Preventive and Social Medicine MCQ

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.

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Evolution of Preventive Medicine Concepts of Health and Disease Epidemiology: Principles and Practice Screening for Disease Epidemiology of Communicable Diseases and Related National Health Programmes Epidemiology of Non-communicable Diseases and Related National Health Programmes Demography and Family Planning Maternal and Child Health, and Geriatric Health Nutrition and Health Social Environment and Health Physical and Biological Environment Occupational Environment and Health Mental Health, Genetics and Health Health Information System and Biostatistics Information Education and Communication for Health Health Planning and Management, Disaster Management Health Care Delivery International Health and Voluntary Health Agencies

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Chapter 1 Evolution of Preventive Medicine 1. Who is the author of this famous quotation, "Since both in importance and in time, health precedes disease, so we ought to consider first how health may be preserved, and then how one may best cure disease". a. Galen b. Hippocrates c. Atreya Answer(a) Galen(130-205 A.D.) the celebrated Roman physician was clearly ahead of his time. He believed that disease is due to three factors: predisposing, exciting and environmental

2. Fatalistic theory of disease in ancient medicine conceptualized health or disease as: a. Effect of spirits and demons b. Reward or punishment based on good or evil deeds c. Imbalance in elements of nature d. Magic Answer(b) disease theory propounded that individuals suffered from due to bad and if the entire tribe indulged in sinful practices, it fell prey to plagues and pestilences. It replaced the demonistic theory practiced by" witch doctors' that believed in disease to be due to demons and spirits. Thus 'witch doctors' were replaced by" priest physicians' advocating appeasement of gods for relief from suffering.

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The concept of' Ayurveda' is detailed in a. Yajurveda b. Rigveda c. Samaveda d. Atharvaveda Answer(d) Ayurveda is elaborated in the Atharvaveda. It is primarily concerned with maintenance of health rather than treatment of sickness. Swasthasya Swastha Rakshitam'. i.e. keep the well healthy.

4. The concept of health in Ayurvedic medicine is a state of balance between: a. Four primary humors b. Three primary humors c. Five natural elements d. None of the above Answer(b) 2

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Ayurveda conceptualizes disease as being due to imbalance between three humors(tridosha) namely Vata (wind), Pitta(bile) and Kapha(phlegm or mucous), whereas the hypothesis in Greek medicine was based on four humors, ie, blood, phlegm. black bile and yellow bile.

5. The system of medicine currently not recognized by the Government of India is a. Homeopathy b. Acupuncture c. Unani Answer(c) Acupuncture and acupressure are well known therapeutic of Chinese origin. As yet these are not recognized as separate entities of disease management in India.

6. Who among the following introduced the concept of relationship of environment with human health? a. Avicenna b. Charaka c. Hippocrates d. Paracelsus Answer(c) Hippocrates, conventionally considered as the Father of Modern Medicine. introduced the concept of human health being closely related to environment. He authored a treatise titled, "Airs, Waters and Places

7. Who propounded the germ theory of disease? a. Leeuwenhoek b. Robert Koch c. Ambroise Parre d. Louis Pasteur Answer(d) Louis Pasteur(1822-1895) demonstrated the presence of bacteria in the air, thereby disproving the theory of 'spontaneous generation' of disease. The theory was strengthened subsequently by discovery of a series of microbes in quick succession, ie. Anthrax bacillus in 1877, sin 1847, Typhoid bacillus and Pneumococcus in 1880, Tubercle bacillus in 1882, Cholera vibrio in 1883 and so on.

8. The pioneer in concept of specific protection with immunization was a. Early Chinese physicians b. Edward Jenner c. James Lind d. Louis Pasteur Answer(a) The Chinese were early pioneers of immunization. They practiced variolation to prevent smallpox. Similar practice is also known to be prevalent in the early Ayurveda period, which was quoted by Edward Jenner to the Royal Society to get approval for his proposed smallpox vaccine.

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9. Which military surgeon successfully evolved the principle of preventing noncommunicable disease with specific diet therapy? a. Major Walter Reed b. James Lind c. Major Ronald Ross d. Bruce Answer(b) James Lind(1716-1794), the British naval surgeon, based on his observations on sailors living on stored preserved rations onboard ships successfully brought down the prevalence of scurvy among them by mandatory issuance of one fresh lime per day to each sailor. British sailors thence became known as Limeys'. Major Walter Reed is associated with discovery of yellow fever transmission with Aedes, Major Ronald Ross with transmission of malaria by mosquito, and Bruce with African sleeping sickness transmission by Tse Tse fly

10. . The earliest public health law was promulgated in: a. England b. USA c. USSR d. Spain Answer(a) Following a series of epidemics related to poor living and working conditions in Europe, a comprehensive report by William Chadwick titled, "The sanitary condition of the laboring population" was submitted to UK Government. This was followed by the "Great Sanitary Awakening" which lead to the enactment of" The Public Health Act of 1848" in England thereby initiating the concept that "The state has a direct responsibility of the health of the people".

11. Who introduced the concept of social medicine? a. Rene Sand b. Neumann c. Jules Guerin d. A Grotjahn Answer(c) Jules Guerin in 1848 introduced the term 'social medicine'. Although pioneers such as Neumann(1847), Virchow(1848) had propounded that medicine was a social science, the idea could not gain groun Alfred Grojahn in 1911 related social factors to etiology of disease and called it" Social Pathology Rene Sand in 1912 founded the Belgian Social Medicine Association.

12. Where was compulsory sickness insurance introduced? a. New Zealand b. German c. USA d. England Answer(b) 4

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Germany was the pioneer in bringing about social control of medicine and lead the way by introducing compulsory sickness insurance in 1883. Other countries followed suit, e.g. England in 1911. France in 1928 and so on. An excellent social and health insurance exists in India also in the form of Employees State Insurance (ESI) enacted in 1948.

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Chapter 2 Concepts of Health and Disease 1. Which of the following dimensions is not included in the WHO definition of health? a. Physical well being b. Occupational well being c. Mental well being d. Social well being Answer(b) WHO in the preamble to its constitution defines health as "Health is a state of complete physical. mental and social well being and not merely an absence of disease or infirmity. In recent years, it has been amplified to include spiritual well being and ability to lead a socially and economically productive life.

2. Physical quality of life index(PQL) includes the following parameters: a. IMR(infant mortality rate), per capita calorie intake and life expectancy b. IMR, life expectancy at 1 year and literacy c. IMR, MMR(maternal mortality rate) and life expectancy d. IMR, life expectancy at birth and literacy Answer(b) In a scale of 0-100, the PQLI is an average of three indicators, i.e. infant mortality rate, life expectancy at 1 year and literacy. It is notable that PQLI does not take GNP into consideration. e.g. oil rich countries of the Middle East have high per capita income but low POLI and Kerala state in India has low per capita income but high PQLI.

3. The Human Development Index(HD) ls a composite of all the following components except a. Life expectancy at birth b. Adult literacy rate and mean years of schooling c. GDP per capita in US dollars d. Life expectancy at 1 year Answer(d) HDI values range between 0 and 1, and reflect the progress a country has made towards maximum possible value of one. also allows comparisons with other countries. As per UNDP's(United Nations Development Programme) Human Development Report for 2006. India with an HDI of 0.611. is ranked at 126 out of 177 countries.

4. A good indicator of the availability, utilization and effectiveness of health care services in a country is: a. Maternal mortality rate. b. Hospital bed occupancy rate. 6

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c. Infant mortality rate. d. Disability adjusted life years (DALYs). Answer(c) Services as it IMR is considered a sensitive index of health child-rearing reflects maternal care, socioeconomic conditions in which nutritional practices and socio-economic condition in which people live as well as availability, effectiveness and utilization of health care services.

5. The following Indices are used for measuring disability except a. Sullivan's index b. HALE(health adjusted life expectancy) c. PQLI (physical quality of life index) d. DALYs(disability adjusted life years) Answer(c) POLI includes infant mortality rate, literacy and life expectancy at 1 year whereas other indicators are directly related to measurement of disability.

6. Sullivan's index is: a. Expectation of life free of disability b. Expectation of life at birth c. Expectation of life at 1 year of age d. Average life expectancy Answer(a) Sullivan's index is calculated by subtracting from the life expectancy the probable duration of bed disability and inability to perform major activities as calculated by data from cross sectional populational surveys.

7. . Years of life lost to premature death and years lived with disability adjusted for the severity of the disability' is known as: a. HALE b. DALYs c. Sullivan's index d. HDI Answer(b) DALYs is the measure of the burden of the disease in a population and the effectiveness of the interventions.

