The U.S. Food and Drug Administration is helping Canadian officials investigate an outbreak of norovirus infections and is recommending that consumers avoid eating certain oysters to avoid infection.

The FDA is also warning restaurants and retailers to not sell the implicated oysters. If oysters are not in their original packaging — such as when dining out — consumers should ask if the oysters came from the implicated areas. If the restaurant cannot provide the information, the oysters should not be consumed.

Oysters contaminated with norovirus may not look, smell or taste any different from non-contaminated oysters.

The implicated oysters were sold between Jan. 16 and Feb. 17 and may have been frozen in the supply chain. They were harvested from Deep Bay, Baynes Sound subarea 14-8 or subarea 13-16 (landfile #140185) in British Columbia, Canada, which should be indicated on packaging.

More specifically, the oysters in question were harvested from the following areas: Deep Bay, Baynes Sound subarea 14-8 landfiles #0278744, #0278742, #0278741, #0278740, #1414396, #0319716, #1414456, #1414457, #1400483, #1411206, #1407063, #1408485, #0278739, #0278737, #1403139, #0278734, #1411153 and #1411195 and subarea 13-16 landfile #1401845 in British Columbia, Canada.

As of the posting of the warning on Feb. 23, there were no confirmed infections in the United States, however many people who suffer symptoms of norovirus do not seek medical treatment. Anyone who has severe vomiting and/or diarrhea for more than 24 hours should seek medical attention and tell their health care provider about the potential exposure to norovirus.

“The Canadian Food Inspection Agency (CFIA) has received multiple reports of illness linked to the Deep Bay area,” according to a notice from the Canadian Food Inspection Agency. “Due to potential contamination, the Pacific Region Interdepartmental Shellfish Committee agrees a closure is warranted for oysters at these aquaculture facilities (listed above) until further notice.”

The FDA is awaiting information on distribution of the oysters and will continue to monitor the investigation and provide assistance to state authorities as needed.

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 shellfish 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 these steps:

• 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.

Symptoms of norovirus infection may include vomiting and/or diarrhea, nausea, muscle aches, fever, and headache, according to the U.S. Centers for Disease Control and Prevention. Symptoms typically start 12 to 48 hours after exposure and can last for one to three days. Most people recover without treatment, however some may need medical attention for dehydration.

Norovirus is highly contagious and infected people can spread the infection easily to others. The virus can live on surfaces for long periods of time. Droplets in the air from the vomiting of infected people can also spread the virus to people and contaminate surfaces.

To prevent others from getting sick always wash hands carefully with soap and warm water after using the bathroom, changing diapers or caring with potentially infected people. Use soap and water to clean toilets or other areas that may be soiled with feces or vomit. 

Hard surfaces can be disinfected with 1/3 cup household bleach mixed with one gallon of water – always wear gloves when handling bleach-based cleaners. Wash soiled clothing and bedding in hot water and detergent. Soft surfaces that cannot be laundered can be steam cleaned.