12.1: Epidemiology Defined
By the end of this section, you should be able to:
- Define epidemiology.
- Explain the objectives of epidemiology.
- Examine the role of epidemiology in public health.
Epidemiology is the scientific study of the distribution and determinants of diseases and health outcomes in populations in order to develop methods of controlling health problems, limit the consequences of illness, and maximize health. Epidemiology relies on a methodical and unbiased approach to data collection , analysis, and interpretation. This multidisciplinary science draws from the biologic, economic, social, and behavioral sciences and the scientific disciplines of biostatistics and informatics . Epidemiology is described as the basic science of public health because it provides the foundation for overseeing public health interventions (Centers for Disease Control and Prevention [CDC], 2012).
Epidemiology seeks to establish causal factors for health events , defined as disease, injury, or death (CDC, 2012). Epidemiologists define the populations to be studied. These populations may be as small as one town or as large as an entire country. They may be selected based on geography, biologic factors such as gender or age, or social factors such as race, lifestyles choices, or income level. Epidemiologists view the entire health spectrum, from safety and injury prevention—such as bicycle or motor vehicle safety—to disease prevention and control.
Epidemiological Objectives
Epidemiology is founded on principles of health, safety, and wellness. It focuses on the overall health and welfare of populations of individuals, studying patterns of disease frequency and distribution and determinants of health and illness (Frérot et al., 2018). Epidemiological objectives include (Celentano & Szklo, 2019):
- Identifying the causes of disease or factors that increase an individual’s risk for disease
- Identifying how diseases are transmitted
- Determining the extent of disease in a community or specified population
- Evaluating preventive and therapeutic measures of health care delivery
- Providing the foundation for developing public policy regarding disease prevention and health promotion
Application of Epidemiology to Public Health
By identifying causes and risk factors for disease development, public health nurses can use evidence-based information to intervene early to reduce morbidity and mortality . For example, in 1950, epidemiologists Doll and Hill demonstrated a causal link between the development of lung cancer and smoking cigarettes. Their studies laid the foundation for public health initiatives to decrease rates of cigarette smoking. In 1965, 42 percent of adults in the United States smoked cigarettes, but by 2021 the rate had fallen to 11.5 percent (CDC, 1999; CDC, 2023).
Epidemiologic studies can identify how diseases are transmitted, enabling public health nurses to advocate for appropriate control programs. Diseases can be transmitted from person to person or from nonhuman sources, such as ticks or mosquitoes, to the human population. Well-designed epidemiologic studies have demonstrated how major communicable diseases are transmitted. For example, measures to ensure staff and client safety where tuberculosis may be present are based on the 1956 work of epidemiologists Riley and Wells (Thomas, 2020).
Determining the prevalence and extent of disease in a community is another function of epidemiology. Public health nurses can use this information to prepare for communicable disease outbreaks. For example, by using epidemiological statistical models, public health nurses can prepare adequate vaccine supplies and plan health services needed to respond to seasonal influenza outbreaks.
Public health nurses can also use evidence-based epidemiological information in health promotion education. For example, epidemiologists study whether screening improves survival for men with prostate cancer. Nurses can use the results of those epidemiological inquiries to assist them in educating at-risk communities. Epidemiological studies, such as studies seeking to discover whether high levels of radon in homes causes disease, can also inform nurses’ work to advocate for public policy at the local, state, and federal levels.