Dear Doctor: My wife and I love raw oysters. Whenever they're on the menu, we always order a dozen or even two. But I recently read that someone died from some kind of bacterial infection after eating them. Just how risky are they?

Dear Reader: We are aware of at least two instances in 2018 when someone died after eating raw oysters. The cause was infection with a bacterium known as Vibrio vulnificus, which lives in the same marine environments that support oysters. One of the deaths occurred in Florida in July, a time of year that warmer waters can encourage bacterial growth. In fact, there's an old saying that oysters should only be eaten during months that contain the letter "r," which excludes the late spring and summer months.

However, that bit of folklore is far from infallible. In warmer waters, the bacterium can be present throughout the year. And since oysters consume nutrients by filtering the water they live in, if Vibrio vulnificus is present, chances are the oysters will contain it. 

Infection with Vibrio vulnificus is the leading cause of death in the United States associated with eating seafood. Symptoms include nausea, vomiting, fever, chills, diarrhea, skin lesions and shock. If anyone who has eaten raw shellfish experiences any of these symptoms, he or she should seek immediate medical care. 

The bacterium can attack on two fronts. Most common among individuals who ingest it in raw shellfish is a systemic blood infection known as primary septicemia. This infection can be life-threatening and must be treated in a hospital as quickly as possible.

Also, Vibrio vulnificus is a so-called "flesh eating" bacterium that can cause necrotizing fasciitis if it enters an open wound. Treatment includes antibiotics and supportive care. 

If you want to protect yourself, don't eat raw oysters or raw or undercooked seafood from coastal waters or estuaries. 

For those cooking seafood at home, always throw away any oysters, clams or mussels with shells that have opened prior to cooking or shucking. In addition:

• Boil in the shell for at least three minutes in order to kill the bacterium.

• When steaming, cook for at least four minutes. 

• When frying or broiling, set the timer for at least three minutes. 

• Baked oysters need at least 10 minutes in a 450-degree oven.

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