What are the most common causes of the stomach flu (gastroenteritis)?

Viral causes of stomach flu

The most prevalent cause of gastroenteritis in the U.S. and the world is Norovirus. It causes about 50%-70% of viral gastroenteritis cases, while Rotavirus, Astrovirus, Adenovirus, and Sapovirus strains cause most of the other viral gastroenteritis infections. Norovirus also was listed as the leading cause of gastroenteritis in children under 5 years old according to the Centers for Disease Control and Prevention (CDC).

Bacterial causes of stomach flu

Bacterial causes of gastroenteritis that occur worldwide are Salmonella, Shigella, Campylobacter Aeromonas, and Escherichia coli (E. coli) strains of bacteria. Other bacteria like Clostridium, Vibrio, Campylobacter, and Yersinia spp can cause outbreaks occasionally. Occasionally, some bacterial causes of gastroenteritis (for example, Salmonella and , certain E. coli strains) may produce hemorrhagic or bloody diarrhea.

Parasitic causes of stomach flu

Parasites such as Giardia, Cryptosporidium, and Entamoeba infections can cause gastroenteritis and occasionally, other parasites have outbreaks such as the Cyclospora outbreak that occurred in 2012 to 2013 in the U.S.

Other causes of stomach flu

There are many other less frequent causes of gastroenteritis such as food allergies (eosinophilic gastroenteritis), antibiotics, and toxins. Gastroenteritis symptoms are frequently listed as possible side effects of many medicines.

How does food become contaminated with gastroenteritis-causing bacteria or viruses?

In most instances, food and drinks come into contact with feces contaminated with the infecting agent. This can happen in the fields, or in transport, storage, and processing of food and drinks. In processed foods and drinks, this contamination is relatively rare, but when it occurs, an outbreak of the disease is often traced back to faulty equipment, human errors in the processing and/or a breakdown of quality-control procedures.