Pathogen

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.

Typically the term is used to describe an infectious agent such as a virus, bacteria, prion, fungus, or parasite that causes disease in its host. The host may be an animal, a plant, a fungus or even another microorganism.