Question

What is a disease? How many types of diseases have you studied? Give examples.

Answer 1

Disruption in the functioning of a tissue, organ or organ system resulting in discomfort is referred to as a disease.
Human diseases can be classified in different ways:
(i) Acute and chronic diseases.
(ii) Infectious and non-infectious diseases.

1. (i) Acute and chronic diseases
   • Acute diseases: These are short duration diseases in which the normal activity of the person is impaired for a few days. These diseases do not have a long term effect on the affected individual. Examples—common cold, typhoid, diarrhoea, etc.
   • Chronic diseases: These are long duration diseases that last for a long time, even as much as a lifetime. These cause long term effects on human health. Examples— elephantiasis, diabetes, arthritis, etc.
2.  Infectious and non-infectious diseases

• • Infectious (or communicable) diseases: These diseases are caused by pathogens such as bacteria, viruses, protozoans, etc. and are spread from a diseased person to a healthy person by means of air, food, water, vectors, physical contact etc. Examples—tuberculosis, chickenpox, dengue, etc.
  • Non-infectious (or non-communicable) diseases: These diseases remain confined to the person who develops them and does not spread to others. These may be caused by deficiency of nutrients, imbalance of hormones, malfunctioning of some organs or of the immune system, etc. Examples Epilepsy, allergy, goitre, Marasmus, etc.