Consider the following definition : "A high level of infection beginning early in life and affecting most of the child population, leading to a state of equilibrium such that the adult population shows evidence of the disease much less commonly than the children." Which one of the following terms best fits this definition?
Q1442
Which of the following statements are correct for incidence rate?
1. It is useful for taking action to control a disease.
2. Rising incidence rates may indicate ineffectiveness of the current control programmes.
3. Fluctuation in incidence rate may indicate a change in aetiology of disease. Select the answer using the code given below.
Q1443
A town in the hills had a mid-year population of 250000 in the year 2021. During the same year, the death registry of the town recorded 1500 deaths due to tuberculosis in 365 calendar days. Given these facts, what is the specific death rate for tuberculosis in the town?
Q1444
In a town, a study was carried out to determine the role of cigarette smoking in causation of lung cancer. It was found that a total of 7000 people in the town were smokers. Of them, 70 developed lung cancer. In the same town, 3000 people were non-smokers. Of them, 3 developed lung cancer. Given these numbers, what would be the attributable risk to cigarette smoking for lung cancer?
Q1445
Which of the following are correct in respect of incidence rate?
1. It is a sum total of new and old cases.
2. It refers to a specified period of time.
3. It refers to a defined population.
4. It must include the unit of time in final expression.
Q1446
Which of the following is the most fundamental criterion that must be met by a disease before it is to be considered suitable for a screening programme?
1. The natural history of the disease should be adequately understood.
2. No effective treatment should exist for the disease.
3. The disease should not have a recognizable latent or asymptomatic stage.
4. There should be a test that can detect the disease prior to onset of signs and symptoms.
Q1447
Virulence of a biological agent is defined as
Q1448
Secular trends of diseases refer to
Q1449
In which system, continuous enumeration of births and deaths by enumerator and an independent survey by investigator supervisor is done?
Q1450
The degree to which a specific health care intervention achieves its objectives, when applied in a given population, is termed as its
Epidemiology Indian Medical PG Practice Questions and MCQs
Question 1441: Consider the following definition : "A high level of infection beginning early in life and affecting most of the child population, leading to a state of equilibrium such that the adult population shows evidence of the disease much less commonly than the children." Which one of the following terms best fits this definition?
A. Hyperendemic
B. Hypoendemic
C. Holoendemic (Correct Answer)
D. Pandemic
Explanation: ***Holoendemic***
- This term describes a situation where an infection is **highly prevalent** early in life, affecting most children, leading to a state of **equilibrium** in adulthood where the disease is less common.
- This pattern is often observed with diseases like **malaria** in endemic regions, where early exposure leads to acquired immunity.
*Hyperendemic*
- Refers to a disease that is **persistently present** at a **high level** of incidence and/or prevalence in a specific population, affecting all age groups, not specifically children.
- While reflecting high prevalence, it doesn't emphasize the early-life infection leading to adult equilibrium as strongly as holoendemic.
*Hypoendemic*
- This term describes a disease with a **low level of incidence and prevalence** within a population.
- It implies infrequent disease occurrence, which is the opposite of the high initial infection rate described in the definition.
*Pandemic*
- A **widespread epidemic** of an infectious disease that has spread across a large region, multiple continents, or even worldwide.
- This term describes the geographical extent of a disease outbreak, not its specific pattern of age-related prevalence or immunity within a single population.
Question 1442: Which of the following statements are correct for incidence rate?
1. It is useful for taking action to control a disease.
2. Rising incidence rates may indicate ineffectiveness of the current control programmes.
3. Fluctuation in incidence rate may indicate a change in aetiology of disease. Select the answer using the code given below.
A. 2 and 3 only
B. 1, 2 and 3 (Correct Answer)
C. 1 and 3 only
D. 1 and 2 only
Explanation: ***1, 2 and 3***
- All three statements about **incidence rate** are correct. Incidence rate measures the rate at which new cases of a disease occur in a population at risk during a specified period.
- **Statement 1 is correct**: Incidence rate is fundamental for **public health action and disease control**. It identifies when and where new cases are occurring, enabling targeted interventions and resource allocation.
- **Statement 2 is correct**: **Rising incidence rates during control programmes** clearly indicate that current measures are ineffective or inadequate. This serves as a critical feedback mechanism for evaluating and modifying disease control strategies.
