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Vibrio vulnificus

Food Safety Advice

What is Vibrio vulnificus?

Vibrio vulnificus is one of several types of Vibrio bacteria found in seawater. It occurs naturally, especially during the warmer months of the year, and is not caused by pollution. Sometimes it is in raw shellfish or shellfish that is not thoroughly cooked, including mussels, clams, scallops and oysters. Oysters are especially likely to contain this bacterium. Vibrio vulnificus does not change the taste or smell of shellfish, so you can't tell whether or not Vibrio vulnificus is present in the raw seafood.

How do you get sick from Vibrio vulnificus?

Exposure can occur in two ways:

  • By eating raw shellfish or shellfish that is not thoroughly cooked, especially oysters, or
  • By getting seawater on an open wound, cut, sore, puncture or burn. This can happen when swimming or wading in seawater, or by puncturing the skin with a crab shell or with an instrument used to peel crab shells.

What are the signs of infection?

  • Fever and chills, and/or
  • Feeling sick to your stomach or vomiting, and/or
  • Skin infection that appears red and warm to the touch.

Who is at high risk?

Anyone can become ill from Vibrio vulnificus, although otherwise healthy people usually recover quickly. If you have certain long-term illnesses or if you are on a treatment that weakens your immune system and reduces your ability to fight off infections, you may become severely sick and be at risk of death when you eat raw shellfish. The diseases and conditions that increase a person's chances of illness or death either from eating raw shellfish or from getting Vibrio vulnificus-contaminated water in a sore or wound are:

  • liver disease, including cirrhosis, hepatitis and hemochromatosis
  • chronic alcohol abuse
  • diabetes
  • cancer or current cancer treatment
  • HIV infection or AIDS
  • low stomach acidity (use of antacids, such as Maalox, Mylanta, etc; achlorhydria)
  • stomach problems, including previous stomach surgery
  • chronic kidney disease
  • high-dose corticosteriod treatment (such as prednisone) or immunosuppressive treatment (after organ transplant)

For high-risk persons, illness can be severe and can cause death.

Seek immediate medical attention if:

  • You are a high-risk person and
  • You have eaten shellfish or gotten seawater on you recently and
  • You show any signs of infection listed above.

How can you avoid infection - ESPECIALLY IF YOU ARE AT HIGH RISK?

  • Do not eat raw shellfish.
  • Eat only thoroughly cooked shellfish: frying, baking, boiling or heavy steaming reduces the risk. Throw away any shellfish that do not open during cooking.
  • For shellfish in the shell, either a) boil until the shells open and continue boiling for 5 more minutes, or b) steam until the shells open and then continue cooking for 9 more minutes. Do not eat any shellfish that do not open during cooking. Boil shucked oysters at least 3 minutes, or fry them in oil at least 10 minutes at 375°F.
  • Avoid cross-contamination of cooked seafood and other foods with raw seafood and juices from raw seafood.
  • Eat shellfish promptly after cooking and refrigerate leftovers.
  • Avoid exposure of open wounds, burns or broken skin to warm salt or brackish water, or to raw shellfish harvested from such waters.
  • Wear protective clothing (such as gloves) when handling raw shellfish.

Does freezing kill Vibrio vulnificus?

No: any type of freezing — commercial or in your home freezer — does not kill these bacteria. If you are at high risk, do not eat shellfish iced or "on the half shell." Only thorough cooking — boiling, heavy steaming, frying, broiling or baking — will kill Vibrio vulnificus.

For Additional Information