Notes from the Field: Outbreak of Norovirus Illness Caused by Consumption of Oysters Harvested from Galveston Bay, Texas — November–December 2022

On December 7, 2022, the Texas Department of State Health Services (DSHS) Public Health Region 6/5 South (PHR 6/5S) and DSHS Consumer Protection Division were notified by Galveston County Health District of 10 consumer complaints of illness after consumption of raw (nine complaints) and smoked (one) oysters at local restaurants during November 27–December 4. Signs and symptoms began within 8 hours after consumption and included diarrhea, nausea, or vomiting. Initially, no consumers sought medical care. Oyster tags from three associated restaurant inspections determined that oysters were from Oyster Harvest Area TX 1 (TX 1) in Galveston Bay, Texas.

Also on December 7, the Florida Department of Health contacted DSHS to report its investigation of 37 cases of gastrointestinal illness associated with raw oyster consumption. The investigation also identified several TX 1 oyster tags. On December 8, 2022, representatives from the DSHS Foodborne Illness Team, Seafood and Aquatic Life Operations Branch, Consumer Protection Division, PHR 6/5S, and Galveston County Health District met to discuss the increase in reports of oyster-related gastrointestinal illness. It was determined that TX 1 had been the only area open for shellfish harvesting in Galveston Bay since December 1, 2022. Based on the increased reports of gastrointestinal illness and National Shellfish Sanitation Program (NSSP) guidelines, DSHS Consumer Protection Division closed TX 1 on December 8 and recalled all oysters harvested in TX 1 during November 17–December 7 (1,2). On December 9, the Florida Department of Health notified DSHS that three associated clinical specimens had tested positive for norovirus GII (Figure).

DSHS compiled resources for local health departments, restaurants, and consumers to provide education on the transmission and prevention of norovirus and proper disinfection protocols (Figure) and informed the Interstate Shellfish Sanitation Conference, which notified other member states. An outbreak-associated case was defined as the onset of diarrhea, nausea, or vomiting within 72 hours after consumption of oysters harvested from TX 1 during November 17–December 7, 2022 (the recall period). A press release was issued, which led to additional consumer complaints and highlighted the importance of public communication regarding foodborne outbreaks.

Noroviruses are a highly contagious group of gastrointestinal viruses and the leading cause of foodborne illness in the United States (3). Norovirus is primarily transmitted through direct contact with an infected person’s stool, consumption of contaminated food or water, or direct contact with contaminated surfaces (3). Approximately 2,500 norovirus outbreaks are reported in the United States annually (3). Although reporting of sporadic cases is not required, norovirus outbreaks are reportable to both DSHS and CDC (3,4). As a result, norovirus outbreaks are primarily detected when persons report illness or health care providers report a suspected outbreak.

Acknowledgments

Irina Cody, Texas Department of State Health Services Foodborne Team; Zulaiha Abdul-Salam, Mariana Fletcher, Donya Guyton, Belinda Hernandez, Angel Mascarenas, Jennifer Peebler, Maria Renovato, Shanique Rose, Ron Schultz, Sharon Stonum, Randy Valcin, Galveston County Health District; Tishara Coleman, Davonna Koebrick, Kirk Wiles, Texas Department of State Health Services Consumer Protection Division; Carlos Plasencia, Texas Department of State Health Services Public Health Region 6/5 South.

MMWR and Morbidity and Mortality Weekly Report are service marks of the U.S. Department of Health and Human Services.

Use of trade names and commercial sources is for identification only and does not imply endorsement by the U.S. Department of
Health and Human Services.
References to non-CDC sites on the Internet are
provided as a service to MMWR readers and do not constitute or imply
endorsement of these organizations or their programs by CDC or the U.S.
Department of Health and Human Services. CDC is not responsible for the content
of pages found at these sites. URL addresses listed in MMWR were current as of
the date of publication.

All HTML versions of MMWR articles are generated from final proofs through an automated process.
This conversion might result in character translation or format errors in the HTML version.
Users are referred to the electronic PDF version (https://www.cdc.gov/mmwr)
and/or the original MMWR paper copy for printable versions of official text, figures, and tables.

Questions or messages regarding errors in formatting should be addressed to
mmwrq@cdc.gov.