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Vibrio Closes Some Oyster Beds in Washington

Several people who ate raw oysters from Washington state’s Samish Bay and Hood Canal areas have become ill from Vibrio parahaemolyticus bacteria.

As a result, oyster harvest has been closed in Samish Bay and in Hood Canal 5, which runs from Clark Creek (about a mile north of Hoodsport) north to Cummings Pointe. State health officials close shellfish beds when there are four or more sporadic illnesses in a specific area.

Other vibriosis cases have been reported this summer in Washington state, which typically sees about 50 cases a year.

Vibrio parahaemolyticus bacteria are found naturally in the environment. When water temperature rises, so does the chance of the dangerous bacterial growth. Cooking shellfish thoroughly prevents vibriosis illness and is recommended during the summer months when warm temperatures and low tides allow the bacteria to thrive.

Symptoms of vibriosis include diarrhea, abdominal cramps, nausea, vomiting, headache, fever, and chills. The symptoms usually appear about 12 hours after eating infected shellfish, but they can begin within two hours or as late as 48 hours after consumption. The illness is usually moderate and lasts for two to seven days; however, it can be more serious, even life threatening to people with weak immune systems or chronic liver disease. Taking certain medications may make vibriosis more likely to occur after eating shellfish.

To help keep shellfish safe to eat, keep them cool from the time they are harvested until the time they are cooked.  Thorough cooking will kill the bacteria, making the shellfish safe to eat. Food safety specialists recommend oysters be cooked to an internal temperature of 145° F to kill the bacteria.

More information, including maps of the affected areas, is available on the Washington state Department of Health’s website. A separate biotoxin web page includes information on shellfish areas that are free from marine biotoxins.

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