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CHAPTER 5 - ALL QUESTIONS (10-Mark Detailed Answers)

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Q44. Epidemiology, Prevention and Control of HIV/AIDS

• Global: ~39 million people living with HIV (2023)
• Sub-Saharan Africa most affected; India has 3rd largest burden
• Mainly affects sexually active age group (15-49 years)
• Sex ratio: males > females (in India); females > males in Africa

1. Sexual contact (homosexual and heterosexual) - most common
2. Blood and blood products (transfusion, needle sharing)
3. Mother to child (vertical) - antenatal, intrapartum, breastfeeding
4. Occupational (needle stick injury)

• A - Abstinence (delay sexual debut)
• B - Be faithful (reduce partners)
• C - Condom use (consistent and correct)
• D - Drugs avoided (no IV drug abuse)
• E - Education and early treatment

• ICTC (Integrated Counselling and Testing Centres)
• PPTCT (Prevention of Parent to Child Transmission)
• Blood safety - screen all donated blood
• Harm reduction in IV drug users (needle exchange)
• ART (Antiretroviral Therapy) - free under NACO
• NACP (National AIDS Control Programme) - Phase I to IV
• 90-90-90 target: 90% know status, 90% on ART, 90% virally suppressed

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Q45. Pandemic Influenza - H1N1

• Emerged in Mexico, March 2009; spread globally
• Post-pandemic phase since August 2010; continues as seasonal virus
• Affects children and young adults (unlike seasonal flu affecting elderly)
• India 2018: 14,971 cases, 1,103 deaths; CFR 7.36%

• Suspected: Acute febrile illness (fever ≥38°C) within 7 days of contact with confirmed case OR travel to affected area
• Probable: Positive for influenza A but unsubtypable for H1/H3
• Confirmed: RT-PCR positive at WHO approved lab

• Oseltamivir (Tamiflu): 75 mg twice daily x 5 days; children 30-75 mg based on weight
• Zanamivir as alternative

• Hand hygiene, cough etiquette, respiratory masks
• Isolation of cases
• Influenza vaccine (trivalent/quadrivalent, annual)
• Category A: home isolation; Category B: antiviral; Category C: hospitalization + antiviral

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Q46. Investigation of Food Poisoning

• Secure complete list of persons involved
• Interview all who shared the meal
• Questionnaire: foods eaten (previous 2 days), place and time of eating, onset of symptoms, symptoms (nausea, vomiting, diarrhea, abdominal pain, fever), personal data (age, sex, occupation)
• Also interview kitchen employees and food handlers

• Stool and vomit samples from affected persons
• Food remnants - aerobic and anaerobic culture
• Blood cultures if systemic illness
• Identify causative organism; phage typing for completeness
• Stool of food handlers

• Feed rhesus monkeys with food remnants
• Protection tests useful in botulism
• Saline filtrate injected subcutaneously with and without antitoxin

• Inspect kitchen, food preparation area
• Check storage temperatures, cross-contamination
• Water source inspection
• Personal hygiene of food handlers

• Attack rate = (those who ate and became ill / total who ate) x 100
• Food specific attack rate for each food item
• Compare attack rates in those who ate vs did not eat each food
• Highest attack rate + lowest non-eater rate = incriminated food

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Q47. Epidemiology, Prevention and Control of Japanese Encephalitis

• Endemic in Southeast Asia, India (UP, Bihar, Assam, Karnataka)
• Mainly in rural agricultural areas
• Seasonal: monsoon and post-monsoon (July-November)
• Children 1-15 years mainly affected
• CFR: 20-40%; survivors have neurological sequelae in 30-50%

• Most infections subclinical (1:25 ratio)
• Sudden fever, headache, vomiting
• Altered consciousness, seizures, meningism
• Flaccid paralysis, extrapyramidal signs
• CSF: lymphocytosis, raised protein

• Vector control: Insecticide spraying, larviciding, elimination of breeding sites
• Pig management: Relocate piggeries away from human habitation; vaccinate pigs
• Personal protection: Mosquito nets, repellents, long clothing
• Vaccination: JE vaccine is most important control measure
  • Live attenuated SA14-14-2 vaccine (single dose, >12 months)
  • Inactivated mouse brain-derived vaccine (Nakayama strain)
  • Under UIP in India (endemic districts)
  • Schedule: 9-12 months with booster at 16-24 months

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Q48. Control of Diarrhoeal Disease

• ORS solution prevents death from dehydration
• WHO/UNICEF low osmolarity ORS: Na 75, K 20, Cl 65, Citrate 10, Glucose 75 mmol/L

• 20 mg/day x 10-14 days (children >6 months)
• Reduces duration and severity; prevents recurrence

• Protective antibodies (SIgA) in breast milk
• Avoids contaminated water and utensils

• Safe drinking water (chlorination, boiling, filtration)
• Hand washing with soap at critical times
• Hygienic disposal of feces (improved latrines)
• Food hygiene

• Continue feeding during diarrhea
• Extra meals after recovery

• Rotavirus vaccine (under UIP since 2016): Rotavac (5 doses), Rotarix (2 doses)
• Cholera vaccine in outbreak setting

• IMNCI (Integrated Management of Neonatal and Childhood Illness)
• Case management at facility level

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Q49. Chikungunya Fever

• Named from Makonde language: "that which bends up" (referring to stooped posture)
• Large outbreaks: Indian Ocean islands 2005-06; India 2006, 2016
• Urban and semi-urban areas
• No age/sex predilection

• Sudden high fever (39-40°C)
• Severe arthralgia/arthritis - bilateral, symmetrical (hallmark); affects wrists, ankles, fingers
• Rash (maculopapular, pruritic) in 40-50%
• Headache, myalgia, conjunctivitis
• Joint pain may persist months to years (chronic chikungunya)
• No hemorrhagic manifestations (unlike dengue)

• RT-PCR: first 5 days
• IgM ELISA: from day 5 onwards
• Serology (plaque reduction neutralization test)

• No specific antiviral; supportive care
• Analgesics: paracetamol (avoid NSAIDs and aspirin in acute phase)
• Chloroquine may help chronic arthritis