8. An Ideal health indicator should be: a. Sensitive b. Specific c. Relevant d. All of the above Answer(d)

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9. Scales used for assessing socio-economic status of populations are the following except a. Modified Udai Pareek scale b. Modified Kuppuswamy scale c. Likert scale d. BG Prasad scale Answer(c) Likert scale is not related to assessment of socio-economic status(SES) and is designed to render scoring criteria for responses during population based studies. BG Prasad scale takes into consideration mainly the total income of the household. Modified Kuppuswamy scale takes into consideration education, occupation and income, whereas Modified Udai Pareek scale assets into consideration in addition to all of the above, household assets, land holding, caste, etc.

10. "The systematic study of the means by which biomedical and other relevant knowledge is brought to bear on the health of individuals and communities under given set of conditions' is the definition given to: a. Biomedical research b. Health systems research c. Inter-sectorial research d. Operations research Answer b Health systems research deals with all aspects of management of health services including prioritization of health problems, planning, management, logistics and delivery of health care services as well as cost benefit and cost effectiveness of health care systems and biomedical research.

11. Sickness is a state of: a. Social dysfunction b. Subjective state of a person feeling unwell c. Impaired physiological function d. Impaired psychological function Answer(a) Susser's terminology suggests that sickness is a state of social dysfunction, i.e. a role an individual assumes when ill; illness is a subjective state of a person who feels that he is not well whereas disease is a physiological/psychological dysfunction.

12. Disease causation is best explained by: a. Theory of one-to-one relationship between causal agent and disease b. Supernatural theory of disease c. Empirical theory of disease causation d. Multi-factorial theory of disease causation Answer(d) 8

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Germ theory of disease. i.e. one-to-one relationship between causal agents(microbes) and disease held ground throughout the and early part of the 20 century. It demolished supernatural theory of disease. The modern concept of disease causation is" Web of Causation" suggested by McMahon and Pugg. It largely dwells on the multi-factorial causation as well as the well-known 'epidemiological triad of disease' being the result of interplay of agent, host and environmental factors.

13. "Course of a disease process without any intervention' is the definition of: a. Spectrum of disease b. Epidemiology of disease c. Natural history of disease d. Icebergs phenomenon Answer(c) Each disease has its own unique natural history in individuals which is not necessarily same in all the individuals. On the other hand, spectrum of disease and iceberg phenomenon are related to behavior of the disease in the community.

14. In the natural history of disease, the" pathogenesis phase' is deemed to start upon: a. Entry of the disease agent in the human host b. Interaction between agent, host and environ- mental factors c. Appearance of signs and symptoms d. Appearance of complications Answer(a) customarily, natural history of disease is described to have two phases, ie. Prepathogenesis and pathogenesis. Prepathogenesis phase is interaction between agent, host and environment, the agent yet to gain entry into the human body. All other states listed above are related to period of pathogenesis. This understanding of natural history in relation to each disease is the key to plan interventions.

15. The term "disease control' employs" all of the following except: a. Reducing the complications b. Reducing the risk of further transmission c. Reducing the incidence of disease d. Reducing the prevalence of the disease Answer(d) In disease control, the agent continues to persist in the community though below the critical level where it ceases to be a public health problem. A state of equilibrium is established between the disease agent, host and environment so that new cases cease to occur. Most control activities focus on primary or secondary prevention or both. As opposed to this, the term' eradication' is used to describe termination of all transmission of infection by extermination of the infectious agent(tear out by roots The term eradication is generally reserved to describe cessation of infection and disease from the entire world. As compared to eradication, the term disease elimination' is used to describe interruption of transmission of disease generally from a region, e.g. elimination of measles, polio, guinea worm, etc. Regional elimination is considered an important precursor of eradication.

16. Morbidity in a community can best be estimated by: a. Active surveillance 9

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b. Sentinel surveillance c. Passive surveillance d. Monitoring Answer(a) Active surveillance implies activities designed to aggressively look for cases of a disease in the community. It thus reveals true pattern of morbidity, whereas in passive surveillance only those cases get counted which report to the health facility with specific symptoms of that disease. Thus many cases will go unrecorded. Sentinel surveillance on the other hand, is the best way to find out hidden cases. In this, all patients reporting to a health facility(sentinel facility) get checked for a particular disease even if they have reported for other morbidities.

17. Sentinel surveillance is employed to: a. Establish natural history of disease b. Detect the total number of cases of a disease in a community c. Detect the missing/hidden cases in a community d. Plan intervention Answer(c)

18. Which level of prevention Is applicable for implementation in a population without any risk a. Primordial prevention b. Primary prevention c. Secondary prevention d. Tertiary prevention Answer (a) Although there is no strict delineation between primordial and primary prevention yet primordial prevention can be considered as primary prevention in its purest sense. It is a series of actions applied to entire communities or populations designed to prevent occurrence of diseases whose risk factors have not yet appeared in the communities. e.g. discouraging children from adopting unhealthy lifestyles like smoking, junk foods. sedentary lifestyle, etc., with the long term aim of preventing obesity. hypertension, coronary heart disease, etc. It is achieved through individual as well as mass health education. As opposed to this. primary prevention is designed to prevent the onset of disease prior to its occurrence with risk factors already existing, diet supplements for pregnant or lactating mothers, healthful housing, etc.

19. Which of the following is not primary prevention? a. Pulse polio immunization b. Vitamin A supplementation c. Breast self-examination for tumor d. Isoniazid(INH) to a baby breastfed by a sputum positive tubercular mother Answer(c) Breast self-examination is a classical example of action taken for early diagnosis and treatment, hence it is secondary

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21. 22. 23. Concept of Hospice' related to: a. Euthanasia for terminally ill patients b. Family health advisory service abandoned c. An association running orphanages for children d. special group of people helping the old and terminally ill patients Answer(d) "Hospice" is derived from French word "Hospitium-Hospes'. Essentially this concept revolves around providing an ashram- like organization designed to care for the terminally ill. It is an approach which focuses on the patient and family rather than the disease, and comfort and pain relief rather than on treating illness or prolonging life.

24. Any restriction or lack of ability to perform an activity in the manner or within the range considered normal for a human being called: a. Impairment b. Handicap c. Disability d. Disease Answer(c) 'Disability' is the consequence of an impairment whereby the affected person may be unable to carry out certain activities commensurate with his/her age, sex, etc. Impairment' is defined as any loss or abnormality of psychological, physiological or anatomical structure or function. On the other hand, a handicap is the disadvantage a person suffers so that he/she is not able to discharge his/her due role in the society. "Disease refers to any departure from a healthy condition in an organism.

25. Choose the correct sequence In order of occurrence. a. Disease "Disability - impairment-Handicap b. Disease - impairment-Handicap- Disability c. Handicap - Disease-Impairment-Disability d. Disease-Impairment-Disability-Handicap Answer(d) In the order of occurrence the process is initiated by disease which leads to impairment. which, if not handled properly, leads to disability. Handicap results as a consequence of disability. The above terms can be explained as follows: Accident of soldier(disease)- Amputation of foot(impairment) Inability to walk(disability)- Unemployment as a soldier(handicap).

26. Which of the following is incorrect in relation to International Classification of Diseases(ICD)? a. It is the standard for international comparisons of morbidity and mortality b. It is revised once in 10 years c. The 10th revision of ICD took place in 1995 d. The 10th revision consists of 21 major chapters 11

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Answer(c) The 10th revision of ICD came into effect in January 1993.

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Chapter 3 Epidemiology: Principles and Practice 1. Epidemiology is a. Branch of medical science which treats epidemics b. Science of the mass phenomenon of infectious diseases c. Study of disease, any disease as a mass phenomenon d. Study of distribution and determinants of disease frequency in masses e. All of the above Answer(e) Epidemiology has been variously described by different authors ranging from Hippocrates to the present day. However, comprehensive definition of the science of epidemiology has been rendered by John M. Last in 1988 as, "the study of the distribution and determinants of the health related states or events in specified populations and the application of this study to the control of health problems". It is no longer restricted to communicable diseases but encompasses all health related phenomenon from genetic disorders to noncommunicable diseases, e.g. accidents.

2. In a community, an increase in new cases of a particular disease is due to: a. Increase in incidence rate b. Increase in prevalence rate c. Both of the above d. None of the above Answer(a) Incidence rate measures occurrence of new cases whereas prevalence rate is conglomerate of new as well as pre-existing cases, thus denoting the total burden of the disease.

3. The most effective tool for measuring incidence of a disease in a community is: a. Case control study b. Cohort study c. Cross sectional study d. Cross over study Answer(b) Cohort study is a longitudinal study in which the number of new cases of a particular disease under study automatically gets counted as the study progresses.

