The Intersection of Epidemiology and Public Health

Epidemiology is the branch of science dedicated to determining the causes of health outcomes and disease patterns. It's often associated with tracking transmissible diseases, such as the avian flu that affected agriculture operations in 2025.¹ In practice, epidemiology deals with more than just infectious diseases. It also involves analyzing how all types of health conditions affect populations and understanding how to mitigate adverse health effects.²

Sometimes people wonder, "What is the role of epidemiology in public health?" Like public health, epidemiology focuses on macro-scale health trends and uses data to determine how to improve health outcomes for populations.

This post explores the way the fields of epidemiology and public health support and reinforce one another.

Public health entities aim to improve quality of life and well-being through a combination of disease prevention, health promotion, and health services. Public health professionals focus on three core pillars:³

1. Assessment: Analyzing community health conditions and threats
2. Policy Development: Creating policies that promote and protect population health
3. Assurance: Deploying effective, reliable public health services to communities and individuals

This combination of assessing health needs, developing solutions, and assuring the public's access to appropriate services applies to the full range of community health concerns. For example, public health methodologies can help people protect themselves in epidemics caused by airborne viruses. However, they are equally valuable in managing behavioral health challenges, such as the increase in overdoses due to access to opioids.

Epidemiology is the scientific, data-driven study of the frequency, patterns, causes, and risk factors of health-related events in specified populations.² It can also be explained as the study of how, when, and why diseases occur in different groups of people.⁴ The Centers for Disease Control and Prevention (CDC) notes that, in epidemiology, the patient is the community; instead of focusing on the diagnosis of an individual with a set of symptoms, epidemiology seeks to understand the collective impacts of health trends.⁵

Public health is the field of medicine that protects and promotes the health of all people.⁶ Both public health and epidemiology seek to manage community-wide health problems. Epidemiological solutions intend to alter disease incidence patterns by introducing interventions that can be applied to entire populations.⁷

Both public health and epidemiology are dedicated to addressing health issues that affect communities or populations. Whereas clinical practitioners treat individual patients and personalize treatment to address the needs of one person, epidemiologists and public health professionals focus on how to understand and mitigate the negative impacts of health problems on large groups of people.

Epidemiologists and public health professionals work like a relay team. Teams in public health are positioned to identify community health problems as they arise. When a health problem is identified, epidemiologists are equipped to use scientific research methods to study its causes, how the health problem moves through populations, and what treatments and preventive measures are effective. After epidemiologists gather the relevant data, epidemiologists and public health professionals can collaborate to develop effective policies to address the problem. Once a solution framework is in place, public health services deliver it to the community, while epidemiologists can follow the situation and study the real-time data to evaluate policy efficacy.

If public health professionals are identifying the "what is happening" aspect of population-scale health trends, epidemiologists address the question of "why and how is it happening." Epidemiologists engage in scientific research and analysis to understand how diseases affect populations. Epidemiological research methodologies include the following:⁸

• Public Health Surveillance: Public health agencies have data-gathering systems to monitor real-time health situations; epidemiologists can use this data to identify trends.
• Field Investigation: Epidemiologists can go to critical locations to address emergencies or perform a deeper study of situations.
• Data Analysis: Epidemiologists use data collected from surveillance and fieldwork to perform in-depth analyses, develop an understanding of the situation, and suggest policies that can address relevant public health concerns.

When considering the question of public health epidemiology, it's helpful to look at the six primary areas of epidemiological investigation, each of which connects directly to public health goals.

This category includes studying the effects of substances in the air, water, and built environment and determining how they affect health. This includes issues like exposure to lead, manufacturing chemicals, UV rays, or car exhaust. It can also address highly specific circumstances, such as the effects of burn-pit exposure on military veterans.

Studying infectious diseases is probably the best-known application of epidemiology. Epidemiologists track the spread of transmissible diseases like influenza, tuberculosis, and HIV, as well as food-borne illnesses like salmonella and listeriosis. The data gathered from recent outbreaks of vaccine-preventable illnesses like measles serve to underscore the risks associated with refusing childhood vaccines.⁹

Studying injuries and their causes can help prevent certain types of injuries. Epidemiological research on car crash injuries illuminates the efficacy of safety mechanisms like seatbelts. Studying the links between injuries and drug and alcohol consumption creates a greater understanding of the risks associated with substance use.

Tracking the incidence of non-communicable diseases like cancer or Alzheimer's allows researchers to study the characteristics of people who develop these conditions and look for links. Epidemiological data related to colon cancer incidence, for example, reveals that people with a family history of colon cancer are at higher risk of developing the disease. As a result of this knowledge, experts recommend people with this risk factor begin colon cancer screening at a younger age.¹⁰

Natural disasters are often the first dominoes to fall, causing a chain of events that affects public health in a region. After a hurricane, for example, populations may suffer from the negative effects of lasting power outages, lack of access to food and clean water, and housing insecurity. Applying an epidemiological analysis to those trends allows public health officials to plan effective responses to future events.

Like natural disasters, terrorist acts can have long-term health effects on affected populations. First responders from the 9/11 attacks have reported a range of illnesses linked to exposure to substances at the World Trade Center site.¹¹ Epidemiologists studying these effects can apply that knowledge to emergency preparedness plans in the event of future attacks. It also sheds light on the risks of using certain materials in building construction.

Both epidemiology and public health are critical to maintaining safe and livable communities and addressing the impacts of diseases on populations. Research into the causes and effects of health conditions allows leaders to develop policies that promote better health and quality of life for entire populations.

Kent State University's online Master of Public Health in Epidemiology or Master of Science in Clinical Epidemiology can help you accelerate your career in these critical fields. These CEPH-accredited programs, designed for working professionals, give you access to expert faculty and cutting-edge coursework. To learn more about these online programs, contact an admissions outreach advisor today.