• Vector control: eliminate Aedes breeding (remove stagnant water in containers, tyres, flower pots)
• Personal protection: repellents, long-sleeved clothing
• No vaccine available
• Source reduction is cornerstone of prevention

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Q50. Investigation of Epidemic of Cholera

• Clinical criteria: profuse watery diarrhea (rice-water stools)
• Lab: stool culture on TCBS medium; dark-field microscopy showing "shooting star" motility; agglutination test

• Suspected: acute watery diarrhea in area with known cholera
• Confirmed: lab proven

• Water source investigation (pipe breaks, contamination)
• Collect water samples for bacteriology
• Food source: common meals, hawker foods
• Spot map - identify clustering

• Go house-to-house in affected area
• Check hospitals and health centers

• Classic: contaminated water (most common)
• Also: contaminated food, flies, direct contact

• Safe water supply: chlorination (0.5 ppm residual chlorine)
• Sanitation: safe disposal of excreta
• Case isolation and treatment with ORS ± antibiotics (Doxycycline single dose in adults; Azithromycin in children)
• Chemoprophylaxis for contacts: single dose Doxycycline
• Health education
• Surveillance: active case finding, lab confirmation
• Notify: cholera is a notifiable disease; international health regulations apply

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Q51. Epidemiology of Filariasis

• 120 million infected globally; 40 million in India
• Mainly tropical countries; India: UP, Bihar, Tamil Nadu, Orissa, Andhra Pradesh, Kerala
• No animal reservoir for W. bancrofti
• All age groups; males more affected clinically (outdoor exposure)
• Microfilaremia shows nocturnal periodicity (10 pm - 4 am) in India

• Infective larva (L3) → enters skin during mosquito bite → lymphatics → adult worm (3-10 cm) → microfilariae in blood

1. Asymptomatic microfilaremia
2. Acute filarial fever (adenolymphangitis - ADL)
3. Hydrocele (most common chronic manifestation in males)
4. Lymphedema of limbs
5. Elephantiasis (chronic lymphedema)
6. Chyluria
7. Tropical pulmonary eosinophilia (TPE)

• Night blood smear (between 10 pm - 2 am) - thick smear
• ICT (Immunochromatographic test) - detects W. bancrofti antigen
• Microfilariae concentration methods (DEC provocation test)

• Mass Drug Administration (MDA): DEC 6 mg/kg + Albendazole 400 mg annually
• Vector control: Culex control
• Personal protection: bed nets, repellents

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Q52. Prevention and Control of Human Rabies

• Prodrome: pain/paresthesia at bite site, fever, anxiety
• Furious rabies (80%): hydrophobia, aerophobia, autonomic dysfunction, agitation
• Paralytic/dumb rabies (20%): ascending paralysis like GBS
• Death invariably occurs once symptoms begin

• Cat I: touching/feeding animal, intact skin - no PEP
• Cat II: nibbling, minor scratches, no bleeding - wound washing + vaccine
• Cat III: transdermal bites, licks on broken skin, bat exposure - wound washing + vaccine + RIG

• Wash immediately with soap and water for 15 minutes
• Apply antiseptic (povidone iodine, alcohol)
• Do NOT suture immediately

• Intramuscular: 0, 3, 7, 14 days (4 doses) - WHO 2018 schedule
• Previously: 0, 3, 7, 14, 28 days (5 doses - Essen)

• Human RIG: 20 IU/kg body weight
• Equine RIG: 40 IU/kg body weight
• Infiltrate into wound; remainder IM at distant site

• Dog vaccination campaigns
• Stray dog population control
• Elimination of wild reservoir hosts

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Q53. Hospital Acquired Infections (HAI) / Nosocomial Infections

1. Urinary tract infections (UTI) - most common (30-40%): catheter-associated
2. Surgical site infections (SSI) - 20%
3. Pneumonia/VAP (Ventilator-Associated Pneumonia) - 15%
4. Bloodstream infections (BSI) - 15%; central line-associated (CLABSI)
5. Skin and soft tissue infections

• Gram negatives: E. coli, Klebsiella, Pseudomonas, Acinetobacter (ESKAPE pathogens)
• Gram positives: MRSA, VRSA, Enterococcus
• Fungi: Candida
• C. difficile (antibiotic-associated diarrhea)

• Patient factors: age extremes, immunocompromised, chronic disease, malnutrition
• Hospital factors: invasive devices (catheters, ventilators), surgical procedures, prolonged stay, antibiotic overuse

1. Hand Hygiene: WHO 5 moments (most important); soap and water or alcohol-based handrub
2. Isolation Precautions: Standard precautions for all patients; contact/droplet/airborne precautions
3. Sterilization and Disinfection: Proper instrument sterilization; safe injection practices
4. Antibiotic Stewardship: Rational use of antibiotics
5. Bundle Care:
   • CAUTI bundle: daily review of catheter necessity
   • VAP bundle: head-of-bed elevation 30-45°, oral chlorhexidine, sedation vacation
   • CLABSI bundle: maximal sterile barrier, chlorhexidine skin prep
6. Infection Control Committee (ICC): Surveillance, guidelines, audit
7. Healthcare Worker Vaccination: Hepatitis B, influenza

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Q54. Post-Exposure Prophylaxis (PEP) for HIV / Modes of Transmission

• Unprotected vaginal/anal/oral sex
• Risk per act: receptive anal (1.4%), insertive anal (0.11%), vaginal (0.1%)
• STIs increase risk 3-5 times (especially those causing ulcers)

• IV drug use (needle/syringe sharing)
• Blood transfusion (0.9/unit risk)
• Needle-stick injury in healthcare workers (0.3% risk)

• Antenatal (in utero): 5-10%
• Intrapartum: 10-20% (highest risk)
• Breastfeeding: 10-15%

• Initiate within 2 hours; maximum within 72 hours; not effective after 72 hours
• Preferred regimen: TDF + 3TC (or FTC) + DTG (Dolutegravir) x 28 days
• Alternate: TDF + 3TC + LPV/r
• Baseline HIV test; repeat at 6 weeks, 3 months, 6 months
• HBV and tetanus prophylaxis as appropriate

