What is the chain of infection?

• A. A way of describing how disease is transmitted from one being to another
• B. A description of how a patient recovers from illness
• C. A chart of medication administration sequence
• D. A list of pathogens common in a facility

Answer: (A)

The chain of infection is a framework for understanding how disease is transmitted from one person to another. It includes several linked parts: the infectious agent (pathogen), the reservoir where the pathogen lives, the portal of exit from that reservoir, the mode of transmission to a new host, the portal of entry into the new host, and a susceptible host who can become infected. In healthcare, breaking any one link prevents spread, so practices like hand hygiene, using gloves and masks, proper cleaning and disinfection, isolating contagious patients, and ensuring vaccination all help interrupt transmission. The other options describe recovery, a medication sequence, or a catalog of pathogens, none of which explain how disease moves from person to person.