PSM Answers - Q.P. 6
Q1. Objectives of Reproductive and Child Health (RCH) Programme + NHM Initiatives to Reduce Mortality Among Mothers and Children (2+8 = 10 Marks)
Part A: Objectives of RCH Programme (2 marks)
The RCH programme was launched in 1997, replacing the earlier Child Survival and Safe Motherhood (CSSM) programme. It adopts a life-cycle approach to health.
Objectives:
- Reduce infant mortality, under-5 mortality, and maternal mortality
- Achieve replacement level fertility (NRR = 1)
- Promote responsible and planned parenthood
- Ensure universal access to contraception and safe abortion services
- Provide quality antenatal, intranatal, and postnatal care
- Reduce incidence of RTIs/STIs/HIV
- Promote full immunization of children and pregnant women
- Improve nutritional status of mothers and children
Part B: NHM Initiatives to Reduce Mortality Among Mothers and Children (8 marks)
The National Health Mission (NHM) was launched in 2013 (combining NRHM 2005 + NUHM). Key initiatives:
A. Janani Suraksha Yojana (JSY)
- Cash incentive scheme to promote institutional deliveries
- Targets BPL women, SC/ST women, and women in LPS states
- Cash benefit: Rs. 1400 (rural LPS), Rs. 600 (urban LPS)
- ASHA acts as link worker
B. Janani Shishu Suraksha Karyakram (JSSK)
- Free and cashless delivery, C-section, and newborn care at government facilities
- Free drugs, diagnostics, blood, transport, diet for mother and sick newborn
- Eliminates out-of-pocket expenditure
C. Pradhan Mantri Surakshit Matritva Abhiyan (PMSMA)
- Fixed day antenatal care on the 9th of every month
- Minimum package of ANC provided to all pregnant women in 2nd/3rd trimester
- Identification of high-risk pregnancies
D. LaQshya (Labour Room Quality Improvement Initiative)
- Improves quality of care in labour rooms and maternity operation theatres
- Aims to reduce preventable maternal and newborn deaths
E. Navjaat Shishu Suraksha Karyakram (NSSK)
- Training of health workers in basic newborn care and resuscitation
- Special Newborn Care Units (SNCUs), Newborn Stabilization Units (NBSUs), Newborn Care Corners (NBCCs)
F. Home Based Newborn Care (HBNC)
- ASHA visits newborn at home (6 visits in first 42 days)
- Promotes early initiation of breastfeeding, skin-to-skin care, cord care
G. Rashtriya Bal Swasthya Karyakram (RBSK)
- Child Health Screening for 4 Ds: Defects at birth, Deficiencies, Diseases, Developmental delays
- Mobile health teams screen children 0-18 years
H. Mission Indradhanush
- Intensified immunization drive to cover unvaccinated/partially vaccinated children under 2 years and pregnant women
- Targets reaching 90% full immunization coverage
I. Integrated Management of Neonatal and Childhood Illness (IMNCI)
- Strategy for managing common childhood illnesses (pneumonia, diarrhoea, malaria, malnutrition)
J. Reproductive, Maternal, Newborn, Child and Adolescent Health (RMNCH+A)
- Comprehensive strategy linking all stages of the life cycle
- Emphasizes continuum of care from pre-pregnancy to adolescence
Q2. Factors for Rising Trend of Cancer + Strategies for Control with Reference to Tobacco (10 Marks)
Factors Responsible for Rising Trend of Cancer:
Host Factors:
- Age (most cancers increase with age; aging population)
- Genetic predisposition (BRCA1/2, APC gene mutations)
- Hormonal factors (estrogen in breast/endometrial cancer)
- Immunosuppression
- Pre-cancerous lesions (leukoplakia, erythroplakia)
Environmental/Behavioural Factors:
- Tobacco use - single largest cause (30% of all cancers); smoking causes lung, oral, laryngeal, esophageal, bladder cancer; tobacco chewing causes oral cancer
- Alcohol - associated with oral, esophageal, liver, breast cancers
- Dietary factors - low fibre, high fat diet, red meat, preserved foods (nitrosamines), aflatoxins
- Occupational carcinogens - asbestos (mesothelioma), benzene (leukemia), vinyl chloride, arsenic
- Radiation - ionizing (X-ray, nuclear) and UV radiation (skin cancer)
- Infections - HPV (cervical cancer), HBV/HCV (liver cancer), H. pylori (gastric), EBV (lymphoma), HIV
- Reproductive factors - early menarche, late menopause, nulliparity (breast/ovarian)
- Urbanization and lifestyle changes - sedentary behavior, obesity
- Aging population - India's demographic transition
- Improved diagnosis and reporting - apparent rise due to better detection
Strategies for Control of Cancer with Reference to Tobacco:
National Cancer Control Programme (NCCP) - launched 1975, revised 1984, 2004-05:
1. Primary Prevention (Tobacco Control)
- COTPA (Cigarettes and Other Tobacco Products Act), 2003:
- Prohibition of smoking in public places
- Ban on advertisement and promotion of tobacco products
- Mandatory pictorial warnings on tobacco packages (85% of pack surface)
- Ban on sale to minors (under 18 years)
- No sale within 100 meters of educational institutions
- MPOWER package (WHO Framework Convention on Tobacco Control - FCTC):
- Monitor tobacco use and prevention policies
- Protect people from tobacco smoke (smoke-free legislation)
- Offer help to quit tobacco use (cessation services - iQuitline 1800-11-2356)
- Warn about dangers of tobacco (health warnings, mass media)
- Enforce bans on advertising, promotion, and sponsorship
- Raise taxes on tobacco
- National Tobacco Control Programme (NTCP) - launched 2007-08
2. Secondary Prevention (Early Detection)
- Population-based screening for oral, cervical, and breast cancer (under NPCDCS)
- Visual Inspection with Acetic Acid (VIA) for cervical cancer
- FNAC, biopsy for diagnosis
- Cancer screening at Health and Wellness Centres
3. Tertiary Prevention
- Treatment: surgery, radiotherapy, chemotherapy
- Regional Cancer Centres (RCCs) - 28 across India
- Pain relief and palliative care
4. Cancer Registry
- Population-based and hospital-based cancer registries
- National Cancer Registry Programme (NCRP) under ICMR
Q3. Causes of Occupational Cancer (5 Marks)
Occupational cancers account for approximately 4-5% of all cancers.
| Carcinogen | Occupation/Exposure | Cancer Type |
|---|
| Asbestos | Mining, insulation workers | Mesothelioma, lung cancer |
| Benzene | Petroleum, rubber industry | Leukemia |
| Aromatic amines (2-naphthylamine, benzidine) | Dye, rubber, leather workers | Bladder cancer |
| Vinyl chloride | PVC manufacturing | Angiosarcoma of liver |
| Arsenic | Smelting, pesticide workers | Skin, lung cancer |
| Chromium (hexavalent) | Electroplating, steel industry | Lung, nasal cancer |
| Nickel | Nickel refining | Nasal, lung cancer |
| Ionizing radiation | X-ray technicians, nuclear workers | Leukemia, thyroid, skin |
| Hardwood dust | Carpenters, furniture makers | Nasal adenocarcinoma |
| Coal tar, soot | Chimney sweeps, gas workers | Scrotal, skin cancer (1st occupational cancer described by Percivall Pott, 1775) |
| Aflatoxin | Grain storage workers | Hepatocellular carcinoma |
Prevention: Substitution of carcinogens, engineering controls, PPE, biological monitoring, pre-employment and periodic medical examination, worker education.