• For sexual assault, unprotected sex with known HIV-positive
• Same drugs; initiate within 72 hours; 28-day course

• Needle stick: wash with soap and water; allow bleeding
• Do NOT squeeze, suck, bleach
• Document: time, depth, source patient status

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Q55. Clinical Management of Dengue / Haemolytic Fever

• Dengue without warning signs
• Dengue with warning signs
• Severe dengue

• Abdominal pain or tenderness
• Bleeding (mucosal)
• Organ impairment
• Decrease in platelet (rapid: <100,000/mm³)
• Fluid accumulation (ascites, pleural effusion)
• Increase in hematocrit (≥20%)
• Nausea/vomiting (persistent)
• Altered level of consciousness

1. Febrile phase (1-3 days): High fever, flushed face, myalgia, retro-orbital pain, "break-bone fever"
2. Critical phase (4-5 days): Defervescence; plasma leakage; risk of shock and hemorrhage
3. Recovery phase (6-7 days): Reabsorption of fluids; bradycardia, rash with islands of white

• Group A (outpatient): Adequate hydration (ORS), paracetamol (avoid NSAIDs/aspirin), rest, monitoring
• Group B (hospitalized): IV fluids (crystalloids), monitoring vitals, platelet transfusion if <10,000 with bleeding
• Group C (severe dengue/ICU):
  • Dengue shock syndrome: rapid fluid resuscitation (20 mL/kg IV bolus isotonic saline)
  • Severe bleeding: packed red cells; fresh frozen plasma
  • Organ support as needed

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Q56. Prevention of Acute Respiratory Illness (ARI)

• Upper ARI: common cold, otitis media, sinusitis, pharyngitis
• Lower ARI: bronchitis, bronchiolitis, pneumonia
• Pneumonia classified by IMNCI: fast breathing, chest indrawing, danger signs

• Pentavalent vaccine (DTP + HBV + Hib): prevents H. influenzae pneumonia
• Pneumococcal vaccine (PCV13): prevents Streptococcus pneumoniae - under UIP since 2017
• Influenza vaccine: annual; recommended for high-risk groups
• Measles vaccine: prevents measles pneumonia
• Hib vaccine: prevents bacterial meningitis and pneumonia

• Exclusive breastfeeding x 6 months (SIgA, lactoferrin)
• Vitamin A supplementation (reduces ARI severity)
• Zinc supplementation

• Reduce indoor air pollution (improved cookstoves, clean fuel)
• Reduce overcrowding
• Improve ventilation in homes
• Hand hygiene

• Cough etiquette (cover mouth/nose)
• Hand washing with soap
• Avoid close contact with sick individuals

• Assess, classify, treat/refer
• Oral amoxicillin for non-severe pneumonia
• Refer severe cases immediately

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Q57. Filarial Survey / Mass Drug Administration in Filariasis

• Blood collected between 10 pm - 2 am (nocturnal periodicity)
• Thick blood smear, stained with Giemsa/Leishman
• Count microfilariae per 20 µL blood (microfilarial rate)
• Microfilarial density rate: number of mf per mL

• Clinical examination for hydrocele, lymphedema, elephantiasis
• Chronic disease rate calculated

• Detects circulating W. bancrofti antigen
• Finger-prick blood; done daytime; sensitivity >96%
• Now preferred over night blood survey

• MDA required if: microfilaraemia rate ≥1% OR antigenemia rate ≥2% by ICT

• DEC (Diethylcarbamazine) 6 mg/kg + Albendazole 400 mg - single annual dose
• In overlap with onchocerciasis areas: Ivermectin + Albendazole
• Administered by field workers to entire eligible population (except: children <2 years, pregnant women, seriously ill)

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Q58. Lab Diagnosis, Prevention and Control of Typhoid Fever

• Positive in 75-90% in 1st week
• 10 mL blood in 100 mL bile broth (1:10 dilution for bacteriostatic effect of blood)
• Colonies: non-lactose fermenters on MacConkey; H2S-producing black colonies on SS agar

• Detects agglutinating antibodies (O and H antigens)
• O antibody rises from end of 1st week; H antibody rises in 2nd week
• Diagnostic titre: O ≥1:160; H ≥1:160 (single sample in endemic areas)
• 4-fold rise in paired sera is diagnostic
• Limitations: false positives (malaria, liver disease), false negatives (early or treated)

1. Safe water supply and sanitation
2. Food hygiene: proper cooking, refrigeration, clean utensils
3. Carrier detection and treatment: Carriers treated with Ciprofloxacin (for non-biliary) or Cholecystectomy (for biliary carriers)
4. Vaccination:
   • Vi capsular polysaccharide vaccine (Typhim Vi): Single IM dose; >2 years; 60-70% efficacy; revaccinate every 3 years
   • Oral Ty21a (Vivotif): Live attenuated; 3 capsules alternate days; >6 years; 50-70% efficacy; not for immunocompromised
   • Vi-TT conjugate (Typbar-TCV): Single IM dose; >6 months; >80% efficacy; preferred in children; part of UIP in India
5. Health education: Hand washing, safe food practices
6. Case notification and isolation

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Q59. Deformities in Leprosy

• Ulnar nerve (cubital tunnel): clawing of ring/little fingers (partial claw hand)
• Median nerve (carpal tunnel): clawing of index/middle finger + thenar atrophy; "ape thumb"
• Combined ulnar + median: complete claw hand
• Radial nerve: wrist drop (rare in leprosy)
• Absorption of digits: due to neurotrophic changes and repeated trauma

• Common peroneal nerve: foot drop; clawing of toes
• Posterior tibial nerve: clawing of all toes; anesthetic sole → plantar ulcers → Charcot foot

• Facial nerve: lagophthalmos (inability to close eye)
• Trigeminal nerve: loss of corneal sensation
• Combined → exposure keratitis → corneal ulceration → blindness

• Collapsed nose (saddle nose): destruction of nasal cartilage in lepromatous leprosy
• Madarosis: loss of eyebrows/eyelashes
• Leonine face: in lepromatous leprosy

