The natural history of diseases for Physiotherapy.pptx

Natural history of disease and Epidimiological Triad.
Natural history of disease refers to the progression of a disease process in an individual over time, in the absence of treatment. For example, untreated infection with HIV causes a spectrum of clinical problems beginning at the time of seroconversion (primary HIV) and terminating with AIDS and usually death.

1. Natural history of diseases

2. NATURAL HISTORY OF DISEASE Disease results from a complex interaction between man, an agent (or cause of disease) and the environment. The term natural history of disease is a key concept in epidemiology. It signifies the way in which a disease evolves over time from the earliest stage of its prepathogenesis ) phase to its termination as recovery, disability or death, in the absence of treatment or prevention. Each disease has its own unique natural history, which is not necessarily the same in all individuals, so much so, any general formulation of the natural history of disease is necessarily arbitrary.

3. Myocardial infarction - Means Heart attack Increased catecholamines thrombotic tendency – Means blood clot Natural History of Diseases

4. Prepathogenesis phase: This refers to the period preliminary to the onset of disease in man . 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. This situation is frequently referred to as "man in the midst of disease" or "man exposed to the risk of disease".

5. The causative factors of disease may be classified as AGENT, HOST and ENVIRONMENT. These three factors are referred to as epidemiological triad.

6. Pathogenesis phase: The pathogenesis phase begins with the entry of the disease "agent" in the susceptible human host. The further events in the pathogenesis phase are clear-cut in infectious diseases, i.e., the disease agent multiplies and induces tissue. and physiological changes, the disease progresses through a period of incubation and later pathogenesis. The pathogenesis phase may be modified by intervention measures such as immunization and chemotherapy.

7. Agent factors: the disease agent is defined as substance,living or non-living, or a force, tangible o r intangible, the excessive presence or relative lack of which may initiate or perpetuate a disease process.

8. Host factors (intrinsic): • In epidemiological terminology, the human host is referred to as "soil" and the disease agent as "seed". • A person or other living animal, that affords subsistence or lodgment to an infectious agent under natural condition.

9. The host factors may be classified as (i) Demographic characteristics such as age, sex, ethnicity; (ii) Biological characteristics such as genetic factors; biochemical levels of the blood (e.g., cholesterol); blood groups and enzymes; cellular constituents of the blood; immunological factors; and physiological function of different organ systems of the body (e.g., blood pressure, forced expiratory ventilation). etc. (iii) Social and economic characteristics such as socioeconomic status, education, occupation, stress, marital status and (iv) Lifestyle factors such as personality traits, living habits, nutrition, physical exercise, use of alcohol, drugs and smoking, behavioural patterns, etc.

10. Environmental factors (extrinsic): Physical environment - Non living things and physical factors(air, water, soil, housing, heat, light, etc) Biological environment - Microbial agents, insects, animals, plants and man himself. Psychosocial environment - Lifestyle, poverty, urbanization, community life, income, education, stress etc.

11. Influence of social, economic and cultural aspects of health diseases