Chain Of Infection - Infection Prevention And Control

Certain conditions must be met in order for a microbe or infectious disease to be spread from person to person. This process, called the chain of infection, can only occur when all six links in the chain are intact.

Infection Control principles are aimed at breaking one or more links in this chain.

  • Caustive Agent - the microorganism (for example bacteria, virus or fungi).
  • Reservoir (source) - a host which allows the microorganism to live, and possibly grow, and multiply. Humans, animals and the environment can all be reservoirs for microorganisms.
  • Portal of Exit - a path for the microorganism to escape from the host. The blood, respiratory tract, skin and mucous membranes, genitourinary tract, gastrointestinal tract, and transplacental route from mother to her unborn infant are some examples.
  • Mode of Transmission - since microorganisms cannot travel on their own; they require a vehicle to carry them to other people and places.
  • Portal of Entry - a path for the microorganism to get into a new host, similar to the portal of exit.
  • Susceptible Host - a person susceptible to the microorganism.