4. In a given population, prevalence of a disease can be rapidly determined by: a. Case control study b. Cross over study c. Cross sectional study 13

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d. Double blind study Answer(c) The simplest tool available for rapid determination of prevalence

5. Prevalence of a disease depends upon the following: a. Incidence b. Duration c. Both of the above d. None of the above Answer (c)

6. In a stable situation: a. Prevalence = Incidence x Duration b. Incidence = Prevalence x Duration c. Prevalence = Incidence x Duration d. Incidence = Prevalence x Duration Answer(a) Prevalence(P) of a disease depends upon two factors: the incidence and duration of illness. Assuming that in a population, incidence and duration are stable: the prevalence will be a product of incidence and duration (P = I x D). Using the same equation, incidence and duration can also be determined as: I = P/D D = P/I It should be noted that the longer the duration. the higher win be prevalence rate, e.g. in tuberculosis where new cases the continue to occur in the background of old cases continuing to exist for a long time virtually adding to the prevalence rate Conversely, the term "prevalence' is not used in the case of onetime events such as food poisoning, accidents, etc.

7. If a drug prevents mortality but does not affect cure, then which of the following will be true: a. Incidence will decrease b. Incidence will increase c. Prevalence will decrease d. Prevalence will increase Answer(d) To understand the above situation, the example of anti-retroviral therapy(ART in case of AIDS can be considered, wherein ART prolongs the life but docs not cure AIDS. hence the prevalence of AIDS continues to increase.

8. if the incidence of a disease in females is 2 times as in males but the prevalence is equal in males and females, what is the inference? a. Proportional mortality from disease in question more in females b. Proportional mortality from disease in question less in males 14

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c. Any of the above d. None of the above Answer(c) In the above situation. as incidence of the disease is 2 times more in females as compared to males but the prevalence is equal. evidently either the mortality in females is more or mortality in males is less or both.

9. Prevalence of a disease: a. Can only be determined by a cohort study b. Is the number of new cases in a defined population c. Describes the balance between incidence, mortality and recovery d. Is the best measure of in disease frequency a etiological studies Answer(c)

10. At the end of year 2000, the population of a tribal district was 2,00,000 and number of cases of tuberculosis were 800. At the end of the year 2001 the population was 2,10,000 and 200 new cases were detected and 12 cases had died. Based on this data, all of the following rates can be calculated except a. Prevalence b. Incidence c. Proportional mortality d. Case fatality Answer(c) For calculating proportional mortality(in this case due to tuberculosis) total number of deaths because of all causes' is essential as a denominator.

11. Prevalence is: a. Rate b. Ratio c. Proportion d. Mode Answer(b) Although referred to as a rate, prevalence rate is actually a ratio. It is of two types: point prevalence(number of all current cases of a specified disease existing at a given point of time per hundred estimated population at the same point of time) and period prevalence(number of existing cases of a specified disease during a given period of time interval per hundred estimated mid-interval population at risk

12. Study of time, place and person distribution of health related events is known as: a. Descriptive epidemiology b. Experimental epidemiology c. Analytical epidemiology d. Clinical epidemiology Answer(a) 15

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Descriptive epidemiology is generally the first phase of epidemiological investigations. The aim is to determine: who are the people affected(person distribution), where are they affected(place distribution), when are they affected(time distribution). Once the time, place and person distribution have been defined, the characteristics associated with presence or absence of disease in an individual can also be identified and a hypothesis formulated.

13. The changes that occur in a disease frequency over many years is called: a. Cyclic trend b. Secular trend c. Seasonal trend d. All of the above Answer(b) The term' secular trend' implies changes in the occurrence of disease(progressive increase or decrease) over a long period of time, generally several years or decades; e.g. communicable diseases have shown a declining trend and non-communicable diseases have shown an increasing trend in developed countries. other terms used regarding fluctuations in disease frequency are seasonal trend and cyclic trend. Seasonal variations in disease occurrence may be related to environmental conditions, i e. temperature, humidity, rainfall, overcrowding, life cycle of vectors, etc. Cyclic trends refer to some diseases, which occur in cycles over short periods of time. Such cyclical occurrences are related to variations in herd immunity(buildup of susceptible

14. Which of the following show seasonal variation? a. Viral conjunctivitis b. Gastroenteritis c. Measles d. Meningococcal meningitis e. All of the above Answer(e)

15. Which not the true reason for cyclic trend of a disease? a. Antigenic variation b. Buildup of susceptible c. Herd immunity variation d. Environmental conditions Answer(d)

16. Seasonal variation of a disease can be assessed by: a. Comparing the prevalence of disease b. Comparing the incidence of disease c. Calculating the survival rates d. Calculating the mortality rates Answer(b)

17. All are true regarding point source epidemic except a. No secondary waves occur 16

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b. Occurs within a specified period c. All cases occur abruptly and simultaneously d. Children are most commonly affected Answer(d) In point source epidemic, the exposure to disease agent is brief and simultaneous, all cases occur within a single incubation period describing a single peak in the epidemic curve. There are no secondary cases. The epidemic tends to be explosive with maximum number of cases clustered around one point of time All ages are equally likely to be affected, e.g. food poisoning.

18. All are true regarding propagated epidemic except a. Progresses slowly b. No secondary waves occur c. Person to person transmission occurs d. spread depends on herd immunity Answer(b) Propagated epidemics usually occur in case of infectious diseases and are commonly the result of person-toperson transmission so that transmission continues to occur until the number of susceptible is depleted or no longer exposed. The rapidity of spread depends upon herd immunity, opportunities for exposure and secondary attack rate. Secondary waves are likely to occur Propagated epidemics may also occur through agency of arthropod vectors or animal reservoirs

19. "Chernobyl" tragedy is an example of: a. Point source epidemic b. Modern epidemic c. Propagated epidemic d. Continuous or repeated exposure epidemic Answer(d) Continuous or repeated exposure epidemics are a type of common source epidemics. The common source epidemics are frequently but not always due to exposure to an infectious agent. They can result from contamination of the environment(air, water, soil) by industrial chemicals or pollutants, e.g. Bhopal gas tragedy(air pollution), Minamata disease in Japan(contaminated food chain), Chernobyl tragedy(radiation pollution). As opposed to this, common source(single exposure) epidemics are called point source epidemics, eg, food poisoning.

20. A disease is called endemic when it a. Occurs in more than one geographical are b. Occurs in more than one season c. Is constantly present at low rates in a specified geographical area d. Occurs in a frequency more than expected in a specified geographical area Answer(c)

21. Which of the following ls the most useful study design In a hospital setting? a. Cohort b. Case control 17

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c. Cross sectional d. Longitudinal Answer(b) The case control studies have three essential features: i. Both exposure and outcome(disease) have occurred before the start of study. ii. The study proceeds backwards from effect to cause. iii. It uses a control group to support or refute an inference. All these conditions are readily met in a hospital setting. Therefore case control studies are readily feasible and cost- effective in a hospital setting. However, quality of hospital records will determine the quality of case control study.

22. All of the following are characteristics of a case control study except a. Least risk to subjects b. Rapid and cost-effective c. Risk factors can be identified d. Less prone to bias Answer(d)

23. In relation to case control study, which of the following is not correct? a. Many etiological/risk factors can be studied at the same time b. Proceeds from effect to cause c. Sequence of events is not known d. Several possible outcomes can be studied Answer(d) Since the case control studies proceed backwards from effect to cause, the outcome(effect is already established. Hence there is no possibility of cases with multiple outcomes being included in the study.

24. All of the following are advantages of case control studies except a. Relative risk can be calculated b. Odds ratio can be calculated c. Useful in rare diseases d. Quick results are obtained Answer(a) Since incidence rates are essential for calculation of relative risk, which are not provided by case control studies as appropriate denominator, or population at risk is not available, relative risk cannot be calculated with the help of case control studies. It can only be determined from a cohort study.

25. In a case control study of a suspected association between breast cancer and contraceptive pill, all of the following are true statements except a. The controls should exclude women known to be taking the pill at the time of the survey b. All the controls need to be healthy 18

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c. The attributable risk of breast cancer resulting from the pill may be directly measured d. The control should come from a population that has the same potential for the breast cancer as the cases Answer(c) The attributable risk cannot be calculated with the help of a case control study as incidence rates among the exposed and non-exposed persons cannot be calculated.

