Which statement accurately describes portal of entry?

• A. The means by which an infectious agent leaves its reservoir
• B. The body opening or skin break that allows an infectious agent to enter the host
• C. The habitat where the agent resides
• D. The mode of transmission

Answer: (B)

Understanding portal of entry means identifying how a pathogen gets into the body to cause infection. The correct statement describes a body opening or skin break that allows an infectious agent to enter the host. This includes openings such as the nose, mouth, or conjunctiva, or any breach in the skin that provides access to tissues. When these entry points are intact, many pathogens cannot invade, which is why protecting barriers is central to infection control.

The other concepts refer to other parts of the infectious process: the way an agent leaves its reservoir (portal of exit), the place where the agent lives (reservoir), and the method by which it moves to a new host (mode of transmission).