Oysters and Vibriosis

"Raw oysters can ruin your summer. That’s because you can get very sick from eating raw oysters. Learn about vibriosis—a disease linked to raw oysters—and how to protect your health when it comes to oysters and certain other shellfish.

Most illnesses from raw oysters occur in summer. Whenever and wherever you like to enjoy oysters, eating raw oysters and certain other undercooked shellfish, such as clams and mussels, can put you at risk for infections.

Oysters eat by constantly drawing in water and materials in the water, including harmful bacteria and viruses. These bacteria and viruses can become concentrated in an oyster’s body and infect people who eat the oysters raw or undercooked. One of the infections people get from eating raw oysters is caused by some types of Vibrio—bacteria that occur naturally in coastal waters where oysters grow. This infection is called vibrioisis. People also can get vibriosis after exposing a wound to salt water or brackish water containing the bacteria. Brackish water is a mixture of fresh and salt water. It is often found where rivers meet the sea.

About 80,000 people get vibriosis—and 100 people die from it—in the United States every year. Most of these illnesses happen from May through October when water temperatures are warmer. However, you can get sick from eating raw or undercooked oysters during any month of the year, and raw oysters from typically colder waters also can cause vibriosis.

An oyster that contains harmful bacteria doesn’t look, smell, or even taste different from any other oyster. The only way to kill harmful bacteria in oysters is to cook them properly.

What are the symptoms of vibriosis?

Most Vibrio infections from oysters, such as Vibrio parahaemolyticus infection, result in mild illness, including diarrhea and vomiting. However, people with a Vibrio vulnificus infection can get very sick. As many as 1 in 5 people with a V. vulnificus infection die. This is because it can lead to bloodstream infections, severe blistering skin lesions, and limb amputations. If you develop symptoms of vibriosis, tell your medical provider if you recently ate or touched raw shellfish or came into contact with brackish or salt water..."
Oysters and vibriosis