NEET-PG 2012 - Community Medicine Practice Questions

Q: In the context of epidemiology, what is the denominator used for calculating incidence?

Population at risk. ***Population at risk*** - Incidence measures the **rate of new cases** of a disease in a population over a specified period. - The denominator for calculating incidence must exclude individuals who are **already diseased** or are **immune** and thus not susceptible to developing the condition. - This is the **most accurate and theoretically correct** denominator as it represents only those who can actually develop the disease. *Mid year population* - While often used as a **practical approximation** in epidemiological calculations when the exact population at risk is difficult to determine. - However, it includes individuals who may not be at risk (e.g., already have the disease or are immune), making it **less precise** than using the actual susceptible population. - For the **theoretical definition** of incidence rate, population at risk is the correct denominator. *Total number of cases* - This value represents the **numerator** for incidence calculations, as it counts the number of new events or diseases occurring. - It cannot serve as the denominator, as the denominator must reflect the pool of individuals from which these **new cases arose**. *Total number of deaths* - This is a measure of **mortality**, not incidence, and is used to calculate death rates. - The denominator for mortality rates is typically the **population at risk of death**, not specifically the population at risk of developing a disease.

Q: Which is the least common cause among these of infant mortality in India?

Birth injuries. ***Birth injuries*** - While significant in some contexts, **birth injuries** are a less common cause of infant mortality in India compared to other factors like infections, prematurity, and congenital malformations. - Progress in **obstetric care** and improvements in delivery practices have helped reduce their incidence as a primary cause of death. *Infections* - **Infections**, particularly **neonatal sepsis**, pneumonia, and diarrhea, remain a leading cause of infant mortality in India. - Poor sanitation, lack of access to clean water, and inadequate vaccination coverage contribute significantly to their prevalence. *Congenital malformations* - **Congenital malformations** (birth defects) are a substantial cause of infant mortality in India, particularly those affecting the heart, brain, and neural tube. - Early detection and intervention for these conditions are often limited, increasing their impact on mortality rates. *Prematurity* - **Prematurity** (being born too early) and its associated complications, such as respiratory distress syndrome and low birth weight, are major contributors to infant mortality in India. - Many premature infants struggle with underdeveloped organs and systems, making them highly vulnerable in the first few weeks of life.

Q: All of the following are characteristics of case control study except:

Measures incidence rate. ***Correct: Measures incidence rate*** - A **case-control study** proceeds from effect (disease) to cause (exposure) and thus does **NOT measure the incidence rate** of a disease. - Case-control studies calculate **odds ratios**, not incidence rates. - **Incidence rate** is typically measured in **cohort studies**, where a group of individuals is followed over time to observe the development of new cases of a disease. *Incorrect: Quick results are obtained* - Case-control studies are generally **retrospective**, meaning they look back in time from the outcome (disease) to identify past exposures. - This design allows for **quicker data collection** and analysis compared to prospective studies like cohort studies, which follow individuals over time. - This IS a characteristic of case-control studies. *Incorrect: Proceeds from effect to cause* - In a case-control study, researchers start by identifying individuals with the **disease (cases)** and a comparable group without the disease (controls). - They then investigate past exposures in both groups to determine potential **risk factors** or causes. - This IS a characteristic of case-control studies. *Incorrect: Inexpensive study* - Case-control studies are typically **less expensive** than other analytical study designs, such as cohort studies. - This is because they do not require long-term follow-up of a large population, reducing costs associated with repeated measurements and participant retention. - This IS a characteristic of case-control studies.

Q: Transovarian transmission is seen in which of the following infections?

Yellow fever. ***Yellow fever*** - **Transovarian transmission** refers to the passage of a pathogen from an adult female arthropod (like a mosquito) to her offspring via the eggs. This mechanism allows the virus to persist in the **vector population** even in the absence of infected vertebrate hosts. - **Yellow fever virus** is known to undergo transovarian transmission in its mosquito vectors, particularly *Aedes aegypti* and other *Aedes* species. *Plague* - Plague is caused by the bacterium *Yersinia pestis* and is primarily transmitted by **flea bites** from infected rodents to humans. - It does not involve transovarian transmission; the fleas acquire the bacteria during a **blood meal** from an infected host. *Ebola fever* - Ebola virus is transmitted through **direct contact** with blood or bodily fluids of infected humans or animals. - It is not an **arthropod-borne disease** and therefore does not exhibit transovarian transmission. *None of the options* - This option is incorrect because **Yellow Fever** clearly demonstrates transovarian transmission within its mosquito vector.

