UPSC-CMS 2021 - Community Medicine Practice Questions

Q: What is the Standardized Mortality Ratio (SMR) for the hazardous industry workers (as compared to national population)?

120. ***120*** - To calculate the Standardized Mortality Ratio (SMR), we first need to calculate the **expected deaths** for the hazardous industry workers based on the national death rates. - The formula for expected deaths in each age group is: (National death rate / 1000) × Number of hazardous industry workers - For age group 25-34: Expected deaths = (2.0 / 1000) × 3000 = **6** - For age group 35-44: Expected deaths = (3.5 / 1000) × 2000 = **7** - For age group 45-54: Expected deaths = (6.0 / 1000) × 2000 = **12** - **Total expected deaths** = 6 + 7 + 12 = **25** - **Total observed deaths** = 8 + 9 + 13 = **30** - **SMR formula**: (Total Observed Deaths / Total Expected Deaths) × 100 - **SMR = (30 / 25) × 100 = 1.2 × 100 = 120** - This indicates that the hazardous industry workers have a **20% higher mortality rate** compared to the national population after age-standardization. *100* - An SMR of 100 would indicate that the observed mortality equals the expected mortality (no difference from the national average). - However, the observed deaths (30) exceed the expected deaths (25), so the SMR must be greater than 100. - This option represents the null value where there is no excess mortality. *110* - This option underestimates the actual SMR calculated from the data. - An SMR of 110 would suggest only a 10% excess mortality, which does not match the observed-to-expected ratio of 30:25. - The calculation clearly shows a ratio of 1.2, not 1.1. *130* - This option overestimates the SMR. - An SMR of 130 would require observed deaths to be 1.3 times the expected deaths (32.5 deaths expected for 30 observed). - The actual ratio is 30/25 = 1.2, making this value too high.

Q: Which one of the following best explains the relationship among Prevalence (P), Incidence (I) and Duration (D) of a disease given the assumption that the population is stable ?

P = I x D. **Fundamental Epidemiological Relationship:** In a stable population with endemic disease, the relationship between prevalence, incidence, and duration is expressed as: **Prevalence = Incidence × Average Duration (P = I × D)** ***P = I × D*** - This is the **correct formula** that describes the relationship under conditions of a **stable population** and **endemic disease**. - Prevalence is directly proportional to both the incidence rate and the average duration of the disease. - This formula reflects that the number of existing cases (prevalence) equals the rate at which new cases occur (incidence) multiplied by how long people have the disease (duration). - Example: If incidence = 10 cases/1000/year and average duration = 5 years, then prevalence = 50 cases/1000. *I = P × D* - This formula incorrectly suggests that incidence increases with both prevalence and duration. - This would mean that longer disease duration causes higher incidence, which is illogical. - Correctly rearranged, this would be I = P/D (incidence equals prevalence divided by duration). *D = P × I* - This formula incorrectly states that duration is the product of prevalence and incidence. - This would mean higher incidence causes longer duration, which is epidemiologically incorrect. - Correctly rearranged, this would be D = P/I (duration equals prevalence divided by incidence). *I = P + D* - This formula implies a simple additive relationship, which is **epidemiologically invalid**. - Prevalence, incidence, and duration are related **multiplicatively**, not additively, in a steady state. - This equation has no basis in epidemiological theory.

Q: A new test was developed for detection of COVID-19. What is the sensitivity of the test as per the information provided above?

37.5%. ***37.5%*** - **Sensitivity** is calculated as the number of **true positives** divided by the sum of true positives and false negatives (i.e., total number of individuals with the disease). - From the table, **True Positives (Test Positive and Disease +)** = 60, and **False Negatives (Test Negative and Disease +)** = 100. So, sensitivity = 60 / (60 + 100) = 60 / 160 = 0.375 or 37.5%. *97%* - This value is incorrect. It might be confused with **Negative Predictive Value (NPV)**, which is the probability that subjects with a negative test truly don't have the disease (1800/1900 ≈ 0.947 or 94.7%), but it's not 97%. - It does not correctly represent the calculation for sensitivity as described above. *20.5%* - This value is incorrect. It does not correspond to any standard epidemiological measure of test performance based on the provided data. - This percentage might arise from an incorrect division or addition of values from the table. *60%* - This value is incorrect. While 60 **true positives** are present, sensitivity requires dividing this by the total number of diseased individuals, not just any other total. - This could be confused with the ratio of true positives to total positive tests (Positive Predictive Value), which would be 60/100, resulting in 60%, but this is not sensitivity.

