Community Medicine
10 questionsWhich one of the following is FALSE regarding confounding factor in epidemiological studies ?
Denominator in calculation of case fatality rate is:
An important measure of communicability of a disease is
Which of the following statements is NOT correct regarding case fatality rate?
Farmer's lung is caused by the inhalation of:
Suraksha Clinics are conducted under the aegis of which National Health Programme?
In a normal distribution, Mean ± 2 S.D. contains
Infant Mortality Rate is expressed per:
Which of the following tests is NOT used for checking quality of pasteurisation of milk?
Which of the following are the components of epidemiological triad?
UPSC-CMS 2017 - Community Medicine UPSC-CMS Practice Questions and MCQs
Question 81: Which one of the following is FALSE regarding confounding factor in epidemiological studies ?
- A. Source of bias is interpretation
- B. Associated both with exposure and disease
- C. Independent risk factor for disease in question
- D. Distributed equally between study and control groups (Correct Answer)
Explanation: ***Distributed equally between study and control groups*** - A **confounding factor** is, by definition, **not equally distributed** between study (exposed) and control (unexposed) groups, as this unequal distribution leads to the observed bias. - If a potential confounder were equally distributed, it would not distort the relationship between the exposure and the outcome. *Source of bias is interpretation* - Confounding is a source of **bias in interpretation** because it can create a spurious association or mask a true one between an exposure and an outcome. - It leads to an incorrect conclusion about the causal relationship, even if the data collection itself was accurate. *Associated both with exposure and disease* - For a variable to be a confounder, it must be **associated with the exposure** being studied (e.g., smoking is associated with alcohol consumption). - It must also be an **independent risk factor for the disease** outcome (e.g., alcohol consumption is an independent risk factor for esophageal cancer). *Independent risk factor for disease in question* - A confounder must be an **independent risk factor** for the disease outcome, separate from its association with the primary exposure. - This means it influences the disease risk regardless of the exposure being investigated.
Question 82: Denominator in calculation of case fatality rate is:
- A. Total number of cases due to the disease concerned (Correct Answer)
- B. Total number of hospital admissions
- C. Total number of deaths due to all causes
- D. Total number of deaths due to the disease concerned
Explanation: ***Total number of cases due to the disease concerned*** - The **case fatality rate (CFR)** measures the **proportion of deaths** among individuals diagnosed with a specific disease. - The denominator for CFR is defined as the **total number of confirmed cases** of that disease in a given population and time period. - Formula: CFR = (Deaths from disease / Total cases of disease) × 100 *Total number of hospital admissions* - This value represents the total number of individuals admitted to the hospital, which may include patients with various conditions, not just the specific disease of interest. - Using this as the denominator would incorrectly dilute the severity of the disease in question by including individuals not directly affected by it. *Total number of deaths due to all causes* - This figure encompasses all deaths in a population, regardless of cause, and is typically used in calculations like the **crude death rate**. - It does not specifically relate to the severity or outcome of a particular disease and therefore cannot serve as the denominator for case fatality. *Total number of deaths due to the disease concerned* - This value represents the **numerator** in the calculation of the case fatality rate, as it quantifies the number of deaths attributable to the specific disease. - Using it as the denominator would lead to a calculation of 100% if the number of deaths equals the number of cases, which would be incorrect for CFR calculations.
Question 83: An important measure of communicability of a disease is
- A. Secondary attack rate (Correct Answer)
- B. Incidence rate
- C. Prevalence rate
- D. Case fatality rate
Explanation: ***Secondary attack rate*** - The **secondary attack rate** quantifies the probability of infection among **susceptible contacts** of a primary case. - It is a direct measure of the **person-to-person transmissibility** or **communicability** of an infectious disease within a defined population. - Calculated as: (Number of cases among contacts / Total number of susceptible contacts) × 100 *Incidence rate* - The **incidence rate** measures the rate at which **new cases** of a disease occur in a population over a specified period. - While related to disease spread, it does not specifically describe transmission from an existing case to a close contact. *Prevalence rate* - The **prevalence rate** measures the **proportion of individuals** in a population who have a disease at a specific point in time or over a period. - It reflects the burden of existing disease but provides no direct information about how easily the disease spreads from one person to another. *Case fatality rate* - The **case fatality rate** (CFR) indicates the **proportion of individuals** diagnosed with a disease who die from that disease. - It is a measure of the **severity or lethality** of a disease, not its communicability or transmissibility.
Question 84: Which of the following statements is NOT correct regarding case fatality rate?