• Early detection and MDT
• Management of reactions (prednisolone for Type 1/reversal reaction)
• Physiotherapy: passive and active exercises
• Self-care: daily inspection, soaking, scraping, oiling (DSSO)
• Protective footwear (MCR - microcellular rubber sandals)
• Reconstructive surgery: tendon transfer, eye surgery, nasal reconstruction
• Aids and appliances

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Q60. Yellow Fever Vaccine

• Live attenuated vaccine (Theiler 1937 - Nobel Prize)
• Derived from Asibi strain by passage in chick embryo
• Sub-strains: 17D-204 (most used) and 17DD

• Children <6 months
• Pregnant women (relative; give if benefit > risk in endemic areas)
• Immunocompromised (HIV with CD4 <200, on immunosuppressants)
• Egg allergy (grown in chick embryo)
• Thymus disease/thymectomy

• Mild: soreness at injection site, low fever (2-5%)
• Vaccine-Associated Neurological Disease (YEL-AND): in infants <6 months
• Vaccine-Associated Viscerotropic Disease (YEL-AVD): rare (0.3-0.4/100,000); mimics wild-type YF; elderly and thymus disease at risk

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Q61. Homemade ORS

• Sodium chloride: 2.6 g
• Glucose anhydrous: 13.5 g
• Potassium chloride: 1.5 g
• Trisodium citrate dihydrate: 2.9 g
• Dissolved in 1 litre of clean water
• Osmolarity: 245 mOsm/L

• 1 litre of clean boiled water
• 6 level teaspoons of sugar (18 g)
• 1/2 level teaspoon of salt (1.5 g)
• Can add: half cup of citrus juice (potassium)

• 1 litre water + 50 g rice flour + 3 g salt; boil 5 minutes
• Advantage: glucose from rice is absorbed along with sodium; less stool output

• Lemon juice, salt, sugar in water

• Children under 2: 50-100 mL after each loose stool
• Children 2-10: 100-200 mL after each loose stool
• Older: as much as needed

• Does NOT reduce stool frequency or volume significantly
• Does NOT work in severe dehydration (need IV fluids)
• Does NOT work if vomiting is severe

• A fistful of sugar (3 tablespoons) + pinch of salt in 1 litre water

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Q62. Aedes aegypti Investigation

• Black mosquito with distinctive white markings on thorax (lyre shape) and banded legs
• Day-biting, peridomestic; prefers clean stagnant water in containers

• % of houses with at least one positive container (with Aedes larvae/pupae)
• HI = (Houses with Aedes larvae / Houses inspected) x 100
• Threshold: HI >1% = dengue transmission risk

• % of water-holding containers positive for Aedes larvae
• CI = (Positive containers / Containers inspected) x 100

• Number of positive containers per 100 houses inspected
• BI = (Positive containers / Houses inspected) x 100
• BI >5 = dengue risk; BI >20 = high risk
• This is the index of choice for dengue vector surveillance

• Number of houses with at least one container with pupae per 100 houses
• Most predictive of adult mosquito density

• Inspect all water containers inside and outside house
• Check overhead tanks, drums, flower pots, tyres, coolers, broken bottles
• Record positive containers; species identification from larval morphology

• BI <5: Continue routine surveillance
• BI 5-20: Targeted source reduction
• BI >20: Emergency vector control measures

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Q63. Multidrug Treatment (MDT) in Leprosy

• ROM therapy: Single dose Rifampicin 600 mg + Ofloxacin 400 mg + Minocycline 100 mg
• Equally effective for 1 lesion PB

• Rifampicin 300 mg monthly; Dapsone 50 mg daily; Clofazimine 150 mg monthly + 50 mg alternate day

• Rifampicin: bactericidal; most potent anti-leprosy drug
• Dapsone: bacteriostatic; inhibits PABA utilization
• Clofazimine: bacteriostatic + anti-inflammatory; binds DNA

• Rifampicin: hepatotoxicity, orange urine/secretions
• Dapsone: hemolytic anemia (especially G6PD deficiency), methemoglobinemia
• Clofazimine: skin discoloration (reddish-brown), ichthyosis, GI disturbance

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Q64. BCG Vaccine

• Intradermal injection (Mantoux technique)
• Right upper arm (deltoid region)
• Dose: 0.05 mL (neonates), 0.1 mL (children >1 year)

• Against TB meningitis and miliary TB in children: 80-85%
• Against pulmonary TB in adults: 0-80% (highly variable)
• Against leprosy: 50-80%
• Against non-tuberculous mycobacteria

• Local reaction appears at 2-6 weeks
• Papule → pustule → ulcer → scar (5-8 mm)
• Scar indicates successful vaccination
• Mantoux test becomes positive

• Immunocompromised children (HIV symptomatic)
• Active TB in family member (relative)
• Eczema at injection site

• Local abscess (if too deep)
• Keloid formation
• Regional lymphadenitis
• BCG osteomyelitis (rare)
• Disseminated BCG (in immunocompromised)

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Q65. DOTS / TB Prevention

1. Government commitment to TB control
2. Case detection by quality sputum smear microscopy
3. Standardized short-course chemotherapy with direct observation
4. Regular uninterrupted supply of drugs
5. Standardized recording and reporting system

• 2HRZE + 4HR (6 months)
• Intensive phase: 2 months - H+R+Z+E daily
• Continuation phase: 4 months - H+R daily

• DST-guided treatment
• Shorter regimen if drug-sensitive

• MDR-TB: resistance to H + R
• Newer regimens: BPaL (Bedaquiline + Pretomanid + Linezolid) - 6 months
• Previously: 20-24 month regimens

• BCG vaccination (primary prevention)
• Case finding and treatment (reducing transmission)
• Infection control in healthcare settings
• TB Preventive Therapy (TPT): Isoniazid 6 months (6H) or 3HP (3-month weekly Isoniazid + Rifapentine) for high-risk contacts
• Nutritional support (malnutrition major risk factor)
• HIV-TB co-infection management (screen all HIV for TB; all TB for HIV)

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Q66. Uses of Skin Test in Leprosy

