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PSM Question Paper - Complete Answers

• Q1 (Long Essay, ~18 marks): Natural history of TB + programmatic management in India
• Q2-10 (Short Essays, ~5 marks each): Biological determinants, PQLI, RCT design, multifactorial causation, quarantine vs isolation, confounding factors, screening criteria, health education sources
• Q11-17 (Short Answers, ~2-3 marks each): Falciparum malaria treatment, PEP in rabies, dengue shock syndrome, leptospirosis, chlorination of water, integrated vector control, biological effects of addiction

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LONG ESSAY (18 Marks)

Q1. Describe the natural history of TB and its programmatic management in India.

A) Natural History of Tuberculosis

• Occurs when a susceptible person inhales droplet nuclei (1-5 µm) expelled by an infectious TB case during coughing, sneezing, or speaking
• The probability of infection depends on: concentration of infectious droplets, duration of exposure, ventilation of space, and immune status of the host

• After inhalation, bacilli reach the alveoli and are engulfed by alveolar macrophages
• A primary complex (Ghon's focus + hilar lymphadenopathy = Ranke complex) forms at the site of initial infection
• Cell-mediated immunity develops within 2-10 weeks (tuberculin test becomes positive)
• In 90% of immunocompetent individuals, infection is contained as Latent TB Infection (LTBI) - no symptoms, not infectious, tuberculin positive
• Approximately 5-10% progress to active disease within 2 years (early progression), and another 5% develop reactivation later in life

• Reactivation occurs when host immunity wanes (HIV infection, malnutrition, diabetes, aging, corticosteroids)
• Clinical features: persistent cough >2 weeks, haemoptysis, low-grade fever (evening rise), night sweats, weight loss, anorexia
• Cavitation occurs in the upper lobes
• Sputum smear becomes positive; patient becomes infectious

• Spontaneous resolution (rare) - ~25% in pre-antibiotic era
• Chronic progression - continued lung damage, cavitation
• Death - ~50% of untreated smear-positive cases died within 5 years (pre-antibiotic era)
• Extra-pulmonary spread: miliary TB, TB meningitis, bone TB, renal TB

• HIV co-infection (greatest risk - 10% per year)
• Recent infection (<2 years)
• Malnutrition and underweight (BMI <18.5)
• Diabetes mellitus
• Silicosis
• Renal failure on dialysis
• Infancy and old age

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B) Programmatic Management of TB in India

• NTP launched 1962 (poor outcomes due to poor compliance)
• RNTCP started as pilot in 1993, expanded nationwide by 2006
• Renamed NTEP in 2020 with ambitious target: End TB by 2025 (5 years ahead of global SDG target of 2030)

1. Political commitment with increased and sustained financing
2. Case detection through quality sputum smear microscopy
3. Standardized short-course chemotherapy under direct observation
4. Uninterrupted supply of quality anti-TB drugs
5. Standardized recording and reporting system

• Passive case finding: symptomatic patients presenting to health facility
• Active case finding: screening in high-risk populations
• Diagnosis: Sputum smear microscopy, CBNAAT (Cartridge-Based Nucleic Acid Amplification Test), X-ray, culture and DST (Drug Sensitivity Testing)
• All presumptive TB cases: ≥2 weeks cough, haemoptysis, fever, weight loss, night sweats

• Nikshay (IT system for case notification and monitoring)
• 99DOTS - technology-based treatment adherence monitoring via missed calls
• All TB patients notified mandatorily since 2012 (private sector mandatory since 2014)
• Nikshay Poshan Yojana: Rs. 500/month nutritional support to all TB patients

• MDR-TB (resistance to at least H + R): treated with longer regimens using second-line drugs
• XDR-TB: additionally resistant to fluoroquinolones + second-line injectable
• Bedaquiline introduced into national program (BPaL regimen for XDR-TB)
• DRTB centres at district/state level

• Treatment Success Rate: target >90%
• Case Notification Rate: cases detected per lakh population
• India contributes ~26% of global TB burden (WHO Global TB Report)

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SHORT ESSAYS (5 Marks Each)

