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Norovirus (Norwalk Virus)

Norovirus causes a gastrointestinal illness. It often occurs in outbreak form and, unfortunately, is sometimes referred to as "stomach flu" though the terms "flu" or "influenza" should really be restricted to a respiratory infection. Norwalk and Norwalk-like viruses are found, worldwide. The viruses are passed in the stool and vomit of infected persons.

People get a Norovirus infection directly from an ill individual who did not wash his hands adequately, or indirectly from food or water contaminated by the stool or vomit from an infected person, or from airborne particles produced by those vomiting. Outbreaks in the United States are commonly linked to food handled by infected food handlers; person-to-person contact especially in day care centers and nursing homes/custodial institutions; and eating raw shellfish, especially oysters and clams that are grown in sewage-contaminated waters.

Anyone can get Norovirus infection, and can get it many times since immunity is not long-lasting.

What are the signs and symptoms of Norovirus infection?

  • Nausea
  • Vomiting
  • Diarrhea
  • Abdominal cramps
  • Low grade fever or none at all

A good clue that an outbreak is due to Norovirus is the prevalence of both vomiting and diarrhea in cases, with many cases experiencing both symptoms. No specific treatment is available. Persons who are severely dehydrated might need fluid and electrolyte therapy.

Wash hands with soap and warm water after toilet visits and before preparing or eating food. People with symptoms of Norwalk-like illness should not prepare food or provide patient care. Cook all shellfish thoroughly before eating. Wash raw vegetables before eating. Custodial institutions need to assure a high level of personal hygiene to avoid person-to-person spread. Caretakers need to increase precautions to avoid transmission, particularly by washing hands frequently and especially before and after patient care.

Last modified on: 2/26/2014 8:53 AM