Noroviruses are a major cause of gastroenteritis in humans. They are highly contagious and cause epidemics, particularly in the winter.

What is the norovirus?

Noroviruses are a group of viruses that cause diarrhea and vomiting in humans. It is a highly contagious virus and the leading cause of gastroenteritis worldwide. The virus is found in feces and vomit, and can be transmitted from person to person.


The symptoms of a norovirus infection appear 24 to 48 hours after infection:

  • sudden diarrhea
  • vomiting
  • abdominal cramps
  • headache
  • mild fever.

These symptoms disappear spontaneously after a few days


The virus is found in the stool and vomit of sick patients and can be transmitted:

  • from person to person via the fecal-oral route (e.g. an infected person prepares food without first washing his/her hands after going to the toilet)
  • through direct contact (e.g. kissing a sick person)
  • via aerosols (small droplets in the air), which can become airborne when vomiting and flushing the toilet
  • by eating contaminated food, such as crustaceans, molluscs, foodstuffs handled by people, red fruit and smoothies or by drinking contaminated water.


Transmission of the norovirus can be prevented by taking hygiene measures. It is import to wash your hands carefully every time you go to the toilet and before preparing or eating food. Also ensure that toilets are kept clean and flush the toilet with the seat closed. 

In residential care centers and hospitals, additional measures are taken to prevent further contamination using contact isolation.


A doctor can diagnose gastric flu based in the clinical findings. The virus can also be detected in vomit or stool samples.

Risk groups

Anyone can get gastric flu, but not everyone who comes into contact with the virus always gets ill. Infection is more common in people who stay or live in groups, such as in a residential care center or hospital. The risk of dehydration due to vomiting and/or diarrhea is higher for the elderly and young children.


Norovirus infections are usually benign diseases that do not require any special treatment. Care should be taken to avoid dehydration by drinking plenty of water. If necessary, medication can be prescribed against vomiting.

Sciensano helps to diagnose norovirus cases, identifies sources of infection, controls food products and monitors the evolution of norovirus in Belgium.

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