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Definition of Pathogen

From Ingrid Koo, Ph.D., for About.com

Created: March 20, 2009

About.com Health's Disease and Condition content is reviewed by the Medical Review Board

Definition: A disease-causing agent.

Most pathogens are infectious microbes, such as bacteria or viruses, which are capable of causing disease. Other parasites, such as fungi and protozoans, are also considered pathogens. Because not all microbes are harmful, pathogens refer specifically to those that can cause disease or other harm.

Pronunciation: PATH-a-jin
Also Known As: infectious agent, infectious microbe, germ, bug
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