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Medical Author:

Mary D. Nettleman, MD, MS, MACP

Mary D. Nettleman, MD, MS, MACP

Mary D. Nettleman, MD, MS, MACP is the Chair of the Department of Medicine at Michigan State University. She is a graduate of Vanderbilt Medical School, and completed her residency in Internal Medicine and a fellowship in Infectious Diseases at Indiana University.

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Medical Editor:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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In this Article

• Norovirus infection facts
• What is a norovirus?
• What causes a norovirus infection?
• What are norovirus infection symptoms and signs in adults, children, and babies?
• What is the incubation period for a norovirus infection? How long are people infected with norovirus contagious?
• How is a norovirus infection diagnosed?
• What is the treatment for norovirus infections in adults, children, and babies?
• What are possible complications of a norovirus infection?
• What is the prognosis of a norovirus infection?
• Can norovirus infections be prevented? Is there a vaccine?
• Where can people get more information about norovirus infections?
• Patient Comments: Norovirus Infection - Symptoms
• Find a local Gastroenterologist in your town
• Norovirus Infection Index

Infection occurs when humans inadvertently ingest material contaminated with small amounts of fluids or feces from an infected person. It only takes a small number of viruses to cause infection, so even microscopic amounts of feces or fluids can be contagious.

An infected person with vomiting or diarrhea can contaminate their environment directly or spread virus particles through aerosolized droplets when throwing up. Contamination may also occur in food and/or in water, which has led to infection spreading widely in restaurants or aboard cruise ships. Outbreaks in school systems occur regularly, sometimes spreading widely as was the case with an outbreak in the Chicago public schools in 2010. The virus is very hardy and can live for days or weeks on surfaces.

Most people get sick within one day of ingesting norovirus (range 12-48 hours). Symptoms and signs include vomiting or watery diarrhea or both. Fever occurs in one-third to one-half of infected people. Cramping abdominal or stomach pain and a general feeling of tiredness, headache, and muscle aches are common.

People are usually thirsty, although they may have trouble keeping fluids down. In general, patients who can orally ingest about the same amount of fluid they lose through diarrhea, vomiting, or both do well. Symptoms in adults may be different than symptoms in children. Young children and babies may not complain of thirst but may appear listless or lethargic as they become dehydrated. Symptoms may be more severe in debilitated, elderly patients. People who are unable to replace their fluids and develop signs of dehydration need medical care.

Most people have a mild illness that lasts two to three days. In contrast to bacterial diarrheas, such as those caused by Shigella or Campylobacter bacteria, norovirus does not cause blood or pus in the stool. The length of infection may be prolonged in patients who are in the hospital or in young children.

Norovirus has been associated with severe inflammation of the colon in newborns and with disease flares in children who have inflammatory bowel disease, but it is not yet clear what role norovirus is playing in these conditions.