What Is Epidemiology? A Guide to Disease Detection

The devastating impact of the COVID-19 pandemic highlighted the vital importance of the field of epidemiology. Epidemiologists are on the front lines of protecting public health by tracking the causes and spread of health threats to the public and finding ways to prevent them.¹

This post will explore how epidemiologists investigate diseases, conduct research and save lives.

Epidemiologists are healthcare professionals, but, unlike doctors or nurse practitioners, they’re primarily concerned with the health of entire communities rather than individuals. A physician’s job is to treat a patient who contracts a disease, while an epidemiologist’s job is to figure out where and how the patient contracted the disease, whether the disease is a threat to others and what measures can be taken to contain it.²

By studying the causes and distributions of health-related issues, injuries, and deaths, epidemiologists can devise effective plans for treatment and prevention. Epidemiologists work within many types of organizations, including state and local governments, universities, hospitals and research facilities. Their duties vary depending on their role and what aspect of public health they’re studying.¹

Although the methods epidemiologists use have changed over the years, many of the core principles remain the same. The classic example of early epidemiology is Dr. John Snow’s study of a London cholera outbreak. He believed that cholera was caused by drinking contaminated water and used data to prove his theory. By charting cholera outbreaks and tracking where affected people obtained their water, he was able to figure out that a local pump was the source of the outbreak. His work led to legislation requiring London water companies to filter their water.³

Advances in technology and medical knowledge have changed the field and led to standardized processes and more effective data analysis. Modern epidemiologists have several primary goals, including the following:⁴

• Finding patterns of adverse health events in different populations 
• Identifying outbreaks of diseases
• Developing tests to identify infectious agents
• Understanding how diseases are transmitted and what factors contribute to the spread
• Discovering treatment protocols and prevention control measures for outbreaks of diseases
• Determining how effective preventative measures are and how they can be improved 

Epidemiologists take a structured approach to studying diseases. They start by identifying an outbreak—a process that includes determining that two or more people from different households have an illness. They then use data analysis to determine if there are more people with the disease than would be expected in the general population and if there are more associated cases.⁵

Next, they work with doctors and other medical professionals to verify diagnoses and decide if they have a case or not. If they do, they do a preliminary study to determine the extent of the outbreak, the people involved, and common sources of exposure that those affected have experienced. This allows them to better understand the full extent of the outbreak.⁵

Based on the results of their initial study, epidemiologists form a hypothesis about the cause of the outbreak and do a thorough investigation. Their investigation typically includes gathering more information and using statistical models to create an epidemic curve that illustrates the scope of the outbreak. Finally, they organize and analyze the data and use it to form a plan for treatment and prevention.⁵

Keeping track of how many people have a disease and where cases are located is fundamental to public health. Real-time health data allows epidemiologists to understand the extent of health issues, implement plans to control them and evaluate if the plans have been effective. Public health agencies, such as the Centers for Disease Control and Prevention (CDC), have established protocols for monitoring various diseases. The process starts with local healthcare providers and includes local, state, federal and international agencies.⁶

As with many other fields of science and medicine, epidemiological research has been affected by technological advances. Artificial intelligence (AI) and big data are playing a key role in transforming epidemiology. Machine learning, a subset of AI, is making epidemiological research more effective. It can analyze massive data sets and uncover hidden patterns and associations among diseases and the factors that contribute to them. These models are capable of integrating data from multiple, disparate sources, which leads to improved accuracy and better causal inference. Epidemiologists can use this information to identify critical windows when intervention will be most effective.⁷

Epidemiologists typically have an undergraduate degree in a science field, such as biology, as well as a master’s degree in public health, often with a concentration in epidemiology.⁸ Either as part of your studies or afterward, you can gain valuable experience through volunteering or interning with research teams. This will give you real-world experience in the data collection methods researchers use to monitor and track illnesses, injuries and diseases.⁸

At each step in your career path, make connections in the industry by networking with fellow students, professors or public health professionals. With this combination of education and experience, you’ll be in a strong position to succeed in the field. Epidemiology is a field where you’ll need to continuously learn and upgrade your skills, so plan to make professional development a regular part of your career.⁸

Epidemiology can be a rewarding career. Kent State offers several programs that will equip you with the knowledge and skills you need to lead healthcare organizations in finding, tracking and controlling disease outbreaks and improving the lives of people dealing with other serious health issues. Our online Master of Public Health (MPH) in Epidemiology program will prepare you to analyze disease patterns and population health outcomes. You can also increase your professional impact and make a positive difference in public health by earning an online Master of Science (MS) in Clinical Epidemiology. If you're ready to take the next step in your career, contact one of our admissions outreach advisors today to learn more.