Biology
🔒 Log in to trackDiseases, pathogens, vectors and vaccines
🔒 Log in to trackDiseases by pathogen
| Pathogen | Diseases |
|---|---|
| Bacteria | Tuberculosis, cholera, typhoid, diphtheria, tetanus, whooping cough (pertussis), leprosy, plague, bacterial pneumonia |
| Viruses | AIDS (HIV), polio, measles, mumps, chickenpox, smallpox, rabies, hepatitis, influenza, dengue, chikungunya, common cold, COVID-19 |
| Protozoa | Malaria (Plasmodium), kala-azar (Leishmania), amoebic dysentery (Entamoeba), sleeping sickness (Trypanosoma) |
| Fungi | Ringworm, athlete's foot |
| Worms (helminths) | Filariasis / elephantiasis (Wuchereria), ascariasis |
Vectors
| Vector | Disease(s) |
|---|---|
| Female Anopheles mosquito | Malaria |
| Aedes mosquito (A. aegypti) | Dengue, chikungunya, yellow fever, Zika |
| Culex mosquito | Filariasis, Japanese encephalitis |
| Rat flea | Plague |
| Sandfly | Kala-azar |
| Tsetse fly | Sleeping sickness |
| Housefly | Carries germs of cholera, typhoid (mechanically) |
- Rabies (hydrophobia) spreads through the bite of an infected dog or other mammal.
Vaccines, drugs and discoverers
| Discovery | Scientist |
|---|---|
| Smallpox vaccine (1796) — first vaccine | Edward Jenner |
| Rabies vaccine, pasteurisation, germ theory | Louis Pasteur |
| TB bacterium (1882), cholera bacterium | Robert Koch |
| Penicillin (1928) — first antibiotic | Alexander Fleming |
| Injectable (killed) polio vaccine | Jonas Salk |
| Oral polio vaccine | Albert Sabin |
| Malaria is spread by mosquitoes (Nobel 1902) | Ronald Ross |
| Blood groups | Karl Landsteiner |
| First human heart transplant (1967) | Christiaan Barnard |
- BCG — tuberculosis; DPT — diphtheria, pertussis, tetanus; MMR — measles, mumps, rubella.
- Smallpox was declared eradicated by WHO in 1980. India was certified polio-free in 2014.
- Diagnostic tests: Widal — typhoid, ELISA — HIV/AIDS, Mantoux — tuberculosis.
- Antibiotics act on bacteria, not on viruses.
- Non-communicable: diabetes, hypertension, cancer (leukaemia = blood cancer). Jaundice affects the liver; conjunctivitis — eyes; glaucoma / cataract — eyes; arthritis — joints.
Disease → pathogen type
| Type | Diseases |
|---|---|
| Bacteria | TB, cholera, typhoid, tetanus, leprosy, plague, whooping cough, anthrax |
| Virus | Dengue, chikungunya, rabies, polio, measles, mumps, AIDS, COVID-19, smallpox, influenza, jaundice (hepatitis) |
| Protozoa | Malaria, kala-azar, amoebiasis (dysentery), sleeping sickness |
| Fungus | Ringworm, athlete's foot |
| Memory hook: cholera–typhoid–TB–tetanus–leprosy–plague travel together as the bacterial six; dengue–rabies–polio–measles–AIDS as the viral five. |
Vectors — who carries what
Female Anopheles → malaria (Plasmodium). Aedes aegypti → dengue, chikungunya, zika. Culex → filariasis/elephantiasis (Wuchereria bancrofti). Sandfly → kala-azar (Leishmania). Tsetse fly → sleeping sickness (Trypanosoma). Rat flea → plague. Only the female mosquito bites. AIDS is NOT spread by mosquitoes — only by blood, unsafe sex and shared needles.
Vaccines, antibiotics and the discoverers
Edward Jenner — the first vaccine (smallpox, 1796; the word comes from 'vacca', cow). Louis Pasteur — germ theory, pasteurisation, rabies vaccine. Robert Koch — the TB bacterium (Mycobacterium tuberculosis), also anthrax and cholera. Alexander Fleming — penicillin, 1928, the first antibiotic (mould Penicillium notatum); florey and Chain made it a medicine. Banting and Best (1921) — insulin for diabetes. Ronald Ross proved malaria is carried by mosquitoes (worked in India; Nobel 1902).
Key numbers and controls
- Smallpox: the first disease eradicated — WHO declared it in 1980.
- BCG vaccine → TB; MMR → measles-mumps-rubella; polio drops → Pulse Polio campaign.
- Normal haemoglobin ≈ 12–16 g/dL; low → anaemia; genetic blood disorders: thalassaemia, sickle-cell anaemia.
- Epidemic = outbreak in a region; pandemic = worldwide (COVID-19); endemic = always present locally.
- Diseases spread through contaminated water and food (cholera, typhoid, jaundice) — safe drinking water and vaccination are the cheapest shields; Joseph Lister introduced antiseptic surgery (carbolic acid).
Question types you will see
Each type: how to recognise it, the method step by step, and one question to try.
Disease → pathogen type
'Tuberculosis is caused by a…', 'which of these is a viral / protozoan disease', 'ringworm is caused by…', odd-one-out among disease types.
Bacterial set: TB, cholera, typhoid, tetanus, leprosy, plague, whooping cough, anthrax.
Viral set: dengue, chikungunya, rabies, polio, measles, mumps, AIDS, influenza, hepatitis, smallpox, COVID-19.
Protozoa: malaria, kala-azar, amoebiasis, sleeping sickness. Fungus: ringworm, athlete's foot.
