Stomach flu

A stomach virus (or stomach flu) is not a form of influenza but a condition that causes the stomach and intestines to become inflamed, resulting in a variety of uncomfortable, digestive-related symptoms. Stomach "flu" is universal, and for most people a private, and usually temporary, annoyance. The symptoms are nausea in the stomach, aches, fever and vomiting. The infectious agent is either a virus, bacterium or parasite.

According to the U.S. National Library of Medicine, there are many types of viruses that can cause this condition, chiefly:

• Norovirus: Norovirus is very contagious and can spread via a number of ways, such as through contaminated food, water or surfaces. It is also considered the most common cause of acute gastroenteritis.
• Rotavirus: The rotavirus belongs to the Reoviridae family of viruses, and is identified by its double-stranded RNA enclosed by a double-shelled outer layer. As with other viruses, it is very contagious and causes severe diarrhea among infants and children.
• Astrovirus: Astrovirus strains are single-stranded, positive-sense and non-enveloped RNA viruses belonging to the Mamastrovirus family. The virus is contagious among children and the elderly, but adults are more resistant to it.
• About 50% of stomach "flu" in winter months is caused by on of the 10 or so variations of the Norwalk virus, one of the caliciviruses.