Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 621: Reservoir of infection in enteric fever?

A. Birds
B. Cow
C. Man (Correct Answer)
D. Water

Explanation: ***Man*** - Humans are the **sole natural reservoir** for *Salmonella Typhi* and *Salmonella Paratyphi*, the causative agents of enteric fever (typhoid and paratyphoid fever). - The bacteria can persist in the **gallbladder** of asymptomatic carriers, who can then shed the bacteria in their feces, contributing to transmission. *Birds* - Birds are not considered a primary reservoir for the **causative pathogens of enteric fever** (*Salmonella Typhi* or *Paratyphi*). - They are more commonly associated with other *Salmonella* serotypes, such as *Salmonella Enteritidis*, which cause **gastroenteritis** rather than systemic enteric fever. *Cow* - Cows are not a primary reservoir for the organisms responsible for **enteric fever**; these pathogens are specifically adapted to humans. - While cows can carry various *Salmonella* species, they are typically associated with **foodborne outbreaks** of *Salmonella*-induced **gastroenteritis**, not typhoid fever. *Water* - Water is a **vehicle for transmission** of enteric fever, becoming contaminated with human feces containing *Salmonella Typhi* or *Paratyphi*. - It is not a reservoir because the bacteria do not naturally **multiply or persist indefinitely** in water without a human source.

Question 622: Which of the following screening methods is primarily used under the National Tuberculosis Elimination Program (NTEP)?

A. Active
B. Passive (Correct Answer)
C. Mass
D. None of the options

Explanation: ***Passive*** - Under the NTEP, **passive screening** involves individuals presenting to health facilities with symptoms suggestive of TB. - This method relies on **patient self-reporting** and healthcare provider suspicion, rather than active outreach. - Passive case finding is the **primary screening strategy** used across the general population in the NTEP framework. *Active* - **Active screening** involves community-based interventions to proactively identify individuals with TB, often in high-risk populations. - While active case finding is crucial for specific vulnerable groups (contacts, HIV patients, etc.), it is **not the primary screening method** under the standard NTEP framework for initial detection across the entire population. *Mass* - **Mass screening** involves testing large numbers of people in the general population, regardless of symptoms, to detect disease. - This is generally **cost-prohibitive** and not routinely implemented as a primary screening strategy for TB by the NTEP due to resource limitations and low yield in the general population. *None of the options* - **Passive screening** is indeed a primary method used under the NTEP, making this option incorrect. - The NTEP heavily relies on individuals seeking care when they experience symptoms, which aligns with the definition of passive case finding.

Question 623: Drug of choice for mass therapy under filariasis control programme?

A. Albendazole
B. Ivermectin
C. DEC (Correct Answer)
D. Mebendazole

Explanation: ***Correct: DEC*** - **Diethylcarbamazine (DEC)** is the drug of choice for **mass drug administration (MDA)** campaigns aimed at eliminating lymphatic filariasis. - It effectively kills **microfilariae** and has some action on adult worms, reducing transmission. - In India's National Filariasis Elimination Programme, DEC is administered along with Albendazole in annual MDA campaigns. *Incorrect: Albendazole* - While **Albendazole** is co-administered with DEC in MDA programs, it is not the sole drug of choice for mass treatment of filariasis. - Its primary role is to provide **macrofilaricidal** activity (killing adult worms) and co-treatment for other helminth infections. - It enhances the effect of DEC but is not used alone. *Incorrect: Ivermectin* - **Ivermectin** is used in MDA programs for filariasis, particularly in areas co-endemic with **onchocerciasis** or where **Loa loa** is prevalent (as DEC is contraindicated in these areas). - However, in India and most lymphatic filariasis endemic areas, **DEC** remains the primary drug. *Incorrect: Mebendazole* - **Mebendazole** is an anthelminthic primarily used for treating **intestinal nematode infections** like ascariasis, trichuriasis, and hookworm. - It is **not used** in lymphatic filariasis mass treatment programs.

Question 624: Which of the following statements is incorrect regarding the strategic plan for malaria control 2012-2017?

A. 50% reduction in mortality by 2017
B. Objective is API < 1 per 10,000 (Correct Answer)
C. Complete treatment to 100% of patients
D. Annual incidence < 1 per 1000 by 2017

Explanation: ***Objective is API < 1 per 10,000*** - The correct objective for the **Annual Parasite Incidence (API)** in the 2012-2017 strategic plan for malaria control was to reduce it to **less than 1 per 1,000 population**, not 1 per 10,000, making this statement incorrect. - This metric measures the number of new malaria cases per 1,000 people per year. *50% reduction in mortality by 2017* - A key objective of the **National Framework for Malaria Elimination in India** (which this strategic plan aimed to contribute to) was indeed to achieve a significant reduction in malaria-related mortality. - Specifically, aiming for a **50% reduction in mortality** by 2017 was a stated goal to lessen the disease burden. *Annual incidence < 1 per 1000 by 2017* - One of the primary goals of the **Malaria Control Strategic Plan 2012-2017** was to reduce the annual parasite incidence (API) to **less than 1 per 1,000 population** in all endemic areas. - This target focused on decreasing the occurrence of new malaria cases. *Complete treatment to 100% of patients* - A core component of malaria control strategies emphasizes ensuring that **all confirmed malaria cases** receive complete and effective treatment. - Achieving **100% complete treatment adherence** is crucial to prevent drug resistance and eliminate the parasite reservoir.