Odd-one-out trick: dengue is VIRAL, malaria is PROTOZOAN — both mosquito-borne, different microbes.
classify the disease first, then check the options against its set.
Ringworm is caused by a —
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Fungus (not a worm, despite the name). Athlete's foot is the other classic fungal infection.
Vector → disease
'Dengue is spread by which mosquito', 'malaria is transmitted by…', 'which fly causes sleeping sickness', 'elephantiasis is carried by…'.
Mosquito map: female Anopheles → malaria; Aedes → dengue, chikungunya, zika; Culex → filariasis (elephantiasis).
Other vectors: sandfly → kala-azar; tsetse fly → sleeping sickness; rat flea → plague.
Only female mosquitoes bite (they need blood for eggs). AIDS never travels by mosquito.
each vector has exactly one disease family — pair them and eliminate.
Elephantiasis (filariasis) is transmitted by —
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Culex mosquito, carrying the worm Wuchereria bancrofti. Aedes gives dengue, Anopheles gives malaria.
Vaccines and eradication
'BCG protects against…', 'first vaccine / who invented vaccination', 'which disease was eradicated', 'MMR stands for', Pulse Polio questions.
Vaccine map: BCG–TB, MMR–measles/mumps/rubella, polio drops–Pulse Polio, rabies vaccine–Pasteur.
History: Jenner, smallpox, 1796 — the first vaccine ('vacca' = cow); smallpox the first eradicated disease (WHO, 1980).
'Vaccine' word root and the eradication year are the two most-repeated facts.
The first disease to be eradicated worldwide (WHO, 1980) was —
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Smallpox. Jenner's 1796 cowpox vaccine against it started immunology — 'vaccine' from vacca, cow.
Scientist → medicine/discovery
'Penicillin was discovered by…', 'who discovered the TB bacterium', 'pasteurisation / germ theory', 'insulin was discovered by', 'who proved mosquitoes spread malaria'.
Fleming — penicillin (1928, from Penicillium mould). Koch — TB, cholera, anthrax bacteria. Pasteur — germ theory, pasteurisation, rabies vaccine.
Banting and Best — insulin (1921). Ronald Ross — mosquito-malaria link (Nobel 1902, work done in India).
Don't mix Koch (bacteriologist) with Pasteur (the wider germ theorist).
Penicillin, the first antibiotic, was discovered by —
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Alexander Fleming in 1928, from the mould Penicillium notatum. Florey and Chain later turned it into a usable drug.
Epidemic vocabulary and lifestyle diseases
'A disease spread worldwide is a…', 'diabetes is caused by deficiency of…', 'AIDS is caused by / spread by', 'epidemic vs endemic vs pandemic'.
Scale words: endemic–local and constant; epidemic–regional outbreak; pandemic–worldwide (COVID-19, 1918 flu).
Diabetes: insulin deficiency (pancreas) — sugar stays in the blood. AIDS: HIV destroys helper T-cells; spread by blood/sex/needles, NOT touch or mosquitoes.
Cancer = uncontrolled cell division; hypertension = persistent high BP.
COVID-19 spread across the world in 2020. Such a worldwide outbreak is called a —
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Pandemic — an epidemic that crosses countries and continents. Endemic diseases stay local; epidemics stay regional.
Health numbers and blood disorders
'Normal haemoglobin range', 'normal WBC count', 'lifespan of RBC', 'sickle-cell / thalassaemia is a … disorder', questions that need 120 × counts.
Normal values: haemoglobin 12–16 g/dL; RBC ≈ 5 million/mm³; WBC ≈ 6,000–8,000/mm³; platelets ≈ 1.5–4 lakh/mm³; RBC life 120 days.
Genetic blood disorders: thalassaemia and sickle-cell anaemia — inherited, not infectious.
Low haemoglobin = anaemia (iron); abnormal WBC rise = leukaemia.
memorise the three normal ranges; disorders hang off them.
The average lifespan of a red blood cell is —
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120 days; the spleen recycles the worn-out cells (its nickname: graveyard of RBCs).
Shortcuts that save time
If the disease is in this list it is bacterial; the rest of the common ones (polio, measles, AIDS, dengue, rabies, chickenpox, hepatitis) are viral. Malaria and kala-azar are protozoan.
Which of these is a viral disease: typhoid, cholera, measles, tetanus?
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Measles.
Aedes also spreads chikungunya, yellow fever and Zika (day-biting). Only the female mosquito bites for blood.
Mistakes to avoid
Where most students lose marks on this subtopic.
Calling malaria a bacterial or viral disease — it is protozoan (Plasmodium).
Crediting Pasteur with the smallpox vaccine — that was Jenner; Pasteur made the rabies vaccine.
Thinking antibiotics cure viral infections — they act only on bacteria.
Quick revision
Read this the night before the exam.
Bacterial six: TB, cholera, typhoid, tetanus, leprosy, plague. Viral five: dengue, rabies, polio, measles, AIDS. Protozoa: malaria, kala-azar, amoebiasis, sleeping sickness.
Anopheles–malaria, Aedes–dengue, Culex–elephantiasis, sandfly–kala-azar, tsetse–sleeping sickness, rat flea–plague.
Jenner smallpox vaccine 1796; Pasteur rabies; Koch TB; Fleming penicillin 1928; Banting & Best insulin.
Smallpox eradicated 1980; BCG–TB; AIDS never by mosquitoes.
Practice: 20 questions
Sets of 10, mixed across the question types above. Every answer has a step-by-step explanation.
Topic test · 10 questions
Suggested time 3 min · wrong answers go to your mistake notebook automatically.