Health = physical, mental, social well-being. Disease = any deviation from normal body function. AMU asks 2–3 MCQs — focus on infectious vs non-infectious, pathogens & diseases, modes of transmission, immunity types, and vaccination.
1) Health and disease
Factors affecting health: Personal hygiene, social environment, economic conditions (poverty → malnutrition), environmental conditions (clean water, sanitation), genetic factors.
• Acute disease: Short duration, sudden onset (cold, flu, diarrhoea).
• Chronic disease: Long duration, gradual onset (TB, diabetes, cancer, AIDS).
• Infectious (Communicable): Caused by pathogens, spreads from person to person.
• Non-infectious (Non-communicable): Genetic, lifestyle, nutritional, environmental — cannot spread.
• Acute disease: Short duration, sudden onset (cold, flu, diarrhoea).
• Chronic disease: Long duration, gradual onset (TB, diabetes, cancer, AIDS).
• Infectious (Communicable): Caused by pathogens, spreads from person to person.
• Non-infectious (Non-communicable): Genetic, lifestyle, nutritional, environmental — cannot spread.
2) Pathogens (Infectious agents)
| Type | Size | Diseases | Treatment |
|---|---|---|---|
| Bacteria | 0.5–5 µm | Typhoid (Salmonella typhi), Cholera (Vibrio cholerae), TB (Mycobacterium tuberculosis), Tetanus, Pneumonia, Leprosy, Plague | Antibiotics (penicillin, tetracycline, streptomycin) |
| Viruses | 20–300 nm | Common cold, Flu, Chickenpox, Measles, Mumps, AIDS (HIV), Hepatitis A/B, COVID-19, Rabies, Polio, Dengue | Antiviral drugs (limited). Antibiotics do NOT work. |
| Protozoa | 2–100 µm | Malaria (Plasmodium), Amoebic dysentery (Entamoeba), Sleeping sickness (Trypanosoma), Kala-azar (Leishmania) | Antiprotozoals (chloroquine, metronidazole) |
| Fungi | 2–10 µm+ | Ringworm, Athlete's foot, Candidiasis | Antifungals (clotrimazole, fluconazole) |
| Helminths | mm–m | Roundworm, Tapeworm, Hookworm, Filariasis (Elephantiasis) | Anthelmintics (albendazole, ivermectin) |
| Prions | ~10 nm | Mad Cow Disease (BSE), Creutzfeldt-Jakob Disease, Kuru | No cure (always fatal) |
🔥 AMU PYQ: Malaria is caused by:
(A) Virus (B) Bacterium (C) Protozoan (D) Fungus Ans: C
(A) Virus (B) Bacterium (C) Protozoan (D) Fungus Ans: C
🔥 AMU PYQ: Typhoid is caused by:
(A) Salmonella typhi (B) Vibrio cholerae (C) Mycobacterium (D) Streptococcus Ans: A
(A) Salmonella typhi (B) Vibrio cholerae (C) Mycobacterium (D) Streptococcus Ans: A
3) Modes of transmission
| Mode | How it spreads | Examples |
|---|---|---|
| Airborne | Coughing, sneezing (droplet nuclei) | Cold, Flu, TB, COVID-19, Chickenpox, Measles |
| Waterborne | Contaminated water (faecal-oral) | Cholera, Typhoid, Hepatitis A, Polio |
| Foodborne | Contaminated/undercooked food | Food poisoning (Salmonella, E. coli), Taeniasis |
| Vector-borne | Insects/animals carry pathogen | Malaria (Anopheles), Dengue (Aedes), Plague (rat flea), Kala-azar (sandfly), Filariasis (mosquito) |
| Direct contact | Physical contact, body fluids | Ringworm, Scabies, HIV, Gonorrhoea, Syphilis |
| Blood-borne | Transfusion, shared needles, mother-to-child | HIV, Hepatitis B, Hepatitis C |
| Sexual | Sexual contact | HIV, Gonorrhoea, Syphilis, Genital herpes, HPV |
🔥 AMU PYQ: Dengue is transmitted by:
(A) Anopheles (B) Aedes (C) Sandfly (D) Tsetse fly Ans: B
(A) Anopheles (B) Aedes (C) Sandfly (D) Tsetse fly Ans: B
4) Organ-specific diseases
| Disease | Agent | Organs affected | Key symptoms |
|---|---|---|---|
| TB | Bacterium | Lungs, bones, brain, lymph | Chronic cough with blood, night sweats, weight loss |