Q2. Describe Biological Determinants of Health

• Hereditary diseases: haemophilia, sickle cell anaemia, cystic fibrosis
• Genetic susceptibility: HLA types influence TB, rheumatoid arthritis, diabetes susceptibility
• Family history increases risk for hypertension, diabetes, cancers

• Infants and elderly have weaker immunity - higher susceptibility
• Childhood infections: measles, whooping cough peak in early years
• Degenerative diseases (CVD, cancer, DM Type 2) increase with age
• Tuberculosis: bimodal peak in young adults and elderly

• Males: higher prevalence of TB, coronary artery disease, accidents
• Females: higher rates of iron deficiency anaemia, autoimmune diseases, osteoporosis, depression
• Hormonal differences affect immune response and disease patterns

• Natural (innate) vs acquired (adaptive) immunity
• Active immunity: from natural infection or vaccination
• Passive immunity: maternal antibodies (IgG) - protects newborns for 3-6 months
• Immunocompromised states (HIV, malnutrition, steroids) increase susceptibility dramatically

• Malnutrition impairs cell-mediated immunity (CMI)
• Vitamin A deficiency increases severity of measles and respiratory infections
• Iron deficiency: impaired bactericidal activity of neutrophils
• Obesity: risk factor for T2DM, CVD, certain cancers, severe COVID-19

• Pregnancy: altered immunity - increased susceptibility to certain infections (listeria, influenza)
• Puberty, menopause: hormonal changes affect disease patterns

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Q3. Describe the Physical Quality of Life Index (PQLI)

1. Infant Mortality Rate (IMR) per 1000 live births
2. Life Expectancy at age 1 (not at birth, to avoid double counting of infant mortality)
3. Literacy Rate (%)

• Each indicator is placed on a scale of 0 to 100
• 0 = worst performance (defined absolutely)
• 100 = best performance (defined absolutely)
• The PQLI is the simple arithmetic mean of all three indicators (equal weighting)
• Final PQLI value: 0-100

• Does NOT include per capita GNP - shows that economic wealth alone does not determine quality of life
• Example: Sri Lanka and Kerala have low per capita incomes but high PQLI due to good social policies
• Oil-rich Middle Eastern countries have high income but comparatively lower PQLI
• Intended to complement (not replace) GNP

• Literacy is an input measure, not an outcome measure
• Does not capture morbidity or mental health
• Life expectancy at age 1 is not widely reported by all countries
• Superseded by the Human Development Index (HDI) by UNDP (1990)

• International and intra-national health comparisons
• Evaluating effect of social, economic and political policies on population health

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Q4. Discuss the Design of Randomised Controlled Trials (RCT)

• Define clear inclusion and exclusion criteria
• Representative sample of target population
• Obtain written informed consent

• Process of allocating participants to groups by chance
• Types: Simple randomisation, Block randomisation, Stratified randomisation
• Ensures comparable groups at baseline - eliminates selection bias
• The "gold standard" feature that defines the RCT

• Comparison arm: receives placebo, standard treatment, or no treatment
• Ensures that outcomes in the treatment group are attributable to the intervention

• Single blind: participant unaware of allocation
• Double blind: both participant and investigator unaware - gold standard
• Triple blind: additionally, data analyst blinded
• Prevents performance bias and assessment bias

• Clearly defined, standardized protocol
• Compliance monitored throughout

• Both groups followed for same duration
• Dropouts and losses tracked (intention-to-treat analysis)

• Primary and secondary outcomes pre-specified
• Measured objectively wherever possible

• Highest level of evidence for causality
• Minimizes confounding through randomisation
• Allows calculation of efficacy, NNT (Number Needed to Treat)

• Expensive and time-consuming
• Ethical constraints (cannot randomize to harmful exposures)
• Poor external validity (highly selected populations)
• Not suitable for rare diseases or long latency outcomes

• Helsinki Declaration principles
• Institutional Ethics Committee approval
• Equipoise must exist (genuine uncertainty about superiority)

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Q5. Discuss the Term "Multifactorial Causation of Disease"

• Germ theory (Koch's postulates, 1880s): single pathogen = single disease - an oversimplification
• Replaced by the "web of causation" (Brian MacMahon) concept

