A pathogen refers to the first stage of infection, and anything that can morph into a disease. A pathogen could be a form of bacterium (strep throat), virus (hepatitis A, B, or C), or a Fungus (athlete’s foot or candida). A virus is a type or subsection of pathogen; therefore, a pathogen is not the same thing as a virus.
Exposure to a pathogen, which can be either living or nonliving, often leads to infection of a host and then disease. However, infection, after exposure, depends on the dose, the amount of the pathogen the body was exposed to, the virulence, the strength of the pathogen, and host resistance, the immune system’s counteractive ability.