Eating raw shellfish, especially oysters, may put you at risk for hepatitis A.

Bivalves such as oysters and clams filter large amounts of water when feeding. If shellfish are living in water that has been contaminated with stool containing the hepatitis A virus, the shellfish may carry the virus. People then may get it when they eat the raw or undercooked shellfish.

Raw shellfish also may carry other viruses and bacteria that can make people sick.

Not everyone who eats contaminated raw oysters or other raw shellfish will become sick. But to reduce the chance of getting sick, make sure that shellfish have been cooked thoroughly.