Noroviruses are a group of viruses that cause gastroenteritis [gas-trō-en-ter-ī-tis] in people. Gastroenteritis is an inflammation of the lining of the stomach and intestines, causing an acute onset of severe vomiting and diarrhea. Norovirus illness is usually brief in people who are otherwise healthy. Young children, the elderly, and people with other medical illnesses are most at risk for more severe or prolonged infection. Like all viral infections, noroviruses are not affected by treatment with antibiotics. Norovirus infections spread very rapidly. Healthcare facilities and other institutional settings (e.g., daycare centers, schools, etc.) are particularly at-risk for outbreaks because of increased person-to-person contact.
The symptoms of norovirus illness usually include nausea, vomiting, diarrhea, and some stomach cramping. Sometimes people also have a low-grade fever, chills, headache, muscle aches, and tiredness. People may suddenly feel very sick and vomit frequently or have several episodes of diarrhea, but most people get better within 1 or 2 days and they have no long-term health effects related to their illness. Diarrhea is more common in children and vomiting is more common in adults.
In some cases, people are unable to drink enough liquids to replace the liquids they lost because of frequent vomiting and diarrhea. This is called dehydration—the loss of a great deal of water from their body. Symptoms of dehydration include decreased urination, dry mouth and throat, and dizziness when standing up. In these cases, patients may be hospitalized and often given fluids through a tube placed in a vein.
Noroviruses are found in the feces and vomit of infected people. This virus is very contagious and can spread rapidly throughout healthcare facilities. People can become infected with the virus in several ways:
In a healthcare facility, patients with suspected norovirus may be placed in private rooms or share rooms with other patients with the same infection. Additional prevention measures in healthcare facilities can decrease the chance of coming in contact with noroviruses: