Next time you belly up to the raw bar to crack open a half-dozen oysters at your local restaurant, you might want to think twice. The fruits of the sea sometimes yield more than just a tasty treat.

If you have a health condition such as liver disease, diabetes or cancer, you could be especially vulnerable to a microscopic culprit that sometimes lurks within the shellfish… vibrio vulnificus… a saltwater-loving bacterium.

One recent study found these ailing individuals were eighty times more likely than their healthy counterparts to develop serious complications after exposure to vibrio. The naturally occurring organism is especially common in the warm waters of the Gulf of Mexico during summer months.

Eating raw or undercooked oysters contaminated with the bug could cause severe gastrointestinal troubles or a serious blood-borne infection, characterized by fever and chills, shock, and blister-like skin lesions.

According to the Centers for Disease Control and Prevention, up to half of these infections are fatal. Health experts say about thirty people become ill from vibrio vulnificus each year in the United States and about half of them die. Vibrio vulnificus also can contaminate open wounds, so swimmers with sores or people who clean shellfish also should take precautions.

Fortunately, cooking quickly kills the organism. So consider trying your oysters boiled, steamed, baked or fried. And if you insist on the raw variety, just remember it's one shell game that might give you more than you bargained for.