1. What is Health?

• WHO Definition: Health is a state of complete physical, mental, and social well-being, not merely the absence of disease.
• Scientific Heritage: Ayurveda teaches that health is a balance of body, mind, and surroundings. This is maintained by following dinacharya (daily routine) and ritucharya (seasonal routine).

2. Types of Diseases

• Communicable Diseases: Caused by pathogens (bacteria, viruses, fungi, protozoa). They spread from person to person through air, water, food, or vectors (mosquitoes). Examples: Flu, Chickenpox, TB, Malaria.
• Non-communicable Diseases (NCDs): Not caused by pathogens; cannot spread between people. Linked to lifestyle, diet, and environment. Examples: Diabetes, Cancer, Asthma, Deficiency diseases.

3. Prevention & Immunity

• Immunity: The body's natural ability to fight diseases.
• Vaccines: Train the immune system to recognize and attack germs. Edward Jenner discovered the first vaccine (for Smallpox) using cowpox material.
• Antibiotics: Medicines that kill bacteria. Discovered by Alexander Fleming (Penicillin). They do NOT work on viruses.

4. Antibiotic Resistance

Taking antibiotics when not needed, or stopping treatment too early, can make bacteria "resistant". This means the medicine stops working, making future infections harder to treat.