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21 to 50 questions answers for homeopathic student for university exam according to best standard book of psm and make sure it's in simple understable language and give answers according to questions not too lengthy

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PSM Park's textbook preventive social medicine important questions 21-50 homeopathic university exam topics

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I now have enough content from Park's textbook. Let me compile the 30 questions (Q21-Q50) based on Park's PSM.

PSM Questions 21-50 for Homeopathic University Exam

(Based on Park's Textbook of Preventive and Social Medicine)
Q21. What is herd immunity? Herd immunity means that when a large portion of a population is immune to a disease (through vaccination or past infection), it becomes difficult for the disease to spread - even unvaccinated people are indirectly protected. The minimum level of immunity needed to stop spread is called the herd immunity threshold, which varies by disease. For example, measles needs about 95% immunity.
Q22. What is the difference between Direct and Indirect transmission of disease?
  • Direct transmission: Disease passes directly from one person to another - by contact, droplets, or transplacental route (e.g., chickenpox by droplets).
  • Indirect transmission: Disease spreads through a vehicle (contaminated water, food, air) or a vector (mosquito, fly) without direct person-to-person contact (e.g., malaria via Anopheles mosquito).
Q23. Define "Reservoir of infection." A reservoir is the natural habitat where a pathogen normally lives, grows, and multiplies. It can be a human (e.g., typhoid carrier), an animal (e.g., rabies in dogs), or the environment (e.g., soil in tetanus). The reservoir acts as the source from which infection is transmitted to a susceptible host.
Q24. What is a carrier? Name its types. A carrier is a person who harbours the infectious agent without showing symptoms but can spread it to others. Types:
  1. Healthy carrier - never shows symptoms (e.g., polio)
  2. Incubatory carrier - spreads disease before symptoms appear (e.g., measles)
  3. Convalescent carrier - spreads after recovery (e.g., typhoid)
  4. Chronic carrier - harbours the organism for months/years (e.g., hepatitis B)
Q25. What are the levels of prevention? Give one example each.
  1. Primordial prevention - prevents risk factors from developing in society (e.g., national tobacco policy)
  2. Primary prevention - prevents disease before it occurs (e.g., vaccination, health education)
  3. Secondary prevention - early detection and treatment (e.g., screening for diabetes)
  4. Tertiary prevention - reduces disability and rehabilitates (e.g., physiotherapy after stroke)
Q26. What is incubation period? Give examples. Incubation period is the time between entry of the infectious agent into the host and the appearance of the first symptom of disease. Examples:
  • Cholera: 6 hours - 5 days
  • Typhoid: 7-21 days
  • Rabies: 10 days - several months
  • COVID-19: 2-14 days
It helps in deciding the period of quarantine and tracing contacts.
Q27. Define epidemic, endemic, and pandemic.
  • Endemic: Disease is constantly present in a particular area at a steady rate (e.g., malaria in sub-Saharan Africa).
  • Epidemic: Sudden increase in disease cases in a community beyond normal expectation (e.g., cholera outbreak).
  • Pandemic: An epidemic that spreads across countries or continents (e.g., COVID-19, influenza 1918).
Q28. What is Oral Rehydration Therapy (ORT)? How does it work? ORT is the treatment of dehydration caused by diarrhoea using a special solution of water, salts (sodium chloride, potassium chloride), and glucose. Glucose enhances intestinal absorption of sodium and water. WHO ORS can treat 90-95% of cholera and diarrhoea cases without IV fluids. ORS is promoted as the first-line treatment for diarrhoeal disease in children. It prevents deaths from dehydration.
Q29. What are the functions of a Primary Health Centre (PHC)? According to the Alma-Ata Declaration, PHC covers 10 functions:
  1. Medical care
  2. MCH including family planning
  3. Safe water and sanitation
  4. Prevention/control of endemic diseases
  5. Vital statistics collection and reporting
  6. Health education
  7. National health programmes
  8. Referral services
  9. Training of health workers and dais
  10. Basic laboratory services
Q30. What is the Expanded Programme on Immunization (EPI)? EPI was launched by WHO in 1974 to ensure all children are vaccinated against 6 killer diseases: tuberculosis, diphtheria, whooping cough (pertussis), tetanus, polio, and measles. India adopted it in 1978. When coverage reaches 80% or more, disease transmission is severely disrupted. It has been renamed the Universal Immunization Programme (UIP) in India.