Q4. Vaccine Schedule in UIP for Under-Five (5 Marks)
The Universal Immunization Programme (UIP) was launched in 1985.
| Age | Vaccine | Route/Site |
|---|
| Birth | BCG | Intradermal, left arm |
| Birth | OPV-0 (Zero dose) | Oral |
| Birth | Hepatitis B - 0 | IM, anterolateral thigh |
| 6 weeks | OPV-1, Pentavalent-1 (DPT+Hib+HepB), IPV-1, Rotavirus-1, PCV-1 | |
| 10 weeks | OPV-2, Pentavalent-2, Rotavirus-2, PCV-2 | |
| 14 weeks | OPV-3, Pentavalent-3, IPV-2, Rotavirus-3, PCV-3 | |
| 9-12 months | Measles-Rubella (MR-1), JE-1 (endemic areas) | SC, right upper arm |
| 9-12 months | Vitamin A - 1st dose (1 lakh IU) | Oral |
| 16-24 months | DPT booster-1, OPV booster, MR-2, JE-2, Vitamin A - 2nd dose | |
| 5-6 years | DPT booster-2 | |
Note: PCV = Pneumococcal conjugate vaccine (added 2017); Rotavirus vaccine (added 2016-19 phased); IPV introduced in 2015.
Q5. Disaster Cycle (5 Marks)
The Disaster Cycle (also called Disaster Management Cycle) consists of 4 phases:
1. Mitigation Phase (Pre-disaster)
- Activities that prevent disasters or reduce their effects
- Examples: Building codes, land-use planning, flood embankments, early warning systems, vulnerability mapping
- Goal: Reduce risk
2. Preparedness Phase (Pre-disaster)
- Activities that improve ability to respond to disasters
- Examples: Training emergency personnel, stockpiling supplies, developing emergency plans, community education, mock drills, establishing early warning systems
- Goal: Reduce impact
3. Response Phase (During/Immediately after disaster)
- Immediate actions to save lives and meet basic needs
- Examples: Search and rescue, emergency medical care, evacuation, food/water/shelter provision, disease surveillance
- Sub-phases: Heroic phase, Honeymoon phase, Disillusionment phase
- Goal: Save lives, reduce suffering
4. Recovery Phase (Post-disaster)
- Actions to restore normalcy
- Short-term recovery: Debris removal, restoration of services, temporary housing
- Long-term recovery (Rehabilitation/Reconstruction): Rebuilding infrastructure, psychosocial support, livelihood restoration
- Goal: Restore and improve pre-disaster conditions
Mitigation → Preparedness → Response → Recovery → (back to Mitigation)
This is a continuous cycle; lessons from each phase inform the next.
Q6. Self-Care in Diabetes Mellitus (5 Marks)
Self-care is central to diabetes management. The 7 self-care behaviours (AADE-7):
1. Healthy Eating
- Calorie-controlled, low glycaemic index diet
- Restriction of refined carbohydrates, saturated fats, trans fats
- Increase dietary fibre (vegetables, whole grains)
- Regular meal timings; avoid skipping meals
2. Being Active (Physical Activity)
- Minimum 150 minutes/week of moderate aerobic exercise
- Resistance training 2-3 times/week
- Reduces insulin resistance, promotes weight loss, improves glycaemic control
3. Monitoring
- Self-Monitoring of Blood Glucose (SMBG): Regular finger-prick testing
- Monitoring HbA1c every 3 months (target <7%)
- Daily foot inspection
4. Taking Medications
- Adherence to oral hypoglycaemic agents or insulin as prescribed
- Understanding signs of hypoglycaemia and its management (15-15 rule)
5. Problem Solving
- Recognizing and managing hypoglycaemia, hyperglycaemia, sick day management
6. Healthy Coping
- Managing diabetes-related distress and depression
- Support groups, stress management techniques
7. Reducing Risks (Foot Care + Complication Prevention)
- Daily foot inspection, proper footwear (no barefoot walking)
- Regular eye examination (for retinopathy), annual kidney function tests
- Blood pressure control (<130/80 mmHg)
- Lipid control, smoking cessation
- Dental hygiene
Q7. Cancer Registry (5 Marks)
A cancer registry is an information system designed for the collection, storage, management, and analysis of data on persons with cancer.
