What are Norwalk and a Norwalk-like viruses?
The Norwalk virus and the "Norwalk-like" family of viruses are a representative of a larger group of viruses called the caliciviruses. 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.

What are the symptoms of an infection with these viruses?
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.

How soon do symptoms appear?
The symptoms may appear from 10 to 50 hours after exposure to the virus, but usually within 24 to 48 hours.

How are these viruses spread?
Norwalk and Norwalk-like  viruses are spread by eating or  drinking food or water  contaminated with feces from an infected person. Food associated outbreaks have been linked to cold prepared, ready to eat foods (e.g., salads, coleslaw, sandwiches) and shellfish harvested in contaminated water. Outbreaks have also been associated with drinking water and recreational water (e.g., swimming ponds, and beaches) where persons may have ingested water contaminated with feces from an infected person. These viruses are easily spread from person-to-person.

For how long is a person infectious?
People are infectious while symptoms are present and up to four days after diarrhea has stopped.

What is the treatment for this illness?
There is no treatment for this illness. Most people recover in two to three days after they become ill. Supportive treatment to prevent dehydration may be needed in severe cases.

What can be done to help prevent the spread of these viruses?
Thorough handwashing following toilet use and prior to handling food is the best way to prevent the spread of these viruses. Persons currently ill with diarrhea or vomiting should not handle food, work in day care centers or care for patients in a health care facility until these symptoms have stopped.