Outbreaks in the United States are often linked to eating raw shellfish, especially oysters and clams. Anyone can get Norwalk virus infection, but it may be more common in adults and older children. Nausea Vomiting Diarrhea Stomach cramps Severe illness or hospitalization is uncommon. Infected persons usually recover in 2 to 3 days without serious or long-term health effects. Symptoms usually appear in 1 to 2 days after swallowing contaminated food or water.
Laboratory diagnosis is difficult.
Diagnosis is often based on the combination of symptoms and the short time of illness. No specific treatment is available. Persons who are severely dehydrated might need rehydration therapy. Norwalk and Norwalk-like viruses are increasingly being recognized as leading causes of foodborne disease in the United States. However, since no routine diagnostic test is available, the true prevalence is not known.