• Lepromin = suspension of killed M. leprae from leprous tissue (heat-killed, autoclaved)
• Dharmendra lepromin: bacillary suspension (fine particle)
• Mitsuda lepromin (whole tissue lepromin): includes tissue debris

• 0.1 mL intradermal injection in forearm
• Read at 48 hours (Fernandez reaction) AND 3-4 weeks (Mitsuda reaction)

• Delayed hypersensitivity (Type IV) response
• Similar to Mantoux reaction
• Indicates prior sensitization to M. leprae antigens
• Positive: erythema + induration ≥5 mm
• Can be positive in BCG-vaccinated, healthy contacts

• Granuloma formation (3-4 mm raised nodule)
• Indicates ability to mount granulomatous immune response to M. leprae
• NOT a test for infection - tests cell-mediated immunity

• Tuberculoid leprosy (TT): Strongly POSITIVE (high CMI)
• Borderline tuberculoid (BT): Weakly positive
• Mid-borderline (BB): Negative
• Borderline lepromatous (BL): Negative
• Lepromatous leprosy (LL): Strongly NEGATIVE (no CMI)

1. Prognostic: Mitsuda positive = good prognosis; negative = may progress to LL
2. Classification: Helps distinguish spectrum of leprosy
3. Epidemiological: Survey immune status of population
4. NOT diagnostic (cannot diagnose leprosy)
5. Research purposes

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Q67. Stable and Unstable Malaria

• High and constant transmission throughout the year
• Entomological Inoculation Rate (EIR) >1 infective bite/person/night (high)
• Most individuals have acquired immunity by adulthood
• Disease mainly in young children and non-immune individuals
• Example: Holoendemic or Hyperendemic areas (Sub-Saharan Africa)
• Epidemics rare; background transmission always present

• Irregular, unpredictable, fluctuating transmission
• EIR low or variable
• Population has little or no immunity (even adults susceptible)
• All age groups affected
• High epidemic potential when conditions change (rainfall, temperature)
• Example: Northern India, Sri Lanka, highland areas

• Hypoendemic: spleen rate <10%
• Mesoendemic: 11-50%
• Hyperendemic: 51-75%
• Holoendemic: >75% (usually stable malaria)

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Q68. Syndromic Approach in STDs

• Lab diagnosis often unavailable or delayed in resource-limited settings
• Many STI agents cause similar syndromes
• Early treatment prevents complications and further transmission
• More than one organism may cause the same syndrome simultaneously
• Patient may not return for treatment if asked to wait for results

• Likely organisms: N. gonorrhoeae, C. trachomatis
• Treatment: Cefixime 400 mg + Azithromycin 1g stat (covers both)

• Cervicitis: N. gonorrhoeae, C. trachomatis
• Vaginitis: Trichomonas vaginalis, BV (Gardnerella), Candida
• Treatment: Cefixime + Azithromycin + Metronidazole + Fluconazole

• Syphilis (Treponema pallidum): painless ulcer
• Chancroid (H. ducreyi): painful, soft ulcer
• Herpes (HSV-2): multiple painful vesicles
• Treatment: Benzathine penicillin + Azithromycin + Acyclovir

• N. gonorrhoeae, C. trachomatis, anaerobes
• Treatment: Cefixime + Doxycycline + Metronidazole

• LGV (C. trachomatis), Chancroid
• Treatment: Doxycycline 100 mg BD x 21 days ± aspiration

• Immediate treatment; prevents further transmission
• Cost-effective
• Suitable for peripheral levels

• Overtreatment; unnecessary drug use
• Missed diagnoses; stigma

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Q69. SARS (Severe Acute Respiratory Syndrome)

• Global epidemic (2002-2003): 8098 cases, 774 deaths; CFR ~10%
• 26 countries affected
• Index case: healthcare worker amplification in hospitals
• No sustained human-to-human transmission since 2004

• Droplet transmission (primary)
• Contact with secretions
• Possibly airborne (super-spreader events in hospitals)
• Fecal-oral (Amoy Gardens, Hong Kong)

• Suspected: Fever >38°C + respiratory symptoms + exposure within 10 days to endemic area or contact
• Probable: Suspected + CXR pneumonia/ARDS OR positive lab test

• High fever, rigors, headache, malaise
• Lower respiratory: dry cough, dyspnea, hypoxia
• CXR: patchy infiltrates, consolidation
• Lab: lymphopenia, thrombocytopenia, raised LDH

• Case isolation (negative pressure rooms)
• Contact tracing and quarantine x 10 days
• PPE for healthcare workers (N95 masks, gown, gloves, goggles)
• Travel advisories
• Hospital infection control
• No vaccine available

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Q70. Prevention and Control of Human Plague

1. Bubonic plague (most common): bubo (swollen lymph node)
2. Septicemic plague
3. Pneumonic plague (most dangerous; person-to-person droplet spread)

• Flea bite (bubonic)
• Droplet inhalation from pneumonic case
• Contact with infected animal

• Bubonic: 2-6 days
• Pneumonic: 1-3 days

• Rat proofing of buildings
• Elimination of rat harborage (garbage, cluttered stores)
• Rodenticides: zinc phosphide, anticoagulants (warfarin)
• Trapping

• Must control fleas BEFORE killing rats (otherwise fleas jump to humans)
• Insecticide dusting: DDT/malathion powder in rat burrows, human dwellings

• Avoid handling sick/dead animals
• Protective clothing, gloves
• Repellents (DEET)

• Contacts of pneumonic plague: Doxycycline 100 mg BD x 7 days
• Alternatively: Tetracycline 250 mg QID

• Streptomycin (drug of choice): 1g IM BD x 10 days
• Gentamicin, Doxycycline, Chloramphenicol (alternatives)

• Killed whole-cell vaccine: 50-60% efficacy; not routinely used
• No vaccine in national programme

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Q71. Pulse Polio Immunization

• Launched: 2 October 1995
• OPV (Oral Polio Vaccine) given to ALL children under 5 years on designated days
• Regardless of previous vaccination status
• "Two drops of life"

• Two rounds per year (January-February)
• All children 0-5 years given OPV0 (zero dose) + subsequent doses
• SNID: Sub-National Immunization Days (high-risk districts)
• Mop-up rounds: house-to-house in outbreak areas

