Norwalk virus infection is an intestinal illness that often occurs in outbreaks. Norwalk and Norwalk-like viruses are increasingly being recognized as leading causes of foodborne disease in the United States. The viruses are passed in the stool of infected persons. People get infected by swallowing stool-contaminated food or water. Outbreaks in the United States are often linked to raw oysters. Infected people usually recover in 2 to 3 days without serious or long-term health effects.
