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Virus

A virus is a microscopic organism that causes infection and disease. Viral illnesses can range from mild to severe, including examples such as the common cold, West Nile virus, polio, and smallpox.

By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer Christine Hahn, MD - Epidemiology
Last Revised July 8, 2010

WebMD Medical Reference from Healthwise

Last Updated: July 08, 2010
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