Public health is the activities that ensure conditions in which people can be healthy. These activities include community wide efforts to identify, prevent, and combat threats to the health of the population (Institute of Medicine Definition of Public Health). Epidemiology is the study of the distribution and determinants of health-related events in specified populations OR Epidemiology is the method/strategy of studying disease/health in populations. Therefore Epidemiology is the core science of public health.
The purposes/ roles of epidemiology are:
- Community diagnosis; i.e., what are the major health problems occurring in a community
- Establishing the history of a disease in a population; e.g., identifying the periodicity of an infectious disease
- Describing the natural history of disease in the individual; e.g., natural history of HIV infection in the individual
- Describing the clinical picture of disease; i.e., who gets the disease, who dies from the disease, and what the outcome of the disease is
- Estimating risk; e.g., what factors increase the risk of heart disease, automobile accidents, and violence
- Identifying syndromes and precursors; e.g., the relationship of high blood pressure to stroke, kidney disease, and heart disease
- Evaluating prevention/intervention programs; e.g., vaccine and clinical trials
- Investigating epidemics/diseases of unknown etiology
Whether you are policymakers, administrators, nutritionists, biostatisticians, health educators, physicians, or other when you study health and disease in a population you are in effect practicing epidemiology.