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Norovirus Infection

What is norovirus? Norovirus is a common cause of gastrointestinal illness. Norovirus infection was previously known as Norwalk-like illness. It is sometimes called “the stomach flu.”

 

 
  •  Norovirus Fact SheetNorovirus Fact Sheet (PDF 254KB)
    View, download and print the Norovirus Fact Sheet. Norovirus infection occurs year round. It is more common during the colder months, when outbreaks of Norovirus illness happen. Outbreaks have been linked to banquets, cruise ships, swimming pools, schools and restaurants. It can be spread through contaminated hands, food and water.
 

Who is at risk for Norovirus infection?

Anyone of any age can become sick from Norovirus. Infections and outbreaks are common in child care centers, nursing homes and other child and adult institutions where people live and work closely. It can spread easily within households.

The stool and vomit of an infected person contains large amounts of the virus, even before the person starts to feel ill. An infected person can spread the infection to co-workers, household members and others around them.

Norovirus illness can reoccur throughout a person’s lifetime. There are many different types of Norovirus and immunity to the virus is short-lived. A person can become infected with more than one type of Norovirus during a season of outbreaks.

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What are the symptoms of Norovirus infection?

The symptoms are similar to other gastrointestinal illnesses. You may have vomiting, watery diarrhea, abdominal cramps and nausea. This will happen suddenly, about 12 to 48 hours after the virus gets into your mouth, and usually lasts from 24 to 60 hours.

You may also get muscle aches, fatigue, headache, low-grade fever or chills, and a general unwell feeling. Children may have mild to moderate diarrhea without vomiting.

Most people feel better in 2 to 3 days without any serious health complications. It is important to drink liquids to prevent dehydration, especially in very young children, the elderly, and people with weakened immune systems. They may need medical attention.

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How is Norovirus infection diagnosed?

The length of time the person is ill with Norovirus symptoms, together with the presence of similar illness in others in the same household, institution and community may suggest Norovirus infection. Laboratory testing is done to detect Noroviruses.

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How do people get Norovirus infection?

Norovirus infection can happen in several ways, including:

  • having direct person-to-person contact with someone who is infected;
  • caring for an ill person;
  • sharing foods or eating utensils with someone who is ill;
  • by unwashed hands of an ill person after using the washroom;
  • from an ill person who is preparing food for others; and,
  • touching contaminated objects in your surroundings.

Noroviruses are very contagious. They can survive in the environment for at least 12 days. Some people, particularly children, can be infected and not show any symptoms, but still spread the infection to others.

When a person is infected, their feces (stool) and vomit can contain large amounts of the virus. They could excrete (shed) Norovirus for 5 to 7 days after the symptoms start or longer. Shedding can continue for as long as 3 weeks and longer in people with weakened immune systems.

Norovirus gets into the air when vomiting occurs. Virus particles can settle on food and surfaces in common dining areas, on other surfaces, and on carpets. You can become sick by touching those contaminated materials, surfaces or objects. The person cleaning up the vomit may get airborne virus particles in their mouth. Sweeping and vacuuming can spread the virus particles into the air.

Foods can be contaminated with Norovirus when the person preparing the food is shedding the virus and not washing their hands thoroughly.

You can get Norovirus infection by drinking water, other beverages and ice cubes that have come from a contaminated water source. This may happen during travel to other countries.

Swimming in contaminated pools and ponds, and eating raw vegetables, fruits and other foods grown in or near contaminated water are other sources of infection.   

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 What can we do to prevent Norovirus infection?

Practice Proper Hand Washing

  • Wash your hands carefully with soap and water, especially after using the toilet, changing diapers and after handling soiled laundry.
  • Wash your hands especially before eating, preparing, or handling food. Alcohol-based hand sanitizers can be used as an addition to hand washing.
  • Visitors to institutional settings should WASH HANDS thoroughly before entering, and before and after visiting.
  • The six steps to good hand washing are:
    1. Wet hands with warm running water
    2. Put liquid soap on hands
    3. Lather hands and scrub for 20 seconds
    4. Rinse under running water
    5. Dry your hands with paper towels
    6. Use the towel to turn off the taps
 
 

Wash fruits and vegetables

  • Wash fruits and vegetables that will be eaten raw carefully under cold running water. Cook oysters and other seafood thoroughly.

Do not prepare food when you are sick

  • When you are sick, do not prepare food or care for others who are sick for at least 2 days after your symptoms stop.

Stay home when you are sick

  • Stay home for at least 48 hours or longer after symptoms have stopped. The virus can stay in your stool for 2 weeks or more after you feel better. Children in group settings should stay home if they are not well enough to participate.
  • Ill people in institutions should be isolated immediately and kept away from others for at least 48 to 72 hours after their symptoms have stopped.

Wash laundry thoroughly

  • Wash laundry thoroughly. Immediately, carefully remove soiled clothes and linens without agitating them.

  • Wear rubber or disposable gloves, and wash your hands afterward.

  • Wash the items with detergent and hot water - heat above 60°C/140°F inactivates the Norovirus, at the maximum available cycle length, and machine dry.

Clean up vomit and diarrhea carefully

  • Carefully clean up vomit and diarrhea with absorbent material such as kitty litter, baking soda paper towels, and discard in a plastic trash bag or biohazard bag. Stool should be flushed in the toilet.

Cleaning and disinfecting surfaces

  • Clean and disinfect washrooms and all hand contact surfaces at least once daily, or more often as needed, with a product that is effective against Noroviruses.
  • To disinfect with a bleach and water solution (approx. 1000 ppm), mix 20 ml (4 teaspoons) unscented household bleach into 1000 ml (4 cups) of water.
  • The solution should be mixed daily to preserve its strength.
  • Leave the solution on the surface for a minimum of one minute or leave it to air-dry.
  • Cleaning with soap and water must be done first before disinfecting.

Avoid vacuuming carpets

  • Avoid vacuum cleaning carpets and buffing floors during an outbreak as it may re-circulate Norovirus.

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Date of creation: November 11, 2015
Last modified on: January 11, 2016

References

1Centers for Disease Control and Prevention. (2015). Noroviruses: Q&A. Retrieved November 3, 2015, from Retrieved from
http://www.cdc.gov/norovirus/about/index.html
2Heymann, D. L. (2015). Control of Communicable Diseases Manual (20th ed.). Washington: American Public Health Association
3PIDAC (2012). Best Practices for Environmental Cleaning for Prevention and Control of Infections In All Health Care Settings (2nd ed.). Toronto: Queens Printer for Ontario. Retrieved from
https://www.publichealthontario.ca/en/eRepository/Best_Practices_Environmental_Cleaning_2012.pdf
4Pickering, L. K. (ed.). (2012). Human Calicivirus Infections (Norovirus and Sapovirus). In 2012 Red Book: Report of the Committee on Infectious Diseases (29th ed; pp. 261-262). Elk Grove Village, IL: American Academy of Pediatrics.