NEET-PG 2015 — Community Medicine
80 Previous Year Questions with Answers & Explanations
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?
Caisson's disease is primarily associated with which of the following?
The strongest occupational risk factor for hematological carcinoma is
Which of the following is not a recognized transmission route for amoebiasis?
What is the most common mode of transmission of HIV?
What is the range of values for the Physical Quality of Life Index (PQLI)?
What is the definition of a reservoir in the context of infectious diseases?
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: 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 6: 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 7: 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 8: 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.
Question 9: 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 10: What is the definition of a reservoir in the context of infectious diseases?
- A. Person, animal or object from which infectious agent is transmitted to host
- B. Person, animal or substance in which infectious agent lives and multiplies (Correct Answer)
- C. Person or animal in which infectious agent causes a disease
- D. Person or animal that transmits the infectious agent mechanically
Explanation: ***Person, animal or substance in which infectious agent lives and multiplies*** - A **reservoir** is the natural habitat where an **infectious agent** normally lives and multiplies, and from which it can be transmitted to a susceptible host. - This definition emphasizes residence and replication, not necessarily direct transmission to a new host or causation of disease in the reservoir itself. - Examples include humans (e.g., typhoid carriers), animals (e.g., rodents for plague), and environmental sources (e.g., soil for tetanus). *Person, animal or object from which infectious agent is transmitted to host* - This option describes a **source of infection**, which can be a reservoir but isn't always. A source is where a host acquires the infection, but not necessarily where the pathogen multiplies. - An object (fomite) can be a source of infection, but it's rarely a reservoir because pathogens generally do not live and multiply there for extended periods. *Person or animal in which infectious agent causes a disease* - This describes a **diseased host** or a **case**, not necessarily a reservoir. A reservoir may or may not experience disease from the pathogen it harbors. - For example, a **carrier** can be a reservoir without showing symptoms of disease. *Person or animal that transmits the infectious agent mechanically* - This describes a **vector**, particularly a mechanical vector (e.g., flies carrying pathogens on their body). - Unlike a reservoir, a vector does not provide a habitat where the pathogen lives and multiplies; it merely transports it from one location to another.