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Medical Author:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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Medical Editor:

Bhupinder Anand, MD

In this Article

• Gastroenteritis (stomach flu) facts
• What is gastroenteritis (stomach flu)?
• What causes gastroenteritis?
• Clostridum difficile as a cause of gastroenteritis
• What are gastroenteritis symptoms?
• Is gastroenteritis contagious?
• Is gastroenteritis a serious illness?
• How does food get contaminated with gastroenteritis viruses?
• Who is at risk of gastroenteritis?
• When should the doctor be called for gastroenteritis?
• How is gastroenteritis diagnosed?
• What is the treatment for gastroenteritis?
• What are gastroenteritis complications?
• Can gastroenteritis be prevented?
• What is the prognosis of gastroenteritis?
• Summer Food Safety FAQs
• Patient Comments: Gastroenteritis (Stomach Flu) - Effective Treatments
• Patient Comments: Gastroenteritis (Stomach Flu) - Symptoms
• Patient Comments: Gastroenteritis (Stomach Flu) - Diagnosis
• Find a local Gastroenterologist in your town
• Gastroenteritis Index

Gastroenteritis, as defined above, has many causes, but the most frequent causes are viral and bacterial. Other causes vary greatly, such as parasites, toxins, food allergies, and medications. Many of the causes of gastroenteritis actually go on to develop additional gastrointestinal symptoms that are considered specific diseases themselves. The incidence of deaths due to gastroenteritis has been recently shown to be increasing. The two major causes of deaths are attributed to C. difficile, and Norovirus. The following lists the major causes of gastroenteritis, and also lists the diseases that have symptoms of gastroenteritis as part of their specific disease process; this list is not all-inclusive but does include the large majority of causes of gastroenteritis that are encountered worldwide.

• Norovirus: causes about 50% to 70% of all gastroenteritis in adults, the most common cause of gastroenteritis in the US, and second most common cause of death due to gastroenteritis.
• Rotavirus: common cause of diarrhea in infants, occasionally producing dehydration
• Adenovirus: usually causes respiratory infection, but some strains cause gastroenteritis symptoms
• Astrovirus: common cause of diarrhea in infants
• Sapovirus: common cause of mild gastroenteritis in children

• Clostridium difficile: bacterial overgrowth and toxin production due to antibiotic suppression of competing intestinal bacteria; disease - C. difficile toxin production; this organism causes the highest number of deaths due to gastroenteritis, mainly in the elderly, over the age of 65 years.
• Staphylococcus: - a frequent cause of diarrhea and abdominal cramps; disease - Staphylococcus food poisoning
• Escherichia coli: food poisoning; diseases - E. coli infections, especially strain 0157:H7 that may cause HUS (hhemolytic-uremic syndrome) or TTP (thrombotic thrombocytopenic purpura)
• Salmonella: food poisoning; disease - salmonellosis
• Shigella: food poisoning; disease - shigellosis
• Listeria: usual source is contaminated dairy products; disease - listeriosis
• Campylobacter: contaminated dairy foods
• Vibrio: contaminated drinking water and seafood; disease - cholera
• Bacillus: usual source is contaminated rice
• Aeromonas: seafood contamination
• Yersenia: pork meat contamination
• Plesiomonas: oysters and other seafood

• Giardia: common source of diarrhea from contaminated water; disease - giardiasis
• Cryptosporidium: food and water sources of diarrhea; disease - cryptosporidiosis
• Entamoeba: contaminated water; disease - amebiasis

• Food allergies: many types; eggs, nuts, milk, and shellfish are fairly common
• Antibiotics: many antibiotics allow bacterial/fungal overgrowth (see Clostridium difficile previously mentioned)
• Toxins: algal toxin in shellfish, heavy metal toxins. (aluminum, cadmium, arsenic, lead, and mercury) and others
• Medications: side effects of many medications are diarrhea