FIGURE SA-3. The epidemiological triad.

FIGURE SA-3The epidemiological triad

The familiar “epidemiological triad” concept (host-pathogen-environment), as illustrated in the famous diagram of Snieszko (1974), neatly illustrates the complex interplay of factors that result in disease at the individual and population levels. The presence of a pathogen is a necessary but not sufficient cause of a particular disease.

SOURCE: Reprinted with the permission of Blackwell Publishing Ltd. from Snieszko (1974). Copyright 1974.

From: Summary and Assessment

Cover of Vector-Borne Diseases
Vector-Borne Diseases: Understanding the Environmental, Human Health, and Ecological Connections, Workshop Summary.
Institute of Medicine (US) Forum on Microbial Threats.
Washington (DC): National Academies Press (US); 2008.
Copyright © 2008, National Academy of Sciences.

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