Prevention of diseases

The goals of medicine are to promote health, to preserve health, to restore health when it is impaired and to minimise suffer­ing and distress Prevention of a disease includes all these three goals.

Levels of prevention

In relation to the natural history of disease, three levels of prevention have been classified:


1. Primary prevention

2. Secondary preventior

3. Tertiary prevention

1. Primary prevention: It is the action taken prior to the onset of disease. The intervention is taken at the prepathogenesis phase of the disease. The interventions are 1) Health promotion 2) Specific protection.


2. Secondary prevention: It is the action taken at the early stage of a disease which halts the progress of a disease and prevents complications. The mode of intervention is early diagnosis and treatment. This intervention arrests the progress of disease, restores health and prevents irreversible damage. Also it protects other members of the community from acquiring the disease.

3. Tertiary prevention: It is the action taken after the disease has advanced beyond the early stages. The intervention is by disability limitation and rehabilitation. These measures minimise the sufferings and help the patient to adjust with the derangement of health.


From the discussion about the levels of prevention, it can be understood that each level of prevention has specific mode of intervention:

Level of prevention

Mode of intervention


Primary prevention –


Health promotion


Specific protection


Secondary prevention


Early diagnosis and



Tertiary prevention


Disability limitation



a. Health promotion

It is aimed at improving the general health and quality of life of individuals and the community. It involves a comprehensive approach towards changes in life-style and human behaviour.

Steps involved in health promotion are:

1. improving food distribution and nutrition

2. improving environmental sanitation 3 improving level of education

4. improving personal hygiene

5. health education

6. sex education

7. genetic counselling

8. marriage counselling

9. family planning

10. limiting the use of tobacco, alcohol and drugs

11. health legislation.

b. Specific protection

It refers to specific measures taken to prevent the occurrence of disease. These measures include:

1. immunisation

2. chemoprophylaxis

3. use of specific nutrients

4. protection of occupational hazards by using gloves, goggles, shields etc.

5. protection against accidents

6. avoidance of allergy

7. protection from cancer producing agents.

c. Early diagnosis and treatment

It is the main intervention in disease control. It is like stamping out the ‘spark’ rather than calling the fire brigade to put out the fire. It the disease is diagnosed and treated earlier, it will prevent com­plications and also secondary cases in the community.

Methods employed for early diagnosis are i) individual and mass case finding ii) screening and surveys ni) periodic examina­tion iv) special examination of people at risk. Treatment depends on the nature of the disease and its condition.

d. Disability limitation

It is the intervention taken in the stage of late pathogenesis. Disability limitation prevents complications and also prevents or postpones death. The major causes of disability are communicable diseases, malnutrition, lack of parental care and accidents. Disabil­ity can be prevented by: i) reducing the occurrence of impairment e.g polio immunisation ii) appropriate treatment e.g treatment of thrombo-angitis obliterans (TAO) can prevent amputation iii) pre­venting the disability to produce handicap e.g. preventing loss of employment in case of loss of limb.

e. Rehabilitation

It is the combined and coordinated use of medical, social, educational and vocational measures for training and retraining the individual to the highest possible level of functional ability. The different types of rehabilitation are:

i. Medical rehabilitation – It is restoration of function

ii. Vocational rehabilitation – It is restoration of the capacity to earn livelyhood.

iii. Social rehabilitation – It is the restoration of family and social relationships.

iv. Psychological rehabilitation – It is restoration of personal dignity and confidence.

Examples of rehabilitation are:

1. provision of aids to the crippled

2. establishment of blind schools

3 reconstructive surgery for leprosy

4. physiotherapy and exercise in polio cases

5. change to a suitable occupation

6. reassurance and socially accepting leprosy patients

7. modification of life in general and especially in cardiac patients.