NEET-PG 2015 — Community Medicine

Q: In hospital infection control, which instrument is used to monitor humidity levels to prevent nosocomial infections?

Hygrometer. ***Hygrometer*** - A **hygrometer** is specifically designed to measure **humidity** or the moisture content in the atmosphere. - Maintaining optimal **humidity levels** (typically 30-60%) is crucial in hospitals to control the spread of **pathogens** and prevent nosocomial infections. *Barometer* - A **barometer** measures **atmospheric pressure**, which is important for weather forecasting but not directly for hospital infection control. - It does not provide information about the moisture content in the air. *Anemometer* - An **anemometer** is used to measure **wind speed**, which is irrelevant to monitoring indoor environmental conditions for infection control. - It does not provide any data related to air humidity. *Thermometer* - A **thermometer** measures **temperature**, which is a separate environmental parameter from humidity. - While temperature control is important in healthcare settings, it does not directly monitor moisture content. [Practice more Community Medicine PYQs on OnCourse]

Q: Consanguineous marriages increase the risk of which of the following diseases?

Autosomal recessive diseases. ***Autosomal recessive diseases*** - Consanguineous marriages increase the likelihood of offspring inheriting two copies of a **recessive deleterious allele** from a common ancestor. - This significantly raises the risk of expressing **autosomal recessive conditions**, as both parents are more likely to be carriers of the same rare recessive gene. - Examples include **thalassemia, sickle cell disease, and cystic fibrosis**. *Autosomal dominant diseases* - These diseases manifest with only **one copy of the mutated allele**, regardless of consanguinity. - The risk is primarily linked to whether one parent carries the dominant gene, not the relatedness of the parents. *X linked dominant diseases* - These conditions are caused by mutations on the **X chromosome** and are expressed dominantly. - Consanguinity does not specifically increase the risk, as the disease manifests when the mutated X-linked gene is inherited from an affected parent. - The inheritance pattern depends on the affected parent's sex, not on parental relatedness. *Environmental diseases* - These diseases are primarily caused by **external factors** such as toxins, diet, lifestyle choices, or infections. - While genetic predisposition may play a role, consanguinity does not directly increase the risk for environmentally triggered diseases. [Practice more Community Medicine PYQs on OnCourse]

Q: Which blinding technique is considered the most effective in clinical trials?

Double blinding. **Double blinding** - Involves both the **participants** and the **researchers/investigators** being unaware of the treatment assignment. - This method effectively minimizes bias from both **subject expectation** (placebo effect) and **observer expectation** (detection bias). *Single blinding* - Only the **participant** is unaware of the treatment they are receiving, while the investigator knows. - While it reduces participant bias, it can still introduce bias from the investigator regarding **outcome assessment** or **patient interaction**. *Triple blinding* - Extends blinding to include the **data analyst** who is also unaware of the treatment assignments during analysis. - While theoretically offering an additional layer of protection against bias, its practical benefits over double blinding are often marginal and it's less commonly implemented due to **complexity**. *No blinding* - Both the **participants** and the **researchers** are aware of the treatment assignments (open-label study). - This approach is highly susceptible to **bias** from both participant and researcher expectations, significantly compromising the study's validity and reliability. [Practice more Community Medicine PYQs on OnCourse]

Q: Randomization is done to reduce?

Selection bias. ***Selection bias*** - **Randomization** ensures that each participant has an equal chance of being assigned to any study group, which helps to distribute both known and unknown confounding factors evenly. - This process minimizes **selection bias** by promoting comparability between groups, making it more likely that any observed differences are due to the intervention rather than pre-existing differences. *Recall bias* - **Recall bias** occurs when there are systematic differences in the way participants remember or report past exposures or events, often seen in retrospective studies. - While randomization helps control for confounding, it does not directly prevent participants from inaccurately recalling information. *Berksonian bias* - **Berksonian bias** is a form of selection bias where the probability of being admitted to a hospital (or selected into a study) is affected by the presence of a co-morbidity, leading to a distorted association between diseases. - Randomization aims to balance characteristics *within* the study groups once participants are recruited, but it doesn't address biases related to the initial selection into the study population from a larger source. *Reporting bias* - **Reporting bias** refers to selective revealing or suppression of information, either by study participants (e.g., social desirability bias) or by researchers (e.g., only reporting positive findings). - Randomization helps ensure internal validity by creating comparable groups, but it does not prevent individuals from selectively reporting outcomes or experiences. [Practice more Community Medicine PYQs on OnCourse]