| Pneumonia | Bacterium/virus | Lungs (alveoli fill with fluid) | Fever, cough, breathing difficulty |
| Typhoid | Salmonella typhi | Intestine → blood → whole body | Step-ladder fever, abdominal pain, rose spots |
| Cholera | Vibrio cholerae | Small intestine | Rice water diarrhoea, severe dehydration |
| Malaria | Plasmodium | RBCs, liver, spleen, brain | Fever with chills every 48–72 hrs, anaemia |
| Dengue | Dengue virus | Blood vessels, platelets, liver | High fever, joint pain, rash, bleeding tendency |
| HIV/AIDS | HIV (retrovirus) | CD4+ T-helper cells (immune system) | Flu-like early; late: opportunistic infections, weight loss |
| Hepatitis A | HAV (faecal-oral) | Liver (acute) | Jaundice, dark urine, nausea |
| Hepatitis B | HBV (blood/sexual) | Liver (chronic → cirrhosis → cancer) | Jaundice, fatigue; can be asymptomatic carrier |
5) Immunity
Innate (Non-specific): Present at birth. Physical barriers (skin, mucous, tears, stomach acid), Cellular defences (phagocytes — neutrophils, macrophages; NK cells), Inflammation, Fever.
Adaptive (Specific): Develops after exposure; has memory.
Adaptive (Specific): Develops after exposure; has memory.
| Type | Subtype | Description | Examples |
|---|---|---|---|
| Active | Natural | Body produces own antibodies after infection | Recovering from chickenpox → lifelong immunity |
| Artificial | Vaccination introduces weakened/killed pathogen | BCG (TB), OPV (Polio), MMR, DPT, Hepatitis B | |
| Passive | Natural | Ready-made antibodies from mother | IgG via placenta; IgA via colostrum (first milk) |
| Artificial | Injection of antibodies from outside | Anti-tetanus serum (ATS), Anti-rabies serum, Snake antivenom |
🔥 AMU PYQ: Baby receives immunity from mother's colostrum — this is:
(A) Natural active (B) Natural passive (C) Artificial active (D) Artificial passive Ans: B
(A) Natural active (B) Natural passive (C) Artificial active (D) Artificial passive Ans: B
6) Vaccination
Key vaccines: BCG (TB), OPV/IPV (Polio), MMR (Measles, Mumps, Rubella), DPT (Diphtheria, Pertussis, Tetanus), Hepatitis B, TT (Tetanus toxoid), Rabies, HPV (cervical cancer), COVID-19 (various types).
• First vaccine: Smallpox (Edward Jenner, 1796).
• Smallpox eradicated globally (1980 — WHO).
• First vaccine: Smallpox (Edward Jenner, 1796).
• Smallpox eradicated globally (1980 — WHO).
7) Disease prevention
Principles:
1. Hygiene — hand washing, clean water, safe food, mosquito nets, safe sex (condoms).
2. Immunisation — vaccination programmes (UIP in India).
3. Sanitation — sewage disposal, waste management, no stagnant water.
4. Vector control — nets, repellents, spraying, Gambusia fish (eat larvae), Bacillus thuringiensis israelensis.
5. Isolation & quarantine — prevent spread from infected individuals.
6. Treatment — medicines (antibiotics for bacteria, antivirals for viruses).
⚠️ Note: Antibiotics work against bacteria ONLY — NOT viruses. Misuse causes antibiotic resistance (MRSA, XDR-TB).
1. Hygiene — hand washing, clean water, safe food, mosquito nets, safe sex (condoms).
2. Immunisation — vaccination programmes (UIP in India).
3. Sanitation — sewage disposal, waste management, no stagnant water.
4. Vector control — nets, repellents, spraying, Gambusia fish (eat larvae), Bacillus thuringiensis israelensis.
5. Isolation & quarantine — prevent spread from infected individuals.
6. Treatment — medicines (antibiotics for bacteria, antivirals for viruses).
⚠️ Note: Antibiotics work against bacteria ONLY — NOT viruses. Misuse causes antibiotic resistance (MRSA, XDR-TB).
