Norovirus is a common cause of gastroenteritis. It is often responsible for outbreaks in schools, child care centers, long term care facilities for the elderly, and on cruise ships. More than 50 percent of all food borne illnesses in the United States are caused by norovirus, most often from ill food workers who contaminate the food they prepare. People infected with norovirus may still be contagious for at least 3 days after they are better.
Norovirus infections occur year round but are more common during the winter months. The illness is sometimes incorrectly called "the stomach flu" or "the 24-hour flu" by both health care providers and lay people. In fact, norovirus and influenza (the virus that causes the flu) are unrelated viruses that typically cause different illnesses. While each virus can produce a wide range of symptoms (from none at all to severe) the table below summarizes the general differences.
|Norovirus infection||Influenza ("the flu")|
|Symptoms||Often has sudden onset of nausea and vomiting and/or watery diarrhea with cramps. Low grade fever, chills, body aches sometimes occur.||Often has sudden onset of fever (up to 104º F), headache, sore throat, cough, body aches and congestion. Vomiting and diarrhea are less common.|
|Duration||Typically between 24 and 72 hours.||Typically between 3 and 7 days, often longer.|
|How serious||Rarely causes severe complications. Dehydration is the most common complication, particularly among young children and the elderly.||Usually gets better on its own but can cause severe complications, especially among young children, the elderly, and people with underlying health problems (such as asthma, chronic lung disease, chronic heart disease, diabetes, etc.)|
Resources for health care professionals
- Norovirus infections: Public health importance and outbreak management guidelines
- Guideline for the Prevention and Control of Norovirus Gastroenteritis Outbreaks in Healthcare Settings, HICPAC
- Norovirus resources for health care providers, CDC
- Prevention of norovirus in health care facilities, CDC
- Norovirus outbreak control resource toolkit for health care settings, CDC
Link/share our site at www.kingcounty.gov/norovirus