EPIDEMIOLOGY

What is epidemiology? There are many different definitions of the term. A simple and useful definition is epidemiology is "the study of disease in populations". It deals with the incidence, distribution, and control of diseases in specific POPULATIONS. Thus, epidemiology does NOT interested in disease processes in affected INDIVIDUALS. Another difference is, epidemiology is concerned with the causes of diseases and sometimes how to prevent them, while other brances of medicine are mostly interested in to find cures for diseases in individuals already affected.

Epidemiology literally means "the study about the people" in origin. The term was initially used to cover the description and causation of epidemic outbreaks of infectious dieseases. Today, however, it is used for disease in general, and even many non-disease health-related conditions, such as obesity high blood pressure. Currently, epidemiology is defined as the study of distribution and determinants of health-related states in populations and use of this knowledge to address health problems. By identifying risk factors for disease, epidemiology is closely related with public health, policy decisions, preventive medicine and evidence-based medicine. Thus, today epidemiologists work in the areas of methodology and design of clinical research, collection of data, statistical analysis, and interpretation and presentation of results. Major areas of epidemiological study include disease etiology, outbreak investigation, disease surveillance and screening, biomonitoring, and comparisons of treatment effects such as in clinical trials.

Epidemiologists believe that the frequency of a disease in a population is depend on the interaction of many factors. Thus, studying these interactions may result in change of some of the determinants involved, so reducing the frequency of the disease in question.

Some essential terms should be explained to understand epidemiological concepts. These are: population, population at risk, determinants (intrinsic or extrinsic). A population can be defined as the complete collection of individuals that have some particular characteristic(s) in common. Depending on the characteristic(s) being considered, a population can be very large or very small. Population at risk is a subset of population which is considered capable of acquiring the particular disease or disease characteristic being studied. A determinant is any factor or variable that can affect the frequency of a disease in a specific population. Determinants can be classified as either intrinsic or extrinsic. Intrinsic determinants are characteristics of the host or disease agent which are generally determined genetically. Extrinsic determinants are normally associated with some form of environmental influence on the host or disease agent. They may also include interventions made by people into the disease process by the use of drugs, vaccines, dips, movement controls and quarantines.