Foodborne illness outbreak investigation
Posted January 27, 2017
Public Health recently investigated a cluster of norovirus-like illness associated with consuming raw oysters. Norovirus is the name of a group of viruses that cause viral gastroenteritis. Norovirus is found in the stool and vomit of infected people and is usually spread person-to-person or by contaminated food. Consuming raw or undercooked shellfish, particularly raw oysters, also increases the chances of becoming ill with norovirus. Symptoms of norovirus include nausea, vomiting, watery diarrhea, stomach cramps, fever, chills, headache, and body aches. Norovirus illnesses typically last 12-60 hours.
On 1/9/17, Public Health was notified of 4 cases of norovirus-like illness from the same meal party who had consumed raw oysters at Taylor Shellfish (located at 124 Republican St in Seattle) on 1/4/17. Two females and two males became ill 20-29 hours after consuming raw oysters with nausea, vomiting, diarrhea, abdominal cramps, headache, and body aches.
As part of the Public Health investigation, on 1/11, Environmental Health inspectors were sent to the restaurant where the oysters were consumed to review the process for handling, preparing, and serving oysters. In addition, oyster tags that provide information about the origin of the shellfish were collected and sent to the Washington Department of Health for trace back and investigation of the oyster growing areas. The investigation of the restaurant did not identify any issues that would contribute to increased risk for norovirus. At this time, the investigation by the Department of Health has not connected these illnesses to any others stemming from the same growing areas.
Norovirus is a highly contagious virus that is frequently spread person-to-person and is often associated with food. Norovirus illness often has a sudden onset of nausea and vomiting and/or watery diarrhea with cramps. A low grade fever, chills, and body aches sometimes occur. Norovirus rarely causes severe complications. Dehydration is the most common complication, particularly among young children and the elderly. No vaccine is available for norovirus.
To prevent norovirus infection:
- Because raw seafood can be contaminated with norovirus, always cook shellfish and other seafood thoroughly before eating.
- Wash cutting boards and counters used for shellfish preparation immediately after use to avoid cross contaminating other foods.
- Wash hands thoroughly with soap after using the bathroom or changing diapers, and before preparing any food or eating.
- Wait at least 48 hours after the last episode of vomiting and/or diarrhea before preparing any food for others.
For more information on norovirus, see: