Infection with these viruses affects the intestine and is common cause of gastrointestinal illness. Infection with these viruses is not reportable in Wisconsin and the incidence is not known. The most common symptoms are nausea with vomiting, diarrhea, and cramps. These symptoms occur in all age groups although diarrhea is more common among adults and vomiting is more common in children.
Many persons also experience headache, fever, chills and muscle aches.
The symptoms may appear from 10 to 50 hours after exposure to the virus, but usually within 24 to 48 hours. Norwalk and Norwalk-like viruses are spread by eating or drinking food or water contaminated with feces from an infected person. People are infectious while symptoms are present and up to four days after diarrhea has stopped. There is no treatment for this illness. Most people recover in two to three days after they become ill.