26. "Systematic error in the determination of the association between the exposure and disease' is termed as: a. Chance b. Probability c. Bias d. Confounding Answer(c)

27. Berksonian bias refers to the bias arising from: a. Different rates of admission to the hospital b. The cases not being representative of the general population c. Presence of confounding factors d. improper selection of cases Answer(a) Berksonian bias named after Dr. Joseph Berkson occurs due to different rates of admission to hospitals for people with different diseases(ie. hospital cases and controls). Other types of biases which are usually confronted in case control studies include bias

28. In a case control study of smoking and lung cancer, which of the following can be a possible conclusion a. Smoking is a cause of lung cancer b. Lung cancer is commoner in smokers than non- smokers c. If smoking is stopped, the number of cases of lung cancer will decrease d. Smoking is associated with lung cancer Answer(d) Since case control studies proceed backward from effect to cause. they mainly indicate statistical association between exposure and occurrence of disease. Statistical association does not imply causation, however, strength of this association can be measured by odds ratio.

29. The ratio between incidence of disease among exposed persons and incidence among non-exposed persons is commonly known as: a. Odds ratio b. Relative risk c. Attributable risk d. Population attributable risk 19

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Answer(b) Relative risk(also known as risk ratio) is an estimate of disease risk associated with an exposure to a risk factor case control studies do not provide incidence rates from which relative risk can be calculated directly as these is no denominator or population available. Relative risk, therefore. can be determined exactly only from a cohort study.

30. "A group of people who share a common characteristic or experience within a defined time period' is known as: a. Cases b. Controls c. Cohort d. None of the above Answer(c) A group of people born on the same day or same period of time form a 'birth cohort', persons exposed to a common drug or infection within a specified period are called "exposure cohort and so on. Such cohorts provide a valuable universe for selection of cases and controls to design a cohort study which is also known as prospective study, incidence study, longitudinal study, forward looking study and so on.

31. In a cohort study, which of the following is incorrect? a. Proceeds from "effect to cause" b. Starts with people exposed to risk factor or suspected cause c. Yields incidence rates and relative risk d. Time consuming and expensive Answer(a) Cohort studies are longitudinal studies which proceed from cause to effect' as opposed to case control studies which proceed from 'effect to cause'. As denominators are known, study accurately gives estimates of incidence rates from which relative risk as well as attributable risk can be deduced. However, being prospective and long tem studies, these are time consuming and expensive.

32. The well known Framingham Heart Study' is an example of: a. Case control study b. Nested case control study c. Cohort study d. Randomization study Answer C

33. Incidence of diarrhea in a community can be calculated by: a. Case control study b. Cross sectional study c. Double blind study d. Cohort study Answer(d) 20

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Incidence rates are best calculated by cohort studies as explained above,

34. All of the following are characteristics of a cohort study except a. Reserved for testing precisely formulated hypothesis b. Suitable for study of rare diseases c. Can yield information about more than one outcome d. Involves large number of subjects Answer(b) As cohort studies are population based. rare diseases may or may not be encountered during the progress of a particular cohort. Case control studies can be designed in super specialty hospitals where admission rates of rare diseases may be high due to referrals. Hence rare diseases are best studied with case control studies.

35. A study began in 1975 in Bombay(now Mumbai) with a group of 10,000 adults who were asked about their alcohol consumption. The occurrence of cancer was analyzed among the same population for the period 1995-2000. This design of study ls known as: a. Case control study b. Retrospective cohort study c. Concurrent cohort study d. Cross sectional study Answer(c) Cohort studies are long term studies entailing follow up of a group of people(cohort) over a period of time. Common types of cohort studies are: prospective(concurrent) cohort studies, retrospective(historical) cohort studies and a combination of retrospective and prospective cohort studies.

36. Which is the best measure for strength of association between exposure and outcome of interest? a. Relative risk b. Attributable risk c. Population attributable risk d. Odds ratio Answer(a) Relative risk(RR) is a direct measure of the strength of association between suspected cause and effect, therefore, it becomes important in etiological enquiries. RR 1 indicates nil association whereas RR 1 suggests positive association between exposure and disease under study, e.g. RR 22 indicates that incidence of disease is 2 times higher in the exposed group as compared to unexposed. In other words, this represents a 100% increase in the risk. It should, however, be noted that risk does not necessarily imply causal association.

37. "Difference of incidence disease among exposed and non-exposed expressed as p is known as: a. Attributable risk(AR) b. Risk ratio(RR) c. Odds ratio(OR) 21

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d. Population attributable risk(PAR) Answer(a) Attributable risk, also known as risk difference. indicates to what extent the disease under study can be attributed to the exposure. Conversely, we can deduce the amount of disease that might be eliminated if the factor under study could be controlled or eliminated in the study population. Therefore all of the above can be calculated by the following formulae:

38. Which is the best measure for estimating impact of health interventions in general population? a. Relative risk b. Attributable risk c. Population attributable risk d. All of the above Answer(c) Both attributable risk and PAR are good measures for the impact of specific interventions. However, PAR is useful applying to general population as it provides an estimate of the amount by which the disease could be reduced in that population if suspected factor was eliminated or modified because PAR is dependent on the prevalence of the risk factor.

39. which of the following is a good measure of the severity of an acute disease? a. Standardized mortality ratio b. Cause-specific death rate c. Case fatality rate d. Age-specific death rate Answer(c) 22

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Case fatality rate(CFR) is actually a ratio of the total number of deaths due to a particular disease to total number of cases due to the same disease expressed as a percentage. The salient features of CFR are: It represents the killing power of a disease and virulence of an agent. The time interval is not specified. It is used in acute infectious diseases(e.g. dengue, cholera, food poisoning, etc.) but its usefulness in chronic diseases is limited because of long and variable period from onset to death CFR may be variable for the same disease in different epidemics of changes in agent, host, and environmental factors.

40. Number of deaths due to a particular cause(or In a specific age group) per 100(or 1000) total deaths' is known as: a. Specific death rate b. Proportional mortality rate c. Case fatality rate d. Standardized mortality rate Answer(b) Proportional mortality rate(PMR) is usually computed for a broad disease group, e.g. communicable diseases on the whole or for a specific disease of major public health importance, e.g. tuberculosis in developing countries. Salient features of PMR(ratio) are: Used when population data are not available. Since it depends on two variables, both of which may differ, it is of limited value in making comparisons between population groups or different time periods. It does not indicate the risk of members of the population contracting or dying of a particular disease. Since the prevailing causes of death may vary according to age and sex, the proportional mortality should be calculated separately for each age and sex group. It is especially useful in relation to preventable conditions.

41. Which is the best measure for evaluating standards of therapy? a. Specific death rate b. Case fatality rate c. Survival rate d. Crude death rate Answer(c) Survival rate is a method of describing prognosis in certain disease conditions and can be used as a yardstick for assessment of standards of therapy. This index is commonly used in cancer studies.

42. Ideally suited measure for comparing health status of the populations is: a. Standardized mortality rate b. Proportional mortality rate c. Specific death rate d. Crude death rate Answer(a) Rates are comparable only if the concerned populations are comparable, which is difficult to obtain in real life. Hence standardization or adjustment for variables likes age, sex, race, parity, etc., needs to be carried out. This is known as age adjustment or age standardization and generates age-adjusted rates, sexadjusted rates and so on. As compared to above, crude death rate is not the correct yardstick because it does not specify the age composition of the population. Similarly, it is not practicable to use a series of age specific-death rates. Hence the answer is age adjustment or age standardization. There are two methods of 23

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standardizing the population: direct and indirect standardization. For both methods, the essential input is choosing a standard population(and not the age structure of the population).

43. All are true about direct standardization except a. Two populations are compared b. Populations should be comparable c. A standard population is needed d. Age-specific death rates are not needed Answer(d)

44. "Ratio of the total number of deaths that occur in the study group to the number of deaths expected to occur if the same group had experienced the death rates of a reference population' is known as: a. Age-specific death rate b. Proportional mortality rate c. Standardized mortality ratio d. Case fatality rate Answer(c)

45. All are true about standardized mortality ratio except a. Can be adjusted for age b. Age-specific death rates are not needed c. Can be used for events other than death d. Expressed as rate per year Answer(d)

46. In the international death certificate, which of the following is true? a. Part I of the certificate deals with the immediate and also the underlying cause b. Part I of the certificate deals with the immediate cause only c. Part ll of the certificate deals with the underlying Cause d. Other morbid conditions not related to the cause of death are not included Answer(a)

47. Verbal autopsy is: a. Examination of the dead body where post-mortem facilities are not available b. Ascertaining cause of death by interviewing the relative of the deceased c. A discussion about lessons learnt after completion of a health camp d. Inquest report or panchnama Answer(b) verbal autopsy is an important tool for ascertaining causes of death in population-based studies where medical certification of cause of death is not available, which is commonly the case in developing countries like India. However, to minimize subjectivity, the interviewer must take care to use standardized structured questionnaires. 24

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48. As compared to a routine case control study, nested case control study avoids problems related to: a. Confounding bias b. Need for long follow up c. Temporal association d. Randomization Answer(c) A nested case control study draws its cases and controls from a cohort population that has been followed for a period of time. Its salient features are:    

It is carried out when it is either too costly or not feasible to perform analysis on the entire cohort. It can utilize the exposure data originally collected before the onset of the disease, thus reducing the risk of recall bias and ambiguity. It includes cases and controls drawn from the same cohort study thus decreasing the chances of selection bias. It is considered a strong observational study; comparable to its parent cohort study in the likelihood of an unbiased association between an exposure and an outcome.

