What is a portal of entry?

• A. Any body orifice or skin break that allows an infectious agent to enter the host.
• B. The means by which an infectious agent leaves its reservoir
• C. The portal of exit
• D. The environment

Answer: (A)

A portal of entry is the route a pathogen uses to enter a new host, typically through body openings or breaks in the skin. This includes mucous membranes of the nose, mouth, eyes, and respiratory or gastrointestinal tracts, as well as punctures, wounds, or other skin breaks, and parenteral routes. Pathogens must have a way to enter the body to cause infection, so identifying these entry points is key to prevention—hence covering wounds, practicing good hand hygiene, and using proper injection techniques help block these routes. The means by which an agent leaves its reservoir is the portal of exit, not entry, and the environment is external to the host rather than a path the pathogen uses to gain entry.