Answer:
Contamination signifies the possible existence of microbes in or on the body. Infection is considered as the successful invasion of the pathogen in the body. The pathogens can acquire access or can invade the body of a human being with the help of portals, like via the skin, placenta, and mucous membranes.
The parenteral route is not precisely considered as a portal, however, it is a way of circumventing the general portals.