Why we fall ill and how diseases are prevented
Being healthy means feeling well in body, mind and social life, not just being free of illness. Diseases can be acute, lasting a short time, like a cold, or chronic, lasting a long time, like tuberculosis or diabetes. Some have immediate causes, such as a virus, and contributory causes, such as poor nutrition, unclean water or crowded living. Non-infectious diseases, like high blood pressure and some cancers, are not spread from person to person.
Infectious diseases spread through air, water, food, physical contact or vectors such as mosquitoes. Cholera and typhoid spread through contaminated water, tuberculosis through air, and malaria and dengue through mosquito bites. Antibiotics act on bacteria but not on viruses. Prevention works through general methods, such as clean water, good sanitation, proper nutrition and avoiding overcrowding, and through specific methods like vaccination. India’s immunisation programme protects children against diseases including polio, measles and diphtheria.
Why it matters
Knowing how diseases spread helps families and communities prevent outbreaks, especially during monsoons. Vaccination protects not just the person vaccinated but also those around them. Understanding that antibiotics do not cure viral infections helps avoid misuse and the spread of antibiotic resistance. This topic leads to immunity and health in Class 12.
Key terms
- Infectious disease
- A disease caused by a microorganism that can spread from one person to another.
- Chronic disease
- A disease that lasts for a long time, often months or years.
- Vector
- An organism, such as a mosquito, that carries a pathogen from one host to another.
- Immunisation
- Making a person resistant to a disease, usually through vaccination.