What Is Epidemiology?

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No matter where you live, you can be affected by any number of public health threats on any given day. From climate change to tobacco usage to health equity, the types of public health issues and the factors that fuel them are quite varied. The COVID-19 pandemic was one major example of a public health crisis, and yet quieter public health crises — from obesity to mental health — affect modern societies on an ongoing basis.

If you’re passionate about pursuing a career that could allow you to work toward nurturing healthier communities and populations, you might want to consider becoming an epidemiologist. What is an epidemiologist and what do they do? Let’s take a closer look.

In This Article:

What Is an Epidemiologist?

Before considering what an epidemiologist is, it’s necessary to understand the answer to the question, What is epidemiology?

Epidemiology is a methodology for identifying the causes of diseases and disorders and their health outcomes in populations. More specifically, epidemiology is the systematic, data-driven and scientific study of the distribution, causes and risk factors of health-related events and states in populations. Epidemiology also encompasses the application of the results of these studies to the control of health issues.1

Public health problems are diverse and can involve everything from infectious and chronic diseases to emergencies and injuries. No matter the type of problem, epidemiologists approach each issue by first identifying the problem and then determining the cause, evaluating solutions and considering methods for implementing a response.

There are various types of epidemiology. Examples of health problems that an epidemiologist might investigate include:

  • Environmental exposures that involve heavy metals, lead or air pollutants
  • Infectious diseases, such as pneumonia and foodborne illnesses
  • Non-infectious diseases, like cancer and major birth defects
  • Injuries in the form of increased domestic violence or homicides
  • Events such as natural disasters and terrorism

Origins of Epidemiology

The origins of epidemiology stretch at least as far back as around 400 B.C., when famed physician Hippocrates began to investigate whether environmental and behavioral factors may contribute to the development of disease, rather than supernatural factors.2

Although the field has roots in ancient times, epidemiology didn’t experience any major advancements until the mid-1600s, when John Graunt published his study of mortality data in London. It sought to identify patterns of death based on factors such as sex, age, season and geographical location.2

Another major step forward came in 1854, when London was suffering a cholera outbreak. John Snow, an anesthesiologist, investigated the outbreak and determined that all cholera patients had obtained water from a specific well. Shutting off access to the well stopped the outbreak.2

For many years, epidemiology was concerned predominantly with infectious diseases. During the 1930s and ‘40s, epidemiologists began to explore other health conditions as well. In the 1980s, epidemiologists began to study patterns of violence and related injuries, and in the 1990s, genetics became a more widely studied issue. In modern times, the field is quite expansive and varied, and epidemiologists’ study everything from car crash injuries to bioterrorism.2

What Does an Epidemiologist Do?

If you’re fascinated by the field of epidemiology and considering it as a career, it can be helpful to know the answer to the question, What does an epidemiologist do? Their day-to-day tasks can vary depending on their employer and the types of epidemiology they specialize in.

In general, however, an epidemiologist may perform the following tasks:3

  • Collect health information and medical samples and analyze them
  • Research trends in populations and identify patterns
  • Execute studies of public health problems, looking for ways to prevent or treat them
  • Publish findings or discuss findings with policymakers, healthcare providers and the public

Becoming an Epidemiologist

The first step toward pursuing a career as an epidemiologist is to obtain a relevant bachelor’s degree, such as a bachelor’s in biology or social science. Epidemiologists also typically need at least a master’s degree, such as a Master of Public Health (MPH).4

As a generalist program designed for healthcare professionals, the Master of Public Health program offered by Grand Canyon University’s College of Nursing and Health Care Professions explores national public health curriculum standards and includes a look at the principles of epidemiology. 

To explore the patterns of injury and disease in the human population, you will be expected to apply epidemiological approaches while earning your MPH degree. In this program, an emphasis is placed on concepts, indicators, principles and methods of chronic and infectious disease epidemiology. Additionally, you will be taught how to conduct statistical analysis of primary epidemiological measures that are used to support evidence-based decision-making.

Pursue your passion for promoting public health at GCU. In addition to our broad selection of science-focused bachelor’s degree programs, the College of Nursing and Health Care Professions is pleased to offer the Master of Public Health degree program. Fill out the form on this page to learn more. 

Mailman School of Public Health. (2020, Oct. 21). What is epidemiology? Columbia University. Retrieved April 15, 2024.

National Center for State, Tribal, Local, and Territorial Public Health. (2012, May 18). Lesson 1: Introduction to epidemiology. Centers for Disease Control and Prevention. Retrieved April 15, 2024. 

U.S. Bureau of Labor Statistics. (2023, Sept. 6). What epidemiologists do. Occupational Outlook Handbook. Retrieved April 15, 2024. 

U.S. Bureau of Labor Statistics. (2023, Sept. 6). How to become an epidemiologist. Occupational Outlook Handbook. Retrieved April 15, 2024. 

Approved by the associate dean of the College of Nursing and Healthcare Professions on May 21, 2024.

The views and opinions expressed in this article are those of the author’s and do not necessarily reflect the official policy or position of Grand Canyon University. Any sources cited were accurate as of the publish date.