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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.

ByHealthwise Staff
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerChristine Hahn, MD - Epidemiology
Last RevisedJuly 9, 2012

WebMD Medical Reference from Healthwise

Last Updated: July 09, 2012
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