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Narayana Medical College - Community Medicine Exam Answers

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ESSAY QUESTIONS

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Essay Question 1 (30 Marks)

Define Diabetes Mellitus. Describe the Epidemiology, Risk Factors, Prevention and Control Measures of Type 2 Diabetes. Add a note on National Programs for Diabetes Control in India.

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Definition

• Fasting plasma glucose ≥ 126 mg/dL (7.0 mmol/L)
• 2-hour plasma glucose ≥ 200 mg/dL (11.1 mmol/L) during OGTT
• Random plasma glucose ≥ 200 mg/dL with symptoms
• HbA1c ≥ 6.5%

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Epidemiology

• Approximately 830 million people worldwide have diabetes (WHO, 2025), predominantly in low- and middle-income countries.
• India is often called the "Diabetes Capital of the World." India has over 77 million people with diabetes, ranking second globally after China.
• Prevalence is rising due to urbanization, aging populations, sedentary lifestyles, and dietary changes.
• T2DM is predominantly seen after age 45 years, but increasing incidence is now reported in adolescents and young adults.

• Prevalence: ~7.5-8.9% in adults; urban prevalence is significantly higher than rural.
• Southern states (Tamil Nadu, Kerala, Andhra Pradesh) show higher prevalence.
• Both urban and rural rates are rising, with more rapid increase in rural areas.
• India had an estimated 1.5 million deaths attributable to diabetes in 2019.

• Approximately 344 million globally have IGT - a major pool for future diabetes.
• IGT is characterized by post-load glucose of 7.8-11.1 mmol/L.

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Risk Factors

1. Age - Risk increases significantly after 45 years
2. Genetic predisposition - Family history (first-degree relative) doubles the risk
3. Ethnicity - South Asians, African-Americans, Hispanics have higher genetic susceptibility
4. History of gestational diabetes mellitus (GDM)
5. Low birth weight (altered intrauterine environment/fetal programming)

1. Obesity - Especially central/abdominal obesity (BMI ≥ 25 kg/m²; waist circumference > 90 cm in Asian men, >80 cm in Asian women)
2. Physical inactivity / sedentary lifestyle
3. Unhealthy diet - High intake of refined carbohydrates, saturated fats, sugar-sweetened beverages; low fruit and vegetable intake
4. Smoking and tobacco use - Increases insulin resistance
5. Hypertension and dyslipidemia (components of metabolic syndrome)
6. Polycystic Ovarian Syndrome (PCOS)
7. Sleep disorders - Short sleep duration increases risk
8. Stress and depression - Promote cortisol-mediated insulin resistance
9. Environmental pollutants (emerging evidence)
10. Medications - Corticosteroids, antipsychotics, thiazides can precipitate T2DM

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Prevention and Control Measures

• Preventing the development of risk factors themselves in the entire population
• National food policies promoting healthy diet
• Urban planning to encourage physical activity
• Regulation of food marketing, especially to children

1. Lifestyle modification - The cornerstone; shown to reduce T2DM incidence by 58% (Diabetes Prevention Program, USA):
   • Regular physical activity: ≥150 minutes/week of moderate-intensity exercise
   • Weight loss: even 5-7% reduction significantly decreases risk
   • Dietary changes: high fiber, low fat, reduced refined sugars
2. Tobacco cessation
3. Stress management
4. Pharmacological prevention - Metformin in high-risk individuals (IGT + obesity)
5. Screening of high-risk groups - Identify and manage pre-diabetes

1. Screening programs - Universal screening above age 45; targeted screening for high-risk groups
2. OGTT / HbA1c for diagnosis
3. Glycemic control - Target HbA1c < 7% to prevent complications
4. Management of hypertension, dyslipidemia, obesity (cardiovascular risk reduction)
5. Regular monitoring - Eye (retinopathy), kidney (nephropathy), foot (neuropathy)

1. Management of established complications
2. Rehabilitation - diabetes foot care clinics, amputation prevention
3. Renal replacement therapy for diabetic nephropathy
4. Laser photocoagulation for retinopathy

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National Programs for Diabetes Control in India

• Launched in 2010 by the Ministry of Health and Family Welfare under the National Health Mission (NHM)
• Key components:
  • Opportunistic screening at health facilities for persons above 30 years
  • Health promotion and awareness at community level
  • Diagnosis and management at District Hospitals/CHCs/PHCs
  • Capacity building of health staff at all levels
  • Referral services