Q: Which of the following diseases does not have a chronic carrier state?

Tetanus. ***Tetanus*** - Tetanus is caused by the toxin produced by *Clostridium tetani*, which is an **environmental bacterium** found in soil and does not establish a persistent infection within humans. - Humans are merely **accidental hosts** for this bacterium, meaning there is **no chronic carrier state** where an infected individual continuously harbors and transmits the pathogen. - The disease occurs through wound contamination with spores, not human-to-human transmission. *Measles* - Measles is an **acute viral infection** with no chronic carrier state in the classical sense. - After acute infection, the virus is cleared from the body in immunocompetent individuals. - While **subacute sclerosing panencephalitis (SSPE)** represents a rare persistent infection, this is **not a carrier state** as the virus is not transmissible from these individuals. - SSPE occurs years after initial infection but does not involve viral shedding or transmission. *Malaria* - Individuals infected with ***Plasmodium* parasites** can develop a **chronic carrier state**, particularly with *P. vivax* and *P. ovale*, which form hypnozoites in the liver. - These parasites can remain dormant and then reactivate, causing **relapses** and allowing for continued transmission to mosquitoes over extended periods. - Chronic asymptomatic carriers can serve as reservoirs for transmission in endemic areas. *Poliomyelitis* - Individuals infected with poliovirus can shed the virus in their stools for **several weeks to months** after infection. - In **immunodeficient individuals**, prolonged excretion can occur for years, creating chronic carriers. - This prolonged shedding allows for the **continued transmission** of the virus within a population.

Q: Secondary prevention is applicable to

Early stage of disease. ***Early stage of disease*** - **Secondary prevention** focuses on early detection and prompt treatment to halt the progression of an existing disease. - This stage is crucial for interventions like **screening tests** and **early diagnosis**, which aim to minimize the impact of the disease once it has begun. *Factors leading to disease* - This relates to **primary prevention**, which aims to prevent the disease from occurring in the first place by addressing risk factors or promoting health. - Examples include **vaccination** or promoting healthy lifestyle choices. *Advanced stage of disease* - This is the domain of **tertiary prevention**, which focuses on managing the disease, preventing complications, and improving quality of life once the disease is well-established. - Rehabilitation and long-term care are key aspects of this stage. *None of the options* - This option is incorrect because secondary prevention specifically targets the **early stage of disease** to prevent further progression and adverse outcomes.

Q: What is the Chandler's Index for Hookworm that indicates a significant health problem?

> 50. ***> 50*** - A Chandler's Index of **> 50** indicates a significant public health problem due to **hookworm infection**. - **Chandler's Index** is calculated as the **average egg count per person in a community** (total hookworm eggs counted ÷ number of persons examined), used to assess the population-level burden of hookworm infection. - A value **> 50** suggests that the community has a significant hookworm problem requiring public health intervention. *> 300* - This value is significantly higher than the threshold for a significant public health problem and would indicate an **extremely severe burden of infection**. - While this represents a very high Chandler's Index, it's not the standard cut-off for defining a "significant" health problem (which is the lower threshold of >50). *> 200* - A Chandler's Index of **> 200** would denote a very high intensity of hookworm infection in the community. - However, this is not the standard threshold used to define when hookworm becomes a "significant" public health issue - the threshold is lower at >50. *> 100* - A Chandler's Index of **> 100** represents a substantial level of hookworm infection within a population. - However, the widely recognized cutoff for a "significant health problem" is **> 50**, indicating public health concern even at this moderate level of community infection burden.

Q: What is the key characteristic of Body Mass Index (BMI) considerations for the Asian population?

