What is stomach flu and how does it spread?
Ask the doctor
Q. What causes stomach flu and how is it transmitted?
A. "Stomach flu" is the commonly used name for gastroenteritis. Gastroenteritis is almost always caused by a virus. But it is not caused by the influenza virus.
The viruses that most often cause gastroenteritis are noroviruses and rotaviruses, but there are a host of others. Some bacteria and parasites also can be the culprit.
The usual symptoms of gastroenteritis include:
- diarrhea
- abdominal discomfort, usually cramps
- an upset stomach
- nausea, occasionally with vomiting.
Gastroenteritis may cause a low fever and mild headache.
Viral gastroenteritis goes away without medication. The main concern until it goes away is dehydration. You can avoid this by drinking plenty of fluids.
Viral gastroenteritis is highly contagious. It spreads from person to person primarily by direct contact.
These viruses can survive in food and beverages. This is why buffets have the potential to infect many people.
Food becomes contaminated most often when people do not wash their hands (or wash them poorly) after using the bathroom. Other sources of viral contamination are drinking water and seafood that has been exposed to untreated sewage.
Image: © Ekaterina Goncharova/Getty Images
About the Author
Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
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