what illness is caused by a virus
Gastrointestinal Infections. Viruses cause viral gastroenteritis, commonly called the stomach flu.. This common illness, characterized by diarrhea, nausea and vomiting, is caused by many different viruses, but not the influenza virus.According to a 2012 article in the journal American Family Physician, viruses cause between 75 and 90 percent of acute gastrointestinal disease in children.Rotavirus is the most common viral cause of gastroenteritis among children.astrointestinal Infections. Viruses cause viral gastroenteritis, commonly called the stomach flu.. This common illness, characterized by diarrhea, nausea and vomiting, is caused by many different viruses, but not the influenza virus.