• Demonstrated that lifestyle modification and metformin use can reduce T2DM incidence in high-risk Indian population

• Pilot phase launched in select districts
• Focus on integrated prevention and control of NCDs

• Screening for diabetes and hypertension at primary care level nationwide
• CPHC (Comprehensive Primary Health Care) targets all adults ≥ 30 years for screening

• Targeted interventions linking diabetes management with HIV care (people with HIV have higher T2DM risk due to ART)

• Integration into existing health infrastructure
• Population-based screening approach
• NCD clinics at district hospital level
• ASHA workers for awareness and follow-up at community level

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Essay Question 2 (2+8+5=15 Marks)

Describe the Epidemiology, Modes of Transmission, Prevention and Control Measures of HIV/AIDS in India

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Epidemiology of HIV/AIDS in India

• Over 39 million people worldwide living with HIV (UNAIDS, 2023)
• ~1.3 million new infections and ~630,000 AIDS-related deaths annually

• HIV prevalence: 0.2% in adults aged 15-49 years (2023)
• Estimated 2.4 million people living with HIV (PLHIV)
• Third largest number of PLHIV globally
• India contributed ~6% of global new HIV infections in 2022
• The epidemic is concentrated - high-risk populations drive the epidemic
• Epidemic was initially concentrated in South India (Andhra Pradesh, Tamil Nadu, Karnataka, Maharashtra, Manipur, Nagaland) but has now spread to many states

1. Female Sex Workers (FSWs)
2. Men who have Sex with Men (MSM)
3. Intravenous Drug Users (IDUs) - especially in Northeast India (Manipur, Nagaland, Mizoram)
4. Transgender persons
5. Truckers and migrant workers (bridge population)
6. Partners of high-risk individuals

• India has seen a significant decline (>50%) in new HIV infections over the past decade due to targeted interventions
• Sexual transmission accounts for 87.4% of HIV infections in India
• Heterosexual transmission is the predominant route
• Women account for a growing share due to infection from partners who visited sex workers
• HIV prevalence among FSWs: ~2-3%, MSM: ~4-7%, IDUs: ~7-10%

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Modes of Transmission

• Unprotected vaginal, anal, or oral sex
• Risk is higher with anal intercourse, presence of STIs (which disrupt mucosal barriers), and higher viral load
• Risk per act: anal receptive ~1.4%, heterosexual vaginal ~0.1%

• Sharing of contaminated needles/syringes among IDUs (major route in Northeast India)
• Blood transfusions with unscreened blood
• Needlestick injuries in healthcare workers
• Use of non-sterile cutting instruments (ritual, tattooing)

• During pregnancy (transplacental - 5-10%)
• During labor and delivery (primary route - 10-15%)
• Breastfeeding (5-20% additional risk)
• Without intervention, MTCT risk is ~25-40%
• With proper PMTCT interventions, risk drops to < 2%

• Casual contact (handshake, hugging, coughing, sharing food)
• Mosquitoes or other insects
• Toilet seats or swimming pools

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Prevention and Control Measures

A. Biomedical Interventions

• Treatment as Prevention (TasP): Undetectable = Untransmittable (U=U); suppressed viral load prevents transmission
• Universal Test and Treat (UTT) policy in India since 2017
• Free ART provided at ART centres across India under NACO

• Daily oral antiretroviral drug (tenofovir + emtricitabine) for HIV-negative high-risk individuals
• Reduces HIV acquisition risk by > 90% in MSM and > 75% in other populations

• 28-day ART course started within 72 hours of exposure
• For healthcare workers (needlestick) and high-risk sexual exposures

• Universal antenatal HIV testing (Option B+)
• ART for all HIV-positive pregnant women regardless of CD4 count
• Safe delivery practices
• Infant prophylaxis (nevirapine/AZT for 6 weeks)
• Advice on safe feeding options (formula feeding where feasible)

• Promotes awareness and entry point to care

• Mandatory screening of all blood donations (HIV, HBV, HCV, syphilis, malaria)
• Voluntary blood donation encouraged

B. Behavioral Interventions

1. ABC approach: Abstinence, Be faithful, Condom use
2. Condom promotion - Male and female condoms; free distribution through social marketing
3. Targeted Interventions (TIs) for high-risk groups (FSWs, MSM, IDUs, truckers) - outreach, peer education, STI management
4. Information, Education, Communication (IEC) campaigns - Red Ribbon campaigns, World AIDS Day awareness
5. Reduction of stigma and discrimination