Q: The strongest occupational risk factor for hematological carcinoma is

Benzene. ***Benzene*** - Benzene exposure is recognized as a potent **carcinogen** linked to various hematological malignancies, including **leukemia** [1]. - It affects the **bone marrow**, leading to dysplastic changes and ultimately malignancy. *Nicotine* - Although nicotine is associated with **smoking-related cancers**, it is not directly linked to **hematological carcinomas**. - Its primary role is in causing **lung cancer**, rather than blood cancers. *Lithium* - Lithium is primarily used for **bipolar disorder** and does not have a known link to causing hematological malignancies. - Side effects are more related to **nephrotoxicity** rather than carcinogenic effects. *Alcohol* - Alcohol consumption is primarily associated with **liver cancers** and not specifically linked to hematological carcinomas [2]. - It can contribute to general malignancy development but is not a direct cause of blood cancers. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 286. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 217-218. [Practice more Community Medicine PYQs on OnCourse]

80 Previous Year Questions with Answers & Explanations

Questions

In hospital infection control, which instrument is used to monitor humidity levels to prevent nosocomial infections?

Consanguineous marriages increase the risk of which of the following diseases?

Which blinding technique is considered the most effective in clinical trials?

Randomization is done to reduce?

The strongest occupational risk factor for hematological carcinoma is

Caisson's disease is primarily associated with which of the following?

What is the range of values for the Physical Quality of Life Index (PQLI)?

Which of the following is not a recognized transmission route for amoebiasis?

Which of the following is NOT one of Bradford Hill's criteria for causation?

Q10

What is the most common mode of transmission of HIV?

NEET-PG 2015 - Community Medicine NEET-PG Practice Questions and MCQs

Question 1: In hospital infection control, which instrument is used to monitor humidity levels to prevent nosocomial infections?

A. Barometer
B. Hygrometer (Correct Answer)
C. Thermometer
D. Anemometer

Explanation: ***Hygrometer*** - A **hygrometer** is specifically designed to measure **humidity** or the moisture content in the atmosphere. - Maintaining optimal **humidity levels** (typically 30-60%) is crucial in hospitals to control the spread of **pathogens** and prevent nosocomial infections. *Barometer* - A **barometer** measures **atmospheric pressure**, which is important for weather forecasting but not directly for hospital infection control. - It does not provide information about the moisture content in the air. *Anemometer* - An **anemometer** is used to measure **wind speed**, which is irrelevant to monitoring indoor environmental conditions for infection control. - It does not provide any data related to air humidity. *Thermometer* - A **thermometer** measures **temperature**, which is a separate environmental parameter from humidity. - While temperature control is important in healthcare settings, it does not directly monitor moisture content.

Question 2: Consanguineous marriages increase the risk of which of the following diseases?

A. Autosomal dominant diseases
B. Autosomal recessive diseases (Correct Answer)
C. X linked dominant diseases
D. Environmental diseases

Explanation: ***Autosomal recessive diseases*** - Consanguineous marriages increase the likelihood of offspring inheriting two copies of a **recessive deleterious allele** from a common ancestor. - This significantly raises the risk of expressing **autosomal recessive conditions**, as both parents are more likely to be carriers of the same rare recessive gene. - Examples include **thalassemia, sickle cell disease, and cystic fibrosis**. *Autosomal dominant diseases* - These diseases manifest with only **one copy of the mutated allele**, regardless of consanguinity. - The risk is primarily linked to whether one parent carries the dominant gene, not the relatedness of the parents. *X linked dominant diseases* - These conditions are caused by mutations on the **X chromosome** and are expressed dominantly. - Consanguinity does not specifically increase the risk, as the disease manifests when the mutated X-linked gene is inherited from an affected parent. - The inheritance pattern depends on the affected parent's sex, not on parental relatedness. *Environmental diseases* - These diseases are primarily caused by **external factors** such as toxins, diet, lifestyle choices, or infections. - While genetic predisposition may play a role, consanguinity does not directly increase the risk for environmentally triggered diseases.

Question 3: Which blinding technique is considered the most effective in clinical trials?