49. All of the following features are true about cross sectional study except a. Follow up is not a necessary feature b. Cause and effect relationship can be established c. All cases are seen at one point in time d. More useful for chronic diseases Answer(b) Cross sectional study is the simplest form of an observational study and includes one-time observation of the population for the presence or absence of a disorder or specific factor. As time sequence, which is essential for establishing the concept of causatively is not there in cross sectional studies, a causal association cannot be deduced with the help of cross sectional studies.

50. Experimental epidemiology deals with: a. Screening of disease b. Epidemics c. Early diagnosis d. Intervention Answer(d) Experimental epidemiological studies are also known as intervention studies. They are more or less similar in approach to cohort studies except that conditions in which the study is carried out are under direct control of the investigator. Thus experimental studies involve taking some action/intervention or manipulation such as deliberate application or withdrawal of the suspected cause in the experimental group while making no change in the control group and then observing and comparing

51. All are true for randomized controlled trial (RCT) except: a. Bias may arise during evaluation b. The groups should be representative of the population c. Both study and control group should be comparable 25

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d. Used only for testing new drugs on human or animal subjects Answer(d) RCT is an epidemiological experiment. It forms the basis of the modem concept of evidence-based medicine. It is used not only for testing new drugs but is an important tool for validating widely used treatment modalities like tonsillectomy. varicose veins stripping. hospitalization of all patients with myocardial infarction and applicability of many preventive and therapeutic procedures.

52. Which of the following is true about double blind study? a. Participant is not aware about the group allocation and treatment received b. Neither the participant nor the doctor is aware about the group allocation and treatment received c. The participant, doctor and investigator are unaware about the group allocation and treatment received d. None of the above Answer(b) Blinding is a useful procedure to minimize bias in randomized controlled studies. It is of three types: i. In a single blind trial, the participant is not aware whether he belongs to the study or the control group. ii. In a double blind trail, neither the doctor nor the participant is aware about the group allocation and the treatment received. iii. In the triple blind trial, the participant, the doctor and the personnel analyzing the data are all blind. This is ideal but the commonest used method is double blinding. When the outcome such as death is being measured, blinding is not so essential.

53. The number of patients required in a clinical trial to treat a specific disease increases as: a. The incidence of the disease decreases b. The size of the expected treatment effect increases c. The drop-out rate increases d. The significance level increases Answer(c)

54. The purpose of a double blind study is to: a. Avoid subject bias b. Avoid observer bias and sampling variation c. Reduce the effects of sampling variation d. Avoid subject bias and sampling variation Answer(b)

55. All of the following are characteristics of cross over studies Except a. All subjects receive the new therapy b. Not suitable if therapy of interest cures the disease c. Ideally suitable if disease changes radically during the study only d. Not suitable if therapy of interest is effective during a certain stage of disease 26

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Answer(c)

Common study designs of controlled trials are concurrent "parallel study'

design and 'cross over' type of study design. In the former, comparisons are made between two randomly assigned groups with one group exposed to specific treatment. Patients remain in the study group or control group for the entire duration of the trial. In the cross over type of design, each patient serves as his own control. The patients are randomly assigned to a study group or control group with study group receiving the treatment under trial and control group receiving a placebo. After a period, both groups cross over. Such a design has a number of advantages including assurance that all patients will receive the new therapy at some stage, thus economizing on time and expense.

56. studies have limitations as listed in the question. Which of the following is not true in a non-randomized trial? a. Approach is crude b. The experiment can serve as its own control or can utilize a natural control c. Degree of comparability is high d. Several trials needed before evaluation is considered conclusive Answer(c) Although the experimental studies or randomized control trials are ideal and almost always to be preferred, it is not always possible to use it in human beings due to administrative, ethical or other reasons, e.g. smoking and lung cancer have never been experimented directly on human beings. In such situations nonrandomized non-experimental trials are resorted to, in which case effects of preventive interventions on community basis(community trials of water fluoridation) can be studied. Further, when disease frequency is low and natural history is long(cancer cervix), RCT will be impracticable, as it will require follow up of thousands of cases for a decade or more. However, non randomized studies have intrinsic disadvantages, as the degree o comparability will be low and chances of spurious results higher due to non-randomization. Some common examples of non- randomized trials are proving validity of Pap test for cervical cancer, John Snow's famous community diagnosis of cholera related to a certain well and before and after comparison study in Australia regarding significant difference in the motor accident deaths before and after compulsory introduction of seat belts.

57. Which of the following is false in relation to correlation? a. Correlation coefficient varies between-1 and +1 b. Causation implies correlation c. Correlation implies causation d. Correlation cannot measure the risk Answer(c) While descriptive studies help in the identification of disease problems in the community, analytical and experimental studies test the hypothesis derived from descriptive studies to confirm or refute the observed association between suspected cause and disease. The notion of cause' becomes confusing when the disease is multifactorial(e.g. coronary heart disease). The primary interest of the epidemiologist is to establish a' cause and effect' relationship for which he proceeds from demonstration of statistical association to demonstration that the association is causal. Association does not necessarily mean a causal relationship. Here the concept of correlation comes in. Correlation indicates the degree of association between the two characteristics within correlation coefficient range of-1.0 to 1.0. A correlation coefficient of 1.0 means that the two variables have a perfect linear relationship. However, Correlation cannot be used to prove causation because the sequence of events preceding the disease(temporal association) cannot be 27

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assumed to have occurred. Similarly, correlation does not measure risk. It may be said that causation implies correlation but correlation does not imply causation

58. Test of association between two variables is done by: a. Correlation b. X2 c. Regression d. All of the above e. None of the above Answer(a)

59. All of the following put together contribute to a probability of the association being causal except a. Temporal association b. Biological plausibility c. Strength of the association d. Predictive value e. Consistency of the association Answer(d) All of the above except predictive value are considered additional criteria for judging causality when controlled experimental evidence is absent. Temporal association centres around the question whether the suspected cause preceded the observed effect, ie. the exposure to the suspected cause must take place before the occurrence of the effect. Strength of association relates firstly to relative risk(it should be large), secondly, if there is a dose-response and/or duration-response relationship. The association is consistent if the results are replicated when studied in different settings and/or by different methods. Biological plausibility means the association agrees with the current understanding of physiology and the response of cells/tissues/ organs systems to stimuli. The other criteria useful when considered with the above include specificity of the association and coherence of the association.

60. The presence of an infectious agent on a body surface and/or on surgical instruments and dressings, articles a. Infection b. Infestation c. Contamination d. Pollution Answer(c) Infection implies entry and development or multiplication of an infectious agent in the body of man or animal wherein there is a specific response of the host, e.g. immune response and/or disease Contamination, on the other hand, does not invoke any response from the host or other inanimate objects like water, milk, table- top, surgical instruments, etc. Therefore presence of Staphylococcus on intact skin means contamination of the skin but causation of abscess by the same Staphylococcus will mean infection of the skin. The term 'infestation' is used in relation to the presence of adult or pre-adult stages of arthropods on the surface or other parasites in the gut/other tissues, e.g. ascariasis, filariasis. Pollution implies presence of offensive but not necessarily infectious matter in the environment. Contamination of the body surface does not imply a carrier state. 28

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61. 61. "A clinically manifest disease of man or animal resulting from an infection' is called: a. Infectious disease b. Contagious disease c. iatrogenic disease d. Nosocomial disease Answer(a) Contagious disease is the one which is transmitted through contact. e.g. scabies, sexually transmitted diseases(STDs), trachoma. etc. Communicable disease is an illness due to a specific infectious agent or its toxic products capable of being directly or indirectly transmitted from man to man, animal to man, man to animal or animal to animal or from environment to man or animal. Infectious disease and communicable disease are both generic terms used interchangeably. The term "nosocomial disease' is restricted to consequence of hospital acquired infection, whereas iatrogenic(physician induced) disease connotates any untoward or adverse consequence of preventive/diagnostic/therapeutic procedure

62. Endemic disease means that a disease: a. Exhibits seasonal trend b. Is constantly present in a given population group c. Occurs clearly in excess of normal expectancy d. is prevalent among animals Answer(b) Endemic disease may burst into an epidemic' which is defined as unusual occurrence of a disease or other health related event in a community or region clearly in excess of the expected occurrence. Sometimes the term 'outbreak' is also used to describe a localized epidemic to minimize public panic. An epidemic is called a "pandemic" when it occurs over a geographic area such as a section of a nation, the entire nation, a continent or the entire world. As opposed to this, the term 'sporadic' is used to describe a situation where cases occur irregularly, haphazardly and generally infrequently. These cases are clearly unconnected to each other in time and space.