- **Statement 3 is correct**: **Fluctuations in incidence rate may indicate changes in disease etiology**. The word "may" is key - while fluctuations can result from detection or reporting changes, they can also signal genuine etiological shifts such as emergence of new pathogen variants, changes in virulence, or alterations in environmental risk factors. Monitoring incidence trends is specifically used to detect such etiological changes.
*1 and 2 only*
- This option incorrectly excludes Statement 3. Fluctuations in incidence rate **can indeed indicate etiological changes**, which is why epidemiologists monitor incidence trends to detect emerging variants, changes in transmission patterns, or new risk factors.
- The statement uses "may indicate" (not "always indicates"), making it epidemiologically accurate.
*2 and 3 only*
- This option incorrectly excludes Statement 1. The **incidence rate is essential for disease control action** - it is the primary metric used to identify disease burden, track trends, and guide intervention strategies.
- Without monitoring incidence, public health authorities cannot effectively plan or implement control measures.
*1 and 3 only*
- This option incorrectly excludes Statement 2. A **rising incidence rate** is a clear indicator of control programme failure or inadequacy, making it crucial for programme evaluation and modification.
- Ignoring this relationship would mean missing vital feedback on intervention effectiveness.
Question 1443: A town in the hills had a mid-year population of 250000 in the year 2021. During the same year, the death registry of the town recorded 1500 deaths due to tuberculosis in 365 calendar days. Given these facts, what is the specific death rate for tuberculosis in the town?
A. 10
B. 60
C. 1
D. 6 (Correct Answer)
Explanation: ***6***
- The **specific death rate** (also called cause-specific death rate) is calculated as **(Number of deaths from a specific cause / Mid-year population) × 1000**
- For tuberculosis: (1500 deaths / 250,000 population) × 1000 = **6 deaths per 1000 population**
- This represents the tuberculosis mortality rate in the community
*10*
- This incorrect value would be obtained if there were 2500 deaths due to tuberculosis instead of 1500
- Calculation error: (2500 / 250,000) × 1000 = 10
- Always verify the numerator (number of deaths) from the given data
*60*
- This is a common calculation error resulting from incorrect multiplication factor
- May occur if using: (1500 / 250,000) × 10,000 = 60 (wrong multiplier)
- Remember: specific death rate uses **per 1000** population, not per 10,000
*1*
- This value results from calculation errors or incorrect rounding
- May occur if dividing by wrong population figure or forgetting the multiplier
- The actual rate (1500/250,000 = 0.006) must be multiplied by 1000 to get rate per 1000 population
Question 1444: In a town, a study was carried out to determine the role of cigarette smoking in causation of lung cancer. It was found that a total of 7000 people in the town were smokers. Of them, 70 developed lung cancer. In the same town, 3000 people were non-smokers. Of them, 3 developed lung cancer. Given these numbers, what would be the attributable risk to cigarette smoking for lung cancer?
A. 30%
B. 10%
C. 60%
D. 90% (Correct Answer)
Explanation: **90%**
- The **attributable risk** (AR) is calculated as the incidence in the exposed group minus the incidence in the unexposed group, divided by the incidence in the exposed group, all multiplied by 100%.
- Incidence in smokers (Ie) = 70 cases / 7000 smokers = 0.01. Incidence in nonsmokers (Io) = 3 cases / 3000 nonsmokers = 0.001. AR = ((0.01 - 0.001) / 0.01) * 100% = (0.009 / 0.01) * 100% = 0.9 * 100% = **90%**.
*30%*
- This percentage is incorrect; it does not align with the formal calculation of **attributable risk** based on the given incidence rates in exposed and unexposed groups.
- A value of 30% would imply a much smaller difference in incidence between smokers and non-smokers relative to the incidence in smokers.
*10%*
- This value might be obtained if the calculation confused **attributable risk** with the proportion of cases in the unexposed group or some other miscalculation.
- It significantly underestimates the proportion of lung cancer in smokers directly attributable to their smoking status.
*60%*
- This answer is incorrect as it does not result from the appropriate application of the **attributable risk formula**.
- The discrepancy between the incidence rate in smokers (0.01) and non-smokers (0.001) is much higher than what would lead to a 60% attributable risk.
Question 1445: Which of the following are correct in respect of incidence rate?
