Vibrio parahaemolyticus - Janice Carr/CDC

Illnesses linked to raw oysters from Puget Sound and Washington coast


Vibrio parahaemolyticus - Janice Carr/CDC

Washington State Department of Health officials have issued an alert warning consumers that 18 people have fallen ill after eating raw oysters containing the bacteria Vibrio parahaemolyticus. 

The bacteria is naturally-occurring that commonly grows in coastal waters where oysters are cultivated and typically thrive in the warm summer months.

The illness, called vibriosis, typical begins within 12 to 24 hours of eating uncooked shellfish contaminated with the bacteria. Symptoms include diarrhea, nausea, stomach cramps, headache, vomiting, fever, and chills.

The illness is usually mild, lasting two to seven days, but occasionally can be severe, even fatal, especially in people with lowered immunity or chronic liver disease, health officials warn.

Cooking shellfish thoroughly will kill the bacteria and prevent vibriosis, health officials note, and is especially important July and August when the regions coastal waters grow warmer.

The Washington State Department of Health Advises:

If you harvest oysters recreationally this summer, follow these steps to avoid vibriosis:

  • Put oysters on ice or refrigerate them as soon as possible after harvest.
  • If a receding tide has exposed oysters for a long time, don’t harvest them.
  • Always cook oysters thoroughly. Cooking oysters at 145° F for 15 seconds destroys vibrio bacteria. Rinsing fully-cooked oysters with seawater can recontaminate them.

For commercial harvesters, special control measures are in place from May through September: Shellfish companies must quickly refrigerate oysters after they’re harvested, and they’re required to keep detailed harvest and temperature control records to show that the oysters were handled properly.

To learn more:

  • Or call the department’s toll-free hotline 1-800-562-5632 for current shellfish safety information.