Q31. What is a vaccine? Name the types. A vaccine is a biological preparation that provides active immunity against a disease by stimulating the immune system without causing the disease. Types:
  1. Live attenuated - weakened live organisms (BCG, oral polio, MMR)
  2. Killed/Inactivated - dead organisms (typhoid, cholera, IPV)
  3. Toxoids - inactivated toxins (tetanus, diphtheria)
  4. Subunit/Recombinant - specific antigens (Hepatitis B, HPV)
Q32. What is the Pentavalent vaccine? Pentavalent vaccine protects against 5 diseases in one injection: Diphtheria, Pertussis, Tetanus, Hepatitis B, and Haemophilus influenzae type b (Hib). It is given at 6, 10, and 14 weeks of age. It replaced the older DPT vaccine for primary doses and has simplified the immunization schedule.
Q33. What is Hib vaccine and why is it important? Hib (Haemophilus influenzae type b) vaccine protects against a bacteria that causes pneumonia and meningitis in young children - especially common in developing countries. It is given at 6, 10, and 14 weeks of age (usually as part of pentavalent vaccine). Children above 12 months who missed primary doses need only a single dose.
Q34. What is the meaning of "zoonosis"? Give examples. Zoonosis is a disease that is naturally transmitted from animals to humans. Examples:
  • Rabies (dog)
  • Brucellosis (cattle, goats)
  • Plague (rats via flea)
  • Leptospirosis (rodents)
  • Bird flu / Avian influenza (poultry)
  • Anthrax (cattle, sheep)
Zoonoses are controlled by controlling animal reservoirs and preventing animal-human contact.
Q35. What is case fatality rate (CFR)? CFR = (Number of deaths due to a disease / Number of confirmed cases of that disease) × 100
It measures the severity (killing power) of a disease. A high CFR means the disease is very deadly once a person is infected (e.g., rabies CFR is nearly 100%). It is different from mortality rate, which is calculated per population.
Q36. What is "incidence" and "prevalence"?
  • Incidence: Number of new cases of a disease in a population over a specific time period. It measures the rate at which people are getting the disease.
  • Prevalence: Total number of existing cases (new + old) at a given point in time.
A simple way to remember: Incidence = new cases; Prevalence = all current cases.
Q37. What is the purpose of quarantine and isolation?
  • Isolation: Separation of infected sick persons from healthy people to prevent spread of disease.
  • Quarantine: Restriction of movement of exposed but apparently healthy persons for the duration of the incubation period to see if they develop disease (e.g., 14-day quarantine in COVID-19).
Both break the chain of transmission.
Q38. What is disinfection? Difference between disinfection and sterilization.
  • Disinfection: Destruction of pathogenic (disease-causing) microorganisms but NOT necessarily all spores. Used for surfaces, clothing, water (e.g., chlorination of water).
  • Sterilization: Complete destruction of all microorganisms including spores (e.g., autoclaving surgical instruments).
Disinfection is used in community settings; sterilization is used for medical equipment.
Q39. What is safe drinking water? How is water purified on a large scale? Safe drinking water is free from harmful pathogens and chemical contaminants. Large-scale purification includes:
  1. Storage and sedimentation - solids settle down
  2. Coagulation/Flocculation - alum added to clump particles
  3. Filtration - slow or rapid sand filters remove remaining particles
  4. Disinfection (chlorination) - kills remaining bacteria
The residual chlorine should be 0.5 mg/L at the consumer's tap to ensure safety.
Q40. What is the maternal mortality ratio (MMR)? MMR = (Number of maternal deaths / Number of live births) × 100,000
A maternal death is the death of a woman during pregnancy or within 42 days of delivery due to causes related to pregnancy. Major causes include hemorrhage, sepsis, eclampsia, obstructed labour, and unsafe abortion. India's national MMR target is below 100 per 100,000 live births.
Q41. Define "infant mortality rate" and state its significance. IMR = (Deaths of infants under 1 year / Total live births in the same year) × 1000
IMR is considered a sensitive indicator of socioeconomic development and the quality of health care in a country. A high IMR reflects poor nutrition, sanitation, lack of immunization, and inadequate maternal-child health services. India's target is to reduce IMR below 25 per 1000 live births.
