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Environmental Health


What is Norovirus?

Noroviruses are a group of viruses that cause gastroenteritis, which is an inflammation of the lining of the stomach and intestines. Norovirus is a highly contagious virus that causes people to vomit and have diarrhea. Norovirus is usually referred to as “stomach flu” or “stomach bug”. Anyone is susceptible of getting infected and sick with norovirus. Norovirus is not related to the flu, which is a respiratory illness caused by the influenza virus.

What are the symptoms of norovirus?

The most common symptoms of norovirus include:

  • Vomiting
  • Diarrhea
  • Nausea
  • Stomach pain

Additionally, others may also experience these symptoms:

  • Headache
  • Fever
  • Body pain
  • Chills
  • Tiredness
How long does norovirus last?

The duration of norovirus infection can vary from person to person, but usually the symptoms last for about 1 to 3 days. Here is a general timeline of norovirus infection:

  • Onset of symptoms: The symptoms of norovirus infection usually appear within 12 to 48 hours after exposure to the virus.
  • Peak symptoms: The symptoms of norovirus often peak within 24 to 48 hours after they begin. This is when the vomiting and diarrhea can be most severe.
  • Duration: In most cases, the symptoms gradually subside over the course of 1 to 3 days.
  • Recovery: After the acute phase of the illness, people generally start to feel better, and the symptoms begin to improve.
  • Contagious period: People infected with norovirus are usually contagious from the moment symptoms start until at least 48 hours after the symptoms have resolved. Some people can remain contagious for several days after their symptoms have cleared.
How does norovirus spread?

Norovirus can spread very quickly and easily. This virus is primarily known to spread through the fecal-oral route, but it can also aerosolize in droplets up to 25 feet away when someone vomits. Here are some ways in which norovirus can spread:

  • Eating food and drinking liquids that are contaminated with norovirus.
  • Eating food prepared by someone who is infected with norovirus.
  • Touching surfaces or objects contaminated with norovirus and then putting your unwashed hands or fingers in your mouth.
  • Having direct contact with someone who is infected with norovirus.
  • Sharing utensils or cups with someone who is infected with norovirus.
  • Accidentally getting tiny particles of feces (poop) or vomit in your mouth from a person infected with norovirus.
  • Placing food on a counter or surface that has poop or vomit particles on it.
  • When an infected person vomits or engages in activities that produce fine liquid droplets and a person inhales the infected droplets.
What should I do if I have symptoms of norovirus?
  • There is no specific medication to treat people with norovirus illness. If you are experiencing symptoms, here are a few things you can do:
    • Drink plenty of liquids to replace fluids lost from vomiting and diarrhea.
      • Sport drinks and other drinks without caffeine or alcohol can help with mild dehydration.
    • If you are experiencing severe dehydration, contact your health care provider immediately.
      • It is important to note that antibiotics do not treat norovirus infections.
    • Stay home while you are sick and if you’re a food handler or work in an industry with a susceptible population such as a daycare or nursing home, you must stay out of work at least 48 after your symptoms have stopped.
    • Do not handle or prepare food for others if you’ve had vomiting or diarrhea within the past 48 hours.
    • Wash your hands with soap and water for at least 20 seconds and dry with a disposable towel after going to the bathroom, before eating, and frequently throughout your illness.
How do I prevent norovirus infections?

Protect yourself and others by following these preventions tips:

  • Wash your hands often and thoroughly with soap and water for 20 seconds, dry with disposable towels.
    • After using the bathroom or restroom.
    • After changing diapers.
    • After caring for someone who is sick.
    • Before eating, preparing, or handling food.
    • Before giving yourself or someone else medicine.

*Hand sanitizer does not work well against norovirus. You can use hand sanitizers in addition to hand washing, but hand sanitizer is not a substitute for handwashing.

  • Avoid touching your face, especially your mouth with your unwashed hands.
  • Wash fruits and vegetables before consuming.
  • Cook oysters and other shellfish thoroughly to an internal temperature of at least 145°F.
  • Clean and sanitize surfaces frequently, especially in areas where there is a risk of contamination. For example, high-touch surfaces such as door handles, cellphones, toilet seats, flush handles, handrails etc.
  • Stay home when sick and for 48 hours after symptoms have stopped.
  • Do not prepare food for others when sick and for 48 hours after symptoms have stopped.
  • Avoid close contact with individuals who are sick, and do not share personal items with them.
  • Be cautious when traveling, especially on cruise ships or in areas where norovirus outbreaks are more common.
How to clean and disinfect areas contaminated with norovirus

Thoroughly cleaning and disinfecting areas that have been contaminated with norovirus is essential to stop its spread to others. Norovirus droplets can aerosolize up to 25 feet away when someone vomits, and norovirus can survive on surfaces for an extended period, therefore proper cleaning and disinfection are important to eliminate norovirus. Here are some ways you can effectively clean and disinfect area contaminated with norovirus:

  • After someone vomits or has diarrhea, always clean and disinfect the entire area immediately.
    • Start cleaning on the outside of the 25-foot radius and work your way towards the center.
    • All surfaces in an enclosed area should be cleaned with a ¾ cup bleach to 1 gallon of water bleach solution or use an EPA-registered disinfecting product against norovirus. Focus on areas that may have come into contact with the contaminated materials. Follow these steps:
      • Wear disposable gloves, disposable booties, and a face mask.
      • Use the bleach solution to wipe down surfaces, working your way towards the vomiting or diarrhea incident.
      • If the incident occurred in a carpeted area, steam cleaning is the recommended procedure for disinfecting the area.
      • If there is visible vomit or diarrhea, wipe up the entire area with paper towels.
      • Dispose the used towels in a plastic trash bag and seal it securely.
      • Disinfect the area as directed on the product label, if using an EPA–registered disinfectant. Pay close attention to the appropriate contact time.
      • If using bleach, leave the bleach disinfectant on the affected area for at least 5 minutes.
      • Clean the entire area again with soap and hot water.
      • After cleaning and disinfecting, remove gloves and booties and dispose in a plastic trash bag.
      • Wash hands thoroughly with soap and water for at least 20 seconds and dry with disposable towels.
  • Use water bleach solution to clean common surfaces before touching them, such as toilet seats, flush handles, handrails or doorknobs.


  • For printable cleaning and sanitizing procedures in English click here
  • For printable cleaning and sanitizing procedures in Spanish click here

Video Resources

  • Vomiting Larry Video 
    • Watch how easily one vomiting event can contaminate a wide area, and how common clean up procedures can be inadequate, accidentally leading to further contamination.
  • Vomit Cleanup Demonstration Video
    • Watch how an ill food worker can contaminate the kitchen by showing up to work with symptoms of foodborne illness. A thorough description of proper vomit clean up begins at minute 2:25.


What are signs of an outbreak in a restaurant, school, childcare, or long-term care facility?
  • More employees or children than normal are calling out sick.
  • Customers are calling to tell you they’ve gotten sick.
  • A vendor or recall alert notifies you that some of the food you served was contaminated.
  • Someone has vomited or had diarrhea in the facility that may have exposed the people nearby.
What do I do if I get norovirus while I’m camping or RVing?

For guidance on controlling norovirus while camping and RVing, click here.

For more information about Norovirus, click here.