Although more serious illnesses can occur, they are not common in healthy adults. On the other hand, children, the elderly, and individuals with compromised immune systems should never eat raw or partially cooked shellfish. These people are susceptible to far more serious illnesses that are caused by naturally occurring marine bacteria called Vibrio vulnificus that may multiply after the shellfish are caught, even when refrigerated. Symptoms include sudden chills, fever, nausea, vomiting, and stomach pain. Vibrio vulnificus can cause blood poisoning, a condition that could be fatal in up to half the people who get it.
Death can occur within two days.
These bacteria are completely killed when the shellfish are thoroughly cooked, removing all danger of the bacteria causing food poisoning. Certain viruses known as Norwalk viruses also could contaminate oysters , clams and mussels and cause severe diarrhea in those who eat them. Here again, thorough cooking kills the virus. People unsure of their medical status should consult their physician before consuming raw or partially cooked shellfish. The information contained herein is presented in good faith and is not intended to be a replacement for professional medical or related technical advice.