Other people at higher risk of severe infection who should not eat raw oysters include those with cancer, AIDS or other conditions that weaken or compromise the immune system. Oysters should be thoroughly cooked to decrease the risk of infection since heat kills the Vibrio vulnificus bacteria. Undercooked oysters, such as those that are lightly steamed, marinated or prepared as Oysters Rockefeller, may also pose a health risk. Vibrio vulnificus infections can cause fever, chills, nausea, vomiting and abdominal pain. The onset of symptoms is usually within 24 hours of eating contaminated shellfish.
Death can occur within two to three days.
Vibrio vulnificus is naturally present in all estuaries and marine environments. Especially high levels of Vibrio vulnificus have been found in raw oysters harvested from the warm waters of the Gulf of Mexico. Consumption of raw Gulf Coast oysters has regularly caused Vibrio vulnificus illnesses in California and other states. Since 1991, DHS has required restaurants, markets and other retailers that sell Gulf Coast oysters to conspicuously display a warning about the risk of eating these oysters. Regulations prohibit retailers from receiving raw oysters if their origin is not clearly identified and require the retailer to retain oysters identification tags for 90 days.