Food and Drug Administration - August 2, 2006
Richard Klein

The Food and Drug Administration is advising consumers to avoid eating raw oysters harvested in the Pacific Northwest as a result of increased reports of illnesses associated with the naturally occurring bacteria Vibrio parahaemolyticus (Vp) in oysters harvested from the area. Oysters harvested from this region have been reported to cause gastrointestinal illness. The threat is particularly important for people who have compromised immune function, including those living with HIV/AIDS.

Until the threat of Vp from oysters harvested in the Pacific Northwest has passed, consumers are advised to thoroughly cook oysters harvested from that area before eating. They also should thoroughly cook oysters if they are not certain of the oysters' origin, or if they wish to further reduce their risk of infection from bacteria that may be found in raw oysters.

In recent months, there has been an unusual increase in bacterial illness associated with eating raw oysters from the Pacific Northwest. The illnesses are associated with the naturally occurring bacterium Vp, which is most prevalent during summer months when water temperatures in the Pacific Northwest are most favorable for its growth. While Vp can cause mild gastrointestinal disorders in healthy individuals, those with weak immune systems and older persons are at greater risk for serious more illness, such as septicemia (infection of the blood system).

Pacific Northwest oysters are distributed nationally. Although to date most of the illnesses reported have occurred in the Pacific Northwest, some have been reported in New York state as well.

In Washington state, shellfish control authorities are identifying and closing areas where people have become sick from eating oysters. Washington state has initiated a recall of all shell stock oysters (oysters in the shell) harvested from areas closed within the state. Because of the potential for nationwide distribution, consumers are advised to follow recall instructions and return associated shell stock oysters to the retailer from which they were purchased.

Cooking destroys the bacteria, eliminating the risk of illness for both healthy and immunocompromised individuals. The majority of illnesses that occur from the consumption of raw oysters are not life-threatening to the general population and commonly range from mild intestinal disorders of short duration to acute gastroenteritis. The symptoms are watery diarrhea, often with abdominal cramping, nausea, vomiting, fever and chills. Usually these symptoms occur within 24 hours of ingestion and last no more than three days. Severe disease is rare and occurs most commonly in persons with weakened immune systems.

Persons with weakened immune systems, including those affected by AIDS; and persons with chronic alcohol abuse, liver, stomach or blood disorders, cancer; diabetes, or kidney disease should avoid raw oyster consumption altogether, regardless of where the oysters are harvested.

Consumers can continue to enjoy oysters in many cooked preparations by following this advice.

At Restaurants and other Foodservice Establishments:

• Order oysters fully cooked.

In the shell:

• Purchase oysters with the shells closed. Throw away any oysters with shells already opened.
• Boil oysters until the shells open. Once open boil for an additional 3-5 minutes.
• Steamer - add oysters to water that is already steaming and cook live oysters until the shells open, once open steam for another 4-9 minutes.
• Use smaller pots to boil or steam oysters. Using larger pots, or cooking too many oysters at one time, may cause uneven heat distribution, which may cause the oysters in the middle to not get fully cooked.
• Discard any oysters that do not open during cooking.

Shucked Oysters:

• Boil or simmer shucked oysters for at least 3 minutes or until the edges curl.
• Fry at 375 degrees for at least 3 minutes.
• Broil 3 inches from heat for 3 minutes.
• Bake at 450 degrees for 10 minutes.

For further information contact: FDA Food Safety Hotline: 1-888-SAFEFOOD

Richard Klein

HIV/AIDS Program Director

Office of Special Health Issues

Food and Drug Administration
060801
FD060801

SOURCE: Food and Drug Administration (FDA).

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