Noroviruses are a group of viruses that can cause inflammation of the stomach and intestines (gastroenteritis). Norovirus is the leading cause of vomiting and diarrhea from acute gastroenteritis among people of all ages in the United States.
Norovirus infection is often called the “stomach flu,” but it is not related to the flu, which is a respiratory illness caused by the influenza virus.
You may not be able to be 100% certain you have norovirus, but some common symptoms that may indicate you could be infected include:
- Vomiting, often many times per day
- Diarrhea
- Stomach cramps
Symptoms come on suddenly and can occur as soon as 12 hours after ingesting contaminated food, but they usually start one to two days after exposure.
Less common symptoms of norovirus infection can include:
Most people recover from norovirus infection within one or two days with no long-term health effects.
How Contagious Is the Stomach Flu?
Noroviruses are very contagious and they are found in the feces or vomit of infected people. When infected people do not properly wash their hands after using the bathroom, the virus can contaminate food, water, or surfaces they touch.
Norovirus is transmitted by:
- Eating food or drinking liquids contaminated with norovirus
- Touching contaminated surfaces or objects and then touching the mouth or eating without washing hands first
- Direct contact with someone an infected person, such as by caring for them or sharing food or eating utensils with them
- Eating uncooked shellfish harvested from contaminated waters
How Is Norovirus Diagnosed?
Norovirus infection is diagnosed with a patient history and physical examination. The diagnosis is usually based on the presence of symptoms, especially vomiting, fever, and short duration of illness.
Testing is usually not required for a diagnosis, however, if there is a known norovirus outbreak in progress, public health officials may want to have people who are sick with characteristic symptoms of norovirus tested.
Lab tests for norovirus may include:
- Reverse transcriptase polymerase chain reaction test (RT-PCR assay)
- Enzyme-linked immunoassay (ELISA) test
What Is the Treatment for Norovirus?
- There is no specific medication to treat norovirus illness.
- The mainstay of treatment for norovirus infection involves drinking plenty of fluids to prevent dehydration from fluid lost due to vomiting and diarrhea. Severe dehydration may require intravenous (IV) fluids administered in a hospital.
- Wash your hands frequently and do not prepare food for others.
- Antibiotics are not prescribed since they are only effective on bacterial infections.
How Do You Prevent Norovirus?
To prevent norovirus infection:
- Wash hands with soap and water for at least 20 seconds, especially:
- After using the bathroom
- After changing diapers
- Before food preparation
- Before eating
- Clean and disinfect surfaces with a household bleach solution immediately after vomiting or diarrheal accidents
- Do not prepare food for others if you have symptoms of norovirus, and for at least three days after you recover
- Steam oysters before eating
From 
Infectious Disease Resources
Featured Centers
Health Solutions From Our Sponsors
https://www.health.state.mn.us/diseases/norovirus/noro.html#:~:text=Common%20symptoms%20of%20norovirus%20infection,as%2012%20hours%20after%20exposure.
https://www.cdc.gov/norovirus/index.html