1. It is a sum total of new and old cases.
2. It refers to a specified period of time.
3. It refers to a defined population.
4. It must include the unit of time in final expression.
A. 2. It refers to a specified period of time. (Correct Answer)
B. 1. It is a sum total of new and old cases.
C. 4. It must include the unit of time in final expression.
D. 3. It refers to a defined population.
Explanation: ***Statement 2: It refers to a specified period of time*** (Most Distinctive)
- Incidence rate MUST be measured over a defined time interval (e.g., 1 year, 6 months)
- This temporal component is the **key distinguishing feature** from point prevalence
- Essential for calculating the rate at which new cases develop
**Note:** Statements 3 and 4 are also technically correct about incidence rate:
**Statement 3: It refers to a defined population** - Also correct
- Incidence rate requires a clearly defined **population at risk** as denominator
- However, this alone is not unique to incidence (prevalence also uses defined populations)
**Statement 4: It must include the unit of time in final expression** - Also correct
- Incidence **rate** is expressed per unit time: "cases per 1,000 person-years"
- This distinguishes it from cumulative incidence (a proportion)
- The time component IS part of the rate expression
*Statement 1: It is a sum total of new and old cases* ✗
- This describes **prevalence**, not incidence
- Incidence counts only **NEW cases** during the observation period
- Existing (old) cases are excluded
**Clarification:** While statement 2 is traditionally considered the most distinctive feature, epidemiologically statements 3 and 4 are also accurate characteristics of incidence rate. If the question asks "which are correct" (plural), technically 2, 3, and 4 would all be correct.
Question 1446: Which of the following is the most fundamental criterion that must be met by a disease before it is to be considered suitable for a screening programme?
1. The natural history of the disease should be adequately understood.
2. No effective treatment should exist for the disease.
3. The disease should not have a recognizable latent or asymptomatic stage.
4. There should be a test that can detect the disease prior to onset of signs and symptoms.
A. 4. There should be a test that can detect the disease prior to onset of signs and symptoms.
B. 3. The disease should not have a recognizable latent or asymptomatic stage.
C. 1. The natural history of the disease should be adequately understood. (Correct Answer)
D. 2. No effective treatment should exist for the disease.
Explanation: ***The natural history of the disease should be adequately understood.***
* This is the **most fundamental criterion** because understanding the natural history (progression from asymptomatic to symptomatic disease) allows for the identification of a **critical window** for early intervention through screening.
* Without this knowledge, it's impossible to determine when to screen, what to screen for, or whether early detection will lead to a better outcome.
*There should be a test that can detect the disease prior to onset of signs and symptoms.*
* While important, the existence of a detectable test *before* symptoms is only useful if the **natural history** is understood, allowing for appropriate timing and interpretation of the test.
* A test without understanding the disease's progression might lead to **overdiagnosis** or diagnosis at a stage where intervention is no longer effective.
*The disease should not have a recognizable latent or asymptomatic stage.*
* This statement is incorrect; a disease *must* have a **recognizable latent or asymptomatic stage** to be suitable for screening.
* Screening aims to detect disease **before** symptoms appear, making the existence of such a stage essential for successful early intervention.
*No effective treatment should exist for the disease.*
* This statement is incorrect; for a screening program to be beneficial, an **effective treatment must exist** for the disease once detected.
* Screening without effective treatment options would merely lead to earlier diagnosis without improving patient outcomes, causing unnecessary anxiety and burden.
Question 1447: Virulence of a biological agent is defined as
A. Proportion of clinical cases in a virgin population
B. Proportion of clinical cases resulting in severe clinical manifestation (Correct Answer)
C. Ability of the agent to induce a clinically apparent illness
D. Ability of the agent to invade and multiply in a host
Explanation: ***Proportion of clinical cases resulting in severe clinical manifestation***
- **Virulence** specifically refers to the **severity** of disease caused by a pathogen, often measured by the proportion of cases that lead to severe symptoms, disability, or death.
- A highly virulent pathogen is one that is more likely to cause significant harm once an infection is established.
*Proportion of clinical cases in a virgin population*
- This definition is more closely related to **attack rate** or **infectivity** in a susceptible population, not directly to the severity of the disease once infection occurs.
- It does not capture the degree of harm caused by the pathogen.