A. Double blinding (Correct Answer)
B. Triple blinding
C. No blinding
D. Single blinding

Explanation: **Double blinding** - Involves both the **participants** and the **researchers/investigators** being unaware of the treatment assignment. - This method effectively minimizes bias from both **subject expectation** (placebo effect) and **observer expectation** (detection bias). *Single blinding* - Only the **participant** is unaware of the treatment they are receiving, while the investigator knows. - While it reduces participant bias, it can still introduce bias from the investigator regarding **outcome assessment** or **patient interaction**. *Triple blinding* - Extends blinding to include the **data analyst** who is also unaware of the treatment assignments during analysis. - While theoretically offering an additional layer of protection against bias, its practical benefits over double blinding are often marginal and it's less commonly implemented due to **complexity**. *No blinding* - Both the **participants** and the **researchers** are aware of the treatment assignments (open-label study). - This approach is highly susceptible to **bias** from both participant and researcher expectations, significantly compromising the study's validity and reliability.

Question 4: Randomization is done to reduce?

A. Recall bias
B. Selection bias (Correct Answer)
C. Berksonian bias
D. Reporting bias

Explanation: ***Selection bias*** - **Randomization** ensures that each participant has an equal chance of being assigned to any study group, which helps to distribute both known and unknown confounding factors evenly. - This process minimizes **selection bias** by promoting comparability between groups, making it more likely that any observed differences are due to the intervention rather than pre-existing differences. *Recall bias* - **Recall bias** occurs when there are systematic differences in the way participants remember or report past exposures or events, often seen in retrospective studies. - While randomization helps control for confounding, it does not directly prevent participants from inaccurately recalling information. *Berksonian bias* - **Berksonian bias** is a form of selection bias where the probability of being admitted to a hospital (or selected into a study) is affected by the presence of a co-morbidity, leading to a distorted association between diseases. - Randomization aims to balance characteristics *within* the study groups once participants are recruited, but it doesn't address biases related to the initial selection into the study population from a larger source. *Reporting bias* - **Reporting bias** refers to selective revealing or suppression of information, either by study participants (e.g., social desirability bias) or by researchers (e.g., only reporting positive findings). - Randomization helps ensure internal validity by creating comparable groups, but it does not prevent individuals from selectively reporting outcomes or experiences.

Question 5: The strongest occupational risk factor for hematological carcinoma is

A. Benzene (Correct Answer)
B. Lithium
C. Radiation exposure
D. Cigarette smoke

Explanation: ***Benzene*** - Benzene exposure is recognized as a potent **carcinogen** linked to various hematological malignancies, including **leukemia** [1]. - It affects the **bone marrow**, leading to dysplastic changes and ultimately malignancy. *Nicotine* - Although nicotine is associated with **smoking-related cancers**, it is not directly linked to **hematological carcinomas**. - Its primary role is in causing **lung cancer**, rather than blood cancers. *Lithium* - Lithium is primarily used for **bipolar disorder** and does not have a known link to causing hematological malignancies. - Side effects are more related to **nephrotoxicity** rather than carcinogenic effects. *Alcohol* - Alcohol consumption is primarily associated with **liver cancers** and not specifically linked to hematological carcinomas [2]. - It can contribute to general malignancy development but is not a direct cause of blood cancers. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 286. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 217-218.

Question 6: Caisson's disease is primarily associated with which of the following?

A. None of the options
B. Underwater construction workers (Correct Answer)
C. Rapid ascent in aircraft
D. Rapid ascent of deep sea divers

Explanation: ***Underwater construction workers*** - Caisson's disease, also known as **decompression sickness (DCS)**, is historically linked to workers in **caissons**, which are watertight structures used for underwater construction. - These workers experience changes in pressure that can lead to nitrogen bubbles forming in their tissues upon surfacing, causing the characteristic symptoms of DCS. *Rapid ascent in aircraft* - While rapid ascent in aircraft can cause **decompression sickness**, especially in unpressurized cabins, it is not the primary association for the historical term "Caisson's disease." - The term "Caisson's disease" specifically refers to the condition in workers exposed to **high atmospheric pressure** during underwater construction. *None of the options* - This option is incorrect because **underwater construction workers** are directly associated with Caisson's disease. - The question has a correct and specific answer. *Rapid ascent of deep sea divers* - **Deep-sea divers** are susceptible to decompression sickness due to rapid ascent, which is physiologically similar to Caisson's disease. - However, the specific term "Caisson's disease" most directly refers to the historical experience of **underwater construction workers** in caissons.

Question 7: What is the range of values for the Physical Quality of Life Index (PQLI)?

