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Gastroenteritis (Viral, Bacterial and Parasitic)

Last Updated: Mar 1, 2019


Gastroenteritis is an inflammation of the lining of the stomach and intestines. It is associated with diarrhea and/or vomiting and can be caused by bacteria, parasites, or viruses. Viral gastroenteritis (often called stomach virus or stomach flu) is extremely common, affecting millions of people each year during the cold seasons. Most individuals recover at home without intervention. The complications resulting from gastroenteritis differ based on the pathogen and can include severe dehydration, kidney failure, and coma.

Causes and Risk Factors

Gastroenteritis is caused by a pathogen, usually a virus, and is transmitted when an individual ingests contaminated food or water. Outbreaks typically happen where a Noroviruslarger number of individuals are in close quarters, such as in childcare centers and cruises.


Diarrhea and vomiting are the most common symptoms of gastroenteritis. Symptoms typically appear within a few days (viral and bacterial) or weeks (parasitic) of becoming infected and may include:

Diagnosis and Treatment

Gastroenteritis is typically diagnosed based on symptoms alone. A stool sample may be used to identify the causative pathogen. Most patients with gastroenteritis treat their symptoms at home and fully recover within days to weeks. Hospitalization becomes necessary when complications such as dehydration, excessive weight loss, and high fever arise.


The pathogens that cause gastroenteritis are very infectious and can survive outside the host for up to weeks. Extensive handwashing and avoiding contact with sick individuals are critical steps in preventing infection. Contaminated surfaces must be cleaned promptly with a dilute bleach or other disinfecting solution. Proper handling of food; adequate refrigeration; and thorough cooking of eggs, meats, and fish help prevent the growth and spread of harmful bacteria. Extra caution is necessary when traveling to countries where parasites like Giardia are common. Drinking water from untreated lakes and rivers is not advisable without first using an effective water purifier.


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Tina Shahian, PhD

Tina is a writer for Innerbody Research, where she has written a large body of informative guides about health conditions.


A communication specialist in life science and biotech subjects, Tina’s successful career is rooted in her ability to convey complex scientific topics to diverse audiences. Tina earned her PhD in Biochemistry from the University of California, San Francisco and her BS degree in Cell Biology from U.C. Davis. Tina Shahian’s Linkedin profile.


In her spare time, Tina enjoys drawing science-related cartoons.