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State Department of Health Closes Two Oyster Beds

August 2, 2010

OLYMPIA - Several cases of illness from eating raw oysters and lab detection of bacteria that can make people sick has led state health officials to close two Hood Canal growing areas.

Lab tests in Hood Canal Six, which runs from Hoodsport south and east to the boat launch area at Twanoh State Park, showed the presence of Vibrio parahaemolyticus, which can cause an illness known as vibriosis. While no illnesses have been linked to oysters from this area this summer, at least four cases of vibriosis have been confirmed in people who ate raw oysters harvested in the neighboring Hood Canal Five, which runs from Clark Creek (about a mile north of Hoodsport) north to Cummings Point.

Both areas have been closed by the state Department of Health to reduce exposure to Vibrio bacteria. There have been several other vibriosis cases identified this summer, scattered around the state's growing areas. Typically, Washington sees about 50 cases of vibriosis a year.

Vibrio parahaemolyticus bacteria are found naturally in the environment. The warm temperatures and daytime low tides are likely contributing to these recent cases.

These two areas are closed for all recreational harvesting of oysters. Some commercial growers may still harvest oysters from these areas, but those oysters can only be sold when they are shucked and intended to be cooked before consumption.

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 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; it can be more serious, and may be 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.

Keep harvested shellfish cool. Thorough cooking will kill the bacteria and leave 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 agency's website (http://www.doh.wa.gov/ehp/sf/default-sf.htm). It's important to remember that just because an area doesn't appear to be closed because of Vibrio parahaemolyticus, it may be closed for marine biotoxins. Check the department's biotoxin Web page (http://ww4.doh.wa.gov/gis/mogifs/biotoxin.htm) to make sure an area you wish to harvest in is free from marine biotoxins.

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