Epidemiology is concerned with the study of factors that determine the distribution of health and disease in human populations.
The purposes of epidemiological research are to discover the causes of disease, to advance and evaluate methods of disease prevention, and to aid in planning and evaluating the effectiveness of public health programs. Epidemiologists are interested in the study of infectious and noninfectious diseases. In recent years, they have turned their attention increasingly toward the study of conditions affected by forces in the social and physical environment.