California Reports Over 100 Illnesses Associated with Canada's Norovirus Outbreak

The California Department of Public Health (CDPH) has issued a warning to the public to avoid consuming raw oysters that had been harvested from the south and central Baynes Sound, as the oysters are linked to an ongoing outbreak of norovirus illnesses in British Columbia, Canada.

Already, as of April 27, 2018, about 100 California residents have reported illness due to consuming the oysters which had been sold through restaurants and retailers throughout the state.

“Laboratory testing has confirmed norovirus infection in several patients from both California and Canada,” the CDPH warning reads. “Although the number of reported new illnesses has decreased during the last week, the investigation is ongoing.”

Norovirus is the biggest cause of acute gastroenteritis worldwide, and there is no antiviral drug or vaccine available to combat the virus, which is responsible for 21 million illnesses each year in the United States. The Centers for Disease Control and Prevention report that food can potentially become contaminated with norovirus during growing, shipping, handling, and preparing. In fact, these viruses are known to cause around half of all outbreaks of food-related illness.

Canada has been struggling with an ongoing norovirus outbreak since mid-March when individuals first started falling ill. In the most recent public health notice released by the Public Health Agency of Canada, officials report that a total of 172 cases of gastrointestinal illness associated with the oysters have been reported in 3 provinces; Alberta and Ontario have reported 15 and 25 cases respectively, with British Columbia reporting the majority of cases (132).

The CDPH reports that 4 oyster farms in British Columbia that had been connected with the illnesses were closed down between March 23 and April 13, 2018; they remain closed until further notice.

The outbreak involves an unusual strain of the virus, according to the Center for Infectious Disease Research and Policy (CIDRAP). “The CDC said…that multiple states are currently affected by outbreaks related to raw oysters from British Columbia,” they write. “It added that lab analysis has identified that an uncommon type of norovirus is involved.”

The US Food and Drug Administration warned of the outbreak last week in a warning to consumers and retailers. The FDA has confirmed that the oysters were distributed to several states including Arkansas, California, Florida, Hawaii, Illinois, Massachusetts, New York, and Washington.

“Avoid eating raw and undercooked shellfish, including oysters, to reduce your risk of illness,” CDPH director and state public health officer Dr. Karen Smith stressed in a recent statement. “If you do eat shellfish, cook it until it reaches an internal temperature of at least 145°F. Quick steaming isn’t sufficient to kill norovirus.”