Noroviruses refer to a group of viruses. They cause inflammation of the stomach and intestines. It is called gastroenteritis or the stomach flu. In the US, they are the second leading cause of illness. Outbreaks have occurred in settings such as:
These viruses are highly contagious. They are spread by fecal to oral contamination of water and food.
Infection can occur as a result of contaminated:
The viruses can also spread by direct contact with an ill person. This is common in a daycare center or nursing home.
The following factors increase your chance of developing noroviruses:
Even if you have been infected with norovirus in the past, you can become ill again if:
If you have any of these do not assume it is due to norovirus. These may be caused by other, less serious health conditions. If you have any one these symptoms, see your doctor:
After exposure to the virus, symptoms often appear within 24-48 hours. You may feel ill as early as 12 hours. Symptoms often last about 24-60 hours.
Your doctor will ask about your symptoms and medical history. A physical exam will be done.
Diagnosis can be made based on a stool specimen. Often, your doctor can determine this illness without ordering any lab tests.
Currently, there are no treatments. Because gastroenteritis is caused by a virus, antibiotics cannot cure it. There are no antiviral medications or vaccines. The illness is often brief.
The only complication would be dehydration due to vomiting and diarrhea. In certain groups of people, this may require a hospital stay to replenish fluids.
Noroviruses can survive extreme heat and cold. The virus can also live in water with up to 10 parts per million of chlorine. This is much higher than what public water supplies have. There are ways, though, to limit exposure.
To help reduce your chance of getting noroviruses take the following steps:
RESOURCES:
National Institute of Allergies and Infectious Diseases
http://www3.niaid.nih.gov/
US Centers for Disease Control and Prevention
http://www.cdc.gov/
US Food and Drug Administration
http://www.fda.gov/
CANADIAN RESOURCES:
BC Health Guide
http://www.bchealthguide.org/
Communicable Disease Control Unit
http://www.gov.mb.ca/health/publichealth/cdc/index.html
Health Canada
http://www.hc-sc.gc.ca/index_e.html
References:
Causes and symptoms of norovirus infection. Minnesota Department of Health website. Available at: http://www.health.state.mn.us/divs/idepc/diseases/norovirus/basics.html . Accessed June 11, 2007.
Foodborne diseases: norovirus infection. National Institute of Allergies and Infectious Diseases website. Available at: http://www3.niaid.nih.gov/healthscience/healthtopics/norovirus/diagnosis.htm . Accessed June 12, 2007.
Norovirus: food handlers. National Center for Infectious Diseases: Respiratory and Enteric Viruses Branch. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/ncidod/dvrd/revb/gastro/norovirus-foodhandlers.htm . Accessed June 11, 2007.
Norovirus in healthcare facilities fact sheet. National Center for Infectious Diseases: Respiratory and Enteric Viruses Branch. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/ncidod/dhqp/id_norovirusFS.html . Accessed June 11, 2007.
Norovirus: Q&A. National Center for Infectious Diseases: Respiratory and Enteric Viruses Branch. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/ncidod/dvrd/revb/gastro/norovirus-qa.htm . Accessed June 11, 2007.
Norovirus: technical fact sheet. National Center for Infectious Diseases: Respiratory and Enteric Viruses Branch. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/ncidod/dvrd/revb/gastro/norovirus-factsheet.htm . Accessed June 11, 2007.
The Norwalk virus family. In: The Bad Bug Book: Foodborne Pathogenic Microorganisms and Natural Toxins Handbook . US Food and Drug Administration; 1992. Center for Food Safety and Applied Nutrition website. Available at: http://www.cfsan.fda.gov/~mow/chap34.html . Accessed June 11, 2007.
Preventing norovirus. Minnesota Department of Health website. Available at: http://www.health.state.mn.us/divs/idepc/diseases/norovirus/prevention.html . Accessed June 11, 2007.
Last reviewed January 2009 by David L. Horn, MD, FACP
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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