• tOPV: types 1, 2, 3 (used until 2016)
• bOPV: types 1 and 3 only (used from April 2016 after type 2 eradication)
• IPV introduced into UIP from 2015 (injectable; inactivated)

• Supplementary immunization activity (SIA) beyond routine UIP
• Booth vaccination (polio booths at fixed sites)
• Mobile teams for transit populations, slums, nomads
• House-to-house vaccination

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Q72. Measles Vaccine

• Live attenuated Edmonston-Zagreb strain (used in India)
• Also: Schwarz, Moraten strains

• 1st dose: 9-12 months
• 2nd dose: 16-24 months (as MR vaccine)
• Measles-Rubella (MR) campaign: 9 months to under 15 years (2017-2020)

• Immunocompromised (HIV with severe immunosuppression)
• High-dose steroid therapy
• Recent Ig injection (delay 3 months)
• Anaphylaxis to neomycin/gelatin

• Pneumonia (most common cause of death)
• Encephalitis (1:1000)
• SSPE (Subacute Sclerosing Panencephalitis): 7-10 years later
• Blindness (Vitamin A deficiency + measles)

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Q73. Social Factors in STDs

• Transactional sex for economic survival
• Sex work as livelihood
• Cannot afford healthcare

• Separation from family → multiple sexual partners
• Truck drivers, migrant laborers as bridge population
• Anonymity in urban settings

• Core transmitters of STDs
• Multiple partners, low condom use
• Social stigma prevents healthcare seeking

• Lowers inhibition → risky sexual behavior
• IV drug users → HIV risk

• Ignorance about transmission, protection, early symptoms
• Self-medication; delayed treatment

• Women lack negotiating power for condom use
• Violence and coercion
• Dependent on male partners for income

• Fear of stigma prevents STI patients from seeking care
• Leads to late presentation and complications

• Taboos about discussing sex
• Opposition to condom use
• Lack of sex education in schools

• Inadequate STI services, privacy concerns
• Trained personnel shortage

• Core groups with high-risk behavior
• Bridge populations connecting core groups to general population

• 100% Condom Use Programme (CUP) in sex work settings
• Targeted interventions for high-risk groups (FSW, MSM, IDU, transgender)
• Peer education; community outreach

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Q74. Hepatitis B Vaccine / Specific Protection of Hepatitis B

• Birth dose: Within 24 hours of birth (HepB0) - most important; prevents perinatal transmission
• Routine: Under UIP as Pentavalent vaccine (DTP-HBV-Hib) at 6, 10, 14 weeks
• Catch-up adults (3-dose): 0, 1, 6 months
• Rapid schedule: 0, 1, 2 months + booster at 12 months

• Passive immunization
• 0.06 mL/kg IM (or 0.5 mL for newborns)
• Used in:
  • Newborns of HBsAg+ mothers: HBIG + HepB vaccine within 12 hours of birth
  • Post-exposure (needle stick, sexual exposure): HBIG + vaccine
  • Unvaccinated organ transplant recipients

• Infant: HBIG 0.5 mL + HepB vaccine within 12-24 hours; complete 3-dose series
• Effectiveness: 95% in preventing perinatal transmission

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Q75. Complications of Measles and Its Prevention

• Pneumonia (most common death cause): primary viral or secondary bacterial (Streptococcus, Staphylococcus)
• Laryngotracheobronchitis (croup): hoarseness, stridor
• Otitis media (secondary bacterial)

• Post-infectious encephalitis (1:1000): 5-15% mortality; 25% neurological sequelae
• SSPE (Subacute Sclerosing Panencephalitis): progressive fatal encephalitis; 7-10 years post-measles; 1:25,000-100,000 cases
• Measles inclusion body encephalitis (immunocompromised)

• Diarrhea: common; worsens malnutrition
• Stomatitis, mouth ulcers

• Keratoconjunctivitis
• Corneal ulceration → blindness (especially in Vitamin A deficient children)

• Immune suppression (measles wipes immune memory - "immunological amnesia")
• Secondary bacterial infections (2-3 years of immune suppression)

• Exacerbation of malnutrition: Protein-Energy Malnutrition (PEM), Vitamin A deficiency

1. Measles vaccine - prevents disease entirely
2. Vitamin A supplementation: Two doses of 200,000 IU on consecutive days reduces complications by 50% (especially pneumonia and diarrhea); WHO recommends for all children with measles
3. Adequate nutrition: Breastfeeding, protein-rich diet
4. Early treatment of complications: Antibiotics for secondary bacterial pneumonia/otitis media
5. Immune globulin: For unvaccinated immunocompromised exposures

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Q76. Malaria Treatment

• Chloroquine 25 mg base/kg over 3 days (10+10+5 mg/kg)
• • Primaquine 0.25 mg/kg/day x 14 days (radical cure - kills hypnozoites)
• Test for G6PD deficiency before primaquine (causes hemolysis in G6PD deficient)

• ACT: Artemether-Lumefantrine (AL) or Artesunate + Amodiaquine
• India: Artemether 20 mg + Lumefantrine 120 mg (4 tablets BD x 3 days for adults)
• • Primaquine 0.75 mg/kg single dose (gametocytocidal; kills gametocytes)

• Artesunate IV: 2.4 mg/kg at 0, 12, 24 hours then daily x minimum 24 hours, then oral ACT
• Alternatives: Artemether IM or Quinine IV + Doxycycline
• Supportive: fluid management, transfusion, dialysis, anti-seizures, ventilation
• Exchange transfusion if parasitemia >10%

• Impaired consciousness/coma (cerebral malaria)
• Respiratory distress
• Severe anemia (Hb <5 g/dL)
• Renal failure, hypoglycemia, circulatory collapse, abnormal bleeding, hyperparasitemia (>5%)

• 1st trimester: Quinine + Clindamycin (artemisinins avoided in 1st trimester)
• 2nd/3rd trimester: ACT safe

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Q77. Control of Airborne Infections

