Introduction to Health and Disease

Concept of Health

The concept of health and disease is changing as the time passes. There are four major concepts of health:

1. Biomedical concept: This theory is based on the germ theory of disease. Robert Koch proposed that to have a disease, there must be presence of some microorganisms. According to Koch's postulates:

1. To have a disease, there must be the presence of some microorganisms.
2. These microorganisms can be isolated from the diseased organisms and can be pure cultured in the laboratory.
3. The causative microorganisms can cause the same disease in the susceptible host.
4. The microorganisms isolable from the diseased susceptible host.

2. Ecological concept: This concept relates equilibrium between human, infectious agent and environment with the health and disease. According to this concept, health is a dynamic equilibrium between human and environment. Health is a relative absence of pain and discomfort, and continuous adaptation and adjustment with environment to ensure optimum function. This concept also accepts the role of social, cultural and economic factors and their effects on health.

3. Psychosocial concept: This concept includes socio-economic factors in defining health and disease.

4. Holistic concept: Holistic approach includes all biomedical, ecological, psychological concepts in defining health and disease. It is the combination of above all concepts.

The Health for All initiative of the World Health Organization defines health into three operational goals: increase in life expectancy and sustainable life; improved equity in health between and within countries; and access for all to sustainable health systems.

Definitions of Health

The following are some definition of health:

1. The condition of being sound in body, mind or spirit, especially freedom from physical disease or pain.
2. Soundness of body or mind , that conditions in which its functions are duly and efficiently discharged.
3. A condition or quality of the human organism expressing the adequate functioning of the organisms in the given conditions, genetic and environmental.
4. A modus vivendi (condition) enabling imperfect men to achieve a rewarding and not too painful existence while they cope with and imperfect world. (R. Dubos. 1968)
5. A state of relative equilibrium of body form and function which results from its successful dynamic adjustment to forces tending to disturb it. It is no passive interplay between body substances and forces impinging upon it but an active response of body, forces working toward readjustment.
6. It is a state of complete physical, mental and social well-being and not merely an absence pf disease or informity (WHO).

The well-being word has subjective and objective meaning. The subjective meaning of well-being refers to the quality of living. The objective meaning states the standard of living.

Definitions of Disease

Disease (dis+ease) is just opposite of health i.e. any deviation from normal functioning or state of complete physical and mental well-being.

Disease is a condition in which body health is impaired, a departure from a state of health, an alteration of the human body interrupting the performance of vital functions.

Disease is a condition of body or some part organ of the body in which its functions are disrupted or disarranged.

Disease is maladjustment of the human organism to the environment.

Illness: Illness is the subjective state of feeling aware of not being well. It is a state in which the equilibrium of the body and its functions are disturbed. if the disturbance is severe and its duration is not long, the person is said to be acute ill. The illness continues for along duration without disability, the affected person is said to be chronically ill.

Sickness: Sickness is a social dysfunction.

Spectrum of Health

Health is a dynamic equilibrium between human, infectious agent and the environment. It is multifactorial and changeable. the person who is healthy today may be ill tomorrow. In a spectrum of health, the lower level is the death whereas highest level is the positive health.

www.slideshare.net Fig. Spectrum of Health

Iceberg Phenomenon of Disease

Many symptomless cases or sub-clinical cases remain in a community. If a large block of ice is kept in water, a large portion remains inside water whereas only a small portion of ice floats over the water. Similarly, among cases of the disease in the community, symptomless and sub-clinical cases, vulnerable cases are not diagnosed by the physician that correspond to large submerged portion of ice in water which is invisible to us. The physician can only diagnose the declared morbid cases corresponding to small floating part of a ice in water. This phenomenon is known as iceberg of the disease.

communitymedicineunlimited.blogspot.comFig. Iceberg phenomenon of disease

Web of Causation

The disease is caused by several factors. Therefore, the cause of the disease is said to be multifactorial. The causes of the disease are linked with each other in a web-like manner. This type of relationship between the causes of the disease is called web of causation.

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Fig. Web of causation- an example of myocardial infarction

Epidemiological triad

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Fig. Epidemiological triad and related factors

Health is a dynamic equilibrium between human, agent and the environment. There is interaction between these factors which lie in the corner of epidemiological triangle. Any imbalance in this triangular relationship results disease or health problem. Agent factors include physical, chemical, mechanical, nutrient and biological factors types. The influencing factors for the transmission of disease with relation to the agents are infectivity, pathogenicity, virulence, immunogenicity, antigenic stability and survival of the agents.

Reference

Gordis, L. Epidemiology. third edition. 2004.

Park, K. Park's Text Book of social and prevention Medicine. 18th edition. 2008.