Epidemiology Practice Questions

Q: Which of the following statements about the Urban Malaria Scheme is incorrect?

It is done in town/city with minimum 50,000 population. ***It is done in town/city with minimum 50,000 population*** - This statement is **INCORRECT** because it misrepresents the eligibility criteria for the Urban Malaria Scheme. - The actual criterion is not based solely on a minimum population threshold; rather, the scheme is implemented in **towns and cities classified as urban areas** as per Census of India definitions, which may vary. - While many urban centers targeted have populations around or exceeding 50,000, the program focuses on **malaria endemicity and urban characteristics** rather than a fixed population cutoff. *Utilization of anti-larva measures* - This is a **CORRECT** statement about the Urban Malaria Scheme. - Anti-larval measures are a cornerstone of the program, including **source reduction, larvicides, and biological control** of mosquito breeding sites. - Urban environments have specific breeding sites (construction sites, overhead tanks, etc.) that require targeted anti-larval interventions. *Introduction of active surveillance* - This is a **CORRECT** statement about the Urban Malaria Scheme. - **Active case detection** through fever surveys and surveillance is a key component for early identification and treatment of malaria cases. - Active surveillance helps prevent outbreaks in densely populated urban areas. *Slide positivity rate more than 10%* - This is a **CORRECT** statement about the Urban Malaria Scheme. - Areas with **Slide Positivity Rate (SPR) ≥ 10%** are prioritized for intensive interventions under the scheme. - High SPR indicates active transmission and helps identify high-burden urban pockets requiring focused control measures.

Q: Vector of trench fever is which one of the following?

Louse. ***Louse*** - **Trench fever** is caused by the bacterium *Bartonella quintana* and is primarily transmitted to humans by the **body louse** (*Pediculus humanus corporis*). - The disease became notorious during World War I due to its prevalence among soldiers living in crowded, unhygienic conditions, which favored louse infestation. *Tick* - Ticks are vectors for various diseases such as **Lyme disease**, **Rocky Mountain spotted fever**, and **Ehrlichiosis**, but not trench fever. - These diseases are caused by different bacterial species and present with distinct clinical manifestations. *Mite* - Mites are known vectors for diseases like **scrub typhus** (transmitted by chiggers) and can cause conditions such as **scabies**, but they do not transmit trench fever. - Mites typically live on or in the skin of their hosts, and their biting patterns and associated pathogens differ from those of lice. *Rat flea* - **Rat fleas** (*Xenopsylla cheopis*) are the primary vectors for **bubonic plague** (caused by *Yersinia pestis*) and **murine typhus** (caused by *Rickettsia typhi*). - These diseases are distinct from trench fever in their causative agents, transmission cycles, and clinical presentations.

Q: Which of the following diseases is not transmitted by lice?

Q fever. ***Correct: Q fever*** - **Q fever** is caused by *Coxiella burnetii* and is primarily transmitted by **inhalation of aerosols** from infected animal products or excretions, not by lice - Exposure to infected livestock (cattle, sheep, goats) or their birth products is the most common route of transmission - This is a zoonotic disease with no arthropod vector involvement *Incorrect: Relapsing fever* - Louse-borne relapsing fever is caused by *Borrelia recurrentis* and transmitted by the body louse (*Pediculus humanus corporis*) - Infection occurs when infected lice are crushed, releasing bacteria into breaks in the skin - Characterized by recurrent episodes of fever, prevalent in areas with poor hygiene and overcrowding *Incorrect: Trench fever* - Caused by *Bartonella quintana* and transmitted by the body louse (*Pediculus humanus corporis*) through its feces - Infection occurs when louse feces are scratched into the skin or mucous membranes, or when inhaled - Associated with homelessness, overcrowding, and poor hygiene *Incorrect: Epidemic typhus* - Caused by *Rickettsia prowazekii* and transmitted by the body louse when its feces containing bacteria are rubbed into abraded skin or mucous membranes - Associated with poor hygiene and crowded conditions, particularly during wars, disasters, or refugee situations - Can cause severe systemic illness with high fever and rash

Q: A drug that does not cure a disease but decreases its symptoms and increases survival leads to increased:

Increased prevalence. ***Increased prevalence*** - A drug that **decreases symptoms** and **increases survival** means people live longer with the disease. - This leads to more existing cases at any given time, thus **increasing prevalence**. *Increased incidence* - **Incidence** refers to the rate of new cases of a disease in a population over a specific period. - A drug that *palliates* symptoms and increases survival does not affect the rate at which new cases develop; therefore, it does not alter incidence. *Decreased prevalence* - **Decreased prevalence** would occur if fewer people had the disease or if people recovered or died more quickly. - Since the drug *increases survival*, it would lead to more people living with the disease for longer, thus increasing, not decreasing, prevalence. *Decreased incidence* - **Decreased incidence** means fewer new cases are occurring. - A palliative drug that extends life does not prevent new cases from arising and therefore does not decrease incidence.

Q: Which of the following attributes are essential for an ideal screening test?

All of the options. ***All of the options*** - An ideal screening test must possess **all three essential attributes**: safety, reliability, and validity. - **Safe**: Minimizes harm to participants and ensures ethical implementation - **Reliable**: Produces consistent, reproducible results with minimal random error - **Valid**: Accurately measures what it intends to measure (high sensitivity and specificity) - These three attributes work together as fundamental requirements for any effective screening program, ensuring that early detection benefits outweigh potential risks. *Safe (alone)* - While safety is absolutely essential, it is **not sufficient by itself** to make an ideal screening test. - A test that is safe but unreliable or invalid would produce inconsistent or inaccurate results, rendering it ineffective for screening purposes. *Reliable (alone)* - Reliability ensures consistent results, which is crucial, but **reliability alone is insufficient**. - A test can be highly reliable (consistently giving the same result) yet completely invalid if it measures the wrong thing or is unsafe. *Valid (alone)* - Validity is critical for accurate measurement, but **validity alone does not make a test ideal**. - Even a valid test must be safe to protect participants and reliable to ensure consistency across different settings and times.

Question 1

Which of the following statements about the Urban Malaria Scheme is incorrect?

Accepted Answer

It is done in town/city with minimum 50,000 population

Answer

Utilization of anti-larva measures

Answer

Introduction of active surveillance

Answer

Slide positivity rate more than 10%

Question 2

Vector of trench fever is which one of the following?

Accepted Answer

Louse

Answer

Tick

Answer

Mite

Answer

Rat flea

Question 3

Which of the following diseases is not transmitted by lice?

Accepted Answer

Q fever

Answer

Relapsing fever

Answer

Trench fever

Answer

Epidemic typhus

Question 4

What is the primary limitation of conducting a one-day census of inpatients in a mental hospital?

Accepted Answer

Provides a snapshot of the current patient demographic but lacks longitudinal data.

Answer

Gives reliable estimates of seasonal factors in admissions.

Answer

Allows for conclusions about the overall mental health trends in India.

Answer

Enables estimation of the distribution of different diagnoses over time.

Question 5

A drug that does not cure a disease but decreases its symptoms and increases survival leads to increased:

Accepted Answer

Increased prevalence

Answer

Increased incidence

Answer

Decreased prevalence

Answer

Decreased incidence

Question 6

Which of the following attributes are essential for an ideal screening test?

Accepted Answer

All of the options

Answer

Safe

Answer

Reliable

Answer

Valid

Epidemiology — MCQs

Epidemiology — MCQs

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