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Bureau of Disease Control

Gastroenteritis and noroviruses (PDF version for printing)

What is gastroenteritis?

The symptoms of gastroenteritis are nausea, vomiting, and/or diarrhea accompanied by abdominal cramps. Some people also complain of headache, fever, chills and muscle aches. Symptoms are usually brief and last only one or two days. However, during that period, people can feel very ill and vomit, often violently and without warning, many times a day. Symptoms usually begin 24 to 48 hours after ingestion of the virus, but can appear as early as 12 hours after exposure.

What is norovirus?

Noroviruses are members of a group of viruses called caliciviruses also known previously as “Norwalk-like viruses.” Norovirus affects the stomach and intestines, causing an illness called gastroenteritis. While this is sometimes incorrectly referred to as “stomach flu,” it is not the flu (or Influenza), which is a respiratory illness.

How serious is norovirus disease?

Norovirus disease is usually not serious, although people may feel very sick and vomit many times a day. Most people get better within one or two days, and they have no long-term health effects related to their illness. However, sometimes people are unable to drink enough liquids to replace the liquids they lost because of vomiting and diarrhea. Those people can become dehydrated and might need special medical attention. This problem with dehydration is usually only seen among the very young, the elderly, and persons with weakened immune systems.

How is norovirus spread?

While there is no evidence that sick people can become long-term carriers of the virus, the virus can be in the stool and vomit of infected people for as long as two weeks after they feel better.

People can become infected with the virus in several ways, including:

  • Eating food or drinking liquids that are contaminated with norovirus,
  • Touching an object, such as a door knob or keyboard, which is contaminated with norovirus, then placing a hand to mouth,
  • Having direct contact with another person who is infected and shows symptoms, for example, sharing foods or eating utensils with someone who is ill.

Because the amount of virus that can cause illness is so small, it is important to reduce the risk of spreading this virus by using appropriate cleaning measures:

  • Using a 1-to-10 chlorine bleach solution on hard surfaces, especially kitchens and bathrooms,
  • Steam cleaning carpet or upholstery that has been contaminated by feces or vomit from an ill person,
  • Not transporting soiled linens, bed clothing or other garments through a food preparation area unless they are bagged.

How contagious is norovirus?

Norovirus is very contagious and can spread easily from person to person. Both stool and vomit are infectious. Particular care should be taken with young children in diapers who may have diarrhea. 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, it is particularly important for people to use good hand washing and other hygienic practices after they have recently recovered from norovirus illness.

Can I get infected with norovirus more than once?

A person can be infected with norovirus more than once. Although there is a short period of time (likely a few months) immediately following infection with Norovirus that a person is protected from reinfection, it is only a temporary protection.

What steps can I take to reduce my risk?

Strict hand washing after using the bathroom and before handling food items is important in preventing the spread of the virus, because it continues to be present in the stool for as long as two to three weeks after the person feels better. One excellent way to prevent spreading the virus to others is daily wiping of doorknobs, faucets and commodes with a mild bleach solution made of one cup of bleach in nine cups of water. Care should be used to keep the solution off your skin and away from fabrics that may be damaged by the bleach. Family members should use separate hand towels for two to three weeks after symptoms go away.

People should keep in mind that the virus is easy to avoid with careful and frequent hand washing. Refrain from chewing on your fingernails, pencils or pens. Don’t even unwrap a piece of candy or gum without first washing your hands.

When should I seek help?

Inability to retain sufficient fluids is the most critical concern, especially with young children. Monitor fluid intake and output, and seek immediate medical care to prevent complications from dehydration.

For more information:
http://www.cdc.gov/norovirus/index.html