Types:
1. Hospital-Based Cancer Registry (HBCR)
- Maintains data on all cancer patients treated in a specific hospital
- Used for clinical management, treatment outcomes, survival analysis
- Does not give incidence rates for the general population
2. Population-Based Cancer Registry (PBCR)
- Collects data on all new cancer cases occurring in a defined geographic population
- Used to calculate cancer incidence, mortality, prevalence rates
- Provides epidemiological data for planning and policy
In India - National Cancer Registry Programme (NCRP):
- Established by ICMR in 1981
- Currently 30+ PBCRs and several HBCRs
- Major PBCRs: Bangalore, Mumbai, Chennai, Delhi, Bhopal, Dibrugarh
- Publishes data in "Cancer Incidence in Five Continents" (IARC/GLOBOCAN)
Uses of Cancer Registry:
- Measure the burden of cancer (incidence, prevalence, mortality)
- Identify high-risk groups and geographic clusters
- Monitor cancer trends over time
- Evaluate screening and prevention programmes
- Provide data for research and clinical trials
- Resource allocation and policy planning
Data Collected:
- Patient demographics (age, sex, address)
- Site and histological type of cancer (ICD-10 codes)
- Date of diagnosis, stage at diagnosis
- Treatment details and survival outcomes
Q8. Principles of Primary Health Care (5 Marks)
Primary Health Care (PHC) was defined at the Alma-Ata Declaration, 1978 as "essential health care based on practical, scientifically sound and socially acceptable methods and technology made universally accessible to individuals and families in the community."
The 8 Essential Components (Mnemonic: FEATS MCE):
- Food supply and proper nutrition
- Education about prevailing health problems
- Adequate safe water and basic sanitation
- Treatment of common diseases and injuries
- Safe motherhood and family planning (MCH + FP)
- Maternal and child health
- Control of endemic diseases
- Essential drugs supply + EPI (immunization)
5 Principles of PHC (Alma-Ata):
- Equitable distribution - services accessible to all, especially underserved
- Community participation - involvement of community in planning and implementation
- Intersectoral coordination - collaboration between health, agriculture, education, water, sanitation sectors
- Appropriate technology - affordable, acceptable, scientifically sound methods
- Multi-level approach - linkage between primary, secondary, and tertiary care
India's PHC Structure:
- Sub-centre: covers 3000-5000 (plain) / 1000-3000 (hilly) population
- PHC: covers 20,000-30,000 (plain) / 3,000-5,000 (hilly) population
- Community Health Centre (CHC): covers 80,000-1,20,000 population
Q9. Iodine Deficiency Disorders (IDD) (5 Marks)
IDD refers to the spectrum of disorders caused by inadequate iodine intake.
Magnitude: ~200 million people at risk in India; goitre belt = sub-Himalayan region.
Consequences of Iodine Deficiency (by life stage):
| Stage | Disorder |
|---|
| Fetus | Cretinism, stillbirth, congenital anomalies, increased perinatal mortality |
| Neonate | Neonatal goitre, neonatal hypothyroidism, increased infant mortality |
| Child/Adolescent | Goitre, hypothyroidism, impaired mental function, retarded growth |
| Adult | Goitre, hypothyroidism, impaired mental function, reduced fertility |
Cretinism - most severe form: irreversible mental retardation, deaf-mutism, spastic diplegia, short stature.
Daily Iodine Requirements:
- Children: 90-120 mcg/day
- Adults: 150 mcg/day
- Pregnant/lactating women: 200-250 mcg/day
National Iodine Deficiency Disorders Control Programme (NIDDCP):
- Formerly National Goitre Control Programme (1962)
- Renamed NIDDCP in 1992
- Universal Salt Iodization (USI) - iodization of all edible salt at 15 ppm at consumer level
- Iodized salt contains potassium iodate (KIO3) added at 30 ppm at production level
- Ban on sale of non-iodized salt for human consumption
- Sentinel surveillance and IDD surveys
Diagnosis: Urinary iodine excretion (UIE) - median UIE <100 mcg/L indicates deficiency
Q10. Hormonal Contraception (5 Marks)
Hormonal contraceptives contain synthetic estrogen (ethinyl estradiol) and/or progestogen.
