NEET-PG 2013 - Community Medicine Practice Questions

Q: Most common mode of transmission of nosocomial infection is -

Hand contact. ***Hand contact*** - **Direct contact** with healthcare workers' contaminated hands is the primary way pathogens are transferred between patients in a healthcare setting. - Failure to perform adequate **hand hygiene** between patient contacts is the single most important factor contributing to nosocomial infection transmission. *Droplet infection* - While droplet transmission can cause nosocomial infections, especially for respiratory viruses, it is not the most common mode of transmission for the overall burden of healthcare-associated infections. - **Droplets** usually travel short distances and deposit on mucous membranes of the nose, mouth, or eyes of a susceptible host. *Blood and blood products* - Transmission through **blood and blood products** is a significant concern for specific infections (e.g., HIV, hepatitis B/C), but the incidence is relatively low due to stringent screening and safety protocols. - This mode accounts for a small fraction of overall nosocomial infections compared to contact transmission. *Contaminated water* - **Contaminated water** can lead to outbreaks (e.g., *Legionella*, *Pseudomonas*), especially in immunocompromised patients, but it is not the most frequent mode of transmission on a day-to-day basis across all types of nosocomial infections. - Healthcare facilities implement measures to ensure water safety, limiting this as the primary route.

Q: Transovarian transmission is seen in-

Rickettsial diseases. ***Rickettsial diseases*** - **Transovarian transmission** is a key mechanism for the maintenance and spread of **rickettsiae** in arthropod vectors. The bacteria can pass from an infected female arthropod (like a tick or mite) to her offspring via the eggs. - This ensures that the next generation of vectors is already infected and can transmit the disease, even without needing to acquire the pathogen from an infected vertebrate host. *Malaria* - Malaria is transmitted via the bite of an infected **Anopheles mosquito**, which acquires parasites from an infected human. - **Transovarian transmission** does not occur in malaria; mosquitoes are not born with the ability to transmit the parasite. *Filaria* - Filariasis is spread by various **mosquito vectors** (e.g., *Culex*, *Anopheles*, *Aedes*) or **black flies**, which acquire microfilariae from an infected host during a blood meal. - The parasite undergoes development within the insect, but **transovarian transmission** to the insect's offspring does not occur. *None of the options* - This option is incorrect because **rickettsial diseases** do exhibit transovarian transmission, making it a valid answer. - The phenomenon of passing pathogens directly from a female parent to her offspring via the egg is a specific mechanism seen in certain vector-borne diseases.

Q: Which of the following insects has shown the least widespread development of resistance to DDT?

Tsetse flies. ***Tsetse flies*** - **Tsetse flies** have shown the least widespread development of **resistance to DDT**, likely due to their specific life cycles and limited exposure in widespread application campaigns. - This has made DDT, or its successor compounds, remain effective in certain tsetse control programs where other insects have developed high resistance. *Mosquitoes* - **Mosquitoes** have developed **widespread resistance to DDT** globally, significantly impacting malaria control efforts. - Their rapid breeding cycles and extensive exposure to DDT over decades led to the selection and proliferation of resistant strains. *Fleas* - **Fleas** have also developed **significant resistance to DDT**, especially in regions where it was heavily used for pest control in homes and livestock. - This resistance is a major factor in the continued prevalence of flea-borne diseases in certain areas. *Ticks* - **Ticks** have shown considerable development of **resistance to DDT** and other acaricides due to widespread use in livestock and agricultural settings. - Their resistance has complicated efforts to control tick-borne diseases and protect animal health.

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.

Q: What is the type of sampling used when a random sample is taken from distinct groups within a population, such as religious groups like Hindus, Muslims, and Christians?