63. Infection maintained in both man and lower vertebrate animals that can be transmitted in either direction is: a. Amphixenoses b. Zooanthroponose c. Anthropozoonoses d. Epornithic Answer(a) a generic All of the above are examples of zoonoses which is term defined as "an infection or infectious disease transmissible from vertebrate animals to man under natural conditions'. It may be enzootic(like endemic in man) or epizootic(like epidemic in man). An outbreak of disease in a bird population is called epornithic.

64. Keeping the frequency of illness within acceptable limits is best described as a. Elimination b. Eradication 29

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c. Control d. Surveillance e. Monitoring Answer(c) Surveillance is defined as "the continuous scrutiny of the factors that determine the occurrence and distribution of disease'. Monitoring is the routine day-to-day activity for carrying out surveillance. Surveillance is necessary for effective control of disease. The term 'elimination' is used to describe removal of a disease from a large geographical area or state, e.g. measles; whereas the term 'eradication' is used to describe termination of all transmission of infection by extermination of the infectious agent itself by surveillance and control measures, e.g. smallpox.

65. "Host in which a parasite attains maturity or passes its sexual stage' is known as: a. Definitive host b. Intermediate host c. Paratenic host d. Incidental host Answer(a)

66. Man is obligatory host for: a. Malaria b. Tetanus c. Rabies d. Measles Answer(d) All the above terms are used in relation to parasitism. As opposed to definitive host intermediate host is the one in which the parasite passes its asexual phase or larval stage, e.g. fresh water snails for Schistosoma spp. A transfer or paratenic host(e.g. large predator fish for Diphyllobothrium latum) is not necessary for the completion of life cycle of the parasite but is utilized as a temporary refuge and vehicle for reaching the definitive host or obligatory host. An incidental host is the one that is accidentally infected and is not required for the parasite's survival(e.g. man for Toxoplasma Gondi).

67. 'Natural habitat in which organism metabolizes and replicates' is known as: a. Reservoir b. Source of infection c. Carrier(d) Host Answer(a) The term reservoir and source are not always synonymous, e.g. in Hookworm infection reservoir is man but the source of infection is the soil contaminated with Hookworm larva. Thus the term 'source' refers to the immediate source of infection which may or may not be a part of the reservoir. Reservoir may be of three types: human reservoir, animal reservoir and reservoir in non-living things.

68. "The first person becoming sick in an epidemic' is called: a. Index case b. Primary case 30

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c. Secondary case d. None of the above Answer(b) The term 'index case' refers to the first case, which is identified by the investigator. It may not always be the primary case. Secondary cases are those, which develop from contact with the primary case

69. All of the following are true about sub-clinical cases except a. Responsible for immunity in adults to a variety of infections(b) b. can be detected only by laboratory tests(c) c. Host does not shed the infectious agent(d) d. Play a significant role in maintaining endemicity (chain of infection) in the community. Answer(c)

Sub-clinical cases are also referred to as "missed' or 'abortive'

cases, 'in-apparent' or 'covert' cases, The disease agent may multiply in the host but does not manifest itself by signs and symptoms. These cases are equally important as sources of infection, hence maintain endemicity in an area by constantly shedding disease agent on the other hand, some of cases harbour disease agent but do not shed the same in the community. The disease agent lies dormant within the host and may not be detectable in blood, tissues or other secretions. For such a situation. the term 'latent infection' is used.

70. Sub-clinical infection is seen in all except a. Hepatitis B b. Measles c. Poliomyelitis d. Japanese encephalitis Answer(b)

71. Latent Infection is not seen in: a. Ancylostomiasis b. Brill Zinser disease c. Japanese encephalitis d. Herpes simplex Answer(c)

72. Which of the following ls the essential criterion for defining a carrier state? a. Presence of disease agent in the body b. Absence of recognizable symptoms and signs of the disease c. Shedding of the disease agent in the discharges or secretions d. All of the above Answer(d)

73. All of the following conditions describe a carrier state except: a. Person shedding disease agent only during incubation period of a disease 31

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b. Person under treatment for clinical disease c. Person shedding the disease agent even after treatment d. Person never having shown any signs and symptoms but shedding the disease agent Answer(b) Person shedding infectious agent during incubation period of disease are called incubatory carriers', e.g. measles, mumps, diphtheria, etc. Persons who continue to shed infectious agent even after treatment are called "convalescent carriers'. e.g. typhoid fever, amoebic dysentery, diphtheria, etc. Persons never having shown any signs and symptoms but shedding the infectious agent are known as healthy carriers'. Such carriers emerge from sub-clinical cases, e.g. meningococcal meningitis. poliomyelitis, cholera, etc.

74. An agent with low pathogenicity and high infectivity would result in: a. Clinical case b. Carrier c. Pandemic d. Epidemic Answer(b)

75. Epidemiological significance of carriers' ls higher than 'cases because: a. They infect more people b. They increase virulence of the agent c. They are more infectious than cases d. They cannot be treated Answer(a)

76. Carriers of a virulent organisms are known as: a. Healthy carriers b. Asymptomatic carriers c. Pseudo carriers d. All of the above e. None of the above Answer(c)

77. All of the following are modes of direct transmission of communicable disease except a. Droplet infection b. Contact with soil c. Transplacental d. Droplet nuclei Answer(d) Droplet nuclei are a type of particles in the range of 1-1o um. These represent dried residues of droplets and have a tendency to remain air-borne for long periods. Particles in the range of 1-5 um are liable to reach 32

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right up to alveoli of the lungs. These are thus indirect modes of transmission(air-borne transmission). Diseases spread by droplet nuclei include tuberculosis, influenza, chickenpox, measles, etc.

78. All of the following diseases are transmissible by contact with soil except a. Ancylostomiasis b. Leptospirosis c. Anthrax d. Leishmaniasis Answer(d) Leishmaniasis is a vector-borne disease transmitted by the bite of Phleboromus spp.

79. Vertical transmission refers to a mode of transmission of disease agent by the agency of: a. Placenta b. Blood transfusion c. Breast milk d. All of the above Answer(a) Vertical transmission is a term exclusively used for Transplacental transmission, which is another form of direct transmission, e.g. TORCH agents, human immunodeficiency virus(HIV). Even some of the non-living disease agents can also be transmitted transplacentally, eg. thalidomide, diethyl stilbestrol. etc.

80. Vertical transmission is seen in all of the following except: a. Hepatitis B b. Measles c. Cytomegalovirus d. Coxsackie B virus Answer(b)

81. In biological mode of transmission, which of the following is incorrectly matched? a. Agent changes in form and number: cyclopropaga- tive b. Agent changes from nymph to adult stage: trans- stadial c. Agent transmitted vertically: transovarial d. Agent changes in form but not in number: cyclopropagative Answer(d) In cyclopropagative mode of biological transmission. the infectious agent changes both in form and number, e.g. malarial parasite in mosquito.

82. Cyclodevelopmental mode of transmission is seen In: a. Malaria b. Filariasis c. Cholera d. Plague Answer(b) 33

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83. cyclopropagative mode of transmission is seen In: a. Plague bacilli in rat flea b. Japanese encephalitis c. Guinea worm embryo in cyclops d. Malarial parasite in mosquito Answer(d)

84. The time interval between receipt of infection by a host and maximal infectivity of that host is: a. Incubation period b. Period of communicability c. Generation time d. Latent period e. Serial interval Answer(c) the incubation period in general, generation time roughly matches period but these two terms are not synonymous, Incubation period (clinical incubation period is defined as, "the time interval between invasion by an infectious agent and appearance of the first sign or symptoms of the disease in question The term" median incubation period' is used to define the time required for 50% of the cases to occur following exposure. Period of communicability" refers to the time during which an infectious agent may be transferred from infected man or animal to another man or animal directly or indirectly. This period may be shorter than incubation period or prolonged beyond incubation period. "Latent period' is the term used in relation to non-infectious diseases such as cancer, heart diseases. etc. as equivalent of incubation period. The term 'serial interval' is applied in relation to outbreaks and describes "the gap in time between the onset of primary case and secondary case'. It gives an indication of the incubation period during an outbreak of the disease

85. The time between invasion of an infectious agent and detection of evidence of the infectious agent by laboratory means' is known as: a. Prepatent period b. Incubation period c. Generation time d. Serial interval Answer(a) Prepatent period is generally shorter than clinical incubation period, e.g. IgM antibodies may become detectable in many cases before appearance of clinical signs and symptoms.

