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24 General Science — Common Notes 🕒 Updated 2026-10-17
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24

🦠 Human Diseases & Health

Diseases caused by bacteria, viruses, protozoa, fungi and worms, vectors, vaccines and their discoverers, immunity, and genetic and lifestyle diseases.

📌 1. Infectious Diseases

PathogenDiseases
BacteriaTuberculosis (Mycobacterium tuberculosis), cholera (Vibrio cholerae), typhoid (Salmonella typhi), tetanus, diphtheria, whooping cough, leprosy, plague, pneumonia
VirusAIDS (HIV), polio, measles, smallpox, chickenpox, rabies, dengue, chikungunya, influenza, hepatitis, COVID-19
ProtozoaMalaria (Plasmodium), amoebic dysentery (Entamoeba), kala-azar (Leishmania), sleeping sickness (Trypanosoma)
FungiRingworm, athlete's foot, mucormycosis ("black fungus")
WormsFilariasis/elephantiasis (Wuchereria), ascariasis
VectorDisease
Female Anopheles mosquitoMalaria
Aedes (Aedes aegypti)Dengue, chikungunya, Zika, yellow fever
Culex mosquitoFilariasis, Japanese encephalitis
SandflyKala-azar
Rat fleaPlague
Tsetse flySleeping sickness
  • Rabies (hydrophobia) — from bite of infected dog etc. Tetanus — Clostridium tetani, "lockjaw". Hepatitis affects the liver, polio the nervous system, TB mainly the lungs.
  • AIDS — HIV (a retrovirus) destroys helper T-lymphocytes (CD4); test — ELISA; World AIDS Day — 1 December.

📌 2. Vaccines & Immunity

  • Edward Jenner (1796) — smallpox vaccine, "father of immunology". Louis Pasteur — rabies vaccine (1885), pasteurisation. Jonas Salk — injectable polio vaccine (IPV); Albert Sabin — oral polio vaccine (OPV).
  • BCG — tuberculosis; DPT — diphtheria, pertussis (whooping cough), tetanus; MMR — measles, mumps, rubella.
  • Antibodies are made by B-lymphocytes (plasma cells); they are immunoglobulin proteins. Vaccine = active immunity; ready-made antibodies/serum = passive immunity.
  • WHO declared smallpox eradicated in 1980. WHO certified India polio-free on 27 March 2014.

📌 3. Genetic & Non-communicable Diseases

  • Haemophilia — blood fails to clot ("royal disease"); colour blindness — cannot distinguish red-green; both X-linked recessive, commoner in males.
  • Sickle cell anaemia — sickle-shaped RBCs; thalassaemia — defective haemoglobin synthesis; Down syndrome — three copies of chromosome 21 (trisomy 21).
  • Diabetes (insulin deficiency/resistance), cancer (uncontrolled cell division), hypertension — lifestyle-related, non-communicable.
⚠️ Exam Traps:
  • Malaria — female Anopheles; dengue — Aedes; filariasis — Culex.
  • TB and typhoid are bacterial, not viral.
  • OPV — Sabin; IPV (injection) — Salk.