Q: A study was conducted to evaluate the effectiveness of a new antidiabetic drug. The fasting blood glucose levels (mg/dL) of 5 diabetic patients after 3 months of treatment were: 110, 94, 102, 98, 96. Consider the following statements about this data: 1. The range of blood glucose levels is 16 mg/dL 2. The median blood glucose level is 98 mg/dL 3. The standard deviation is √10 mg/dL

1 and 2 only. ***1 and 2 only*** - **Statement 1 is correct**: The **range** is calculated as maximum value minus minimum value. Ordering the data: 94, 96, 98, 102, 110 mg/dL. Range = 110 - 94 = **16 mg/dL** ✓ - **Statement 2 is correct**: For the ordered dataset (94, 96, 98, 102, 110), with n=5 observations, the **median** is the middle (3rd) value = **98 mg/dL** ✓ - **Statement 3 is incorrect**: To calculate standard deviation: - Mean (x̄) = (110 + 94 + 102 + 98 + 96) / 5 = **100 mg/dL** - Deviations from mean: 10, -6, 2, -2, -4 - Sum of squared deviations: 100 + 36 + 4 + 4 + 16 = **160** - Sample variance = 160 / (n-1) = 160 / 4 = **40** - Standard deviation = √40 = **2√10 ≈ 6.32 mg/dL** (NOT √10 ≈ 3.16 mg/dL) ✗ *1, 2 and 3* - This would only be correct if all three statements were true. However, **statement 3 is incorrect** as the actual standard deviation is √40 (or 2√10), not √10. *1 and 3 only* - This is incorrect because **statement 3 is false** (SD = √40, not √10), while statement 2 is actually correct. *2 and 3 only* - This is incorrect because **statement 1 is correct** (range is indeed 16 mg/dL) and **statement 3 is incorrect** (SD ≠ √10).

Q: Hepatitis B vaccine administered at birth is

A monovalent vaccine of Hepatitis B. ***A monovalent vaccine of Hepatitis B*** - The **initial dose** of the Hepatitis B vaccine given at birth is a **single-antigen (monovalent)** preparation. It is given as a **standalone vaccine** to ensure prompt protection against Hepatitis B virus. - This early administration is critical for preventing **perinatal transmission** of Hepatitis B from an infected mother to her newborn, and establishing immunity as soon as possible. *A pentavalent vaccine* - **Pentavalent vaccines** typically protect against five different diseases: **Diphtheria, Tetanus, Pertussis (DTP), *Haemophilus influenzae* type b (Hib), and Hepatitis B**. - While Hepatitis B is one component, the vaccine administered at birth is usually monovalent, and the pentavalent vaccine is given later in the infant's immunization schedule. *A fixed combination vaccine of Hepatitis B and Hib* - A fixed combination vaccine of Hepatitis B and **Hib (Haemophilus influenzae type b)** is available and used in some immunization schedules. - However, the **first dose** given at birth is specifically a monovalent Hepatitis B vaccine, not a combined Hib vaccine, to target immediate Hepatitis B protection. *A combined vaccine of inactivated Polio and Hepatitis B* - Combined vaccines that include **inactivated Polio vaccine (IPV)** and **Hepatitis B** do exist but are generally administered later, at 6 weeks and subsequent doses. - The **birth dose** of Hepatitis B vaccine is exclusively for Hepatitis B protection and does not typically include polio antigen.

Q: Which of the following are correct in respect of Diphtheria? 1. The incubation period is 14 to 28 days 2. Diphtheria antitoxin is used in treatment of cases 3. It is one of the diseases protected from, by the Pentavalent vaccine given in National Program

2 and 3 only. **Correct Answer: Option B (2 and 3 only)** **Analysis of Statements:** **Statement 1: INCORRECT** - The incubation period for diphtheria is **2 to 5 days** (range: 1-10 days), NOT 14 to 28 days - The stated period of 14-28 days is inaccurate **Statement 2: CORRECT** - **Diphtheria antitoxin (DAT)** is the mainstay of treatment - It neutralizes the exotoxin produced by *Corynebacterium diphtheriae* - Must be given early to prevent irreversible toxin-mediated tissue damage **Statement 3: CORRECT** - **Pentavalent vaccine** (DPT-HepB-Hib) is given under India's Universal Immunization Programme - Protects against 5 diseases: Diphtheria, Pertussis, Tetanus, Hepatitis B, and *Haemophilus influenzae* type b - Contains diphtheria toxoid for active immunization **Why Other Options are Incorrect:** *Option A (1, 2 and 3)* - Incorrect because Statement 1 has wrong incubation period *Option C (1 and 3 only)* - Incorrect because Statement 1 has wrong incubation period - Also omits the important fact about antitoxin treatment *Option D (1 and 2 only)* - Incorrect because Statement 1 has wrong incubation period - Also omits the important fact about Pentavalent vaccine protection