86. The importance of secondary attack rate is that it reflects: a. Fatality b. Severity c. Communicability d. All of the above 34

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Answer(c) Secondary attack rate(SAR) is defined as, "the number of exposed persons developing the disease within the range of incubation period following exposure to the primary case'. It is deduced from the formula: Number of exposed persons developing the disease within one incubation period x 100 SARA Total number of exposed susceptible contacts It may be noted that immune contacts are to be excluded from the denominator: primary case is to be excluded both from numerator and denominator, e.g. in a family of eight including the parents(immune), the grandparents(immune) and four children(susceptible), for a disease like measles, if there is a primary case of measles followed by two secondary cases among the remaining children the SAR will be 2/3, ie. 66.6%.

87. All of the following are used as proxy measures for incubation period except a. Serial interval b. Period of communicability c. Latent period d. Generation time Answer(b)

88. Infants are protected against infectious diseases in first 3 months of life on account of: a. Antibodies and other factors in breast milk b. Presence of foetal haemoglobin c. Maternal antibodies transferred to the baby d. All of the above e. None of the above Answer(d)

89. All of the following are true statements in relation to herd immunity except a. It is affected by occurrence of clinical cases b. It is not affected by occurrence of sub-clinical Cases c. It is affected by the presence and distribution of alternative animal hosts d. It refers to group protection beyond that afforded by the protection of immunized individuals Answer(b) Herd immunity implies level of resistance of a community or a group of people(herd) to a particular disease. It depends on three factors: i. Occurrence of clinical and sub-clinical infections in the herd ii. Immunization status of the herd iii. Herd structure, which is never constant due to new births. deaths, migrations, etc. and includes presence of hosts of other species like animals, insects as well as environmental and social factors It may be noted that herd immunity does not protect the individual in case of tetanus.

90. Active immunity can be acquired by all of the following except a. Inoculation with immune serum b. Inoculation with live or killed vaccine 35

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c. Inoculation with toxoids d. Exposure to infectious agents Answer(a)

Immune serum contains immunoglobulins, which only render passive immunity. 91. Active Immunity with sub-clinical infection is seen In: a. Measles b. Poliomyelitis c. Rubella d. Chickenpox Answer(b)

92. Nature and extent of primary response to an antigen depends on a. Nature and dose of antigen b. Route of administration c. Adjuvants d. Nutritional status of host e. All of the above Answer(e)

Primary response depends on the dose of antigen, to the extent that with a small dose only IgM response may be elicited which is immediate. I response peaks in 7-10 days but needs about 50 times the dose of antigen. An important outcome of the response is development of immunological memory based on T The accelerated secondary response on a subsequent antigenic stimulus(booster) is the result of this immunological memory. 93. All of the following are characteristics of a secondary immune response' except a. Antibody production is more abundant b. Antibodies have greater capacity to bind with the antigen c. Response lasts for a shorter period d. Shorter latent period Answer(c)

94. Which of the following statements is not true in relation to live vaccines? a. Produce a long and durable immunity b. Are more potent than killed vaccines because have the entire major and minor antigenic components c. Booster doses are required to maintain the level of immunity d. Are more potent than killed vaccines as organisms can multiply in the host thus resulting in greater antigenic dose Answer(c) 36

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95. Which of the following is not a contraindication for live vaccines? a. Pregnancy b. Corticosteroid therapy c. Malignancy d. Administration of another vaccine Answer(d) Two live vaccines can be given simultaneously, however, they should be administered at different sites or with an interval of at least 3 weeks.

96. All of the following are live vaccines except a. Rubella b. Measles c. Salk d. 17-D Answer(c) Salk is a killed polio vaccine given parentally

97. Frozen DPT vaccine should be: a. Shaken thoroughly before use b. Allowed to melt before use c. Brought to room temperature before use d. Discarded Answer(d)

98. 98. After administration of live vaccine, immunoglobulins can be given after: a. 1 week b. 2 weeks c. 8 weeks d. 12 weeks Answer(b) Immunoglobulins should not be given within 2 weeks of administration of live vaccine as this may jeopardize the immune response to the vaccine.

99. Which class of immunoglobulins is transported across placenta? a. IgM b. IgD c. IgG d. IgA Answer(c)

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100. Which of the following vaccines must be stored in the freezer compartment of the refrigerator? a. Oral polio b. Measles c. Both of the above d. None of the above Answer(c) All vaccines as a general rule must be stored under the conditions recommended by the manufacturer. Polio and measles are live vaccines which are thermo-labile and should be stored preferably at-20°C. Vaccines which must never be allowed to freeze but stored in the cold part of the refrigerator(4-8°C) are typhoid, DPT, DT, TT, BCG and diluents.

101. Cold chain equipment located at regional level is: a. Deep freezer 300 L b. Deep freezer 140 L c. Ice lined refrigerator(ILR) 300 L d. Walk in cold rooms Answer(d) Walk in cold rooms are meant to store vaccines for 3 months and serve 4-5 districts. Large deep freezers and ILRs are placed at district headquarters. Small deep freezers and ILRs are placed at Primary Health Centres (PHCs, Urban Centres, etc. lce packs are prepared in deep freezer. Smaller cold chain equipment like cold boxes/vaccine canniers day carriers are used for transportation of vaccines from larger centres or for outreach services.

102. A-year-old child has not received primary immunization. Which of the following is the best vaccination advice to such a child? a. BCG, DPT1, OPV1, and DPT2, OPV2 after 4 weeks b. BCG, DT1, OPV1, measles, Vitamin A c. BCG, DPT1, OPV1, measles, HB1, Vitamin A d. DTI, DT2 and booster after 1 year. Answer(c) As per Indian Academy of Pediatrics(LAP) guidelines, schedules have been suggested for unimmunized children aged less than 5 years as apart from more than 5 years. The schedules take into consideration possibility of faulty compliance on subsequent dosage. Hence measles/MMR vaccine can be given at the first contact itself along with other vaccines. The suggested schedule for unimmunized child is as under:

103. The Expanded Programme of Immunization(EPI) was started in India in 1978. It included all of the following vaccines except: a. BCG b. Measles c. Typhoid d. DPT Answer(b) 38

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The EPI was originally started by WHO in 1974 and was adopted by the Government of India in 1978. It included only BCG, DPT and typhoid for children under 5 years of age. It did not include measles vaccine and OPV was added in 1979. This programme continued up to 1987. EPI was supplanted by Universal Immunization Programme(UIP) in 1985. The Government of India subsequently set up the Technology mission on vaccination and immunization of vulnerable populations, specially children'. The UIP is current till now and is integral part of Reproductive and Child Health(RCH) Programme since 1997. The immunization activities in India are largely supported by UNICEF.

104. The funding agency for Global Alliance for Vaccine and Immunization(GAVI) is: a. UNICEF b. WHO c. Ford foundation d. Bill and Melinda Gates foundation Answer(d) GAVI was set up in 1999 as an international coalition of multinational funding agencies, vaccine manufactures, non government organizations(NGOs) and governments of 74 developing countries. The activities are organized through a vaccine fund. Bill and Melinda Gates foundation and Rockefeller foundation are the main funding agencies for GANI The GAVI India project has launched free hepatitis B immunization in some urban slums and promotes safe injection practices and use of auto-disable syringes for immunization as part of a countrywide initiative

105. For HIV positive infants, the immunization schedule recommended is: a. No vaccine b. Only killed vaccines c. Normal schedule as per UlP d. Killed and live vaccines without BCG Answer(c) WHO UNICEF categorizes HIV positive children for the purpose of immunization into symptomless and symptomatic HIV infection. Normal UIP schedule is recommended for both categories except for BCG, which is contraindicated in symptomatic HIV infection being dependent on cell-mediated immunity

106. Measles vaccine is prepared from which of the following viral strains? a. Edmonston-Zagreb strain grown on human diploid cells b. OKA strain grown on human diploid cells c. Genetically engineered recombinant vaccine d. Sabin strain grown in primary monkey kidney(PMK) cells Answer(a)

107. Ring vaccination is: a. Given to produce a ring lesion b. Given around 100 yards of a case detected c. Given by ring-shaped machine d. Given around a mile of a case 39

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Answer(b) Ring vaccination immunization is an operational device for creating a virtual isolation of the infected person with a barrier of immune persons in order to contain the infection locally. This method was successfully used for eradication of smallpox. This method is also being applied in North America in measles control and eradication.

