Which term describes the pathway for pathogens to leave the reservoir?

• A. Portal of Exit
• B. Mode of Transmission
• C. Portal of Entry
• D. Susceptible Host

Answer: (A)

Pathogens leave their source through a specific exit route, known as the portal of exit. This is the point where the microorganism leaves the reservoir to reach others—examples include droplets expelled during coughing or sneezing from the respiratory tract, blood from a wound, or urine or feces from an infected person. Understanding this helps you trace how an infection starts its spread from the original source. It’s different from the portal of entry, which is how a pathogen gets into a new host (such as the lungs, gut, or through broken skin), and from the mode of transmission, which describes the method by which the pathogen travels between hosts after leaving the reservoir (direct contact, droplet spread, airborne, vector, etc.). A susceptible host is simply someone who can become infected if exposure occurs.