Problem Definition: What is Epidemiology?
Basic Concepts and Principles
Epidemiology is the branch of science that deals with the study of the dynamics of health and ill health in populations.
Important epidemiologic concepts
* The health/ill health continuum in a population
* Population dynamics
* Multiple causality and multiple determinants
In the definition of epidemiology, reference is made to "population". This aspect is a distinct epidemiologic entity in that epidemiology per se is not concerned with an individual animal or human as such, but in terms of what happens to the population; including the healthy and unhealthy ones. It is only then that one could understand and unravel patterns and frequencies of events in order to proceed with further corrective actions and appropriate followups.
The study of epidemiology is therefore inherently population based in comparison to such fields as clinical medicine where the individual is the unit of concern. The components of the population include the various stages of health/ill health as given above. Additionally, although the thrust is one of population medicine, this by no means restricts the study to groups (herds, kennels, communities, etc.), of animals, humans or etiological agents; the same population concepts apply even at the cellular and molecular level.
The emergence of specialities such as Molecular Epidemiology, Cellular Epidemiology and even Anatomic Epidemiology to name just a few of over a dozen sub-specialities is therefore understandable. Epidemiology as a discipline deals with the study of populations from the level of the ecosystems of the cell to that of animals and humans. The classical area of the zoonoses falls in this domain.