1. Early case detection: Active/passive surveillance; index case identification
2. Isolation: Airborne isolation (negative pressure room) for TB, measles, chickenpox; droplet isolation for influenza, meningococcal
3. Treatment: Effective treatment reduces infectiousness (TB becomes non-infectious after 2-4 weeks of DOTS; measles - 4 days after rash)
4. Cough etiquette: Cover mouth/nose; dispose tissues; hand washing

1. Ventilation: Natural and mechanical ventilation; dilute and remove droplet nuclei
2. UV irradiation: UVGI (Upper Room UV Germicidal Irradiation) - kills M. tuberculosis
3. Air filtration: HEPA filters in negative pressure rooms
4. Overcrowding reduction: Spacing in wards, queues

1. Vaccination: Most effective
   • BCG (TB), Measles vaccine, Varicella vaccine, MMR, Influenza vaccine, Meningococcal vaccine, DTP (pertussis, diphtheria)
2. Chemoprophylaxis: TB preventive therapy (IPT/TPT) for contacts; post-exposure Oseltamivir for influenza
3. PPE: N95 respirators for airborne (TB); surgical masks for droplet
4. Immune status: Adequate nutrition, Vitamin A

• Healthcare worker training
• Triage of respiratory patients
• Respiratory hygiene stations
• Sputum collection in open/outdoor space

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Q78. 17D Vaccine (Yellow Fever Vaccine)

• Produced in embryonated chicken eggs
• Seed-lot system (WHO guidelines)
• Minimum 1000 mouse LD50 per dose (potency)

• Required for entry into 40+ African and South American countries
• Some countries require proof of vaccination from ALL arriving travelers
• International Certificate valid for LIFE since July 2016

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Q79. Epidemiology of TB and Yellow Fever

• 10.6 million new cases/year; 1.3 million deaths (2022)
• India: 28% of global TB burden (highest); 2.8 million new cases/year
• India, China, Indonesia, Philippines, Pakistan = 56% of global burden

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1. Jungle/Sylvatic YF: Haemagogus mosquitoes; forest monkeys → humans; sporadic
2. Intermediate/Savannah YF: Aedes bromeliae; villages in Africa
3. Urban YF: Aedes aegypti; human-mosquito-human; epidemic potential

• Period of infection (days 1-3): fever, headache, myalgia, nausea
• Period of remission (day 4): improves
• Period of intoxication (day 5+): severe; hemorrhages, jaundice, renal failure, Faget sign (bradycardia with fever); black vomit (hematemesis); CFR 20-50%

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Q80. DPT Vaccine

• D - Diphtheria toxoid (formaldehyde-inactivated toxin)
• P - Pertussis (whole cell killed Bordetella pertussis)
• T - Tetanus toxoid

• DTP (whole cell pertussis): wP - more reactogenic but more immunogenic
• DTaP (acellular pertussis): aP - less side effects; used in developed countries
• DT, Td, TT: combination without pertussis

• Primary: 6, 10, 14 weeks (as Pentavalent = DTP + HBV + Hib)
• Booster 1: 16-24 months (as DPT)
• Booster 2: 5 years (DPT)
• Td: 10 and 16 years (diphtheria-tetanus only; adult formulation)

• Encephalopathy within 7 days of previous DTP
• Progressive neurological disorder
• Anaphylaxis to previous dose
• High fever at time of vaccination (postpone)

• Local: Pain, redness, swelling at injection site (very common)
• Systemic: Fever (50%), irritability
• Serious (rare): Febrile convulsion (1/1750), HHE (Hypotonic-Hyporesponsive Episode) (1/1750), Persistent screaming, Anaphylaxis

• Diphtheria: 85%
• Tetanus: ~100%
• Pertussis: 80-85% (wP); 71-85% (aP)

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Q81. Hepatitis A - Prevention and Control

• Hyperendemic in developing countries (India)
• In high endemicity areas: most acquire immunity in childhood; adults generally immune
• Paradox: In improved sanitation areas, children escape infection → susceptible young adults → large outbreaks
• No chronic carrier state; no chronic liver disease

• Safe drinking water (chlorination)
• Proper sewage disposal
• Food hygiene: thorough cooking of shellfish
• Hand washing

• Inactivated HAV vaccine (Havrix, Vaqta):
  • 2 doses: 0 and 6-18 months
  • Efficacy >95%; long-lasting (20-30 years)
  • For travelers to endemic areas, children in epidemic settings, chronic liver disease, food handlers
• Combined HAV + HBV (Twinrix): 3 doses: 0, 1, 6 months

• Normal human immunoglobulin (IgG): 0.02 mL/kg IM
• Pre-exposure (short stay travel): single dose, protection 3 months
• Post-exposure (within 2 weeks of exposure)

• Identify and eliminate source
• Boil water/chlorination
• IgG to close contacts
• School/childcare closure if needed

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Q82. Antigenic Drift and Antigenic Shift

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• Definition: Minor, gradual, progressive changes in influenza surface antigens (H and N) through accumulation of point mutations in RNA
• Mechanism: RNA-dependent RNA polymerase lacks proofreading activity → mutations accumulate → altered antigenic sites
• Result: Seasonal variations; partial immunity escape; reason for annual flu vaccine update
• Type: Involves ALL influenza types (A, B, C)
• Clinical impact: Seasonal epidemics; existing immunity partially protective
• Example: Gradual changes in H1N1 over years

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• Definition: Major, abrupt change in influenza A antigens resulting in completely new H and/or N subtype
• Mechanism: Genetic reassortment (gene segment exchange between two different influenza A viruses infecting the same host cell) - "mixing vessel" (often pigs, which have receptors for both human and avian influenza)
• Result: Entirely novel subtype; no pre-existing immunity in population → pandemic potential
• Type: Only influenza A (has multiple subtypes of H and N)
• Clinical impact: Pandemics (most susceptible population with no immunity)
• Examples:
  • 1918 Spanish flu: H1N1 (novel reassortant) - 50 million deaths
  • 1957 Asian flu: H2N2
  • 1968 Hong Kong flu: H3N2
  • 2009 Swine flu: H1N1pdm09