Stratified random. ***Stratified random*** - This method involves dividing the population into **distinct, non-overlapping subgroups (strata)** based on a shared characteristic (e.g., religious groups). - A **random sample** is then drawn from each stratum, ensuring representation from all groups. *Simple random* - Involves selecting individuals entirely at **random** from the entire population, with each individual having an equal chance of being chosen. - It does not guarantee representation from specific subgroups within the population. *Systematic random* - This method selects individuals at **regular intervals** from a randomly ordered list of the population (e.g., every 10th person). - While it offers a degree of randomness, it does not specifically account for or ensure representation of distinct subgroups. *Cluster* - This method involves dividing the population into **clusters (natural groupings)**, usually geographically, and then randomly selecting entire clusters to sample. - Unlike stratified sampling, where individuals are selected from each stratum, cluster sampling involves sampling all individuals within chosen clusters.

Q: In a clinical study examining the relationship between weight and height in pediatric patients, what is the maximum possible value of the correlation coefficient if the correlation is very strong?

+1. ***+1 (perfect positive correlation)*** - A correlation coefficient of **+1** indicates a perfect positive linear relationship between two variables, meaning as one variable increases, the other increases proportionally. - This value represents the **maximum possible strength** for a positive correlation. *0* - A correlation coefficient of **0** indicates no linear relationship between two variables. - This would contradict the premise that the correlation is "very strong". *+2 (invalid value for correlation coefficient)* - The correlation coefficient, also known as Pearson's r, can only range from **-1 to +1**. - A value of +2 is outside this possible range and is therefore an **invalid value**. *No correlation (not possible for strong correlation)* - **No correlation** implies a correlation coefficient of 0 or close to 0. - This directly contradicts the statement that there is a **very strong correlation** between weight and height.

Q: The population is divided into homogeneous subgroups, and then individuals are randomly selected from each subgroup. What type of sampling is this?

Stratified random. ***Stratified random*** - In **stratified random sampling**, the population is first divided into homogeneous subgroups (strata), and then a simple random sample is drawn from each stratum. - This method ensures representation from all subgroups, which is implied by the description "separated into groups, from each group people are selected randomly." *Simple random* - **Simple random sampling** involves selecting individuals from an entire population purely by chance, where each individual has an equal probability of being chosen. - This method does not involve an initial division of the population into distinct groups before selection. *Systematic random* - **Systematic random sampling** involves selecting every nth individual from a list after a random starting point. - This method does not involve dividing the population into groups and then sampling from each group. *Cluster* - **Cluster sampling** involves dividing the population into clusters (usually naturally occurring groups), randomly selecting a few clusters, and then sampling *all* individuals within the selected clusters. - In cluster sampling, individuals are not randomly selected *from each* group; instead, entire groups are selected.

Q: What is the common threshold for statistical significance in hypothesis testing?

0.05. ***Correct: 0.05*** - A **p-value of 0.05 (or 5%)** is the most widely accepted and **conventional threshold** for statistical significance in most scientific fields, including medicine - This represents a **5% probability** of observing the results if the **null hypothesis** were true (Type I error or α level) - This is the **standard alpha level** taught in biostatistics and most commonly used in medical research *Incorrect: 0.01* - While 0.01 indicates **higher statistical confidence** (1% chance of Type I error), it is more stringent than the standard threshold - Used in studies requiring **greater certainty** or where false positives have severe consequences - Not the most common or default threshold in general hypothesis testing *Incorrect: 0.02* - A p-value of 0.02 represents a **2% chance of Type I error** - While statistically valid, it is **not a conventional alpha level** for most hypothesis tests - Not the standard threshold taught or applied in medical statistics *Incorrect: 0.03* - A p-value of 0.03 represents a **3% chance of Type I error** - This is **not a standard choice** for statistical significance testing - Not the conventionally prescribed alpha level in biostatistics

