The Chain of Infection Copy
A chain of events needs to occur to allow germs to be transmitted and for infection to spread. There are six links in the chain.
Micro-organisms, the first link in the Chain, spread directly or indirectly from person to person. Micro-organisms can only be spread through a microscope and only some cause infections. Micro-organisms include bacteria (ex. MRSA), viruses (ex. Norovirus), Fungi (ex. Candida), and Protozoa (ex. Giardia).
The reservoir, the second link in the Chain, is where micro-organisms are found. In reservoirs, micro-organisms have everything they need to grow and multiple, including moisture and warmth. Humans, damp areas, spores released into the air, and food are all examples of reservoirs.
The portal of exit, the third link in the Chain, is where the micro-organisms exits the reservoir and is able to spread. This may be through the mouth, saliva, vaginal fluid, airborne droplets from the lungs, faeces or urine, blood or vomit, or skin cells.
The mode of transmission, the fourth link in the chain, is how micro-organisms spread from one person to another. This may be through direct contact transmission, which occurs when there is physical contact between people, or through indirect contact, such as through touching a contaminated object.
The portal in entry, the fifth link in the Chain, is the entry point for the other person. This may be through the nose, mouth, urethra, cuts, or broken skin.
A susceptible host, the sixth link in the Chain, is a person with severe or chronic illness who has a damaged immune system, a patient requiring the use of medical devices that bypass their external defenses against infection, or people that are very old or very young.