Q: A person has presented with history of dog-bite on the uncovered surface of his right leg. There is a minor abrasion without bleeding. Consider the following statements about management : 1. The bite should be taken as a category I contact with suspect animal 2. The bite requires local treatment of the wound 3. The person requires immediate vaccination 4. The person requires immediate administration of rabies immunoglobulin Which of the above statements are correct ?

2 and 3 only. ***2 and 3 only*** - A minor abrasion without bleeding falls under **Category II exposure** per WHO guidelines, requiring **local wound treatment** and **immediate vaccination**. - **Category II exposures** are defined as nibbling of uncovered skin, minor abrasions without bleeding, or scratches without bleeding. *1 and 2* - The bite described (minor abrasion without bleeding) is classified as **Category II exposure** by WHO, not Category I. - **Category I contact** involves touching or feeding an animal, or licks on intact skin, requiring **no post-exposure prophylaxis** as there is no breach of skin integrity. *2, 3 and 4* - While local wound treatment and vaccination are correct for Category II exposure, **rabies immunoglobulin (RIG)** is not indicated for Category II. - RIG is reserved for **Category III exposures**, which involve single or multiple transdermal bites or scratches, contamination of mucous membranes with saliva, or licks on broken skin. *3 and 4 only* - Immediate vaccination is correct, but **rabies immunoglobulin** is not necessary for a minor abrasion without bleeding (Category II exposure). - Administration of RIG is only indicated after **Category III exposures** due to the higher risk of rabies transmission.

Q: Consider the following stages of modern sewage treatment plants : 1. Use of Grit chamber 2. Use of Primary sedimentation tank 3. Screening 4. Use of Sludge digester What would be the correct sequence of the above stages ?

3→1→2→4. ***3→1→2→4*** - The correct sequence for modern sewage treatment begins with **screening** (3) to remove large debris, followed by **grit chambers** (1) for sand and gravel, then **primary sedimentation tanks** (2) to settle organic solids. Finally, the collected sludge is processed in a **sludge digester** (4). - This order ensures progressive removal of contaminants, from large physical objects to settled organic matter, optimizing the efficiency of each treatment stage. *2→3→4→1* - This sequence incorrectly places the **primary sedimentation tank** (2) as the first step, which would be inefficient as large debris and grit would interfere with its operation. - It also reverses the order of screening and grit removal, which are crucial initial physical processes. *3→2→1→4* - While starting with **screening** (3) is correct, this sequence incorrectly places the **primary sedimentation tank** (2) before the **grit chamber** (1). - Grit removal should precede primary sedimentation to prevent abrasive materials from damaging equipment and accumulating in sedimentation tanks. *4→2→1→3* - This sequence is entirely incorrect, as it begins with the **sludge digester** (4), which is a final step in sludge processing, not the initial treatment of raw sewage. - It also drastically misorders the preliminary physical treatment stages.

Q: A vital layer, also known as "Schmutzdecke" is seen in which one of the following ?

Slow sand filter. ***Slow sand filter*** - A vital biological layer known as **"Schmutzdecke"** or **"filter skin"** forms on the surface of slow sand filters. - This layer, composed of **algae, bacteria, fungi**, and protozoa, is crucial for effective water purification by trapping and breaking down organic matter and pathogens. *Air filter* - Air filters primarily remove particulate matter from air, not water, and do not develop a biological layer like **Schmutzdecke**. - Their mechanism involves mechanical filtration, not biological degradation. *Reverse osmosis filter* - Reverse osmosis filters use a **semi-permeable membrane** to remove dissolved solids and contaminants from water under pressure. - They operate on a physical process and do not rely on the formation of a biological "Schmutzdecke" layer for filtration. *Rapid sand filter* - Rapid sand filters primarily rely on **physical straining** and **coagulation/flocculation** for clarification, followed by backwashing to clean the filter media. - While some biological activity may occur, they do not form a distinct, vital **"Schmutzdecke"** layer as seen in slow sand filters, and their primary mechanism is different.

