California based S&M Shellfish Co. has issued a product recall for oysters after confirming multiple illnesses due to norovirus contamination. The oysters affected were sold under the names Fanny Bay, Buckley Bay and Royal Miyagi Oysters and were harvested between December 1st and 9th in British Columbia. 

California restaurants and businesses affected by the recall include San Francisco’s Waterbar, San Francisco’s Mission Street Oyster Bar, Redwood City’s Hurrica, Santa Rosa’s Santa Rosa Seafood and San Pablo’s Mariscos La Playita, according to a notice from the California Department of Public Health. The oysters were also distributed in Arizona, Colorado, Washington, D.C., Florida, Georgia, Hawaii, Illinois, Kentucky, Missouri, Nevada, New Jersey, New York, North Carolina and Pennsylvania.

The U.S. Food & Drug Administration is recommending businesses dispose of these products or return them to their distributor for destruction. The oysters can be identified by the original harvesters or producers, printed on the shellfish tag: Pacific Northwest Shellfish and Union Bay Seafood.

Washington company Rudy’s Shellfish also recently issued a recall of oysters and Manila clams harvested from Nov. 15 to Dec. 11 due to a norovirus outbreak. The affected shellfish were distributed in California as well as other states.

More than 70 people reported feeling ill after eating oysters at the LA Times’ 101 Best Restaurants event in Los Angeles on Dec. 3, according to L.A. Taco. The Los Angeles County Department of Public Health is investigating a norovirus outbreak associated with the oysters served at “an event on December 3,” a spokesperson told L.A. Taco without referring to the LA Times party specifically. An LA Times spokesperson told L.A. Taco that the oysters served at the event were Fanny Bay Oysters originating from British Columbia and sourced by Santa Monica Seafood.

The Desert Sun reported this week that there have been 57 confirmed and probable cases of norovirus reported by people who ate raw oysters from British Columbia at California restaurants, according to the CDPH. 

Norovirus symptoms include diarrhea, vomiting, nausea, stomach pain, fever, headache and body ache, according to the FDA. Symptoms usually develop between 12 and 48 hours after exposure and last one to three days. 

What is Norovirus?

    When someone talks about having “the stomach flu,” they are probably describing acute-onset gastroenteritis caused by one of the noroviruses, which are members of the “calcivirus” family (Caliciviridae).[1] Noroviruses are entirely unrelated to influenza viruses.[2]

    The Centers for Disease Control and Prevention (CDC) estimates that noroviruses cause nearly 21 million cases of acute gastroenteritis annually, making noroviruses the leading cause of gastroenteritis in adults in the United States. Norovirus is highly contagious and transmitted by infected individuals at an enormous rate. It is simple genetically and evolves quickly, and exposure does not lead to lasting immunity. It is estimated that each individual experiences norovirus five times during their life.[3]

    How Common is Norovirus?

    Currently, norovirus is the most common cause of acute gastroenteritis in the United States.[4] While bacterial causes of foodborne illness, such as pathogenic Escherichia coli and Salmonella, are often cited as commonly reported sources of food poisoning, noroviruses cause 58% of foodborne illnesses acquired in the U.S. Thus, norovirus is the leading cause of outbreaks from contaminated food in this country. According to CDC estimates, this translates into about 2,500 reported norovirus outbreaks in the United States each year. Norovirus outbreaks occur throughout the year but are most common from November to April. About 1 in every 15 individuals in the U.S. will get norovirus illness annually. By five years of age, one out of every 14 children will visit an emergency room, and one out of 278 children will be hospitalized due to norovirus.

    In humans, norovirus is transmitted primarily through the fecal-oral route, with as few as 10 to 100 virion particles needed to initiate infection. Transmission occurs either person-to-person or through contamination of food or water. It can also transmit through several other means such as droplets of vomit and fomites (surfaces contaminated with either feces or vomit) contaminated with norovirus. The infection spreads mainly among the people in crowded and enclosed places such as schools, shelters, hotels, resorts, nursing homes, cruise ships, and airline flights, even those of short duration. The probability of norovirus infections is increased among the people with compromised immune systems, as well as people following unhygienic practices. 

    Symptoms & Risks of Norovirus Infection

    The most common symptoms are sudden onset of vomiting and watery diarrhea, although stomach cramps and pain also often occur. Some people experience fever and body aches. Symptoms usually start 12 to 48 hours after being exposed and typically last about 1 to 3 days.[5]

    Although symptoms usually only last 1 to 2 days in healthy individuals, norovirus infection can become quite serious in children, the elderly, and immune-compromised individuals. In some cases, severe dehydration, malnutrition, and even death can result from norovirus infection, especially among children, and among older and immune-compromised adults in hospitals and nursing homes. 

    [1]           Tripathi, M., & Kumar, S. (2019). Developments of an Emerging Infectious Agent: Norovirus. Annual Research & Review in Biology, 31(4), 1-6. https://doi.org/10.9734/arrb/2019/v31i430054

    [2]           Desai AN. (2019). What Is Norovirus? JAMA. 322(20):2032.

    [3]           “Updated Norovirus Outbreak Management and Disease Prevention Guideline.” Centers for Disease Control and Prevention, 4 Mar 2011. Available at: https://www.cdc.gov/mmwr/preview/mmwrhtml/rr6003a1.htm.

    [4]           Chikara Ogimi, Yae Jean Kim, Emily T Martin, Hee Jae Huh, Cheng-Hsun Chiu, Janet A Englund, What’s New With the Old Coronaviruses?, Journal of the Pediatric Infectious Diseases Society, Volume 9, Issue 2, June 2020, Pages 210–217, https://doi.org/10.1093/jpids/piaa037

    [5]           “Facts About Noroviruses.” Centers for Disease Control and Prevention, 15 Oct 2018. Available at: https://www.cdc.gov/nceh/vsp/pub/Norovirus/Norovirus.htm.