Any person can get these infections. Infected humans are the only known source of this group of viruses. The viruses are primarily spread by having direct contact with vomitus or feces from an infected person and then transferring the virus to the mouth from the hands. Food may be contaminated by infected foodhandlers who fail to thoroughly wash their hands after using the bathroom. Outbreaks of Norwalk-like illness have occurred due to consumption of raw or undercooked oysters harvested from fecally contaminated waters.
Cooking kills the virus.
Drinking water contaminated by sewage can also be a source of spread of these viruses. Other symptoms include nausea and stomach cramps. A low-grade fever occurs in about half of cases. Most people recover on their own within 24 to 48 hours. It can be a serious illness, however, for persons who are unable to drink enough fluids to replace what they lose through vomiting or diarrhea.