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Term: Norovirus

The Norovirus infection is the major cause of stomach illness in closed and congested environments, such as cruise ships, hospitals, and nursing homes. The infection is highly contagious and usually spread through food or water polluted by fecal matter during preparation. It can also be acquired through close contact with an infected person. Norovirus is a self-limited viral gastroenteritis (inflammation of the lining membrane of the stomach and the intestines that causes nausea, vomiting, diarrhea, and cramps).It’s also known as the Norwalk virus gastroenteritis, Norwalk-like virus infection, winter vomiting, and cruise ship virus infection. The norovirus genogroup I, II, and IV strains infect humans. It’s generally mild and usually last between 12-72 hours, but in some cases, it can last for 1 week or longer. There are no long-term affects and strain immunity is short term: weeks to months.

The norovirus genogroup I, II, and IV strains infect human beings. The genogroup II is the largest cause of worldwide outbreaks since the mid-90’s. Genogroup II is linked to 53% of norovirus epidemics during September to December 2012 in the U.S. Most infections are cause by 1 strain, but there are some cases with infection of more than 1 strain. This usually occurs with the consumption of tainted shellfish or sewage contaminated water.

Typical symptoms include headaches, nausea, abdominal cramps, watery diarrhea (especially in adults), and vomiting (especially in children).

Additional symptoms include:
  • Anorexia
  • Malaise
  • Low-grade fever
  • Fatigue
  • Muscle aches
  • Chills
  • Myalgia

There is no specific treatment for Norovirus. The best form of treatment is to maintain fluid intake and avoid dehydration and hypovolemia. Some patients may be hospitalized for fluid and electrolyte replacement if needed. Also, antiemetics and analgesics are known treatments. However, Nitazoxanide (an antiprotozoal agent used to treat diarrhea) may be used to shorten symptom duration. This is based on small-randomized trial of 50 patients with gastroenteritis that tested positive for norovirus.

Some methods of controlling Norovirus in hospitals are strict personal hygiene by staff, patients, and visitors, prohibit staff and patients from moving between affected areas in the hospital. Check new patients that came from affected areas, quarantine patients that were affected by the virus for at least 48 hours, and after resolution of symptoms, immediately disinfect contaminated areas. Avoid contaminated food and water. Detergent and sodium hypochlorite solution combined is an effective method used for disinfecting and cleaning contaminated surfaces. Also, avoid contaminated food and water.

Web Resources:
CDC Reporting and Surveillance for Norovirus - http://www.cdc.gov/norovirus/php/reporting.html
Healthcare Provider Information on Norovirus - http://www.health.state.mn.us/divs/idepc/diseases/norovirus/healthcare.html

Related Terminology:
Norwalk Virus
Viral gastroenteritis


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The above image illustrates how Norovirus is transmitted thorough the environment.