Virus

Top of the page Virus A virus is a microscopic organism that causes infection and disease. Viral illnesses can range from mild to severe. Some examples are the common cold, West Nile virus, polio, and smallpox. Current as of:
November 18, 2017Author:
Healthwise Staff Medical Review:
E. Gregory Thompson, MD – Internal Medicine & Adam Husney, MD – Family Medicine & Elizabeth T. Russo, MD – Internal Medicine