Infection transmission occurs when the agent leaves its reservoir or host through a portal of exit, is conveyed by some mode of transmission, and enters through an appropriate portal of entry to infect a susceptible host. The six links that must all be present (and in sequential order) for an infection to develop are: infectious agent, reservoir, portal of exit from the reservoir, mode of transmission, and portal of entry into a susceptible host.
From a Public Health standpoint, interventions are focused on (CDC):
- Controlling or eliminating agent at source of transmission
- Protecting portals of entry
- Increasing host’s defenses
Breaking any link in the chain of infection results in disruption.
