Norovirus Infection (Norwalk virus, Norwalk-like virus)
Last Reviewed: October 2011
What is norovirus infection?
Noroviruses are a group of related viruses that cause acute gastrointestinal illness sporadically or in outbreaks. Noroviruses are sometimes referred to as "Norwalk virus" or "Norwalk-like virus," based on the name given to the first strain identified in the 1970s.
Who gets norovirus infection?
Anyone can become infected. It only occurs in humans and is found worldwide.
How is it spread?
Noroviruses are spread by exposure to infected people or contaminated food and water. The virus is passed in stool and vomit. Outbreaks have been linked to sick food handlers, contaminated shellfish or water contaminated with sewage. It is generally spread from person to person by direct contact, but some medical reports suggest that the virus can spread through the air during vomiting.
What are the symptoms?
Although the virus is easy to spread, serious illness rarely occurs. The most common symptoms include nausea, vomiting and stomach cramps. Diarrhea may occasionally accompany vomiting. Fever is usually low grade or absent. Infected people generally recover in one to two days.
How soon after exposure do symptoms appear?
The incubation period is one to two days.
What is the treatment for norovirus infection?
No specific treatment is available. Persons who become dehydrated might need to be rehydrated by taking liquids by mouth. Occasionally patients may need to be hospitalized to receive intravenous fluids.
How can norovirus infection be prevented?
The following recommendations may reduce the risk of acquiring or spreading the infection:
- Wash hands thoroughly after each toilet visit and before and after preparing food.
- People who experience nausea, vomiting or diarrhea should not attend school or work and should not handle food for others while ill.
- Avoid drinking untreated water.
- Cook shellfish thoroughly before eating.