Q: Highest level of health care system in India -

Tertiary health care. ***Tertiary health care*** - **Tertiary healthcare** represents the highest level within the healthcare system, offering highly specialized and technologically advanced medical services. - It includes facilities like **super-specialty hospitals** and research centers that provide treatments for complex and rare diseases, often requiring referral from lower levels of care. *Primary health care* - **Primary healthcare** is the first point of contact for individuals, families, and communities with the healthcare system, focusing on prevention, health promotion, and basic curative care. - It is delivered at facilities such as **Sub-centers** and **Primary Health Centers (PHCs)**, addressing common health problems. *Secondary health care* - **Secondary healthcare** provides more specialized medical care than primary care, often involving consultation with specialists and access to basic diagnostic and treatment services. - It is typically delivered at **Community Health Centers (CHCs)** and district hospitals, serving as a referral point from primary care. *All are same* - The different levels of healthcare (primary, secondary, and tertiary) represent a **hierarchical structure** with distinct roles, functions, and levels of specialization. - They are designed to provide a continuum of care, with patients being referred between levels based on their medical needs, ensuring that "all are same" is incorrect.

Q: Most basic level of Health Care System in India -

Primary health care. ***Primary health care*** - **Primary health care** is the first point of contact for individuals with the health system, providing essential and accessible healthcare services - In India, it is delivered through **sub-centers** (the most peripheral unit) and **primary health centers (PHCs)**, forming the **most basic and widespread layer** of the healthcare system - This represents the foundational level of care, focusing on preventive, promotive, and basic curative services *Secondary health care* - **Secondary health care** involves more specialized services, typically provided in district hospitals or community health centers (CHCs) - It serves as a referral point from primary care for patients requiring diagnostics, specialist consultations, or inpatient care - This is a **higher level of care** than primary, not the most basic level *Tertiary health care* - **Tertiary health care** offers highly specialized and advanced medical care, often involving complex procedures, specialized investigations, and management of rare or severe diseases - Provided in medical colleges, research institutes, and super-specialty hospitals - This represents the **highest and most advanced level** of the healthcare system, not the most basic *All are same* - This option is incorrect because the Indian healthcare system is structured in a **hierarchical manner** with distinct levels - Each level (primary, secondary, and tertiary) provides different services, varying in complexity, specialization, and accessibility - Primary care is clearly the most basic level, while secondary and tertiary represent progressively higher levels of specialization

Question 1

Most common mode of transmission of nosocomial infection is -

Accepted Answer

Hand contact

Answer

Droplet infection

Answer

Blood and blood products

Answer

Contaminated water

Question 2

Transovarian transmission is seen in-

Accepted Answer

Rickettsial diseases

Answer

Malaria

Answer

Filaria

Answer

None of the options

Question 3

Which of the following insects has shown the least widespread development of resistance to DDT?

Accepted Answer

Tsetse flies

Answer

Mosquitoes

Answer

Fleas

Answer

Ticks

Question 4

Randomization is done to reduce?

Accepted Answer

Selection bias

Answer

Recall bias

Answer

Berksonian bias

Answer

Reporting bias

Question 5

What is the type of sampling used when a random sample is taken from distinct groups within a population, such as religious groups like Hindus, Muslims, and Christians?

Accepted Answer

Stratified random

Answer

Simple random

Answer

Cluster

Answer

Systematic random

Question 6

In a clinical study examining the relationship between weight and height in pediatric patients, what is the maximum possible value of the correlation coefficient if the correlation is very strong?

Accepted Answer

+1

Answer

0

Answer

+2

Answer

No correlation

Question 7

The population is divided into homogeneous subgroups, and then individuals are randomly selected from each subgroup. What type of sampling is this?

Accepted Answer

Stratified random

Answer

Simple random

Answer

Cluster

Answer

Systematic random

Question 8

What is the common threshold for statistical significance in hypothesis testing?

Accepted Answer

0.05

Answer

0.01

Answer

0.02

Answer

0.03

Question 9

Highest level of health care system in India -

Accepted Answer

Tertiary health care

Answer

Primary health care

Answer

Secondary health care

Answer

All are same

Question 10

Most basic level of Health Care System in India -

Accepted Answer

Primary health care

Answer

Secondary health care

Answer

Tertiary health care

Answer

All are same

NEET-PG 2013 — Community Medicine