Raw oysters, norovirus warning issued after multiple people in area become ill

(File photo by Chris Graythen/Getty Images)

SEATTLE — Public Health-Seattle & King County said Tuesday it has investigated “multiple reports” of persons ill with nausea, vomiting and diarrhea after eating raw oysters at some restaurants or private events in King County from Jan. 10 to March 20.

“We do not have laboratory confirmation for any of the cases, but symptoms are suggestive of norovirus. Often in norovirus outbreaks no laboratory testing is done.”

Public Health said as many as 39 people may have become ill.

The Washington State Department of Health said shellfish such as oysters, clams, and mussels are filter feeders and ingest norovirus if it is present in the water. Potential sources of contamination include faulty wastewater treatment plants, failing septic systems, stormwater runoff, dumping of boat sewage waste, and vomiting overboard near shellfish beds.

"Public Health has reported the illnesses to Washington State Department of Health (DOH) Shellfish Program which is responsible for tracking the reports and harvest locations of the oysters implicated in these illnesses. The oysters served at each of the meals in the table below were harvested from different growing areas/bays in Washington State with the exception of four meals, accounting for 22 of the reported illnesses, which included oysters harvested from a small area in the Samish Bay growing area; a section of that growing area was closed on 3/17/17 for all species," Public Health said in a news released.