What are the causes of viral gastroenteritis?

The viruses that cause viral gastroenteritis damage the cells in the lining of the small intestine. As a result, fluids leak from the cells into the intestine and produce watery diarrhea. Four types of viruses cause most viral gastroenteritis. They are as follows:

- Rotavirus is the leading cause among 3- to 15-month-old children, and the most common cause of diarrhea in children under the age of five years. Symptoms of rotavirus infection appear one to two days after exposure. Rotavirus typically causes vomiting and watery diarrhea for three to eight days, along with fever and abdominal pain. Rotavirus can also infect adults who are in close contact with infected children, but the symptoms in adults are milder.
- Adenovirus occurs mainly in children under the age of two years. Of the 49 types of adenoviruses, one strain affects the gastrointestinal tract, causing vomiting and diarrhea. Symptoms typically appear one week after exposure. Adenovirus infections occur year round.
- Caliciviruses cause infection in people of all ages. This family of viruses is divided into four types, the noroviruses being the most common and most responsible for infecting people. The noroviruses are usually responsible for epidemics of viral gastroenteritis and occur more frequently from October to April. Infected people experience vomiting and diarrhea, fatigue, headache, and sometimes muscle aches. The symptoms appear within one to three days of exposure.
- Astrovirus also infects primarily infants, young children, and the elderly. This virus is most active during the winter months. Vomiting and diarrhea appear within one to three days of exposure.

Viral gastroenteritis is often mistakenly called "stomach flu," but it is not caused by the influenza virus and it does not infect the stomach. Also, viral gastroenteritis is not caused by bacteria or parasites.

This answer is based on source information from the National Digestive Diseases Information Clearinghouse (NDDIC).

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