warning consumers not to eat certain oysters harvested in Canada because of their link to a norovirus outbreak that has sickened hundreds.

“The (U.S. Food and Drug Administration) FDA and the states conducted a trace forward investigation to determine where the raw oysters were distributed and to ensure they’re removed from the food supply. Retailers should not serve raw oysters harvested from the following harvest locations (or landfiles) within Baynes Sound: #1407063, #1411206, #278737 in BC 14-8 and #1400036, in BC 14-15. “Baynes Sound” will show on product tags as “14-8”and/or “DEEP BAY”, or “14-15.,” according to the public warning issued today.

The FDA reports that the implicated oysters were distributed to retail stores and restaurants in the states of California, Colorado, Florida, Hawaii, Illinois, Maine, Minnesota, New Jersey, Nevada, New York, Oregon, Texas, and Washington.

“Oysters can cause illness if eaten raw, particularly in people with compromised immune systems. Food contaminated with norovirus may look, smell, and taste normal,” the FDA warns. Norovirus causes severe diarrhea and vomiting and is highly contagious. It can live on hard surfaces for long periods of time. Some patients may require hospitalization for rehydration.

As of today, health officials in Canada and three U.S. states have reported illnesses:

  • Canada – 279
  • California – 34
  • Minnesota – 29
  • Washington – 18

Reports of illnesses began in Canada in January. Reports in the United States continue to be logged, with the most recent having been made in late March.

Some oyster harvest areas in B.C. that have been associated with illnesses in this outbreak have been closed as a part of the investigation. Food recalls were issued in Canada on Feb. 18, March 20, March 23 and March 27 for oysters from certain areas of British Columbia.

The U.S. officials are working with Canadian public health authorities on an investigation into the outbreak.

Although there have been some recalls, “additional illness has been reported in California residents linked to oysters from British Columbia that have not been recalled.”

Anyone who becomes ill after eating raw oysters should contact their health care provider as well as report their illness to their local health department. 

“Avoid eating raw and undercooked shellfish, including oysters, to reduce your risk of illness,” said Dr. Tomás J. Aragón, California Department of Health Director and State Public Health Officer. “If you do eat shellfish, cook it until it reaches an internal temperature of at least 145 degrees F. Quick steaming isn’t sufficient to kill norovirus.”

Norovirus contaminated the marine environment through untreated human sewage and vomit. This may come from leaky septic systems, faulty waste water treatment plants, boaters, or beach-goers. Shellfish are filter feeders, which means they filter seawater through their bodies to get food floating in the water. When norovirus particles are in the water, shellfish can accumulate the virus in their bodies. For more information on outbreaks linked to ousters, please see: A Baker’s Dozen of years of Oyster Norovirus Outbreaks.

What Do Consumers Need to Do?
People should not eat any raw oysters from the locations listed above. If they have any of the listed products, they should throw them in the garbage.

People who think they might have become ill from eating possibly contaminated raw oysters should talk to their health care providers immediately.

Consumers should always practice safe food handling and preparation measures. Wash hands, utensils, and surfaces with hot, soapy water before and after handling food.

For food preparation surfaces and food cutting utensils that may have come in contact with the potentially contaminated oysters, it is very important that the consumers thoroughly clean these areas and items.

It is also important to be aware that noroviruses are relatively resistant to heat. They can survive temperatures as high as 145 degrees F. Quick steaming processes that are often used for cooking shellfish may not heat foods enough to kill noroviruses.

What Do Restaurants and Retailers Need to Do?
Restaurants and retailers should not sell the potentially affected raw oysters. Restaurants and retailers should dispose of any products by throwing them in the garbage or returning to their distributor for destruction.

Restaurants and retailers should also be aware that the oysters may be a source of pathogens and should control the potential for cross-contamination of food processing equipment and the food processing environment. They should follow the steps below:

  • Wash hands with warm water and soap following the cleaning and sanitation process.
  • Retailers, restaurants, and other food service operators who have processed and packaged any potentially contaminated products need to be concerned about cross contamination of cutting surfaces and utensils through contact with the potentially contaminated products.
  • Retailers that have sold bulk product should clean and sanitize the containers used to hold the product.
  • Regular frequent cleaning and sanitizing of food contact surfaces and utensils used in food preparation may help to minimize the likelihood of cross-contamination.

(To sign up for a free subscription to Food Safety News, click here)