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Objectives
• Introduction• Phases• Epidemiological Triad• Factors causing disease: Agent, Environment, Host• Risk Factors• Risk groups• Spectrum of Disease• Iceberg of Diseases
FAQ’s in RGUHS
• Natural history of Disease with stages• Macroenvironment• Risk Factors in Disease• Epidemiological Triad• Iceberg Phenomenon• Spectrum of Disease
Introduction
• Natural history of disease refers to the progress of a disease process in an individual over time, in the absence of treatment or prevention.
• Key concept in Epidemiology• Each disease has its own, unique natural
history.
Pre-Pathogenesis
• Period of disease before man is involved• Process of disease in the environment• Man in the Midst of disease• The disease agent has not yet entered man,
but the factors which favour its interaction with the human host are already existing in the environment.
Pathogenesis Phase
The pathogenesis phase begins with the entry of the disease “agent’’ in the susceptible human host. The disease agent multiplies and induces tissue and physiological changes, the disease progresses through a period of incubation and later through early and late pathogenesis .
Agent
• A substance , living or non-living, or a force, the excessive presence or relative lack of which may initiate or perpetuate a disease process.
• May be a single agent/combination of 2 independent agents
Macro-environment
All that which is external to the individual human host, living and non-living, and with which he is in
constant interaction.
Risk Factors
• Applicable to those diseases where the disease agent cannot be established.
• Definition : An attribute or exposure that is signifiantly associated with the development of a disease.
• Presence of a risk factor disease will occur• Absence of a risk factor absence of disease