• Host: age, sex, genetics, immune status, nutritional status
• Agent: biological (bacteria, virus), chemical (toxins), physical (radiation), nutritional
• Environment: physical (climate, geography), biological (vector, reservoir), social (poverty, education, sanitation) Disease occurs when the balance between these three is disturbed

• Disease results from a complex interweaving of multiple causal pathways
• No single factor is sufficient; removal of one strand may break the web
• Best demonstrated in coronary artery disease: genetics + diet + smoking + hypertension + obesity + sedentary lifestyle + stress - all interacting

• Host (genetic core) at centre surrounded by biological, social, and physical environment
• Emphasises the relative contribution of each

• Multiple entry points for prevention (primordial, primary, secondary)
• Attributable risk quantification
• Justifies multi-pronged public health interventions

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Q6. Differentiate Between Quarantine and Isolation

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Q7. Confounding Factors in Analytical Studies

1. Associated with the exposure of interest
2. Associated with the outcome (disease)
3. NOT an intermediate step in the causal chain between exposure and outcome

• Study: Coffee drinking and lung cancer association
• Confounder: Smoking (smokers tend to drink more coffee AND smoking causes lung cancer)
• True association: Coffee - lung cancer link disappears when smoking is controlled for

• Positive confounding: Confounder exaggerates the apparent association
• Negative confounding: Confounder masks or reduces the apparent association

1. Randomisation - distributes known and unknown confounders equally (RCTs)
2. Restriction - limit study to subjects with fixed value of confounder
3. Matching - pair cases and controls on potential confounders
4. Stratification - design with strata for known confounders

1. Stratified analysis (Mantel-Haenszel method)
2. Multivariate analysis - logistic regression, Cox regression
3. Standardisation - direct or indirect

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Q8. Criteria for Screening a Disease

1. Condition: The condition sought should be an important health problem (common, serious, or treatable)
2. Natural history: There should be an accepted treatment or intervention for cases identified
3. Facilities: Facilities for diagnosis and treatment should be available
4. Latent stage: There should be a recognisable latent or early symptomatic stage
5. Test: There should be a suitable, acceptable screening test
6. Test acceptability: The test should be acceptable to the population
7. Natural history (progression): The natural history of the condition, including development from latent to overt disease, should be adequately understood
8. Agreed policy: There should be an agreed policy on whom to treat as patients
9. Cost-benefit: The cost of case finding (including diagnosis and treatment) should be economically balanced in relation to possible expenditure on medical care as a whole
10. Continuing process: Case finding should be a continuing process and not a once-and-for-all project

• High sensitivity (few false negatives - detects all true cases)
• High specificity (few false positives - avoids over-referral)
• High Positive Predictive Value (especially important in low-prevalence conditions)
• Simple, cheap, safe, and acceptable to the target population

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Q9. Enumerate the Various Sources of Health Education. Briefly Discuss Any One.

1. Health worker-patient communication (counselling)
2. Peer education
3. Home visits by health workers
4. Telephone/hotline helplines

• Reach: penetrates both urban and rural populations; over 800 million viewers in India
• Audio-visual medium: combines sight, sound, and motion - high retention and impact
• Demonstrations possible: handwashing technique, ORS preparation can be shown
• Entertainment-education (edutainment): soap operas with health messages (e.g., Hum Log, promoting family planning)
• Government campaigns: Pulse Polio drives, COVID-19 vaccination, TB Harega Desh Jeetega
• Limitations: one-way communication, no personalisation, expensive to produce, language barrier

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SHORT ANSWERS (2-3 Marks Each)

Q11. Treatment of Falciparum Malaria

• ACT-SP regimen:
  • Artesunate (AS): 4 mg/kg/day for 3 days
  • Sulfadoxine-Pyrimethamine (SP): 25/1.25 mg/kg on Day 1
  • Primaquine (PQ large): 0.75 mg/kg on Day 2 (gametocidal)
• Available in colour-coded blister packs by age group