C. Harm Reduction for IDUs

1. Needle and Syringe Exchange Programs (NSEP) - provide sterile equipment
2. Opioid Substitution Therapy (OST) - buprenorphine/methadone programs

D. Structural Interventions

1. Legal protections for key populations
2. Removing barriers to healthcare access
3. Addressing poverty and gender inequality

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National Response - NACO

• NACP-I (1992-1999): Surveillance and awareness
• NACP-II (1999-2007): Prevention focused, targeted interventions
• NACP-III (2007-2012): Scaling up interventions, reduction of new infections by 50%
• NACP-IV (2012-2017): Consolidation and systems strengthening
• Current focus: Achieving 95-95-95 targets (95% of PLHIV know status, 95% of those diagnosed on treatment, 95% on treatment virally suppressed)

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SHORT NOTES (10 × 5 = 50 Marks)

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1. Pasteurization of Milk

• Kills ~90% of bacteria in milk, including the heat-resistant tubercle bacillus (Mycobacterium bovis) and Q fever organisms (Coxiella burnetii)
• Does NOT kill thermoduric bacteria or bacterial spores
• Pasteurized milk rapidly cooled to 4°C has a keeping quality of 8-12 hours at 18°C

1. Phosphatase test - Raw milk contains the enzyme phosphatase, which is destroyed at 60°C for 30 min (same conditions as pasteurization). A positive test indicates inadequate pasteurization or addition of raw milk.
2. Standard Plate Count - Should be < 30,000 organisms/mL
3. Coliform count - Coliforms should be absent in 1 mL; their presence indicates improper pasteurization or post-pasteurization contamination.

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2. Indices of Thermal Comfort

1. Air Temperature - The earliest index; inadequate alone as it ignores humidity and air movement.
2. Air Temperature + Humidity - Combined measure; still found unsatisfactory.
3. Cooling Power (Kata Thermometer) - Measures combined effect of temperature, humidity, and air movement.
   • Instrument: Kata Thermometer (devised by Hill)
   • Dry Kata reading ≥ 6 and wet Kata reading ≥ 20 indicate thermal comfort
   • Later found to be unreliable indices
4. Effective Temperature (ET) - An arbitrary index combining temperature, humidity, and air movement.
   • Devised in 1923 by Houghton and Yaglou in Pittsburgh Laboratory
   • ET value of 30°C means the environment feels as warm as still saturated air at 30°C
   • Does not account for radiant heat - a limitation
5. Corrected Effective Temperature (CET) - An improvement on ET
   • Uses Globe Thermometer reading instead of dry bulb temperature
   • Accounts for all four factors: air temperature, velocity, humidity, mean radiant heat
   • CET is preferred when a source of radiation is present
6. Predicted 4-Hour Sweat Rate (P4SR) - by McArdle et al.
   • Takes 4.5 litres of sweat in 4 hours as maximum allowable sweat rate
   • P4SR value of 3 = upper limit of comfort zone

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3. Doctor-Patient Relationship

1. Paternalistic - Doctor acts as guardian; makes decisions for patient's good
2. Informative - Doctor provides all facts; patient decides
3. Interpretive - Doctor helps patient clarify values and decide
4. Deliberative - Doctor engages in moral dialogue; best model

• Trust and rapport - Patient must feel comfortable sharing sensitive information
• Communication - Clear, non-technical language; active listening
• Empathy - Understanding patient's concerns and emotional state
• Confidentiality - Information shared by the patient must be kept private
• Autonomy - Respecting patient's right to make informed decisions
• Continuity of care - Long-term relationship improves outcomes

• Time constraints
• Increasing technology (depersonalization)
• Commercial pressures
• Medico-legal concerns

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4. Principles of Primary Health Care (PHC)

1. Education about prevailing health problems and methods to prevent and control them
2. Promotion of food supply and proper nutrition
3. Adequate supply of safe water and basic sanitation
4. Maternal and child health care including family planning
5. Immunization against major infectious diseases
6. Prevention and control of locally endemic diseases
7. Appropriate treatment of common diseases and injuries
8. Provision of essential drugs

• Health services must be shared equally by ALL people regardless of ability to pay
• Redresses imbalance between urban (70% budget) and rural (70% people)
• Shifts the centre of gravity of healthcare toward rural areas

• Involvement of individuals, families, and communities in planning, implementation, and maintenance of health services
• In India: ASHA workers, Anganwadi workers, village health guides
• "Health by the people, placing people's health in people's hands"
• Influenced by China's "bare-foot doctors"

