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Living > Public Health, Safety

Norwalk Virus (Norovirus)

What is it?

The Norwalk Virus or Noroviruses are a group of viruses that cause gastrointestinal illness. They were previously called norwalk-like viruses. These illnesses are common in North America, especially in the winter months. It can affect all age groups. However, this group of viruses can cause serious illness in very young children, the elderly and those with weak immune systems.

What are the symptoms?

Symptoms are upset stomach, vomiting, stomach cramps, diarrhea, low grade fever, chills and a sore throat. The illness usually begins suddenly and the person may feel very sick. Symptoms last for 24-48 hours in a healthy individual, but it can take longer for some people. Children tend to experience more vomiting than adults. Severe illness is rare and hospital care is not usually required.

How soon do symptoms appear?

Symptoms of norovirus usually begin 24-48 hours and can appear as soon as 12 hours after exposure to someone with the infection.

How is it spread?

  • Direct contact with another person who is infected and showing symptoms (for example, when caring for someone with illness or sharing foods or eating utensils with someone who is ill) There is also a possibility that the virus can get into the air from vomiting
  • The virus can survive on surfaces for up to 12 hours (door handles, sinks, railings, keyboards, telephones). You can become ill if you do not clean your hands after touching these surfaces and place your hands in your mouth
  • There is a large amount of virus in the stool. Food handlers ill with norovirus can easily pass the infection to a lot of people if hand washing is not done after using the washroom and before preparing or handling food
  • Outbreaks can occur in schools, daycares, long term care facilities and cruise ships because of close contact

How long is a person contagious?

People with this infection begin to spread the virus when symptoms first start, until 48 hours after symptoms stop. Both stool and vomit are infectious. Some people may continue to shed the virus for up to 2 weeks.

Is there treatment?

There is no vaccine or medications that prevent illness caused by norovirus. Drink plenty of fluids because it can cause dehydration.

How can it be prevented?

  • Wash your hands often and always after using the washroom, changing a diaper, before preparing and eating food. If using an alcohol based hand sanitizer, be sure that it contains 60-90% alcohol
  • Clean fruits and vegetables before eating; eat well cooked foods
  • Clean all surfaces after an illness with hot soapy water and disinfect
  • Keep washroom facilities clean and if possible avoid sharing washroom facilities with an infected person
  • Clean all dishes and utensils with hot soapy water or in a dishwasher
  • Discourage visitors until everyone is better and the house has been cleaned and disinfected
  • Persons who are infected with the virus should not prepare food while having symptoms and up to three days after symptoms stop

How can areas soiled with diarrhea or vomit be cleaned?

  • Wear disposable gloves and clean hands after removal
  • Use paper towel to soak up extra liquid
  • Dispose of paper towel and solid matter in plastic garbage bag
  • Clean area with soap and hot water
  • Disinfect with a chlorine bleach based household cleaner
  • Do not reuse cloth or sponge without laundering it

This information is intended to provide general health-related information about norovirus.  It is not intended to replace medical consultation by your physician and/or other health care professionals.

Source: Control of Communicable Diseases Manual 2008, 19th Edition, David L. Heymann, MD. Centers for Disease Control and Prevention, (2008). www.cdc.gov.


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