Types:
A. Combined Oral Contraceptive Pills (COCPs)
- Contain estrogen + progestogen
- Mechanism: Inhibit ovulation (primary), thicken cervical mucus, alter endometrium
- Efficacy: Pearl Index = 0.1-0.3 (perfect use)
- Types: Monophasic, biphasic, triphasic
- Examples: Mala-D (govt.), Mala-N (low-dose), Saheli (centchroman - non-steroidal, weekly pill)
- Contraindications: Thromboembolic disease, breast cancer, liver disease, smokers >35 years, uncontrolled hypertension, pregnancy
B. Progestogen-Only Pills (Mini-pills)
- Suitable for lactating mothers (no estrogen to suppress lactation)
- Example: Centchroman (Saheli) - taken weekly
C. Injectable Contraceptives
- Depot Medroxyprogesterone Acetate (DMPA/Depo-Provera): 150 mg IM every 3 months
- MPA (Antara programme in India): 3-monthly injection introduced under FP programme
- Noristerat: 200 mg IM every 2 months
D. Implants (Subdermal)
- Levonorgestrel (Norplant/Jadelle): 5 years protection
- Etonogestrel (Implanon): 3 years
E. Intrauterine System (IUS)
- Levonorgestrel-IUS (Mirena): 5 years; reduces menstrual blood loss
F. Emergency Contraception
- Levonorgestrel 1.5 mg (i-pill) within 72 hours
- Ulipristal acetate within 120 hours
- Cu-IUD within 120 hours (most effective EC)
Non-contraceptive benefits of COCPs:
- Reduced risk of ovarian and endometrial cancer
- Treatment of dysmenorrhoea, endometriosis, PCOS
- Reduced PID risk
Q11. Pasteurization of Milk (2-3 Marks)
Pasteurization is the process of heating milk to destroy pathogenic organisms without significantly altering its nutritive value or taste.
Methods:
- HTST (High Temperature Short Time) / Flash method: 72°C for 15 seconds - most common commercial method
- LTLT (Low Temperature Long Time) / Holder method: 63°C for 30 minutes
- UHT (Ultra High Temperature): 135-150°C for 2-4 seconds - sterilization, not just pasteurization; shelf-stable for 3-6 months
Phosphatase Test: Used to confirm adequate pasteurization (alkaline phosphatase enzyme destroyed at pasteurization temperatures). A positive phosphatase test = inadequately pasteurized milk.
Pathogens destroyed: M. tuberculosis (test organism - most heat resistant pathogen of public health significance), Brucella, Salmonella, Listeria, Campylobacter, E. coli O157:H7.
Q12. Balanced Diet (2-3 Marks)
A balanced diet is one that provides all essential nutrients (macronutrients and micronutrients) in adequate amounts and correct proportions to maintain optimal health.
Components:
- Macronutrients: Carbohydrates (55-60% of total calories), Proteins (10-15%), Fats (25-30%)
- Micronutrients: Vitamins (fat-soluble: A, D, E, K; water-soluble: B-complex, C), Minerals (Ca, Fe, Zn, I)
- Dietary fibre: 25-30 g/day
- Water: 2-3 litres/day
ICMR Recommended Dietary Allowances (RDA) for a reference adult Indian man (60 kg, moderate work):
- Energy: 2730 kcal/day
- Protein: 60 g/day (1 g/kg/day)
- Fat: minimum 20 g/day
Food Groups (ICMR's 5 food groups):
- Cereals and millets
- Pulses and legumes
- Milk and milk products
- Fruits and vegetables
- Fats and oils
ICMR's "My Plate" concept: Half the plate = fruits and vegetables; quarter = cereals; quarter = protein foods.
Q13. Panel Discussion (2-3 Marks)
Panel discussion is a health education method used for groups.
Definition:
A structured discussion by a selected group of 4-8 experts/resource persons who discuss a topic from different perspectives before an audience, followed by audience participation.
Characteristics:
- Moderator/chairperson guides the discussion
- Panelists have different viewpoints or areas of expertise
- Audience can ask questions at the end
- Size of audience: 20-100 or more
Advantages:
- Presents multiple perspectives on a topic
- Audience exposed to expert opinions
- Stimulates thought and discussion
- Good for controversial/complex topics
Disadvantages:
- One-way communication mostly
- Dominance by one panelist possible
- Needs skilled moderator
- May confuse audience with conflicting views
Uses in Health Education:
- Community meetings on health issues (e.g., vaccine hesitancy, HIV stigma)
- Medical/public health conferences
Q14. Vitamin A Prophylaxis (2-3 Marks)
Vitamin A Prophylaxis is the administration of high-dose Vitamin A supplements to prevent Vitamin A Deficiency (VAD) and associated complications.