• IV Artesunate: 2.4 mg/kg at 0, 12, 24 hours, then daily
• Alternatively: IV Quinine + Doxycycline
• Supportive care: anti-pyretics, IV fluids, management of complications (cerebral malaria, acute renal failure, severe anaemia)

• ACT-AL: Artemether + Lumefantrine regimen used instead

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Q12. Describe the PEP (Post-Exposure Prophylaxis) in Rabies

• Wash wound thoroughly with soap and water for minimum 15 minutes
• Apply antiseptic (povidone iodine or 70% alcohol)
• Do NOT suture the wound primarily
• Tetanus prophylaxis if needed

• Human RIG (HRIG): 20 IU/kg body weight
• Equine RIG (ERIG): 40 IU/kg body weight
• Infiltrate maximum amount into and around wound; remainder IM at distant site
• Given only once (Day 0)

• Intra-muscular (IM) schedule (Essen protocol): 5 doses on Days 0, 3, 7, 14, 28
• Intra-dermal (ID) schedule: 2-site ID on Days 0, 3, 7, 28 (more economical)
• Tissue culture vaccines used (PCECV, PVRV, HDCV)
• Cell culture vaccines are safe and effective; old nerve tissue vaccine (Semple) no longer recommended

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Q13. Dengue Shock Syndrome

• High fever (2-7 days)
• Haemorrhagic manifestations (positive tourniquet test / petechiae / bleeding)
• Thrombocytopaenia (platelet count <100,000/mm³)
• Evidence of plasma leakage (raised haematocrit ≥20% rise, pleural effusion, ascites)

• Tachycardia
• Cool extremities and delayed capillary refill (>2 sec)
• Weak/thready pulse
• Restlessness or lethargy (reduced brain perfusion)
• Pulse pressure ≤ 20 mmHg (e.g., BP = 100/80 mmHg) - narrow pulse pressure is hallmark
• Hypotension: systolic <80 mmHg in children <5 years; 80-90 mmHg in older children/adults

• IV crystalloids (Ringer's lactate/NS) rapidly
• Monitor haematocrit, urine output, vital signs closely
• Platelet transfusion only if active significant bleeding with low platelets
• Avoid aspirin/NSAIDs
• ICU care for severe cases

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Q14. Mode of Transmission and Management of Leptospirosis

• Indirect contact with water/soil contaminated with urine of infected animals (rats, cattle, dogs, pigs)
• Entry through: skin abrasions, mucous membranes (eyes, nose, mouth), intact skin with prolonged water contact
• Occupational hazard: farmers, sewer workers, veterinarians, military personnel
• Associated with flooding (post-flood outbreaks common)
• Direct contact with infected animal urine (rare)
• NOT transmitted person-to-person

• Incubation period: 2-30 days (usually 5-14 days)
• Anicteric leptospirosis (90%): flu-like illness, fever, headache, myalgia (especially calf muscles), conjunctival suffusion
• Icteric leptospirosis / Weil's disease (5-10%): jaundice + acute renal failure + haemorrhage (classic triad)

• Mild-moderate: Oral Doxycycline 100 mg twice daily for 7 days (drug of choice)
• Alternatively: Ampicillin or Amoxicillin
• Severe (Weil's disease): IV Benzyl Penicillin 1.5 MU every 6 hours for 7 days; alternatively IV Ampicillin/Cefotaxime
• Supportive: dialysis for renal failure, transfusions for bleeding
• Chemoprophylaxis: Doxycycline 200 mg once weekly (for high-risk occupational exposure)

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Q15. Method of Chlorination of Water

1. Liquid chlorine (Cl₂ gas in cylinders)
2. Bleaching powder (Chlorinated lime) - Ca(ClO)Cl, contains ~33% available chlorine
3. High Test Hypochlorite (HTH) - ~70% available chlorine
4. Sodium hypochlorite solution (household bleach)
5. Chloramine tablets (for field/emergency use)

• Chlorine dose: 0.5 mg/L (required dose)
• Residual chlorine at consumer end: 0.2 mg/L (minimum acceptable)
• Break-point chlorination: sufficient chlorine added to satisfy all chlorine demand + leave residual free chlorine
• Chlorinators automatically dose water at treatment plants