• Health cannot be provided by the health sector alone
• Involvement of agriculture, animal husbandry, food, industry, education, housing, public works, and communication
• Requires strong political will and multi-ministerial cooperation

• Technology that is scientifically sound, adaptable to local needs, acceptable to people, and maintainable within local resources
• Example: ORS is appropriate technology; expensive ICU ventilators are not appropriate for rural PHC
• Avoids costly and unnecessary high-tech interventions

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5. Primary Prevention of Cancer

• Smoking causes ~30% of all cancers: lung, oral cavity, pharynx, larynx, esophagus, bladder, kidney
• Measures: COTPA Act (India), pictorial warnings, ban on public smoking, tobacco taxation
• MPOWER strategy (WHO Framework Convention on Tobacco Control)

• Increase fruits, vegetables, dietary fiber
• Reduce red/processed meat, smoked/pickled foods, aflatoxin-contaminated foods
• Limit alcohol (causes oral, liver, breast, colorectal cancer)
• Reduce obesity (prevents endometrial, breast, colorectal cancer)

• Asbestos → mesothelioma, lung cancer
• Benzene → leukemia
• Aromatic amines → bladder cancer
• Protective equipment, industrial hygiene measures

• HPV vaccine (Cervarix/Gardasil) - Prevents cervical cancer (HPV 16, 18 cause ~70% of cervical cancers)
• Hepatitis B vaccine - Prevents hepatocellular carcinoma
• India's National Immunization Programme now includes HPV vaccine for girls 9-14 years

• Limit unnecessary diagnostic X-rays
• Radon mitigation in homes
• Protection from UV radiation (sunscreen, clothing)

• Aspirin and NSAIDs reduce colorectal cancer risk
• Tamoxifen reduces breast cancer risk in high-risk women
• Finasteride for prostate cancer prevention

• Regular exercise reduces risk of breast, colon, and endometrial cancers

• Early first pregnancy, breastfeeding reduce breast cancer risk
• Limiting use of exogenous hormones/HRT

• NPCDCS includes cancer screening (oral, cervical, breast)
• National Cancer Grid for standardized care

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6. Chlorination of Water

1. Chlorine gas (Cl₂) - Most efficient; used in large waterworks
2. Bleaching powder (Calcium hypochlorite, Ca(OCl)Cl) - Available chlorine ~30%; widely used in India; used for wells and small supplies
3. High Test Hypochlorite (HTH) - 60-70% available chlorine; more stable than bleaching powder
4. Chloramine - Slower acting but provides more stable residual; less taste/odor

1. Plain chlorination - Residual chlorine of 0.5 ppm after 30 min contact time
2. Breakpoint chlorination - Addition of chlorine until chlorine demand is satisfied; ensures residual of 0.2 ppm at consumer end
3. Super-chlorination - Addition of 5-15 ppm; used in emergencies and for badly polluted water; requires subsequent de-chlorination
4. Double chlorination - Applied at two points in water treatment

• Residual chlorine at consumer end: minimum 0.2 ppm (0.2 mg/L)
• Chlorine used in treatment: 1-2 ppm typically

• pH (more effective at lower pH)
• Temperature (more effective at higher temperature)
• Contact time (30 minutes minimum)
• Turbidity (reduces efficacy - hence pre-treatment with coagulation/filtration is needed)
• Organic matter and ammonia (increase chlorine demand)

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7. Principles of Arthropod Control

• Elimination of breeding habitats
• Draining stagnant water, clearing bushes, filling pits
• Larviciding (applying chemicals to breeding sites)
• Biological control: introduction of larvivorous fish (Gambusia affinis, Lebistes reticulatus) in water bodies

• Insect repellents (DEET-based)
• Protective clothing (long sleeves, trousers)
• Bed nets (especially Long-Lasting Insecticidal Nets - LLINs treated with permethrin)
• House screening (wire mesh on windows/doors)

• Indoor Residual Spraying (IRS) - application of residual insecticide (DDT, malathion, deltamethrin) to interior walls
• Space spraying (Ultra-Low Volume - ULV fogging) - to kill adult mosquitoes in emergency outbreaks
• Larvicides - temephos (Abate) applied to water bodies
• Rotation of insecticides to prevent resistance

• Larvivorous fish
• Bacillus thuringiensis israelensis (BTI) - a biological larvicide
• Entomopathogenic fungi and nematodes

