Topic Selection Concepts of Epidemiology
PUH 5303, Concepts of Epidemiology 1
Course Learning Outcomes for Unit I Upon completion of this unit, students should be able to:
1. Evaluate key concepts regarding evaluation of the etiology of major health problems in populations. 1.1 Explain the importance of epidemiology for community health in the United States. 1.2 Discuss historical and modern applications of epidemiology for public health.
5. Discuss measures of disease frequency and measures of effect in public health.
5.1 Explain the scope, goal, and objectives of epidemiology.
Course/Unit Learning Outcomes
Learning Activity
1.1 Unit Lesson Chapter 1 Unit I Topic Selection
1.2 Unit Lesson Chapter 1 Unit I Topic Selection
5.1 Unit Lesson Chapter 2 Unit I Topic Selection
Required Unit Resources Chapter 1: The Approach and Evolution of Epidemiology Chapter 2: Measures of Disease Frequency
Unit Lesson Introduction Welcome to the first unit of our course. Like many others, you may be wondering what epidemiology has to do with public health or health care. Believe it or not, epidemiology is a cornerstone of public health, etiology of disease, health behavior, and other areas of scientific advancement. It not only directly affects our daily lives as individuals but also impacts communities, government, public health organizations, medical agencies, and all other agencies that make decisions that affect how we live (Aschengrau & Seage, 2020).
UNIT I STUDY GUIDE
Historic and Modern Approaches to Epidemiology
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As the basic foundation of public health, epidemiology has four main aims: (1) to describe disease patterns and the health status in human populations; (2) to identify and explain the etiology of disease and discern causes of disease; (3) to provide data and predict the occurrence of disease for management, planning of services, control, and treatment of disease; and (4) to control and prevent the occurrence of new cases of a disease within a population. Epidemiology is an interdisciplinary field that draws from medicine, social sciences, economics, microbiology, mathematics, law, statistics, and virology, to name a few. In this lesson, we are going to start from the beginning. We will gain an understanding and perspective regarding what epidemiology is. We will also define etiology and other important terms used with epidemiological studies, and we will
analyze how each contributes to the important issues that affect our individual health and the overall health of our nation. We will also learn about the history and origins of epidemiology. Finally, we will read about and discuss the major contributors and key components of epidemiology in the healthcare profession. The history of epidemiology is fascinating. Studying the history helps us make connections concerning how epidemiology has evolved over time, which will give us an important perspective on modern epidemiology. It will help us realize just how far we have come. Understanding the history of epidemiology will also help us see how much more progress we need to make in our quest for the advancement of public health on this planet. We have made great strides; however, there are always new problems that arise as time progresses. Origins of Epidemiology
“The historical development of epidemiology spans almost 400 years and is best described as slow and unsteady” (Aschengrau & Seage, 2020, p. 8). The term epidemiology derives from the root word epidemic and originates from the Greek word epi- (upon) demos (people) -logy (study of). Therefore, when you combine these three pieces, you can say that epidemiology is the study of disease that is upon the people. The London Epidemiological Society, which was formed in 1850, defined epidemiology as “the study of that which falls upon the common people” (Aschengrau & Seage, 2020, p. 5). Over the years, several definitions of the word
epidemiology have been created. Some of these definitions will be explored in this unit; however, the key principle that applies to each definition is that we study disease to protect the people. Another common term you will see throughout this course that is very similar to epidemiology is the word etiology.
Etiology is the biological cause of a disease. Knowing the etiology of a disease may dictate how the disease is studied. More in-depth explanation and detail about research studies will be provided in later units. Most of you have heard of the highly respected and prolific Greek physician Hippocrates. Hippocrates is the man who drafted the Hippocratic Oath, which is typically taken by physicians upon completion of their medical degree. The Hippocratic Oath of service has been around for thousands of years and is
respected by physicians around the world. In approximately 400 B.C., Hippocrates began his work on public health and explored the idea that disease was a result of a person’s environment. He realized that people reacted to the environment differently when the seasons changed. We know this seasonal reaction now as allergies, which can be impacted by weather as well as geographic location.
