The Washington State Department of Health reports that 22 people have recently been sickened by Vibrio Parahaemolyticus bacteria after eating raw oysters. 18 vibriosis illnesses have been linked to commercial operations and four illnesses to recreational harvesting in Puget Sound and on the Washington coast.
Cooking shellfish thoroughly will prevent vibriosis illness and is always a good idea. This is especially important during the summer months of July and August when warm temperatures and low tides along ocean beaches and in Puget Sound allow the bacteria to thrive.
Naturally-occurring bacteria such as Vibrio parahaemolyticus are more likely to grow in warmer water. Vibriosis symptoms may include diarrhea, nausea, stomach cramps, headache, vomiting, fever, and chills — that typically appear within 12 to 24 hours after infected shellfish is eaten. Vibriosis is often mild to moderate, with symptoms lasting for two to seven days. It can threaten the lives of people with lowered immunity or chronic liver disease.
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 to keep people from getting sick if they eat raw oysters. Shellfish companies must quickly refrigerate oysters after they’re harvested. They’re required to keep detailed harvest and temperature control records to show that the oysters were handled properly.