*Ability of the agent to induce a clinically apparent illness*
- This describes the concept of **pathogenicity**, which is the ability of an organism to cause disease in the first place, regardless of its severity.
- While related, pathogenicity is a broader term than virulence.
*Ability of the agent to invade and multiply in a host*
- This characteristic refers to the **infectivity** and **invasiveness** of a pathogen, which are factors contributing to its ability to establish an infection.
- It doesn't define the severity of the disease once the infection has taken hold.
Question 1448: Secular trends of diseases refer to
A. Changes in incidence as per climate
B. Differences in incidence across different religions
C. Variation in occurrence across various social strata
D. Changes in occurrence over long period of time (Correct Answer)
Explanation: **Changes in occurrence over long period of time**
- **Secular trends** describe the changes in the **frequency or pattern of a disease** or health condition over a long-term period, often spanning decades.
- This concept is crucial in epidemiology for understanding the **evolution of diseases** and the impact of long-term public health interventions or societal changes.
*Changes in incidence as per climate*
- This refers to **seasonal variation** or **geographic variation** related to climate, not the sustained, long-term changes that define secular trends.
- While climate can influence disease incidence, it typically causes cyclical or regional patterns rather than continuous long-term shifts.
*Differences in incidence across different religions*
- This describes **religious or cultural variations** in disease occurrence, which are a form of **social or demographic determinant**, but not secular trends.
- Secular trends focus on changes over time, while religious differences are usually cross-sectional comparisons at a given point or period.
*Variation in occurrence across various social strata*
- This refers to **socioeconomic disparities** or **social gradients** in health outcomes, indicating differences between various social classes or groups.
- While social factors can drive secular trends, secular trends specifically denote **changes over time**, not static differences between groups.
Question 1449: In which system, continuous enumeration of births and deaths by enumerator and an independent survey by investigator supervisor is done?
A. Sample Registration System (Correct Answer)
B. Decadal census enumeration
C. Model Registration System
D. National Family Health Survey
Explanation: ***Sample Registration System***
- This system employs a **dual record approach** where a local enumerator continuously records vital events (births and deaths), and an independent investigator supervisor conducts periodic surveys.
- The combination of continuous enumeration and independent surveys helps to improve the **accuracy and completeness** of vital statistics by cross-checking data.
*Decadal census enumeration*
- This involves a **complete enumeration** of the population, typically conducted every ten years, to gather demographic and social data.
- While it collects population counts and some vital statistics, it is not designed for **continuous monitoring** or a dual-record system for births and deaths.
*Model Registration System*
- This system focuses on developing and testing **improved methods** for vital event registration in a localized or pilot area.
- It is not a nationwide system for continuous enumeration and independent surveys, but rather a framework for **methodological development**.
*National Family Health Survey*
- This is a large-scale, multi-round survey that provides data on **family health, fertility, child mortality**, and other health indicators.
- It uses **recall methods** and questionnaires to collect data from households and does not involve continuous enumeration of births and deaths by enumerators or independent supervisor verification.
Question 1450: The degree to which a specific health care intervention achieves its objectives, when applied in a given population, is termed as its
A. Sensitivity
B. Impact
C. Effectiveness (Correct Answer)
D. Efficiency
Explanation: ***Effectiveness***
- **Effectiveness** measures how well an intervention performs in a **real-world setting** under usual conditions in a given population [1]
- It assesses the degree to which a healthcare intervention achieves its **intended objectives** when applied in actual practice (as opposed to controlled trial conditions) [1]
- Key distinction: effectiveness = real-world performance; efficacy = performance under ideal/controlled conditions [1]
*Sensitivity*
- **Sensitivity** is a diagnostic test parameter measuring the proportion of actual positive cases correctly identified by the test
- It relates to **test accuracy**, not to the achievement of intervention objectives in a population
*Impact*
- **Impact** refers to the broader, longer-term consequences of an intervention on **health outcomes** or population health status
- While related to effectiveness, impact is a more **comprehensive measure** that includes indirect effects and long-term changes, not just the direct achievement of specific intervention objectives [1]
*Efficiency*
- **Efficiency** relates to the relationship between **resources used** (cost, time, personnel) and **results achieved**
- It addresses whether an intervention achieves its objectives with **optimal resource utilization**, focusing on cost-effectiveness rather than simply whether objectives are met