8) HIV/AIDS case study
• HIV (Human Immunodeficiency Virus) — retrovirus (RNA + reverse transcriptase).
• Attacks CD4+ T-helper cells → progressive immune deficiency.
• AIDS = final stage (CD4 < 200 cells/µL).
• Transmission: sexual, blood, shared needles, mother-to-child.
• NOT transmitted by: casual contact, mosquito bites, sharing food.
• Diagnosis: ELISA → Western Blot. Treatment: ART (Antiretroviral Therapy) — suppresses virus, no cure.
• Attacks CD4+ T-helper cells → progressive immune deficiency.
• AIDS = final stage (CD4 < 200 cells/µL).
• Transmission: sexual, blood, shared needles, mother-to-child.
• NOT transmitted by: casual contact, mosquito bites, sharing food.
• Diagnosis: ELISA → Western Blot. Treatment: ART (Antiretroviral Therapy) — suppresses virus, no cure.
9) AMU PYQs — quick revision
Q1. Which is a viral disease?
(A) Cholera (B) Typhoid (C) Influenza (D) TB Ans: C
(A) Cholera (B) Typhoid (C) Influenza (D) TB Ans: C
Q2. BCG vaccine prevents:
(A) Cholera (B) TB (C) Typhoid (D) Tetanus Ans: B
(A) Cholera (B) TB (C) Typhoid (D) Tetanus Ans: B
Q3. Which is NOT infectious?
(A) Malaria (B) Diabetes (C) Cholera (D) HIV Ans: B
(A) Malaria (B) Diabetes (C) Cholera (D) HIV Ans: B
Q4. Penicillin is an:
(A) Antibiotic (B) Antiviral (C) Antifungal (D) Antiprotozoal Ans: A
(A) Antibiotic (B) Antiviral (C) Antifungal (D) Antiprotozoal Ans: A
Q5. HIV attacks:
(A) RBCs (B) T-helper cells (C) B-cells (D) Platelets Ans: B
(A) RBCs (B) T-helper cells (C) B-cells (D) Platelets Ans: B
Q6. The first vaccine was against:
(A) Polio (B) Smallpox (C) Rabies (D) Cholera Ans: B
(A) Polio (B) Smallpox (C) Rabies (D) Cholera Ans: B
Q7. Pneumonia affects:
(A) Liver (B) Lung (C) Kidney (D) Heart Ans: B
(A) Liver (B) Lung (C) Kidney (D) Heart Ans: B
Q8. Which STD is viral?
(A) Gonorrhoea (B) Syphilis (C) Genital herpes (D) Chlamydia Ans: C
(A) Gonorrhoea (B) Syphilis (C) Genital herpes (D) Chlamydia Ans: C
Q9. Antibiotics are effective against:
(A) Viruses (B) Bacteria (C) Protozoa (D) All Ans: B
(A) Viruses (B) Bacteria (C) Protozoa (D) All Ans: B
Q10. Elephantiasis is caused by:
(A) Bacteria (B) Virus (C) Filarial worm (D) Fungus Ans: C
(A) Bacteria (B) Virus (C) Filarial worm (D) Fungus Ans: C
Q11. Female Anopheles mosquito transmits:
(A) Dengue (B) Malaria (C) Chikungunya (D) Yellow fever Ans: B
(A) Dengue (B) Malaria (C) Chikungunya (D) Yellow fever Ans: B
Q12. Which is non-communicable?
(A) Ringworm (B) HIV (C) Cancer (D) Malaria Ans: C
(A) Ringworm (B) HIV (C) Cancer (D) Malaria Ans: C
Q13. Vitamin C deficiency causes:
(A) Scurvy (B) Rickets (C) Anaemia (D) Goitre Ans: A
(A) Scurvy (B) Rickets (C) Anaemia (D) Goitre Ans: A
📝 Pro Tip for AMU: Know which pathogen causes which disease — TB (bacteria), Malaria (protozoan), Chickenpox (virus), Ringworm (fungus). Vectors: Anopheles = malaria; Aedes = dengue. Vaccines: BCG (TB), OPV (Polio), MMR. Immunity: natural passive (mother to child via colostrum); artificial active (vaccination). Antibiotics work against bacteria only.