Epidemiological Triad Overview

The Epidemiological Triad is one of the traditional models for depicting disease causation, but is by far the simplest of them all. The triad is used to determine the cause of infectious diseases, non-infectious diseases, and accidents or injuries. It considers the interaction between the external agent, the susceptible host, and the environment. Used as an epidemiological tool, the triad is utilized to determine all factors internal and external to the host (the human), making them more susceptible to the agent (the “germ”), and has been used for decades to determine specific factors contributing to disease.