National Programme for Prevention of Nutritional Blindness due to Vitamin A Deficiency:
Schedule (under UIP/RBSK):
| Age | Dose | Route |
|---|
| 9-12 months (with MR-1) | 1,00,000 IU | Oral |
| 16-18 months (with DPT booster) | 2,00,000 IU | Oral |
| Every 6 months from 18 months to 5 years | 2,00,000 IU | Oral |
- Total: 9 doses up to 5 years
- Given as oily preparation of retinol palmitate
Indications for therapeutic supplementation:
- Severe acute malnutrition
- Measles
- Persistent diarrhoea (>14 days)
- Night blindness, Bitot's spots, xerophthalmia
Dietary sources: Liver, egg yolk, dairy, yellow/orange vegetables (beta-carotene), dark green leafy vegetables
Q15. Health Problems of the Elderly (2-3 Marks)
With India's aging population (>60 years = ~10% of population), elderly health is a growing concern.
Common Health Problems:
Physical:
- Cardiovascular diseases (hypertension, IHD, heart failure)
- Diabetes mellitus (Type 2)
- Arthritis and musculoskeletal problems (osteoarthritis, osteoporosis)
- Cancers (higher incidence with age)
- Respiratory diseases (COPD)
- Sensory impairments: Presbyopia, cataracts, presbycusis (hearing loss)
- Dental problems: Tooth loss, xerostomia
- Urinary incontinence, BPH in males
- Falls and fractures (hip fracture = major cause of disability)
Mental:
- Dementia (Alzheimer's disease most common)
- Depression and anxiety
- Delirium
Social:
- Social isolation, loneliness
- Neglect and elder abuse
- Financial dependency
- Polypharmacy (multiple medications)
National Programme for Health Care of Elderly (NPHCE): Launched 2010-11; provides dedicated wards, rehabilitation services, and geriatric OPD.
Q16. Child Abuse (2-3 Marks)
Child abuse is any act or failure to act that results in harm, potential for harm, or threat of harm to a child under 18 years.
Types:
- Physical abuse - hitting, burning, shaking, biting
- Sexual abuse - any sexual activity involving a child (POCSO Act 2012 in India)
- Emotional/Psychological abuse - verbal abuse, humiliation, rejection, threats
- Neglect - failure to provide basic needs (food, shelter, education, medical care)
- Child labour - economic exploitation
Indicators of Physical Abuse:
- Bruises in unusual locations (back, buttocks, face)
- Burns in specific patterns (cigarette burns, immersion burns)
- Fractures inconsistent with developmental stage
- Retinal haemorrhage (shaken baby syndrome)
- Delay in seeking medical care
Management (4 R's):
- Recognize - identify signs of abuse
- Report - mandatory reporting (Childline 1098 in India)
- Respond - immediate medical care and safety
- Refer - to social services, child protection units
Q17. Baby Friendly Hospital Initiative (BFHI) (2-3 Marks)
BFHI is a global programme launched jointly by WHO and UNICEF in 1991 to promote, protect, and support breastfeeding.
The "Ten Steps to Successful Breastfeeding":
- Written breastfeeding policy communicated to all staff
- Train all health care staff in skills to implement the policy
- Inform all pregnant women about the benefits and management of breastfeeding
- Help mothers initiate breastfeeding within half an hour of birth (early initiation)
- Show mothers how to breastfeed and maintain lactation even if separated
- Give newborns no food or drink other than breast milk (no prelacteal feeds)
- Practice rooming-in (allow mothers and infants to remain together 24 hours a day)
- Encourage breastfeeding on demand
- Give no artificial teats, pacifiers, or dummies
- Foster establishment of breastfeeding support groups and refer mothers on discharge
In India: "Maa" (Mothers' Absolute Affection) programme (2016) promotes breastfeeding.
