Diseases
Communicable diseases; vaccines and ORS intro.
Diseases
Communicable Diseases
What you'll learn
- Communicable diseases spread from person to person — often by microbes (bacteria, viruses, protozoa, fungi).
- Examples: cold, tuberculosis (intro), malaria (mosquito), diarrhoea (contaminated water).
- Prevention: vaccines, clean water, mosquito control, covering mouth when coughing.
- NCERT Looking Around 5, Chapter 8 (A Treat for Mosquitoes) — malaria, dengue awareness.
Key concepts
Level 1 — How diseases spread
Verbal: Pathogens travel through air droplets, water, food, insect bites, or touch.
Symbolic: Source → route → new host.
| Disease (intro) | Agent | Spread by |
|---|---|---|
| Common cold | Virus | Air, touch |
| Malaria | Protozoa (Plasmodium) | Female Anopheles mosquito |
| Dengue (intro) | Virus | Aedes mosquito |
| Diarrhoea | Bacteria/virus | Dirty water, food |
| TB (intro) | Bacteria | Air from cough |
NCERT link: Ch 8 — mosquito life cycle; preventing stagnant water.
Level 2 — Vaccines and ORS
Verbal: Vaccines train body to fight specific diseases — polio, measles, BCG (intro list).
Real-life: Pulse Polio campaign; school vaccination records; ORS sachet ₹ low cost saves lives in diarrhoea.
| Prevention | Target |
|---|---|
| Vaccination | Polio, measles, etc. |
| Mosquito nets / no stagnant water | Malaria, dengue |
| Boiled water | Waterborne diseases |
| ORS + doctor | Dehydration from diarrhoea |
Worked example
How can malaria be reduced in a village?
Step 1 — Remove stagnant water (breeding sites).
Step 2 — Use mosquito nets while sleeping.
Step 3 — Community spray/larvicide (health workers).
Answer: Break mosquito life cycle + personal protection (Ch 8).
Why cover mouth when sneezing?
Step 1 — Sneze releases droplets with viruses/bacteria.
Step 2 — Others inhale or touch surfaces → spread.
Answer: Reduces airborne and contact transmission.
Common mistakes
| Mistake | Why it happens | Fix |
|---|---|---|
| Antibiotics cure cold | Cold mostly viral | Rest, fluids; doctor for bacterial infections |
| All mosquitoes cause malaria | Species differ | Anopheles — malaria; Aedes — dengue (intro) |
| Vaccine gives the disease | Side effect confusion | Vaccines use weakened/killed germs — protect |
| ORS replaces all medicine | Dehydration focus | ORS for fluids; doctor if severe or bloody stool |
Quick check
- Define communicable disease.
- How does malaria spread?
- Name two prevention methods for mosquito diseases.
- Stretch: Why is polio vaccine given to children nationwide?
Revision tip: Draw mosquito life cycle from Ch 8 — egg, larva, pupa, adult — mark where to break the chain (stagnant water).
Open the Practice tab for graded questions on Communicable Diseases.
Key Takeaways (TL;DR)
- What you'll learn
- Key concepts
- Worked example
- Common mistakes
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