Definition of Epidemiology
The word epidemiology (epi-demi-ology) means “the study of what is upon the people.” The etymological breakdown of epidemiology is (Greek – English):
epi – Above or upon
demos – The people
logos – The study of
Epidemiology is the study of the distribution and determinants of health-events, health-characteristics in well-defined populations, and the application of this study to the control of diseases and other health problems. It is the principal methodology of public health research, and helps inform policy decisions and evidence-based medicine by identifying risk factors for disease and targets for preventive medicine.
Initially the concept of epidemiology was applied to epidemics but quickly grew to incorporate any health condition, both disease and non-disease in nature, as it remains today. For example, both the control of West Nile Virus and the application of seat-belt laws are in the realm of public health and may be studied with epidemiological methodologies.
Epidemiology in Depth
Epidemiologist study the variation of disease (or non-disease conditions) in relation to age, sex, race, occupational and social characteristics, place of residence, susceptibility, exposure to specific agents or other pertinent characteristics. Many of the tools of epidemiology are borrowed from other fields such as microbiology, immunology, medicine, statistics, demography and medical geography.
A key component of epidemiology is that its focus remains on health problems in population groups rather than on an individual. This by definition marries epidemiology to statistical data and statistical research and in fact core epidemiological training rest upon firm statistical foundation.
Epidemiologists employ a range of study designs from the observational to experimental and generally categorized as descriptive, analytic (aiming to further examine known associations or hypothesized relationships), and experimental (a term often equated with clinical or community trials of treatments and other interventions). Epidemiological studies are aimed, where possible, at revealing unbiased relationships between exposures such as alcohol or smoking, biological agents, stress, or chemicals to mortality or morbidity. The identification of causal relationships between these exposures and outcomes is an important aspect of epidemiology and the distinction and separation of correlation from causation is a central element to proper epidemiological training and practice. Epidemiology alone may identify causal factors of disease but without supporting research, epidemiology alone will not (generally) prove causality.
Epidemiology represents a broad spectrum of specializations and the nature of any epidemiology career can be quite diverse. Epidemiologists may focus on a wide range of disease and non-disease topics and work within a broad range of industries and institutions. It is easier to understand a career in epidemiology after exploring the specializations below. Alternatively if you’d like to keep things simpler still, General Epidemiology careers will provide the best overview.
Selecting epidemiology as a career is a personal choice and a complex one for that matter. To get you thinking about the right ideas and prepared to ask yourself and schools the right questions, refer to our comprehensive guide on selecting epidemiology as a career. Once you make your decision about the field of epidemiology, then it’s a matter of exploring which schools could be ideal for you and we’ve prepared a guide for the best programs here.
Areas of Focus in Epidemiology
These are the major areas in epidemiology, but know that there are additional fields beyond what’s identified. To keep things organized, information about each specialty can be found on the Branches of Epidemiology page.
Infection control and hospital epidemiology
Infectious disease epidemiology
Occupational Injury & Illness epidemiology
Public Health practice epidemiology