Q18. MDR (Multi-Drug Resistant Tuberculosis) (2-3 Marks)
MDR-TB is defined as tuberculosis caused by Mycobacterium tuberculosis resistant to at least both Isoniazid (H) and Rifampicin (R), the two most effective first-line anti-TB drugs.
Types of Drug Resistance:
- Primary resistance: In a patient with no prior TB treatment
- Acquired (secondary) resistance: Develops during or after inadequate treatment
- XDR-TB (Extensively Drug Resistant): MDR-TB + resistance to any fluoroquinolone AND at least one of the second-line injectable drugs (amikacin, kanamycin, capreomycin)
- TDR-TB (Totally Drug Resistant): Resistant to all first and second-line drugs
Causes of MDR-TB:
- Irregular/incomplete treatment
- Inadequate drug regimens
- Poor quality drugs
- Malabsorption
- Transmission from MDR-TB cases
Treatment (under PMDT - Programmatic Management of Drug Resistant TB in India):
- Bedaquiline-based shorter oral regimen (6-9 months) - now preferred
- Older longer regimens: 18-24 months
- Managed through NIKSHAY portal in India
India's Burden: India has the highest MDR-TB burden globally (~26% of global cases).
Q19. Define Epidemic and Endemic (2-3 Marks)
Endemic:
The constant presence of a disease or infectious agent within a given geographic area or population group, without importation from outside. The disease occurs at the expected (baseline) level.
- Example: Malaria in sub-Saharan Africa; Kala-azar (visceral leishmaniasis) in Bihar/Jharkhand
Epidemic:
The occurrence of cases of illness (or events) clearly in excess of normal expectancy in a community or region. An epidemic implies a rate of occurrence that is significantly higher than the expected (endemic) level.
- Example: COVID-19 epidemic in 2020, cholera outbreak
Related Terms:
- Pandemic: An epidemic that has spread over several countries/continents, usually affecting a large number of people (e.g., COVID-19 pandemic, Influenza 1918)
- Outbreak: Similar to epidemic but often more localized, or used when the number of cases is small (e.g., food poisoning outbreak at a party)
- Sporadic: Occasional cases occurring irregularly, with no particular pattern
- Cluster: Aggregation of cases in a specific time and place
Q20. Principles of Chlorination (2-3 Marks)
Chlorination is the most widely used method of water disinfection. It involves addition of chlorine to water to destroy pathogenic microorganisms.
Principles:
1. Mechanism of Action:
- Chlorine reacts with water to form hypochlorous acid (HOCl) and hypochlorite ion (OCl-)
- HOCl is the active disinfecting agent (more germicidal than OCl-)
- Destroys cell membranes and inactivates enzymes of microorganisms
- Effective against bacteria, viruses, and some protozoa (not Cryptosporidium)
2. Residual Chlorine Concept:
- Free residual chlorine = 0.2 mg/L (ppm) at the consumer's tap after 30 minutes contact time at pH 7 (Horrock's apparatus used for field testing)
- Ensures continued disinfection during distribution
3. Chlorine Demand:
- Amount of chlorine consumed by organic matter, bacteria, and other reducing agents before residual chlorine remains
- Chlorine demand = Total chlorine added - Residual chlorine
4. Break-point Chlorination:
- Sufficient chlorine is added to oxidize all organic matter and ammonia, after which residual chlorine appears. The point at which this occurs is the break-point. Adding chlorine beyond this gives free residual chlorine.
5. Factors Affecting Efficacy:
- pH (lower pH = more HOCl = better germicidal action; optimal pH 6-7)
- Temperature (higher temperature = faster action)
- Contact time (minimum 30 minutes)
- Turbidity (organic matter consumes chlorine; hence pre-treatment/sedimentation needed)
6. Superchlorination and Dechlorination:
- Adding very high dose (1-2 ppm) followed by removal of excess chlorine by sodium thiosulphate
Forms of chlorine used:
- Chlorine gas, bleaching powder (contains 30-35% available chlorine), chloramines, sodium hypochlorite, high-test hypochlorite (HTH - 60-70% available chlorine)
All answers are based on Park's Textbook of Preventive and Social Medicine (25th edition) and standard PSM curriculum.