- A. It is the ratio of deaths to cases expressed as percentage
- B. Very useful indicator for both acute and chronic diseases
- C. Variation can occur for the same disease because of changes in the agent factors
- D. One of the measures related to virulence (Correct Answer)
Explanation: ***One of the measures related to virulence*** - This statement is **incorrect**. The **case fatality rate (CFR)** is a measure of the **severity of a disease** within a specific population of affected individuals, typically related to a specific outbreak or period. - While it reflects disease severity, it is not a direct measure of **virulence**, which describes the pathogen's ability to cause damage to the host and is an intrinsic property of the infectious agent itself. *It is the ratio of deaths to cases expressed as percentage* - This is a **correct definition** of the case fatality rate (CFR), calculated as the number of deaths from a disease divided by the total number of cases of that disease, expressed as a percentage. - It quantifies the proportion of individuals diagnosed with a specific disease who ultimately die from it. *Very useful indicator for both acute and chronic diseases* - This statement is **correct**. The case fatality rate is a valuable indicator for assessing the severity and impact of both **acute diseases** (e.g., infectious outbreaks) and **chronic diseases** (e.g., cancer survival). - It helps in understanding the prognosis and lethality of a condition in affected individuals. *Variation can occur for the same disease because of changes in the agent factors* - This statement is **correct**. Case fatality rates for the same disease can vary significantly due to changes in **agent factors** (e.g., strain virulence, drug resistance), host factors (e.g., age, immune status), and environmental factors (e.g., access to healthcare). - For example, different strains of influenza can have varying case fatality rates due to differences in their inherent pathogenicity.
Question 85: Farmer's lung is caused by the inhalation of:
- A. Cotton fibre dust
- B. Sugarcane dust
- C. Grain dust with actinomycetes (Correct Answer)
- D. Silica dust
Explanation: ***Grain dust with actinomycetes*** - **Farmer's lung** is a type of **hypersensitivity pneumonitis** caused by inhaling dust from moldy hay or other agricultural products contaminated with **thermophilic actinomycetes**. - These bacteria trigger an immune response in the lungs, leading to inflammation and respiratory symptoms. *Cotton fibre dust* - Inhalation of **cotton fiber dust** is associated with **byssinosis**, a different occupational lung disease. - Byssinosis typically presents with chest tightness and shortness of breath, often worse on the first day of the work week. *Sugarcane dust* - Exposure to **sugarcane dust** can lead to **bagassosis**, another form of hypersensitivity pneumonitis. - While similar in mechanism to farmer's lung, the specific antigen is different (from sugarcane rather than moldy hay). *Silica dust* - Inhalation of **silica dust** causes **silicosis**, a chronic, progressive occupational lung disease characterized by pulmonary fibrosis. - Silicosis is common in miners, quarry workers, and others exposed to silica, and it is not a hypersensitivity reaction but a direct fibrotic response.
Question 86: Suraksha Clinics are conducted under the aegis of which National Health Programme?
- A. Iodine Deficiency Disorders Programme
- B. Reproductive and Child Health Programme (Correct Answer)
- C. National AIDS Control Programme
- D. Revised National Tuberculosis Control programme
Explanation: ***Reproductive and Child Health Programme*** - **Suraksha Clinics** (also known as Surakshit Matritva Suraksha or SMS Clinics) are established under the **Reproductive and Child Health (RCH) Programme** to provide comprehensive **maternal and child health services**. - These clinics offer services including **antenatal care (ANC), postnatal care (PNC), institutional deliveries, family planning**, and management of complications during pregnancy and childbirth. - They are part of India's efforts to ensure **safe motherhood** and reduce maternal and infant mortality rates. *National AIDS Control Programme* - This program focuses on **HIV/AIDS prevention, care, and treatment** through services like counseling, testing (ICTC), and antiretroviral therapy (ART centers). - While it operates various specialized centers for HIV care, **Suraksha Clinics are not part of NACP** but are specifically for maternal and child health. *Iodine Deficiency Disorders Programme* - This program aims to prevent **iodine deficiency** through universal salt iodization and monitoring of IDD prevalence. - It does not involve clinic-based maternal health services like Suraksha Clinics. *Revised National Tuberculosis Control Programme* - This program (now National TB Elimination Programme) is dedicated to **tuberculosis diagnosis, treatment, and control** through DOTS and other strategies. - It operates designated microscopy centers (DMCs) and treatment facilities, not Suraksha Clinics for maternal care.