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Q83. Prevention of Tetanus

1. Generalized tetanus (most common)
2. Localized tetanus
3. Cephalic tetanus (head injury)
4. Neonatal tetanus (umbilical stump infection)

• Tetanus Toxoid (TT) / Td:
  • Primary series: 3 doses (0, 1 month, 6 months)
  • Booster every 5-10 years
  • In UIP: as DTP at 6, 10, 14 weeks; DPT booster at 16-24 months and 5 years; Td at 10 and 16 years
• Pregnant Women:
  • TT1: as early as possible
  • TT2: 4 weeks after TT1
  • If previously vaccinated: TT Booster (single dose)
  • Protects mother and newborn (Maternal and Neonatal Tetanus elimination)

• Clean delivery (clean hands, clean surface, clean cord cut, clean cord care)
• 3 cleans principle: Clean hands, clean blade, clean tie
• Avoid application of dung/ash on cord stump
• Maternal TT immunization

• Tetanus-prone wound: Deep, puncture, contaminated with soil/feces, devitalized tissue, animal bites
• TIG (Human Tetanus Immunoglobulin): 250 IU IM (passive immunization)
• Wound debridement and cleaning

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Q84. Zika Virus Disease

• Mosquito bite (primary)
• Sexual transmission (persists in semen up to 6 months; urine, saliva)
• Vertical (mother to fetus)
• Blood transfusion

• 80% asymptomatic
• Mild febrile illness: low-grade fever, maculopapular rash (spreads from face), arthralgia, conjunctivitis (non-purulent), myalgia, headache
• Self-limiting in 2-7 days
• Serious Complications:
  • Microcephaly in neonates (if infected in 1st trimester)
  • Guillain-Barre Syndrome (GBS) in adults
  • Other congenital brain abnormalities (Congenital Zika Syndrome)

• RT-PCR: first 1-7 days (blood, urine, semen)
• IgM ELISA: from 4th day; cross-reactivity with dengue is a problem
• Plaque Reduction Neutralization Test (PRNT): confirmatory

• Vector control (eliminate Aedes breeding sites)
• Personal protection: repellents (DEET), long clothing, bed nets
• Sexual protection: condoms; abstinence advised for men returning from Zika areas for 6 months
• Pregnant women: avoid travel to Zika-endemic areas; use contraception
• Blood screening

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Q85. DB (Difference Between) IPV/OPV

• IPV: 1 dose at 14 weeks (fractional dose 0.1 mL ID) under UIP since 2015
• bOPV: 0 (birth), 6, 10, 14 weeks; booster at 16-24 months
• Rationale: IPV prevents VAPP from type 2 OPV (after global switch to bOPV, type 2 coverage through IPV)

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Q86. Polio Eradication / End Game Strategy Plan

1. Detection and interruption of all poliovirus transmission
2. Strengthening immunization systems and delivering polio vaccines
3. Withdrawal of OPV and introduction of IPV
4. Containment of poliovirus in labs and facilities

• tOPV → bOPV switch (April 2016): Type 2 OPV withdrawn globally; type 2 VAPP eliminated
• Sequential OPV withdrawal: eventually bOPV withdrawal after type 1 eradication

• At least 1 IPV dose in all national schedules before tOPV withdrawal
• Provides protection against type 2 after withdrawal of type 2 OPV

• Rapid outbreak response with mOPV (monovalent OPV)
• nOPV2 (novel OPV2): genetically stabilized; lower VDPV risk; deployed from 2021

• Containment of all wild-type poliovirus stocks (Poliovirus Essential Facilities - PEF)
• Eventually withdraw all OPV
• IPV only in routine immunization

• Polio-free since 2011; certified 2014
• 172 million children immunized during NIDs
• Model for global eradication

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Q87. Natural History of TB

• Inhalation of droplet nuclei (<5 µm) containing M. tuberculosis
• 1-10 bacilli sufficient to establish infection
• Probability of infection depends on: closeness, duration of exposure, infectiousness of source

• 90% of those infected remain latent (LTBI)
• Ghon focus forms in lung (Ghon complex with lymph node)
• Tuberculin test (Mantoux) becomes positive in 4-12 weeks
• No symptoms, not infectious

• Direct progression from primary infection
• Mainly in young children, malnourished, immunocompromised
• Forms: miliary TB, TB meningitis, Ghon focus enlargement

• From latent focus, reactivation occurs years-decades later
• Triggered by: immunosuppression (HIV, diabetes, malnutrition, steroids), stress, silicosis
• Post-primary pulmonary TB: upper lobe cavities, fibrosis
• Smear positive → highly infectious

• Spontaneous cure (host resistance) - ~25-30%
• Chronic ill health - ~25%
• Death - ~50% within 5 years
• With HIV co-infection: mortality approaches 100% if untreated

• I nfected: exposure leading to LTBI
• C linical disease: 10% of LTBI progress
• U ntreated: death in 50%

• 10% of LTBI develop disease in lifetime
• Of those, 10% die (with treatment)
• Without treatment: 50% die within 5 years

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Q88. Management of Pneumonia in a Child (2 months - 5 years)

• 2-12 months: ≥50 breaths/minute
• 12 months - 5 years: ≥40 breaths/minute

• Oral Amoxicillin 40 mg/kg/day in 2 divided doses x 5 days (WHO 2023)
• Continue feeding and fluids
• Return if fast breathing worsens, difficulty breathing, unable to drink
• No cough syrups/antihistamines

• IV/IM Ampicillin + Gentamicin (first-line)
• Alternative: Cefotaxime or Ceftriaxone
• Oxygen therapy (target SpO2 >94%)
• IV fluids if unable to feed
• Fever control (paracetamol)
• Monitor respiratory rate, oxygen saturation, hydration

• Neonates: Group B Streptococcus, Klebsiella, E. coli
• 1-3 months: RSV, S. pneumoniae, H. influenzae
• 3 months - 5 years: S. pneumoniae (most common), H. influenzae, RSV

• Vaccines: PCV (Pneumococcal), Pentavalent (Hib), Influenza, Measles
• Exclusive breastfeeding x 6 months
• Vitamin A supplementation
• Zinc supplementation
• Reduce indoor air pollution

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