• Add bleaching powder to wells: 2.5 g per 1000 litres (approximately) - depends on available chlorine content
• Mix and leave for 30 minutes before use
• Chlorine demand test using orthotolidine (OT) test or DPD test

• Used for heavily polluted water
• Large dose of chlorine added (5-10 mg/L) then excess removed by sodium thiosulphate or activated charcoal
• Used in emergency/disaster situations

• OT (Orthotolidine) test: yellow colour = chlorine present
• DPD (N,N-Diethyl-p-phenylenediamine) test - more accurate

• Ineffective against Cryptosporidium (protozoan cysts)
• Tastes and odour objectionable at high doses
• Forms trihalomethanes (THMs - potential carcinogens) with organic matter

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Q16. Integrated Vector Control Measures

• Larvivorous fish: Gambusia affinis, Lebistes reticulatus placed in stagnant water bodies
• Bacillus thuringiensis var. israelensis (Bti) - bacterial larvicide
• Bacillus sphaericus
• Copepods (Mesocyclops) for mosquito larvae

• Larvicides: temephos (abate) for breeding sites, pyriproxyfen (insect growth regulator)
• Adulticides: Indoor Residual Spraying (IRS) with DDT, malathion, synthetic pyrethroids
• Space spraying/fogging (thermal or ULV) - for epidemic control
• Insecticide-treated bed nets (ITNs/LLINs)

• Elimination of breeding sites: drain stagnant water, fill ditches, desilting
• Anti-larval measures: cover water storage containers
• Solid waste management (prevents Aedes breeding in discarded containers)
• Intermittent irrigation in rice fields

• Repellents (DEET, Picaridin)
• Protective clothing
• Bed nets, window screens

• Sterile Insect Technique (SIT): releasing sterile males
• Wolbachia-infected mosquitoes (reduces dengue transmission)

• Delays resistance development
• Reduces insecticide use and environmental contamination
• More cost-effective and sustainable
• Addresses multiple vectors simultaneously

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Q17. Biological Effects of Addiction

• All addictive substances act on the mesolimbic dopamine system (reward pathway)
• Nucleus accumbens (reward centre): dopamine surge produces euphoria/pleasure
• Prefrontal cortex: impaired decision-making and impulse control with chronic use
• With repeated use: neuroadaptation (tolerance) and withdrawal syndrome develop

• Cocaine/amphetamines: hypertension, arrhythmias, myocardial infarction, sudden cardiac death
• Opioids: bradycardia, hypotension, cardiac arrest in overdose
• Alcohol: cardiomyopathy (alcoholic), arrhythmias, hypertension

• Tobacco smoking: chronic bronchitis, emphysema (COPD), lung cancer, laryngeal cancer
• Opioids: respiratory depression (primary cause of overdose death)
• Cannabis: chronic bronchitis

• Alcohol: fatty liver → alcoholic hepatitis → cirrhosis → hepatocellular carcinoma
• IV drug use: hepatitis B, hepatitis C (blood-borne transmission)

• Wernicke-Korsakoff syndrome (alcohol + thiamine deficiency)
• Opioid-induced miosis, sedation, seizures in withdrawal
• Cocaine: cerebral haemorrhage/stroke
• Peripheral neuropathy (alcohol)

• Alcohol: hypogonadism, gynaecomastia in males; menstrual irregularities in females
• Opioids: decreased testosterone, impotence
• Smoking: reduced fertility

• Alcohol: impairs neutrophil function and cell-mediated immunity
• IV drug use: HIV/AIDS (needle sharing), opportunistic infections
• Smoking: impairs mucociliary clearance

• Physiological adaptation requiring increasing doses for same effect
• Withdrawal: rebound hyperactivity of suppressed pathways (e.g., opioid withdrawal = autonomic hyperactivity; alcohol withdrawal = delirium tremens, seizures)

• Alcohol: Foetal Alcohol Syndrome (FAS) - microcephaly, intellectual disability, facial dysmorphia
• Smoking: IUGR, preterm birth, SIDS
• Opioids: Neonatal Abstinence Syndrome (NAS)

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