📌 4. Practice MCQs

📝 Practice MCQs (prepared by SF Prep — not PYQs)
Q1. The vector of malaria is the: Practice
(A) Female Anopheles mosquito
(B) Aedes mosquito
(C) Culex mosquito
(D) Housefly
Correct answer: (A)
Pathogen — Plasmodium (protozoan).
Q2. Dengue is spread by which mosquito? Practice
(A) Aedes
(B) Anopheles
(C) Culex
(D) Mansonia
Correct answer: (A)
Also chikungunya and Zika.
Q3. Tuberculosis is caused by: Practice
(A) Bacterium
(B) Virus
(C) Protozoan
(D) Fungus
Correct answer: (A)
Mycobacterium tuberculosis.
Q4. Which of these is a viral disease? Practice
(A) Tetanus
(B) Cholera
(C) Typhoid
(D) Polio
Correct answer: (D)
The other three are bacterial.
Q5. The vector of kala-azar is the: Practice
(A) Sandfly
(B) Tsetse fly
(C) Rat flea
(D) Aedes mosquito
Correct answer: (A)
Pathogen — Leishmania.
Q6. Plague is spread by the: Practice
(A) Mosquito
(B) Rat flea
(C) Housefly
(D) Bedbug
Correct answer: (B)
Bacterium — Yersinia pestis.
Q7. Filariasis (elephantiasis) is spread by: Practice
(A) Anopheles mosquito
(B) Culex mosquito
(C) Sandfly
(D) Tsetse fly
Correct answer: (B)
Worm — Wuchereria bancrofti.
Q8. HIV mainly destroys: Practice
(A) Platelets
(B) Red blood cells
(C) Helper T-lymphocytes
(D) Liver cells
Correct answer: (C)
CD4 cells; immunity weakens.
Q9. The test used for detecting HIV/AIDS is: Practice
(A) Schick
(B) Widal
(C) Mantoux
(D) ELISA
Correct answer: (D)
Widal — typhoid, Mantoux — TB.
Q10. The smallpox vaccine was developed by: Practice
(A) Jonas Salk
(B) Louis Pasteur
(C) Edward Jenner
(D) Robert Koch
Correct answer: (C)
1796; "father of immunology".
Q11. The rabies vaccine was developed by: Practice
(A) Fleming
(B) Edward Jenner
(C) Albert Sabin
(D) Louis Pasteur
Correct answer: (D)
In 1885.
Q12. The oral polio vaccine (OPV) was developed by: Practice
(A) Louis Pasteur
(B) Jonas Salk
(C) Edward Jenner
(D) Albert Sabin
Correct answer: (D)
Salk — the injectable (IPV).
Q13. BCG vaccine protects against: Practice
(A) Measles
(B) Polio
(C) Tuberculosis
(D) Cholera
Correct answer: (C)
Bacillus Calmette-Guérin.
Q14. DPT vaccine protects against: Practice
(A) Diphtheria, plague, typhoid
(B) Dengue, polio, TB
(C) Diphtheria, pertussis, tetanus
(D) Measles, mumps, rubella
Correct answer: (C)
MMR — measles, mumps, rubella.
Q15. Hepatitis mainly affects the: Practice
(A) Liver
(B) Lungs
(C) Kidney
(D) Heart
Correct answer: (A)
Viral inflammation of the liver.
Q16. The "royal disease" is: Practice
(A) Colour blindness
(B) Haemophilia
(C) Diabetes
(D) Gout
Correct answer: (B)
Among Queen Victoria's descendants.
Q17. Down syndrome is caused by: Practice
(A) Loss of one X chromosome
(B) Trisomy of chromosome 21
(C) Vitamin deficiency
(D) Bacterial infection
Correct answer: (B)
47 chromosomes.
Q18. Tetanus causes "lockjaw" by affecting the: Practice
(A) Skin only
(B) Digestive system
(C) Excretory system
(D) Nervous-muscular system
Correct answer: (D)
Toxin of Clostridium tetani.
Q19. When did WHO certify India polio-free? Practice
(A) 2011
(B) 2014
(C) 2005
(D) 2018
Correct answer: (B)
27 March 2014; last case January 2011.
Q20. Ringworm is caused by a: Practice
(A) Virus
(B) Worm
(C) Fungus
(D) Protozoan
Correct answer: (C)
Despite its name, not a worm.

📝 Practice questions

General Science — Practice MCQs (Bilingual) Ch 24: Human Diseases & Health | मानव रोग
📝 Test this chapter Practice questions

Practice MCQs SF Prep द्वारा तैयार (PYQ नहीं)। तथ्य मानक पाठ्य-सामग्री (NCERT) व आधिकारिक स्रोतों से जाँचे गए।