​​​​Norovirus causes what often is called the stomach flu, although it is not the influenza virus. Symptoms including vomiting and diarrhea in people. Anyone can become infected with these viruses. Because there are many different norovirus strains, norovirus infection and illness can re-occur throughout a person’s lifetime if precautions are not taken.


Norovirus illness usually begins 24-48 hours after exposure, but can appear as soon as 10 hours after exposure.

Symptoms usually include nausea, vomiting, diarrhea and stomach cramping. Sometimes people have a low-grade fever, chills, headache, muscle aches and general fatigue and tiredness. The illness-related symptoms typically last only one or two days.


Norovirus disease usually is not serious, but people with the norovirus may feel very sick. Most people get better within one or two days and have no long-term health effects from the illness. Sometimes people are unable to drink enough liquids to replace what they lose from vomiting and diarrhea, and they can become dehydrated and need to see a doctor. This problem usually occurs only among the very young, the elderly, and persons with weakened immune systems.

How norovirus spreads

Noroviruses are very contagious and spread easily from person to person. The virus is found in the stool and vomit of infected people. People can become infected in several ways, including eating food or drinking liquids contaminated by infected food handlers, touching surfaces or objects contaminated with norovirus and then touching their mouth before hand washing or having direct contact with an infected​ person and then touching their mouth before hand washing. Outbreaks also have occurred from eating undercooked oysters harvested from contaminated waters - cooking kills the virus. Drinking water contaminated by sewage also can be a source of the virus. Persons working in day-care centers or nursing homes should pay special attention to children or residents who have norovirus illness. This virus can spread quickly in these places.

Contagious period

People infected with norovirus are contagious from the moment they begin feeling ill to at least three days after recovery. Some people may be contagious for as long as two weeks after recovery. Therefore, good hand washing is important. Persons infected with norovirus should not prepare food while they have symptoms and for three days after they recover. Infected people do not become long-term carriers of norovirus.​


Currently, no specific medication or vaccine is available for norovirus. Norovirus infection cannot be treated with antibiotics. Drinking fluids, such as juice or water, can reduce the risk of dehydration. Sports drinks do not replace the nutrients and minerals lost during this illness.

While infected with norovirus

Since the virus is passed in vomit and stool, children should not go to daycare or school while they have diarrhea or vomiting. Once illness ends, children can return to daycare, but hand washing must be strictly monitored. Nursing homes workers who take care of patients or handle food should stay off work until at least three days after symptoms end.


Follow these tips to decrease your chance of coming in contact with noroviruses:

  • Wash hands frequently with soap and warm water.
  • Promptly disinfect contaminated surfaces with household chlorine bleach-based cleaners
  • Wash soiled clothing and linens
  • Avoid food or water from sources that may be contaminated
  • Cook oysters completely to kill the virus

Norovirus Outbreak

A gastrointestinal (GI) illness outbreak is defined as two or more persons in the same facility (e.g., nursing home, school, prison) or group (e.g., sport team), experiencing an acute onset of diarrhea, nausea or vomiting. Outbreaks of GI illness in Kentucky are reported to the district or county health department where the outbreak occurs. If the district or county health department cannot be reached, contact the Kentucky Department for Public Health toll free at (888) 9REPORT (888 973-7678).

See 902 KAR 2:020 Sections 7 and 12 for more information regarding outbreaks.