Medical Specialties: Family practice, Gastroenterology, Internal medicine

Clinical Definition

Triggered by a group of Calicivirus viruses, norovirus is a viral infection that causes gastroenteritis. It is highly contagious and can be transmitted through drinking contaminated water or eating contaminated food or undercooked shellfish. 

In Our Own Words

Norovirus is a contagious infection that causes vomiting, diarrhea and gastroenteritis (i.e., inflammation of the lining of the stomach and intestines). This type of infection is the most common cause of gastroenteritis in the U.S. Although it is often referred to as  “stomach flu,” norovirus is not influenza.


Norovirus outbreaks often occur in closed settings or among people who are in close proximity to each other, such as on a cruise ship or in a dormitory. The virus is spread from person to person and is found in the stool or vomit of people who are infected. Drinking contaminated water, eating contaminated food or eating undercooked shellfish can also spread norovirus.  

Relevant Conditions
  • Gastroenteritis
  • Viral diarrhea
Side Effects
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  • Baylor College of Medicine. “Norovirus.” Accessed September 2013.
  • Centers for Disease Control and Prevention. “Norovirus.” Updated July 2013. Accessed September 2013
  • National Institute of Allergy and Infectious Disease. “Norovirus Infection.” Accessed September 2013.
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