In biology, a pathogen (Greek: πάθος pathos “suffering, passion” and -γενής -genēs “producer of”) in the oldest and broadest sense is anything that can produce disease, a term which came into use in the 1880s.he host may be an animal, a plant, a fungus, or even another microorganism. There are several substrates including pathways where the 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.