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Graunt and Snow After Hippocrates and other scientists established their views concerning what epidemiology is centuries ago, the practice went unchanged for many years. However, in 1662, John Graunt changed our view and understanding of epidemiology within the field of public health. His publication Nature and Political Observations Made Upon the Bills of Mortality made significant advances in community health through the realization that qualitative methods and measurements play a role in the study of disease in a population. Today, we refer to these trends and measurements as vital statistics. The next big advance occurred in 1850 when John Snow began to conduct natural experiments. His most famous epidemiological study centered on the cholera outbreak during the mid-19th century in Broad Street, Golden Square, London. Snow decided to tackle the rising public health problem by studying the common environmental exposures of those who fell ill. He discovered that the drinking water was contaminated, causing the rapid spread of the disease to those who were in closest proximity to the water source on Broad Street. Because of his discovery, Snow’s research methods were taught and applied by other researchers. This breakthrough was the beginning of a research method that focuses on the cause of disease and disorders—not only the results. 20th Century Epidemiology Now that we have touched on the historical background of epidemiology, let’s take a look at more recent applications and uses of epidemiology in public health. Significant advancements in the field of public health were made during the 1950s. Researchers Richard Doll and A. Bradford Hill created a robust case-control study design focusing on the relationship between smoking and lung cancer. The research Doll and Hill conducted is viewed as a major breakthrough in epidemiology. This famous case-control study sparked a change in the way we see and understand environmental causes of disease and chronic diseases. Since this correlation was discovered and proven, efforts have been made to reduce and eliminate smoking in public places. While the smoke-free movement has been a target of controversy over the last decade, especially in states that produce tobacco and tobacco-based products, there have also been several levels of success. For example, it was documented in April 2019 that half of the states in the United States, as well as U.S. territories Puerto Rico and the Virgin Islands, have enacted legislation that prohibits smoking in restaurants, bars, and certain types of workplaces, resulting in these locations becoming smoke-free environments (American Nonsmokers’ Rights Foundation, 2019). Like the advancements we have made with providing smoke-free environments, notable progress has been made with increasing vaccinations in the United States. Around the time when Doll and Hill were conducting their research, Thomas “Tommy” Francis was piloting poliomyelitis field trials in the area of childhood vaccinations. Francis worked as a virologist, physician, and epidemiologist. Shortly after college, he joined an exclusive team of scientists and physicians to assist with the preparation of vaccines against bacterial pneumonia. After working with this elite team for some time, Francis decided to concentrate his efforts on researching influenza, becoming the first American to isolate the flu virus (University of Michigan, n.d.; Venkatesan, 2015). His research in this area provided him with special opportunities to design field trials of the polio vaccine. After conducting field trials using a double-blind study on almost 2 million children in the United States, Canada, and Finland, Francis declared the polio vaccine effective and safe for use in 1955 (University of Michigan, n.d.). The famous Framingham Heart Study was one of the longest-running generational studies of heart disease conducted in the world. This research study, which began in 1948, originally included more than 5,000 participants. By the time the study concluded in 2015, about 200 of the original participants were still alive and continued to get follow-up exams by researchers and doctors (National Institute of Health, n.d.). This study shed light on the environmental factors that influence the prevalence of cardiovascular disease as well as the genetic factors. The Framingham Study, like the work of Doll and Hill, created a new emphasis on noninfectious diseases, which—unlike the majority of previous studies—focused solely on infectious
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diseases. This study is considered “the foundation stone for current ideas about risk factors in general and the prevention of ischemic heart disease in particular” (Susser, as cited in Aschengrau & Seage, 2020, p. 26).
Modern Epidemiology Since the 18th and 19th centuries, the field of epidemiology has grown and provided influence in size, scope, and direction of modern epidemiological studies. Modern epidemiology developed from seven separate sciences that have specific elements in common. Let’s take a brief look at each of these sciences and how they come together to create modern epidemiology. First, the science of acute disease investigation in biology and the environment is essential to epidemiology. Microbiology, bacteriology, and virology help epidemiologists understand the cause of diseases, disease etiology, and disease outbreaks. They also help reveal specific information about disease agents and disease morphology. For example, thanks to the inclusion of these particular sciences, we have a better understanding of diseases such as anthrax, Legionnaires’ disease, tarsal tunnel syndrome (TTS), and foodborne illnesses (e.g., E. coli). The microbiologic procedures applied to epidemiology help us learn to expose common attributes of bacteria involved in an outbreak and how to prevent morbidity and mortality in human communities. Second, clinical medicine forms an important foundation for our work. All of the early epidemiologists were physicians. Only later in the evolution of our science did the idea of a graduate-prepared, healthcare professional—specifically in public health—come along. The Master of Public Health (MPH) degree, which is now highly valued in so many community health circles, is a relatively recent innovation. The inclusion of clinical medicine in epidemiology helps us diagnose patients and also helps define a specific disease or condition.
