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What are noroviruses?

Noroviruses are a group of viruses that cause the “stomach flu”, or gastroenteritis (GAS-tro-en-ter-I-tis), in people. Norovirus is also commonly known as Norwalk or the “cruise ship disease”. Viruses are very different from bacteria and parasites. They are not affected by treatment with antibiotics, and they cannot grow outside of a person’s body. This illness is not the same as influenza, which is a respiratory illness.


What are the symptoms of noroviruses?

The symptoms of norovirus illness typically include nausea, vomiting, diarrhea (that can be explosive and watery), and stomach cramping. Sometimes people can have a low grade fever, chills, headache, muscle aches, and fatigue. The illness often begins suddenly, and the infected person may feel very sick. The illness is usually brief, with symptoms lasting only about 1 or 2 days. In general, children experience more vomiting than adults. Most people with norovirus illness experience both vomiting and diarrhea.


How serious is norovirus disease?

Norovirus disease is usually not serious, although people may feel very sick and may vomit many times a day. Most people get better in 24-48 hours, and most have no long-term health effects related to norovirus infection. However, sometimes people may become dehydrated due to vomiting and diarrhea and may need special medical attention. Dehydration problems are usually only seen among the very young, the elderly, and persons with weakened immune systems. There is no evidence to suggest that an infected person can become a long-term carrier of norovirus.


How do people become infected with norovirus?

Noroviruses are found in the stool or vomit of infected people. People can become infected when they accidentally ingest material that is contaminated with norovirus. This accidental ingestion can occur in several ways:

  • Eating food or drinking liquids that are contaminated with norovirus;
  • Touching surfaces or objects contaminated with norovirus, and then placing their hand in their mouth;
  • Having direct contact with another person who is infected and showing symptoms (for example, caring for someone with illness, or sharing foods or eating utensils with someone who is ill).

Persons working in day-care centers or nursing homes should pay special attention to children or residents who have norovirus illness. This virus is very contagious and can spread rapidly throughout such environments.


When do symptoms begin?

Symptoms of norovirus illness usually begin about 24 to 48 hours after ingestion of the virus, but they can appear as early as 12 hours after exposure.


Are noroviruses contagious?

Noroviruses are very contagious and can spread easily from person to person. Both stool and vomit contain the virus. Particular care should be taken with young children in diapers who may have diarrhea.


How long are people contagious?

People infected with norovirus are contagious from the moment that they begin feeling ill to at least 3 days after recovery. Some people may be contagious for as long as 2 weeks after recovery. Therefore, it is important to use good handwashing and other hygienic practices.


Who gets norovirus infection?

Anyone can become infected with noroviruses. There are many different strains of norovirus, which makes it difficult for a person’s body to develop immunity, so people can become infected with noroviruses more than once. In addition, because of differences in genetic factors, some people are more likely to become infected and develop more severe symptoms than others.


What treatment is available for people with norovirus infection?

Currently, there is no antiviral medication that works against norovirus, and there is no vaccine to prevent infection. Norovirus infection cannot be treated with antibiotics. This is because antibiotics work to fight against bacteria not viruses.


What should I do if I have norovirus infection?

Norovirus illness is usually brief in healthy individuals. When people are ill with vomiting and diarrhea, they should drink plenty of fluids to prevent dehydration. Dehydration among young children, the elderly, and the chronically-ill can be common, and it is the most serious health effect that can result from norovirus infection. By drinking oral rehydration fluids (ORF), juice, or water people can reduce the chance of becoming dehydrated. Sports drinks do not replace the nutrients and minerals lost during this illness. If you work in food-handling, healthcare, or child care, you should not attend work while you are ill and you should not return to work until 72 hours after your symptoms cease. If you experience blood in your stool and/or if your illness lasts more than 72 hours, this may be indicative of a more serious gastrointestinal, bacterial infection like E. coli or Salmonella and you may want to see your primary healthcare provider for testing.


Can norovirus infections be prevented?

YES. You can decrease your chance of becoming infected with norovirus or spreading the virus by following these preventive steps:

  1. Frequently wash your hands, especially after using the restroom, after changing diapers, and before eating or preparing food.
  2. If you are ill, stay home from work and school, especially if you work in food-handling, healthcare, or child care.
  3. Thoroughly clean and disinfect contaminated surfaces immediately after an episode of illness by using a solution of 1/3 cup bleach per 1 gallon of water (50:1 dilution). Always follow the manufacturer’s safety precautions.
  4.  Immediately remove and wash clothing or linens that may be contaminated with the virus after an episode of illness (use hot water and soap).
  5.  Flush or discard any vomit and/or stool in the toilet and make sure that the surrounding area is kept clean.


Norovirus Resources and Guidelines


Reporting illness:

Norovirus illnesses are not reportable to the Wyoming Department of Health unless they are part of a cluster of illness or outbreak. If you suspect that your illness is part of a larger cluster of illnesses or an outbreak related to the same venue (i.e. restaurant, nursing home, daycare, etc…), please contact the Wyoming Department of Health’s Infectious Disease Epidemiology Program at 1-877-996-9000 or call the 24/7 emergency number at 1-888-996-9104.