A. 0 to 10
B. 0 to 50
C. 0 to 100 (Correct Answer)
D. 100 to 200

Explanation: ***0 to 100*** - The **Physical Quality of Life Index (PQLI)** is an index that measures the quality of life or well-being of a country, with values ranging from **0 (worst)** to **100 (best)**. - This standardized range allows for easy comparison of living standards and societal progress across different nations. *0 to 10* - This range is too small and does not accurately represent the comprehensive scoring system used for the **PQLI**, which aggregates multiple indicators. - While some individual metrics might use a 0-10 scale, the composite PQLI itself uses a broader range. *0 to 50* - This range is insufficient to capture the full spectrum of development indicators factored into the **PQLI**. - A maximum value of 50 would compress the data too much, making fine distinctions between countries less apparent. *100 to 200* - The **PQLI** is capped at 100, which signifies the highest possible quality of life; therefore, values above 100 are not possible. - This range suggests an overly optimistic or unstandardized index, which is not the case for PQLI.

Question 8: Which of the following is not a recognized transmission route for amoebiasis?

A. Sexual transmission
B. Blood and blood products
C. Vector transmission (Correct Answer)
D. Fecal-oral route

Explanation: ***Vector transmission*** - Amoebiasis, caused by *Entamoeba histolytica*, is primarily an **intestinal infection** transmitted through the **fecal-oral route**. - Its life cycle **does not involve any arthropod vector** (e.g., mosquito, tick, fly) for transmission. - This is the **only route among the options that is definitively NOT recognized** for amoebiasis transmission. *Sexual transmission* - Amoebiasis **can be transmitted** through **oral-anal sexual contact**, particularly documented in men who have sex with men (MSM). - This represents an **indirect fecal-oral transmission** route and is a recognized mode of spread. *Blood and blood products* - While *E. histolytica* can disseminate to cause **amoebic liver abscesses** and rarely systemic disease, transmission via blood transfusion is **extremely rare and not well-documented**. - However, theoretically possible in cases of parasitemia during invasive disease. - Unlike vector transmission, this cannot be definitively ruled out as "not recognized." *Fecal-oral route* - This is the **primary and most important transmission route** for amoebiasis. - Infection occurs through ingestion of **cysts** from contaminated food, water, or through direct person-to-person contact with poor hand hygiene.

Question 9: Which of the following is NOT one of Bradford Hill's criteria for causation?

A. Consistency of association
B. Specificity of association
C. Strength of association
D. Absence of temporal relationship (Correct Answer)

Explanation: ***Absence of temporal relationship*** - Bradford Hill's criteria include **temporality** (temporal relationship), which states that the cause must precede the effect in time. - The criterion is the **presence** of a temporal relationship, not its absence. - "Absence of temporal relationship" is therefore NOT one of Bradford Hill's criteria—it is the opposite of what the criterion requires. - This is the correct answer to this "NOT" question. *Strength of association* - This **IS** one of Bradford Hill's criteria. - It refers to the **magnitude of the association** between exposure and outcome (measured by relative risk, odds ratio, etc.). - A stronger association provides more evidence for causality. *Consistency of association* - This **IS** one of Bradford Hill's criteria. - It means the association is observed **repeatedly** across different studies, populations, settings, and times. - Consistent replication strengthens the causal argument. *Specificity of association* - This **IS** one of Bradford Hill's criteria. - It suggests that a specific exposure leads to a specific outcome with limited alternative explanations. - While supportive of causation, Hill noted this criterion is less essential as many exposures have multiple effects.

Question 10: What is the most common mode of transmission of HIV?

A. Occupational exposure (needle stick injury)
B. Perinatal transmission (mother to child)
C. Sexual contact (Correct Answer)
D. Transmission via blood and blood products

Explanation: ***Sexual contact*** - **Unprotected sexual intercourse**, both heterosexual and homosexual, is overwhelmingly the most common way HIV is transmitted globally. - The virus can be exchanged through **bodily fluids** such as semen, vaginal fluids, and rectal fluids during sexual activity. - Accounts for approximately **80% of new HIV infections** worldwide. *Occupational exposure (needle stick injury)* - While a recognised mode of transmission, **needle stick injuries** account for a very small percentage of total HIV infections, primarily affecting healthcare workers. - The risk of transmission per exposure is relatively low (approximately **0.3%**), especially compared to sexual contact. *Perinatal transmission (mother to child)* - **Mother-to-child transmission** can occur during pregnancy, childbirth, or breastfeeding. - Although significant, especially in resource-limited settings, global efforts and **PMTCT programs** have resulted in a significant reduction in this type of transmission. *Transmission via blood and blood products* - This mode was once a major concern but is now extremely rare in countries with robust **blood screening programs**. - While sharing contaminated needles among **intravenous drug users** remains a risk, transfusion-related HIV is largely controlled.