Timeline of epidemiological advancement
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Third, we consider statistics and biostatistics more specifically. Without statistics, there would be no epidemiology. Statistics allow us to measure and manipulate variables while observing important changes. The use of statistics in epidemiology allows us to separate meaningful observations from chance and to determine the multiple factors of causality for a disease in a population. Statistics were crucial to the success of all landmark epidemiological investigations of the 1950s and beyond. Next, social and behavioral sciences must be considered. They allow us to explain and analyze the role of race, social class, behavioral practices, culture, education, and gender in health-related occurrences. Human behavior is crucially related to disease, and the social sciences help us to evaluate such behaviors in individuals, families, and groups. This area of science applies the social and behavioral aspects to epidemiology and allows us to approach the methodology of sampling, measurement, study design, and delivery of health interventions appropriately. Additionally, they help epidemiologists apply appropriate theory to specific studies of behavior in a community. Fifth, computer sciences have changed everything in epidemiology, allowing us to handle
large volumes of data, observe trends, track the impact of interventions, and present information in ways that were never before thought possible. We can even use epidemiology to help understand computer viruses (Murray, 1988). Along with computers, management science has played an important role through management of project funds, administration, and keeping projects on track and within budget. Finally, genomics is the most recent addition to our list of epidemiological sciences. The year 2001 marked the first publication of draft sequences of the human genome. This knowledge has permitted researchers to identify disease susceptibility genes, gene-environment interactions, and gene-gene interactions. The science of genomics is now a big part of what we do in epidemiology, and it likely will lead to methods of prevention and/or treatment for several diseases, which currently are not addressed well by traditional medicine. Bringing It All Together Epidemiology is a fascinating field of public health, and we can learn a lot about it from understanding its origins. After reading this lesson, you will hopefully have a better grasp on the history and origins of epidemiology. As the field of epidemiology continues to grow and develop, many new opportunities for education and employment will emerge for you to consider. Epidemiology training programs in schools and public health agencies offer more subspecialties to address the need for research in the field. The field is currently experiencing an unprecedented amount of interest from our government, and that points to a promising future as a part of both American and international health. Welcome again to the wonderful world of epidemiology!
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References American Nonsmokers’ Rights Foundation. (2019). Overview list – number of smokefree and other tobacco-
related laws. Retrieved from http://no-smoke.org/wp-content/uploads/pdf/mediaordlist.pdf Aschengrau, A., & Seage, G. R., III. (2020). Essentials of epidemiology in public health (4th ed.). Burlington,
MA: Jones & Bartlett Learning. Murray, W. H. (1998). The application of epidemiology to computer viruses. Computers & Security, 7, 139–
150. Retrieved from https://nnt.es/The%20Application%20of%20Epidemiology%20to%20Computer%20Viruses.pdf
National Institute of Health. (n.d.). Framingham Heart Study (FHS). Retrieved from
https://www.nhlbi.nih.gov/research/resources/obesity/population/framingham.htm University of Michigan. (n.d.). About Thomas Francis, Jr. Retrieved from https://president.umich.edu/honors-
awards/francis-medal/about-thomas-francis-jr/ Venkatesan, P. (2015). Historical profile: Thomas “Tommy” Francis, Jr. The Lancet, 3, 679. Retrieved from
https://www.thelancet.com/action/showPdf?pii=S2213-2600%2815%2900317-3
Learning Activities (Nongraded) Nongraded Learning Activities are provided to aid students in their course of study. You do not have to submit them. If you have questions, contact your instructor for further guidance and information. Focused questions related to the information in the textbook are presented at the end of each chapter. Answering these questions will help you to master the information in the chapters. After you read the assigned textbook chapters for this unit, check your knowledge by completing the chapter review questions below.
Chapter 1 Questions, pp. 31-32
Chapter 2 Questions, pp. 54-56 Answers to the review questions are provided in Chapter 18 of the textbook. Once you have answered the questions, compare your answers to the ones provided in order to see how well you did!