Lesson 1: Introduction to Epidemiology

Summary, References, and Websites

As the basic science of public health, epidemiology includes the study of the frequency, patterns, and causes of health-related states or events in populations, and the application of that study to address public health issues. Epidemiologists use a systematic approach to assess the What, Who, Where, When, and Why/How of these health states or events. Two essential concepts of epidemiology are population and comparison. Core epidemiologic tasks of a public health epidemiologist include public health surveillance, field investigation, research, evaluation, and policy development. In carrying out these tasks, the epidemiologist is almost always part of the team dedicated to protecting and promoting the public’s health.

Epidemiologists look at differences in disease and injury occurrence in different populations to generate hypotheses about risk factors and causes. They generally use cohort or case-control studies to evaluate these hypotheses. Knowledge of basic principles of disease occurrence and spread in a population is essential for implementing effective control and prevention measures.


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For more information on: Visit the following websites:
CDC’s Epidemic Intelligence Service https://www.cdc.gov/eis/
CDC’s framework for program evaluation in public health https://www.cdc.gov/mmwr/preview/mmwrhtml/rr4811a1.htm
Updated Guidelines for Evaluating Public Health Surveillance Systems https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5013a1.htm
Case Definitions for Infectious Conditions Under Public Health Surveillance https://www.cdc.gov/osels/ph_surveillance/nndss/casedef/
John Snow http://www.ph.ucla.edu/epi/snow.html


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