Q1.
Are diseases always caused by infections?
Answer
No. Infection is only one of the two ways a disease can arise.
| Caused by infection | Not caused by infection | |
|---|---|---|
| Name | Communicable (infectious) diseases | Non-communicable diseases |
| Cause | A pathogen — bacteria, virus, fungus, worm or protozoa | Lifestyle, diet and/or environment; or lack of a nutrient |
| Spread | Pass from one person to another | Do not spread from person to person |
| Examples | Typhoid, dengue, flu, chickenpox, COVID-19 | Cancer, diabetes, asthma, heart disease; and the deficiency diseases scurvy, anaemia and goitre |
In fact, the chapter points out that in India the non-infectious group is now the larger problem: non-communicable diseases are the most common cause of death in India.
Why it happens: a disease is any condition that affects the normal working of the body or mind. A pathogen is one way to disturb that working — but so is a diet short of vitamin C, or years of breathing polluted air, or a body that can no longer control its blood sugar. No germ is needed for the working to go wrong.