Epidemiological Concepts

Abstract

Epidemiology is the study of the distribution and determinants of health-related states, conditions, or events in specified populations and the application of the results of this study to the control of health problems.(1) It is a quantitative science concerned in infectious diseases with the circumstances under which disease processes occur, the factors that affect their incidence and the host response to the infectious agent, and the use of this knowledge for control and prevention.(2) It includes the pathogenesis of disease in both the community and the individual. For infectious diseases, one must study the circumstances under which both infection and disease occur, for these may be different. Infection is the consequence of an encounter of a potentially pathogenic microorganism with a susceptible human host through an appropriate portal of entry, and usually involves a demonstrable host response to the agent. Exposure is the key factor, and the sources of infection lie mostly outside the individual human host, within the environment, or in other infected hosts. Disease represents one of the possible consequences of infection, and the factors important in its development are mostly intrinsic to the host, although the dosage and virulence of the infecting microbe play a role.KeywordsLyme DiseaseTyphoid FeverSexually Transmitted DiseaseOral Poliovirus VaccineFoodborne OutbreakThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.