A Pathogen (from Greek ????? pathos "suffering, passion", and ?ἰ?????? (???-) gignomai (gen-) "I give birth to"), infectious agent, or more commonly germ, is a biological agent that causes disease or illness to its host. The term Pathogen is derived from the Greek "that which produces suffering." There are several substrates and pathways whereby Pathogens can invade a host; the principal pathways have different episodic time frames, but soil contamination has the longest or most persistent potential for harboring a Pathogen.   Wikipedia