Health and Disease: Class 9 Study Guide
Health means more than not being ill. Many diseases are caused by germs and can be prevented.
Health is a state of physical, mental and social well-being. It depends on food, clean surroundings, exercise, sleep and relationships. A disease is a condition that disturbs the normal working of the body. An acute disease lasts a short time, like a cold, and a chronic disease lasts a long time, like diabetes or tuberculosis.
Infectious diseases are caused by germs that spread from one person to another. Non-infectious diseases, such as cancer or diabetes, do not spread.
Causes and examples
| Cause | Examples |
|---|---|
| Virus | Common cold, influenza, dengue, polio, COVID-19 |
| Bacteria | Typhoid, cholera, tuberculosis |
| Protozoa | Malaria, amoebiasis |
| Fungi | Ringworm, athlete's foot |
How germs spread and how we prevent it
Germs spread through air, water, food, touch and animal bites such as mosquitoes. We prevent disease by washing hands, drinking safe water, covering food, keeping drains clean and avoiding stagnant water where mosquitoes breed. Vaccines teach the body to recognise a germ, so it can fight quickly if it meets it. Antibiotics kill bacteria but do not work against viruses.
Hands, food and water.
No stagnant water.
Follow the schedule.
If you are ill for long.
Public health
Hospitals, clean water, sanitation and vaccination programmes protect a community. Pulse Polio drops have helped India become free of polio. Everyone must also follow rules during outbreaks, such as staying home when sick.
Worked examples and common mistakes
Example: Malaria is caused by a protozoan spread by mosquitoes. Example: Why are antibiotics no use against a cold? A cold is caused by a virus. Common mistakes: thinking that antibiotics work against all germs, that all diseases spread from person to person, and that being well means only having no disease.
Check your understanding: model answers
1. Chronic, because it lasts a long time. 2. For example malaria or dengue. 3. Mosquitoes breed in it.
✨ Key Takeaways
- Health includes physical, mental and social well-being.
- Infectious diseases are caused by germs.
- Vaccines help to prevent disease.
- Antibiotics work on bacteria, not viruses.
💬 Questions for Discussion & Reflection
- Is tuberculosis acute or chronic?
- Name a disease spread by mosquitoes.
- Why should we avoid stagnant water?