Norovirus / Norwalk-like Virus

Norwalk-like viruses are a common cause of non-bacterial outbreaks of stomach upset. Viral gastroenteritis, often referred to as "winter vomiting disease" or “stomach flu,” is a common illness. It should not be confused with influenza, which is commonly referred to as the “flu.”

Where does the virus come from and how is it spread?

The virus is easily spread. The main source of the virus is stool (feces) and vomit from infected persons. The virus is most often spread from person-to-person on unwashed hands. The virus can also be spread by food, water or ice that has been handled by a sick person. Vomiting may spread the virus through the air. The virus can survive on surfaces such as countertops or sink taps for a long time. Outbreaks of Norovirus have been caused by food (including shellfish) and water contaminated with the virus.

What are the symptoms?

The main symptoms are sudden onset of nausea and vomiting (common in the young), diarrhea (more common in adults), stomach pain, muscle aches, tiredness, headache and low grade fever. Symptoms generally last between 24 and 48 hours. Fluid loss resulting from vomiting and diarrhea can cause serious problems, especially for the elderly and the very young.

Is there a treatment available?

Drinking lots of clear fluids while ill is important. If diarrhea or vomiting lasts more than two to three days, see a doctor. If three or more persons are ill at the same time, this should be reported to your local public health unit.

How can this illness be prevented?

There is no vaccine or medicine that can prevent Norwalk virus infection. Also there are different types of Norwalk-like viruses, so people who have had it once can get the illness again.

  • Hand washing is the key to reducing person-to-person spread of Norwalk virus. A proper hand wash requires warm running water, soap and rubbing hands together for about 30 seconds.
  • Stay home if you're ill and avoid going to work until 48 hours after symptoms disappear (especially if you are a food handler or caregiver). Even after they are well, people can carry the virus in their stool for a few days, so careful hand washing should continue.
  • Frequent disinfection with a dilute bleach solution (at least one part household bleach to 50 parts water) of high traffic areas and commonly touched items including:
    • Bathrooms;
    • Doorknobs;
    • Hand rails;
    • Floors;
    • Counters; and
    • Dishes.
  • Laundry should be washed in hot water with detergent. Soiled carpets should be cleaned with detergent and hot water. Wear disposable gloves if possible. Do not use the cleaning cloth or sponge to clean other areas of the house as this may lead to further spread of the virus.
  • Do not share towels. Quickly machine-wash any towels used by ill family members.
  • Food should be well cooked. Any food handled by an ill person should be discarded, unless it will be thoroughly cooked before eating.
  • Visitors should be asked to stay away while there are sick persons in the house and for a few days after until the house is cleaned. If only one person is sick, other family members may become sick after 24–48 hours. The sick person should try to keep to his or her own room and have little contact with the other family members.