Noroviruses are a group of viruses that cause the “stomach flu,” or gastroenteritis (inflammation of the stomach and intestines) in people. This “stomach flu” is not related to influenza and there is no antiviral medication or vaccine. Anyone can become infected with noroviruses and it is estimated that fewer than 100 norovirus particles can make a person sick. There are many different strains of norovirus which makes it difficult for a person’s body to develop long-lasting immunity.

Noroviruses are found in the stool or vomit of infected people and can be transmitted in several ways, including:

  • Eating or drinking items contaminated with norovirus.
  • Touching norovirus contaminated surfaces which may include: furniture, railings, carpeting, doors, etc surfaces and then placing that hand into a mouth.
  • Having direct contact with another person who is infected (caring for someone that is showing symptoms of norovirus).

Noroviruses symptoms can appear within 12 – 48 hours after exposure and generally last 1 – 2 days. Symptoms include:

  • Vomiting, diarrhea, nausea, stomach cramps, fever, headache, chills, and muscle aches.

Dehydration is often a serious concern (generally with young and elderly persons) because of vomiting and diarrhea. Drinking oral rehydration fluids (ORF), juice, or water, can decrease the chance of becoming dehydrated.

Noroviruses are very contagious and can be easily spread from person to person. People are contagious the moment they feel ill and remain contagious for at least three days and possibly as long as two weeks after recovery. You can decrease your chance of acquiring noroviruses by:

  • Washing your hands. Especially after using the toilet, changing diapers, and before eating or preparing food.
  • Washing fruits and vegetables.
  • Immediately clean and disinfect contaminated surfaces.
  • Remove and wash clothing or linens that may be contaminated with the virus.

When cleaning up a possible norovirus incident it is important to wear personal protective equipment like disposable gloves and a face mask. 

Visible contamination should be promptly cleaned with disposable towels and disinfected (for a list of disinfectants see below).

  • Immediately bag and discard the soiled disposable towels.
  • Linens (including clothes, towels, tablecloths, napkins) should be promptly washed and dried separately at high temperature.
  • Food items that may have become contaminated with norovirus should be thrown out.
  • All equipment used in the cleanup should be disinfected.
  • Hands should be washed with soap and water for at least 20 seconds.

The CDC recommends that chlorine (household bleach) be applied to hard non porous surfaces like floors and walls. Amounts vary but a minimum concentration of 1000 ppm (1/3 cup of bleach) has been demonstrated in the laboratory to be effective against viruses similar to noroviruses. Some information recommends chlorine levels as high as 5000 ppm (1 2/3 cups of bleach). Bleach at these concentrations may damage materials.

Other disinfectants that may be used are:

  • Hydrogen peroxide
  • Hot water/steam >170ºF
  • Parachlorometaxylenol (PCMX)
  • Accelerated Potassium Peroxymonosulphate


****Careful**** Always read the manufacturer’s instructions and do NOT mix chemicals. Quaternary ammonia compounds are NOT EFFECTIVE for norovirus disinfection.

Please contact the Sioux Falls Health Department with any questions.