Increased morbidity at lower values. ***Increased morbidity at lower values*** - Due to differences in body composition and fat distribution, Asian populations tend to experience **higher risks of developing obesity-related diseases** (e.g., type 2 diabetes, cardiovascular disease) at **lower BMI values** compared to non-Asian populations. - This increased morbidity at lower BMI values highlights the need for population-specific BMI cut-offs for health risk assessment. *BMI cut-offs for obesity differ from international standards* - While it is true that **BMI cut-offs for obesity differ for Asian populations**, this option does not fully describe *why* these cut-offs differ. - The difference in cut-offs is precisely *because* increased morbidity is seen at lower BMI values, making this option less specific than the correct answer. *Increased morbidity at higher BMI values* - While morbidity does increase at higher BMI values in all populations, this statement is **true for Caucasians and other populations**, but the defining characteristic for Asian populations is the *lower* BMI at which morbidity risk begins to significantly increase. - This option does not capture the unique aspect of BMI and health risks in the Asian population. *Obesity is defined as > 25 kg/m2* - For many Asian populations, a BMI of **> 25 kg/m²** is often used as the cut-off for **overweight**, not necessarily obesity, and **obesity is often defined at > 27.5 kg/m² or 30 kg/m² depending on the specific group**. - The international standard for obesity (BMI ≥ 30 kg/m²) is often considered too high for many Asian populations to capture risk effectively.

Q: Which disease is associated with a propagative cycle?

Filaria. ***Filaria*** - The **filarial worm** undergoes a **biological transmission cycle** in the mosquito vector where microfilariae develop through larval stages (L1 → L2 → L3) with multiplication. - This represents a **cyclopropagative cycle** (both development and multiplication occur in the vector). - In the context of this question and classical teaching, filaria is considered the standard example of biological transmission with vector multiplication. - The infective L3 larvae multiply from a single microfilaria, and multiple larvae can develop within one mosquito. *Plague* - **Plague** (*Yersinia pestis*) is transmitted by fleas through **mechanical transmission**. - Bacteria multiply in the flea's gut causing blockage (blocking transmission), but this is not considered a true biological cycle. - The pathogen does not undergo developmental stages in the vector. *Malaria* - **Malaria** (*Plasmodium* spp.) undergoes the **sporogonic cycle** in the mosquito, which is also a **cyclopropagative cycle**. - Gametocytes → ookinete → oocyst → sporozoites (development with multiplication). - While biologically similar to filaria, in classical epidemiology teaching, filaria is more commonly cited as the example for propagative transmission. *None of the options* - This option is incorrect as filaria demonstrates biological transmission with multiplication in the vector. - Both filaria and malaria technically undergo cyclopropagative cycles, but filaria is the conventional answer in medical education contexts.

Question 1

In the context of epidemiology, what is the denominator used for calculating incidence?

Accepted Answer

Population at risk

Answer

Mid year population

Answer

Total number of cases

Answer

Total number of deaths

Question 2

What is the purpose of work sampling in industrial engineering?

Accepted Answer

Assessment of how workers spend their time on various activities

Answer

None of the options

Answer

Conducted over a short duration

Answer

Sampling done for individual tasks

Question 3

Which is the least common cause among these of infant mortality in India?

Accepted Answer

Birth injuries

Answer

Infections

Answer

Congenital malformations

Answer

Prematurity

Question 4

All of the following are characteristics of case control study except:

Accepted Answer

Measures incidence rate

Answer

Quick results are obtained

Answer

Inexpensive study

Answer

Proceeds from effect to cause

Question 5

Transovarian transmission is seen in which of the following infections?

Accepted Answer

Yellow fever

Answer

Plague

Answer

Ebola fever

Answer

None of the options

Question 6

Which of the following diseases does not have a chronic carrier state?

Accepted Answer

Tetanus

Answer

Malaria

Answer

Measles

Answer

Poliomyelitis

Question 7

Secondary prevention is applicable to

Accepted Answer

Early stage of disease

Answer

Factors leading to disease

Answer

Advanced stage of disease

Answer

None of the options

Question 8

What is the Chandler's Index for Hookworm that indicates a significant health problem?

Accepted Answer

> 50

Answer

> 200

Answer

> 100

Answer

> 300

Question 9

What is the key characteristic of Body Mass Index (BMI) considerations for the Asian population?

Accepted Answer

Increased morbidity at lower values

Answer

BMI cut-offs for obesity differ from international standards

Answer

Increased morbidity at higher BMI values

Answer

Obesity is defined as > 25 kg/m2

Question 10

Which disease is associated with a propagative cycle?

Accepted Answer

Filaria

Answer

None of the options

Answer

Plague

Answer

Malaria

NEET-PG 2012 — Community Medicine