Viral gastroenteritis is inflammation of the stomach and intestines caused by a virus. The infection can lead to diarrhea and vomiting. It is sometimes called the "stomach flu."

Viral gastroenteritis is a leading cause of severe diarrhea in both adults and children. Many types of viruses can cause gastroenteritis. The most common ones are:

• Astrovirus
• Enteric adenovirus
• Norovirus (also called Norwalk-like virus). It is common among school-age children.
• Rotavirus, the leading cause of severe gastroenteritis in children. It can also infect adults exposed to children with the virus. Outbreaks may also occur in nursing homes.

These viruses are often found in contaminated food or drinking water. Symptoms of viral gastroenteritis usually appear within 4 - 48 hours after exposure to the contaminated food or water.

Those with the highest risk for severe gastroenteritis include the young, the elderly, and people who have suppressed immune systems.