108. Toxic shock syndrome(TSS) is an adverse reaction related to: a. Any vaccine b. OPV c. BCG d. Measles Answer(d) TSS is consequent of contamination of measles vaccine with Staphylococcus aureus. It occurs within 30 minutes to few hours and is characterized by mounting fever, vomiting, diarrhoea and septic shock. It is managed with IV fluids, antimicrobials such as cloxacillin 50-100 mg/kg/24 hour, steroids, antipyretics and supportive therapy.

109. "Separation for the period of communicability of infected persons or animals from others' is termed as: a. Quarantine b. Segregation c. Isolation d. All of the above Answer(c) 'Isolation' is generally applied to patients suffering from infectious disease for the period of communicability. The purpose of isolation is to protect the community by preventing transfer of infection from the possible susceptible hosts. has distinct value in control of some highly infectious diseases such as diphtheria, pneumonic plague, cholera, and streptococcal respiratory disease. Isolation is unlikely to be effective for spread of diseases which has large component of sub-clinical infections and/or carrier state, e.g. polio, hepatitis A, typhoid fever, etc. 'Segregation' is the term used conventionally for contacts of the infectious patient. It is carried out for the duration of longest known incubation period with segregated persons kept under close observation. "Quarantine' is defined as limitation of freedom of movement of such well persons or domestic animals exposed to a communicable disease, for a period not longer than the longest usual incubation period of the disease in such a manner as to prevent effective contact with those not so exposed' Quarantine measures are also applied by health authorities to a ship, an aircraft, a train or container to prevent the spread of disease.

110. Isolation is useful in preventing the spread of all of the following diseases except a. Cholera b. Diphtheria c. Hepatitis A d. Pneumonic plague Answer(c)

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111. Chemoprophylaxis is indicated in all of the following except: a. Typhoid b. Malaria c. Cholera d. Meningococcal meningitis Answer(a)

112. The process, which destroys all microbial life including spores' is known as: a. Disinfection b. Antisepsis c. Deodorization d. Sterilization Answer(d) "Antisepsis' relates to destruction or inhibition of microorganisms in living tissues, e.g. Savlon, Dettol, chlorhexidine,etc. Deodorant is a substance which suppresses or neutralizes bad odours, e.g. lime, bleaching powder. Detergents' are surface cleaning agents and act by lowering the surface tension there breaking up the by fat covering of dirt, e.g. Disinfection' is the killing of infectious agents outside the body by direct exposure to chemical or physical agents. The term is usually applied to inanimate objects or surfaces, e.g. phenol, sunlight, cresol, hypochlorite solution, etc. Chemical disinfectants in small doses or dilutions can also act as antiseptics.

113. Which of the following is not a complete sterilizing agent? a. Glutaraldehyde b. Absolute alcohol c. Hydrogen peroxide d. Sodium hypochlorite Answer(b) Absolute alcohol is not effective against spores, hence cannot be termed as complete sterilizing agent.

114.

Disinfectant action of sunlight is due to: a. UV rays b. Infrared rays c. Heating effect d. None of the above Answer(a)

115. Glass vessels and syringes are best sterilized by: a. Hot air oven b. Gamma irradiation c. Autoclaving d. Ethylene dioxide Answer(a) 41

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116. All of the following can be sterilized by autoclaving except: a. Gloves b. Plastic material c. Linen d. Culture media Answer(b)

117. Choleric stool is best disinfected by: a. Phenol b. Formaldehyde c. Cetrimide d. Bleaching powder Answer(d) Bleaching powder in a dose of 50 g/L is used for disinfecting stools.

118. Gamma irradiation is used to sterilize: a. Linen b. Surgical instruments c. Disposable material d. Glass syringes Answer(c

119. Spores are killed by using: a. Bleaching powder b. Formaldehyde c. Autoclaving d. Absolute alcohol Answer(c)

120. Best method of sterilization of linen is: a. Autoclaving b. Hot air oven c. Radiation d. Chemicals Answer(a)

121. Dettol is: a. Hexachlorophane b. Cetavlon c. Chloroxylenol d. Cetrimide Answer(c) 42

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122. Which of the following is not a suitable agent for disinfection of faeces and urine? a. 5% cresol b. 1-2% formalin c. 5% bleaching powder d. 10% phenol A nou or Answer b

123. The most effective skin antiseptic is: a. Alcohol solution of chlorhexidine b. Dettol c. Alcohol d. None of the above Answer(a)

124. Which of the following best describes the objective of an epidemic investigation? a. To define the magnitude of the epidemic b. To determine particular conditions and factors responsible c. Identify the cause/source of infection d. To make recommendations to prevent recurrence e. All of the above Answer(e)

125. First step in the sequence of actions for investigation of an epidemic is: a. Confirmation of the existence of an epidemic b. Defining the population at risk c. Rapid search for all cases and their characteristics d. Verification of diagnosis Answer(d) Verification of diagnosis is the first step in an epidemic investigation as it may happen, not infrequently, that the so- called occurrence of an epidemic may be based on misinterpretation of signs and symptoms by the lay public and or media. Once the diagnosis has been verified on the spot as quickly as possible, the logical sequence of steps to be taken for investigation is as follows: i. ii. iii. iv. v.

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Step 1: Confirmation of the existence of the epidemic. Step 2. Defining the population at risk. Step 3: Rapid search of all cases and their characteristics. Step 4: Data analysis. Step 5: Formulation of hypotheses. After that, the hypothesis should be tested followed by evaluation of ecological factors, further investigation of population at risk and writing of report.

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Chapter 4 Screening for Disease 1. The active search for unrecognized disease or defect in apparently healthy people using rapidly applied tests or procedures' is: a. Case finding b. Active surveillance c. Screening d. Monitoring e. All of the above Answer(c) Screening is the fundamental disease prevention action. It is an effective device to uncover the hidden portion of iceberg of disease' and thus forms the cornerstone for secondary prevention action, i e. 'early diagnosis and treatment'. Screening has got a wider application than mere "case finding' as we are able to detect disease very early in its natural history when clinical signs and symptoms may not be present.

2. Periodic health examinations differ from screening for disease in the following respects: a. Not capable of wide application b. Relatively expensive c. Require considerable physician time d. All of the above Answer(d)

3. The time interval between diagnosis by early detection and diagnosis by other means is: a. Serial interval b. Lead time c. Time lag. d. Latent period Answer(b) Lead time is the advantage gained by screening. Therefore screening Programmes are useful for those conditions where the time lag between the disease onset and final critical point for treatment to be effective is sufficiently long.

4. All of the following are true for a screening test except a. Less accurate b. Forms the basis for treatment c. Test results are arbitrary 44

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d. Less expensive Answer(b) Screening tests are only arbitrary, less accurate, less expensive and do not form the basis for treatment as a specific diagnostic test' will need to be performed to confirm the diagnosis suggested by a screening test in order to start a specific treatment.

5. Multiphasic screening' means: a. Application of two or more screening tests in combination at one time b. Application of two or more screening tests in combination at different time c. Application of two or more screening tests in combination at different geographical area d. Application of separate screening tests for a single disease Answer(a) Multiphasic screening is losing its popularity now on account of high costs, unproven validity of results and insignificant benefits towards reduction of morbidity and mortality. "High risk' or 'selective screening' is more feasible and cost-effective, e.g. screening for cancer cervix in lower socio-economic groups is likely to yield more cases than upper socio-economic groups due to its prevalence patterns. The concept has been extended to screen selected populations for risk factors rather than the disease, e.g. elevated serum cholesterol. Mass screening is simply screening of a whole population or a sub-group irrespective of the individual being at risk for a particular disease or not. It is not considered a useful preventive measure.

6. Criteria for a disease fit for screening include: a. It should be an important public health problem b. Facilities should be available for confirmation of diagnosis c. Effective treatment should be available d. There should be sufficiently long lead time available e. All of the above Answer(e)

7. In addition to the acceptability and cost effectiveness, a good screening test should be: a. Repeatable b. Not repeatable c. Highly specific though may not be sensitive d. None of the above Answer(a) The criteria for an ideal screening test include acceptability. Repeatability and validity in addition to other parameters as

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