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 |
© 1995-2011 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated. This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.
