Introduction To Concept Of Disease Notes

Introduction To Concept Of Disease

{Chapter  2}

2.Introduction To Concept Of Disease

  • The term disease literally means without ease.
  • There have been many attempts to defined ease.
  • A distinction is also made between the words disease illness & sickness which are not wholly synonymous.
  • Disease:- A physiological / psychological dysfunction.
  • illness:- A subjective state of the person who feels aware of not being well.
  • Sickness:- A state of social dysfunction i.e. a role that the individual assumes when ill.

Definition of Disease-

  1. A condition in which body health has impaired a departure from a state of health and alteration of the human body interrupting the performance of vital functions-webster.
  2. A condition of the body or some part of an organ of the body in which it function is disrupted o disarranged-oxford English dictionary.
  3. Maladjustment of the human organism to the environment- Ecological point of view.

Concept of causation:-

Up to the time of Louis Pasteur, various concepts of disease caution were in vogue.

  1. The supernatural theory of disease
  2. The theory of humor
  3. The concept of contagion
  4. Miasmatic theory of disease
  5. The theory of spontaneous generation etc

Natural history of the disease

  1. Disease results from a complex interaction between man agent (caution) & the environment. the term natural history of disease is a key concept in epidemiology.
  2. Each disease has its own unique natural history which is not necessarily the same in all individuals.
  3. The natural history of disease is best established by cohort studies what the physician has seen in the hospital is just an episode in the natural history of disease pathogenesis phase.

The phase begins with the entry of the agent. the disease agent multiplies & induces tissue & physiological changes, thus the disease process started & progresses through early & late pathogenesis.

The final outcome of the disease may be recovery disability or death.

  1. 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 a man in the midst of disease of man exposed to the risk of disease.
  2. The causative factors of the disease may be classified as agents. host & environment. these factors are known as the epidemiological triad.
  3. Even though these factors are present disease process will not occur unless there is an interaction.

Agent factors

The first link in the chain of disease transmission is a disease agent.

An agent is defined as a substance living or non-living or a force, tangible or intangible the excess presence or relative lack of which may initiate the disease process.

  • Biological agent- e.g. bacteria, viruses, protozoa.
  • Nutrient agents- e.g. PEM occurs, due to deficiency of protein anaemia due to deficiency of protein, anaemia due to lack of iron, etc.
  • Physical agents- lie excessive heat col radiation, etc.
  • Chemical agents- This could be endogenous (serum bilirubin ketones, uric acid) or exogenous (dust, ages, insecticide)
  • Mechanical agent- like friction mechanical forces like crushing tearing sprain, etc.
  • Absence/insufficiency or excess of a factor necessary to health- congenital heart disease, chromosomal defects immunological factors, etc.
  • Social agents – like poverty, smoking, alcohol & drug abuse, etc

Concept of prevention

Disease prevention

Definition– Activities designed to protect patients and other members of the public from actual or potential health threats & their harmful consequences-(Mosby’s medical dictionary)

Disease prevention covers measures not only to prevent the occurrence of disease, such as risk factor reduction but also to arrest its progress & reduce its consequences once established. ( References adopted from the glossary of terms used in health for series WHO Geneva [1984])

Successful prevention depends upon:-

  1. Knowledge of causation
  2. Dynamics  of transmission
  3. Identification of risk factors & risk groups
  4. Availability of prophylactic or early detection & treatment measure
  5. Facilities fox these treatment procedures
  6. Evaluation & development of  these procedures

Levels of  prevention

The concepts of prevention can be best defined in the context of levels of prevention.

but how many levels of prevention?

Primordial prevention

  1. Mainly associated with chronic disease
  2. Intervention- individual & mass education
  3. Has to start in childhood when health risk behavior begins. eg. of primordial prevention
  4. National programs & policies on-

(1) Food & Nutrition

(2) Against smoking & drugs

(3) To promote regular physical activity.

Responsibility of primordial prevention

  1. Parents teachers & peers, groups, imparting health education.
  2. Government, legislating & enacting laws.
  3. Professional & non-professional organizations industry.
  4. Hospitals, health practitioners, health care workers.
  5. Approaches for primary prevention for chronic disease (WHO)

A) Population (mass) strategy

  • Directed at whole population irrespective individuals risk levels
  • Directed towards socio-economical, behavioral lifestyle changes

B) High-risk strategy

To individual special risk

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