Introduction to Epidemiology
Epidemiology is considered the basic science of public health, and with good reason. Epidemiology is: • • • A quantitative basic science built on a working knowledge of probability, statistics, and sound research methodology A method of causal reasoning based on developing and testing hypotheses pertaining to occurrence and prevention of morbidity and mortality A tool for public health action to promote and protect the public’s health based on science, causal reasoning, and a dose of practical common sense (2).
As a public health discipline, epidemiology is instilled with the spirit that epidemiologic information should be used to promote and protect the public’s health. Hence, epidemiology involves both science and public health practice. The term applied epidemiology is sometimes used to describe the application or practice of epidemiology to address public health issues. Examples of applied epidemiology include the following: • • • • the monitoring of reports of communicable diseases in the community the study of whether a particular dietary component influences your risk of developing cancer evaluation of the effectiveness and impact of a cholesterol awareness program analysis of historical trends and current data to project future public health resource needs
After studying this document and answering the questions in the exercises, you should be able to do the following: • • • • • • • • • • • Define epidemiology Summarize the historical evolution of epidemiology Describe the elements of a case definition and state the effect of changing the value of any of the elements List the key features and uses of descriptive epidemiology List the key features and uses of analytic epidemiology List the three components of the epidemiologic triad List and describe Hill’s criteria of causation Understand the natural history of disease and the three types of prevention Understand infectivity, pathogenicity, and virulence List and describe primary applications of epidemiology in public health practice List and describe the different modes of transmission of communicable disease in a population
Applied Epidemiology I
A number of exercises are provided. It is suggested you attempt to answer these questions and then compare your answers with those at the end of this document.
The word epidemiology comes from the Greek words epi, meaning “on or upon,” demos, meaning “people,” and logos, meaning “the study of.” Many definitions have been proposed, but the following definition captures the underlying principles and the public health spirit of epidemiology: “Epidemiology is the study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems.” (17)
Key terms in this definition reflect some of the important principles of epidemiology. Study Epidemiology is a scientific discipline with sound methods of scientific inquiry at its foundation. Epidemiology is data-driven and relies on a systematic and unbiased approach to the collection, analysis, and interpretation of data. Basic epidemiologic methods tend to rely on careful observation and use of valid comparison groups to assess whether what was observed, such as the number of cases of disease in a particular area during a particular time period or the frequency of an exposure among persons with disease, differs from what might be expected. However, epidemiology also draws on methods from other scientific fields, including biostatistics and informatics, with biologic, economic, social, and behavioral sciences. In fact, epidemiology is often described as the basic science of public health, and for good reason. First, epidemiology is a quantitative discipline that relies on a working knowledge of probability, statistics, and sound research methods. Second, epidemiology is a method of...