• Sterile Insect Technique (SIT) - mass release of sterile males
• Release of Insects with Dominant Lethality (RIDL)
• Wolbachia-infected mosquitoes (reduces dengue transmission)
• Genetically Modified Mosquitoes

• Anti-larval laws
• Notification of vector-borne diseases
• Entomological surveys to monitor vector density and insecticide resistance

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8. Composition and Osmolality of ORS

• Reduces stool volume by ~20%
• Reduces vomiting
• Reduces the need for IV fluid

• The Government of India's ORS follows WHO reduced osmolarity formula
• Available as Jeevan Jal (ORS sachets)

• 1 litre clean water + 6 teaspoons sugar + 1/2 teaspoon salt
• Approximately 90 mEq/L sodium, 111 mmol/L glucose

• Na-glucose co-transporter (SGLT1) continues to function even in secretory diarrhea
• Each molecule of glucose absorbed pulls a molecule of sodium - and water follows osmotically

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9. Lathyrism

• Toxin: Beta-Oxalyl Amino Alanine (BOAA) - water-soluble, present in seeds of Lathyrus sativus
• Eating diets where > 30% is Khesari dhal over 2-6 months causes neurolathyrism

• Common names: Khesari dhal, Teora dhal, Lak dhal, Batra
• Triangular seeds, grey color; looks similar to red gram or Bengal gram when dehusked
• Eaten by poor agricultural labourers due to its low cost

• Endemic in Madhya Pradesh, Uttar Pradesh, Bihar, Orissa, Maharashtra, West Bengal, Rajasthan, Assam, Gujarat
• Also reported from Spain and Algeria
• Affects mainly young men (15-45 years)

1. Latent stage - Apparently healthy; ungainly gait on physical stress; complete remission possible if pulse is withdrawn
2. No-stick stage - Short jerky steps without a stick
3. One-stick stage - Crossed gait, walks on toes, needs one stick for balance
4. Two-stick stage - More severe; needs two crutches; slow, clumsy gait
5. Crawler stage - Cannot maintain erect posture; crawls by supporting on hands; muscle atrophy of thighs and legs

1. Vitamin C - 500-1000 mg/day of ascorbic acid (some reversibility)
2. Banning the crop - Prevention of Food Adulteration Act (India) has banned lathyrus in all forms (not effectively enforced)
3. Removal of toxin:
   • Steeping method: Soak in hot water for 2 hours, discard water, wash again (can be done at home; causes some vitamin/mineral loss)
   • Parboiling method: Boil the pulse and discard water
4. Dietary advice: Proportion of Khesari dhal should not exceed one-quarter of total cereals and pulses eaten per day

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10. Post-Exposure Prophylaxis (PEP) for Rabies

• Immediate and thorough washing with soap and water for minimum 15 minutes
• Application of povidone-iodine or 70% alcohol
• Do NOT suture immediately (delays healing, increases risk)
• Antibiotics and tetanus prophylaxis as indicated

• Human Rabies Immune Globulin (HRIG): 20 IU/kg body weight
• Equine Rabies Immune Globulin (ERIG): 40 IU/kg (with sensitivity testing)
• Infiltrate as much as possible into and around the wound; remainder given IM at a site distant from vaccine
• Given only ONCE (on day 0)
• Provides immediate passive protection until vaccine-induced immunity develops
• Do NOT give in the same syringe or same site as vaccine

• Tissue culture vaccines (preferred): HDCV (Human Diploid Cell Vaccine), PCECV (Purified Chick Embryo Cell Vaccine), PVRV (Purified Vero Cell Rabies Vaccine)
• Previously (brain-based) Semple vaccine is now obsolete
• Schedules for previously unvaccinated persons:
  • Standard IM (Essen) regimen: Days 0, 3, 7, 14 (4 doses)
  • Zagreb (2-1-1) regimen: 2 doses on day 0 (one in each deltoid), 1 dose on day 7, 1 dose on day 21
  • ID (Intradermal) regimen: 0.1 mL at 2 sites on days 0, 3, 7, 28 (cost-saving)
• For previously vaccinated persons: 2 doses only - days 0 and 3 (NO RIG required)

• Rabies PEP has no contraindications - pregnancy, immunosuppression, and infancy are NOT contraindications
• PEP should be started as soon as possible after exposure
• There is no upper time limit to starting PEP if the person presents late with no symptoms
• Once clinical symptoms of rabies appear, PEP is ineffective

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