What Is Epidemiology? Key Terms in Public Health

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Crowds of pedestrians wearing protective masks pass through a busy transit station in Hong Kong.


What is epidemiology? It is a complex science that measures the variables related to disease, pathogens, and viruses in accord with human behavior, climate, and environmental factors. The Centers for Disease Control and Prevention (CDC) states that epidemiology dates back to 400 B.C. when Hippocrates  detailed how environmental factors have an impact on the frequency of disease. The CDC began its epidemiology division in 1947. It credits its research on preventing the spread of disease for increasing the average lifespan of Americans by 25 years.

American communities and the health care industry as a whole benefit from the exemplary work that epidemiologists perform. Becoming an epidemiologist entails acquiring the proper skills and education. An online Master of Public Health degree can prepare students who are looking to enter the health care field as epidemiologists, as well as those asking what is epidemiology?

What Is Epidemiology?

The CDC defines epidemiology as the “method used to find the causes of health outcomes and diseases in populations.” The field studies populations instead of individuals to predict how data-driven public health problems affect communities. Epidemiologists investigate health-related problems pertaining to the environment (air pollutants), natural disasters (earthquakes), injuries (domestic violence cases), infectious diseases (COVID-19, for instance), and non-infectious diseases (diabetes). Epidemiologists conduct studies by collecting and analyzing data to understand the health implications of the environment, natural disasters, injuries and infectious diseases. The scope of these studies can range from global populations to specific neighborhoods.

In 2018, the town of Satellite Beach, Florida, was overcome by a number of cancer cases among former Satellite High School students. The Brevard County school district decided to conduct a test of the groundwater surrounding the schools in the district. Epidemiologists discovered that the groundwater contained the carcinogens perfluorooctane sulfonate (PFOS) and perfluorooctanoic (PFOA). However, upon further testing of the tap water, epidemiologists concluded there was no trace of PFOS or PFOA in the drinking water. It was determined that further research needed to be conducted to conclude what other environmental factors may be contributing to the high cancer rates.

What Does an Epidemiologist Do?

Epidemiologists are commonly called “Disease Detectives,” because they are responsible for discovering what is causing communities to get sick, who are the most vulnerable, and what steps can be taken to curb the spread of the disease. As previously mentioned, the primary responsibility of an epidemiologist is to conduct and analyze data pertaining to the implications that disease has on a community. They use a variety of tools to collect data, such as interviews; questionnaires; collaborations with other scientists; and blood, water and tissue samples. Epidemiologists work closely with biologists, mathematicians, and chemists to derive data and understand the variables relating to the spread of disease in a population.

Epidemiology studies involve a dynamic collaboration of professionals from different fields. For example, the epidemiological report on COVID-19 — The Effect of Human Mobility and Control Measures on the COVID-19 Epidemic in China — was jointly written by mathematicians, epidemiologists, zoologists, and biologists. The article reported how China’s steps to limit transportation may have affected the speed by which the virus is transmitted. By using mobility data, scientists have been able to follow the impact that these regulations have had on the growth rate of COVID-19.

Epidemiologists work closely with public health officials and health care professionals to provide the public with the information and contingency planning to deal with unprecedented cases of disease. It is the responsibility of epidemiologists to provide the public, health care professionals, and state and local governments with data to make informed health safety decisions.

Essential Skills in Epidemiology

Those who are pursuing a career in epidemiology must exhibit certain competencies to be effective at their jobs.

o   Analytical Skills: Epidemiologists must demonstrate the ability to think analytically to identify trends in data. By identifying trends, they are better able to conduct experiments that can support their data.

o   Statistical Analysis: Essential is the ability to collect quantitative data and be able to analyze that data to make inferences. After making inferences, epidemiologists are able to group the data into categories and convert the quantitative data into visual representations for reporting (graphs, etc.).

o   Critical Thinking: This skill is one of the most important for an epidemiologist. In some cases, there is no data regarding the spread of a disease, so they must be able to use critical thinking to understand how human behavioral trends and environmental factors impact the spread of disease.

o   Communication: Communication is always a key skill, but for epidemiologists it is incredibly important. Epidemiologists are responsible for communicating to public health officials, health professionals, and the general public their findings on the spread of disease. It is important that they effectively communicate the conclusions of their research to help develop a health strategy for combating the spread of disease.

Epidemiologist Salary and Job Growth

Epidemiologists work in a variety of environments, including hospitals, universities, pharmaceutical companies, and local and state governments. Those who are pursuing a career in epidemiology can choose to be research epidemiologists or applied epidemiologists. Applied epidemiologists study and track the spread of disease, while research epidemiologists conduct research to understand what is impacting the health of a community. Both tracks require an advanced degree in public health, epidemiology, medicine, statistics, or biochemistry. Research epidemiologists can pursue federal government careers at the CDC or the National Institutes of Health (NIH).

According to the latest data from the U.S. Bureau of Labor Statistics (BLS), the median salary for an epidemiologist is $69,660. The job outlook is expected to rise 5% between 2018 and 2028. Those who are pursuing a career in epidemiology and possess prior experience can expect to earn a higher salary than those just starting off. The top 10% of epidemiologists receive a salary of $112,600 and typically work in research.

Learn How to Pursue a Rewarding Career in Epidemiology

Professionals who are looking for a career in public health would do well to consider earning a Master of Public Health degree. Ohio University’s online Master of Public Health (MPH) prepares students to become public health leaders in the community. The MPH degree enables students to work with experienced faculty and learn to apply public health knowledge and theories to real-world health care problems.

The program offers a unique curriculum that studies the societal, cultural, and behavioral influences on community health, as well as courses to develop strategies to assess these influences. The MPH programs offer courses that include Public Health Concepts, Biostatistics in Public Health, Health Disparities, Environmental Health and Grant Writing in Public Health Practice.

Additionally, the program offers a course in Epidemiology in Public Health. This trains students in the fundamentals of epidemiological concepts and its application to real-world health-safety situations. Overall, the course prepares students with a better understanding of what epidemiology is and how it applies to their chosen career.

Explore how Ohio University’s online Master of Public Health can prepare students for rewarding occupations as epidemiologists — as well as health care managers, health educators, public health specialists, health administrators, environmental scientists, and public health nurses.

Recommended Readings

How to Become a Health Educator

How to Become an Epidemiologist in Public Health

3 Lucrative MPH Career Opportunities for Graduates


Centers for Disease Control and Prevention,Epidemiology

Houston Chronicle, What Are the Duties of an Epidemiologist?

Nature Communications, Epidemiology Is a Science of High Importance

Ohio University, Online Master of Public Health

Science Mag, The Effect of Human Mobility and Control Measures on the COVID-19 Epidemic in China

U.S. Bureau of Labor Statistics, Epidemiologists

USA Today, Satellite Beach Finds Cancer-Causing Chemicals in Groundwater: 5 Things to Know

World Health Organization, Epidemiology