Q42. What is malnutrition? Name the protein-energy malnutrition syndromes. Malnutrition means deficiency of essential nutrients. In children, severe protein-energy malnutrition (PEM) presents as:
  • Marasmus: Severe calorie AND protein deficiency. Child looks like a "bag of bones" - very thin with loose skin.
  • Kwashiorkor: Mainly protein deficiency with adequate calories. Child has oedema (swelling), pot belly, skin/hair changes.
  • Marasmic-Kwashiorkor: Mixed form of both above.
Q43. What is Vitamin A deficiency? What are its signs? Vitamin A deficiency is the most common cause of preventable blindness in children. Signs (Xerophthalmia):
  • Night blindness (earliest sign)
  • Bitot's spots (foamy white patches on conjunctiva)
  • Corneal xerosis (dryness)
  • Keratomalacia (corneal softening/melting - leads to blindness)
Prevention: Vitamin A supplementation, dietary diversification, fortification of foods.
Q44. What is iodine deficiency disorder (IDD)? IDD occurs due to insufficient iodine intake. The spectrum includes:
  • Goitre (enlarged thyroid gland) - most visible sign
  • Cretinism - irreversible intellectual disability in newborns
  • Hypothyroidism
  • Increased stillbirths and miscarriages
Prevention: Iodization of salt is the most effective and cheapest method. India's programme is the National Iodine Deficiency Disorders Control Programme (NIDDCP).
Q45. What is the role of flies in disease transmission? Flies (especially housefly) are mechanical vectors - they carry pathogens on their body, legs, and gut from faeces/garbage to food/water. Diseases spread by flies:
  • Diarrhoea and dysentery
  • Typhoid and paratyphoid
  • Cholera
  • Trachoma (eye infection)
  • Polio
Control: Proper disposal of garbage and sewage, covering food, fly screens, use of insecticides.
Q46. What is "chain of infection" in communicable diseases? The chain of infection has 6 links:
  1. Infectious agent (bacteria, virus, parasite)
  2. Reservoir (human, animal, environment)
  3. Portal of exit (respiratory tract, GI tract, skin)
  4. Mode of transmission (contact, airborne, vector)
  5. Portal of entry (mouth, nose, skin, mucosa)
  6. Susceptible host
Breaking any one link stops disease spread. This is the basis of all disease control measures.
Q47. What is family planning? What are the methods used? Family planning means helping individuals and couples to decide the number, spacing, and timing of their children. Methods:
  • Spacing methods: Condoms, oral contraceptive pills, IUCD (copper T), injectables
  • Permanent methods (terminal): Tubectomy (female), vasectomy (male)
  • Natural methods: Rhythm/calendar method, lactational amenorrhoea
  • Emergency contraception: Pills within 72 hours of unprotected sex
India's family planning programme aims to stabilize population and improve maternal-child health.
Q48. What is the Global Burden of Disease (GBD)? What is DALY? GBD measures the impact of diseases on health worldwide. DALY (Disability Adjusted Life Year) is the unit used:
DALY = YLL + YLD
  • YLL = Years of Life Lost due to premature death
  • YLD = Years Lived with Disability
1 DALY = 1 year of healthy life lost. It helps compare the burden of different diseases and guides health policy priorities.
Q49. What is the role of health education in disease prevention? Health education provides people with knowledge, attitudes, and skills to adopt healthy behaviours. Its role:
  • Promotes vaccination uptake
  • Improves personal and environmental hygiene
  • Encourages early treatment-seeking
  • Supports family planning acceptance
  • Reduces tobacco, alcohol abuse
The aim is behaviour change at individual, family, and community levels. It is a key tool of primary prevention.
Q50. What is "surveillance" in public health? Surveillance is the continuous, systematic collection, analysis, and interpretation of health data, followed by timely action. Types:
  • Passive surveillance: Routine reporting by health facilities (e.g., weekly disease reports)
  • Active surveillance: Health workers actively search for cases (e.g., polio surveillance)
  • Sentinel surveillance: Monitoring at selected sites (e.g., HIV sentinel surveillance)
Surveillance is the backbone of disease control - it detects outbreaks early and guides public health response.
Reference: Park's Textbook of Preventive and Social Medicine, K. Park, M/S Banarasidas Bhanot Publishers
Tip for exam: For Q21-50, focus on definitions, classifications with examples, and national programme names - examiners reward clear structure and accuracy. These answers are kept concise and exam-friendly. If you need questions 1-20 or specific topic-wise sets, just ask!
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