Question 87: In a normal distribution, Mean ± 2 S.D. contains
- A. 68.3 % values
- B. 95.4 % values (Correct Answer)
- C. 91.2 % values
- D. 99.7 % values
Explanation: ***95.4 % values*** - According to the **empirical rule** (or 68-95-99.7 rule) for normal distributions, approximately **95.4%** of data falls within two standard deviations of the mean. - This interval covers from (Mean - 2 S.D.) to (Mean + 2 S.D.) and represents the likelihood of a value falling in this range. *68.3 % values* - This percentage corresponds to the data contained within **Mean ± 1 S.D.** in a normal distribution, not Mean ± 2 S.D. - It signifies that roughly two-thirds of all observations lie within one standard deviation from the mean in a bell-shaped curve. *91.2 % values* - This value is not a standard percentage associated with common multiples of standard deviations (1, 2, or 3) from the mean in a normal distribution. - It does not correspond to any universally recognized interval like ±1 S.D., ±2 S.D., or ±3 S.D. *99.7 % values* - This percentage represents the data contained within **Mean ± 3 S.D.** in a normal distribution. - It indicates that almost all (99.7%) of the data points are expected to fall within three standard deviations from the mean.
Question 88: Infant Mortality Rate is expressed per:
- A. 1000 pregnancies
- B. 1000 live births (Correct Answer)
- C. 100,000 live births
- D. 1000 under five children
Explanation: ***1000 live births*** - The **Infant Mortality Rate (IMR)** specifically measures the number of deaths of infants **under one year of age** per **1,000 live births** in a given population. - This definition is crucial for accurately assessing and comparing infant health outcomes across different regions and over time. *1000 pregnancies* - This option would include pregnancy losses that are not considered live births, such as **stillbirths** and miscarriages, which are distinct statistical measures. - The IMR specifically focuses on infants who were born alive and subsequently died within their first year of life. *100,000 live births* - While some rates might be expressed per 100,000 (e.g., maternal mortality ratio), **infant mortality rate** is universally standardized to a base of **1,000 live births**. - Using 100,000 live births would result in a disproportionately small and less intuitive number for IMR comparisons. *1000 under five children* - This definition refers to the **Under-5 Mortality Rate (U5MR)**, which includes deaths of children from birth up to their fifth birthday. - The IMR is a narrower measure, specifically focusing on infants who die **before their first birthday**.
Question 89: Which of the following tests is NOT used for checking quality of pasteurisation of milk?
- A. Phosphatase test
- B. Coliform count
- C. Orthotoluidine test (Correct Answer)
- D. Standard Plate count
Explanation: ### ***Orthotoludine test*** * The **Orthotoluidine test** is used to detect residual **chlorine** in drinking water. * It is not employed to assess the quality of pasteurization in milk, which focuses on enzyme inactivation and microbial reduction. ### *Phosphatase test* * The **phosphatase test** is the most widely accepted and reliable method for checking the adequacy of **pasteurization** in milk. * It works by detecting the activity of **alkaline phosphatase**, an enzyme naturally present in raw milk that is destroyed at pasteurization temperatures. ### *Coliform count* * The **coliform count** is an indicator of **post-pasteurization contamination** or inadequate sanitation. * While not a direct measure of the pasteurization process itself, a high coliform count suggests a failure in hygiene after heating, indicating poor overall quality control. ### *Standard Plate count* * The **Standard Plate Count (SPC)**, also known as the **aerobic plate count**, measures the total number of viable microorganisms in milk. * A reduction in SPC after pasteurization indicates the effectiveness of the heat treatment in killing bacteria, making it an indirect measure of pasteurization efficiency and overall microbial quality.
Question 90: Which of the following are the components of epidemiological triad?
- A. Sensitivity, specificity and predictive value
- B. Prevalence, incidence and attack rate
- C. Time, place and person distribution
- D. Agent, host and environmental factors (Correct Answer)
Explanation: ***Agent, host and environmental factors*** - The **epidemiological triad** is a traditional model that explains disease causation by focusing on the interaction between an infectious **agent**, a susceptible **host**, and the **environment** that brings them together. - Understanding these three components helps to analyze and prevent the spread of diseases. *Sensitivity, specificity and predictive value* - These terms relate to the **performance and accuracy of diagnostic tests**, assessing how well a test identifies true positives and true negatives. - They are measures used in the evaluation of screening programs and diagnostic procedures, not directly in the causation model. *Prevalence, incidence and attack rate* - These are **measures of disease occurrence** or frequency within a population, used to quantify the burden of disease. - While essential for understanding disease patterns, they describe the *results* of the disease process rather than the *factors* causing it. *Time, place and person distribution* - These refer to the **descriptive epidemiology** aspects of disease, outlining **who** is affected, **where** they are, and **when** the disease occurs. - These elements characterize disease patterns but are not the fundamental components responsible for disease causation in the epidemiological triad model.