Q: A 25 year old woman is a sedentary worker. She is a lactating mother with a 3 month old child. Which one among the following is the best approximation of her energy requirement in terms of kilocalories per day ?

2500 kcal/d. ***2500 kcal/d*** - A lactating woman generally requires an additional 500 kcal/day above her baseline energy needs to support milk production. - For a sedentary woman, a typical baseline intake is around 2000 kcal/day, making 2500 kcal/day a good approximation during lactation. *1500 kcal/d* - This value is significantly low for a lactating woman, as it would likely lead to a **caloric deficit** and could compromise milk supply and maternal health. - This energy level might be appropriate for a woman on a **weight-loss diet**, but not for supporting lactation. *2250 kcal/d* - While closer than 1500 kcal/d, this value still falls slightly short of the recommended additional energy intake for lactation, which is typically an extra 500 kcal/day. - This might represent a moderate activity level for a non-lactating woman, but not optimal for **milk production**. *2830 kcal/d* - This amount would be more appropriate for a lactating woman with a **higher activity level** or a greater baseline energy requirement than a sedentary individual. - While some lactating women may need this much, it is likely an **overestimation** for a sedentary worker.

Question 1

What is the Standardized Mortality Ratio (SMR) for the hazardous industry workers (as compared to national population)?

Accepted Answer

120

Answer

110

Answer

100

Answer

130

Question 2

Which one of the following best explains the relationship among Prevalence (P), Incidence (I) and Duration (D) of a disease given the assumption that the population is stable ?

Accepted Answer

P = I x D

Answer

I = P x D

Answer

D = P x I

Answer

I = P + D

Question 3

A new test was developed for detection of COVID-19. What is the sensitivity of the test as per the information provided above?

Accepted Answer

37.5%

Answer

97%

Answer

20.5%

Answer

60%

Question 4

A study was conducted to evaluate the effectiveness of a new antidiabetic drug. The fasting blood glucose levels (mg/dL) of 5 diabetic patients after 3 months of treatment were: 110, 94, 102, 98, 96.

Consider the following statements about this data:

1. The range of blood glucose levels is 16 mg/dL
2. The median blood glucose level is 98 mg/dL  
3. The standard deviation is √10 mg/dL

Accepted Answer

1 and 2 only

Answer

1, 2 and 3

Answer

1 and 3 only

Answer

2 and 3 only

Question 5

Hepatitis B vaccine administered at birth is

Accepted Answer

A monovalent vaccine of Hepatitis B

Answer

A pentavalent vaccine

Answer

A fixed combination vaccine of Hepatitis B and Hib

Answer

A combined vaccine of inactivated Polio and Hepatitis B

Question 6

Which of the following are correct in respect of Diphtheria?

1. The incubation period is 14 to 28 days
2. Diphtheria antitoxin is used in treatment of cases
3. It is one of the diseases protected from, by the Pentavalent vaccine given in National Program

Accepted Answer

2 and 3 only

Answer

1, 2 and 3

Answer

1 and 3 only

Answer

1 and 2 only

Question 7

A person has presented with history of dog-bite on the uncovered surface of his right leg. There is a minor abrasion without bleeding. Consider the following statements about management :

1. The bite should be taken as a category I contact with suspect animal
2. The bite requires local treatment of the wound
3. The person requires immediate vaccination
4. The person requires immediate administration of rabies immunoglobulin Which of the above statements are correct ?

Accepted Answer

2 and 3 only

Answer

1 and 2

Answer

2, 3 and 4

Answer

3 and 4 only

Question 8

Consider the following stages of modern sewage treatment plants :

1. Use of Grit chamber
2. Use of Primary sedimentation tank
3. Screening
4. Use of Sludge digester
What would be the correct sequence of the above stages ?

Accepted Answer

3→1→2→4

Answer

2→3→4→1

Answer

3→2→1→4

Answer

4→2→1→3

Question 9

A vital layer, also known as "Schmutzdecke" is seen in which one of the following ?

Accepted Answer

Slow sand filter

Answer

Air filter

Answer

Reverse osmosis filter

Answer

Rapid sand filter

Question 10

A 25 year old woman is a sedentary worker. She is a lactating mother with a 3 month old child. Which one among the following is the best approximation of her energy requirement in terms of kilocalories per day ?

Accepted Answer

2500 kcal/d

Answer

1500 kcal/d

Answer

2250 kcal/d

Answer

2830 kcal/d

UPSC-CMS 2021 — Community Medicine