Question 625: Human, animal, fomite or objects from which infective organism enters the host is called?

A. Infective Reservoir
B. Infective Carrier
C. None of the above
D. Source of infection (Correct Answer)

Explanation: ***Source of infection*** - The **source of infection** refers to the person, animal, object, or substance from which an infectious agent passes immediately to a host. - This can include humans, animals, fomites, or contaminated objects that directly transmit the infectious organism. - This is the proximate source from which the agent enters the host. *Infective Reservoir* - An **infective reservoir** is the long-term habitat where an infectious agent normally lives, grows, and multiplies. - The reservoir can be human, animal, plant, soil, or inanimate matter where the agent is normally found. - While a reservoir can be a source, the source is specifically the immediate point from which transmission occurs. *Infective Carrier* - An **infective carrier** is an infected person or animal that harbors a specific infectious agent without showing clinical symptoms but can transmit it to others. - A carrier is a type of source (when transmission occurs from them), but the term "source" is broader, encompassing inanimate objects and fomites as well. *None of the above* - This option is incorrect because **Source of infection** accurately describes the concept presented in the question.

Question 626: Which of the following is the most epidemiologically distinctive feature of chickenpox?

A. Caused by varicella-zoster virus
B. Most commonly affects children under 10 years old
C. Secondary attack rate (SAR) is approximately 90% (Correct Answer)
D. Infectious period is 1-2 days before rash until all blisters have scabbed over

Explanation: ***Secondary attack rate (SAR) is approximately 90%*** - A **secondary attack rate (SAR)** of around 90% is exceptionally high, indicating that chickenpox is one of the most **contagious infectious diseases**, readily spreading among susceptible household contacts. - This high SAR highlights the disease's **distinctive epidemiological characteristic** of efficient person-to-person transmission within close-contact settings. *Caused by varicella-zoster virus* - While true, many diseases are caused by specific viruses, and this fact alone is not an **epidemiologically distinctive feature** in terms of transmissibility or population impact. - The causative agent defines the disease, but doesn't uniquely describe its spread or contagiousness in an epidemiological sense. *Most commonly affects children under 10 years old* - Many common childhood infections, such as measles or mumps, also primarily affect children, making this less of a **distinctive epidemiological feature** for chickenpox specifically. - The age group affected is common for many highly transmissible diseases of childhood. *Infectious period is 1-2 days before rash until all blisters have scabbed over* - Many infectious diseases have similar **infectious periods** spanning from a prodromal phase to resolution, making this a general feature of viral infections rather than one highly distinctive to chickenpox epidemiologically. - While important for infection control, it doesn't stand out as uniquely characteristic of chickenpox's epidemiological profile compared to other common infectious diseases.

Question 627: Which of the following statements about universal precautions is false?

A. Includes use of hand washing
B. Consider that all body fluids are contaminated with blood (Correct Answer)
C. Includes use of gloves and masks
D. To prevent transmission of blood borne pathogens

Explanation: ***Correct: Consider that all body fluids are contaminated with blood*** - This statement is **FALSE** and therefore the correct answer to this question asking what is false about universal precautions. - **Universal precautions** do NOT assume all body fluids are "contaminated with blood." Instead, they specify that **certain body fluids** (blood, semen, vaginal secretions, cerebrospinal fluid, synovial fluid, pleural fluid, peritoneal fluid, pericardial fluid, amniotic fluid, and any body fluid visibly contaminated with blood) should be treated as **potentially infectious for bloodborne pathogens** (HIV, HBV, HCV). - The distinction is important: it's about **potential infectivity for bloodborne pathogens**, not that all body fluids are literally contaminated with blood. Universal precautions do NOT apply to feces, nasal secretions, saliva, sputum, sweat, tears, urine, or vomitus unless they contain visible blood. *Incorrect: Includes use of hand washing* - This statement is **TRUE** about universal precautions (therefore incorrect as an answer to what is false). - **Hand hygiene** is a **fundamental component** of universal and standard precautions, essential for preventing transmission of microorganisms between patients and healthcare workers. *Incorrect: Includes use of gloves and masks* - This statement is **TRUE** about universal precautions (therefore incorrect as an answer to what is false). - **Personal protective equipment (PPE)** including gloves, masks, gowns, and eye protection are **integral to universal precautions**. - Gloves are used when contact with blood or specified body fluids is anticipated; masks and eye protection are used during procedures likely to generate splashes or sprays. *Incorrect: To prevent transmission of blood borne pathogens* - This statement is **TRUE** about universal precautions (therefore incorrect as an answer to what is false). - The **primary goal** of universal precautions is to **prevent transmission of bloodborne pathogens** such as HIV, Hepatitis B (HBV), and Hepatitis C (HCV) by creating barriers between healthcare workers and potentially infectious materials.

Question 628: Which of the following statements about pathogenic mosquitoes is correct?

A. Mansonia mosquitoes lay their eggs in rafts.
B. Culex mosquitoes are primarily vectors for West Nile virus.
C. Aedes mosquitoes are known for their distinctive black and white striped markings.
D. Anopheles mosquitoes are known for transmitting malaria. (Correct Answer)

Explanation: ***Correct: Anopheles mosquitoes are known for transmitting malaria.*** - **Anopheles mosquitoes** are the **primary and only vectors** for **malaria**, a parasitic disease caused by Plasmodium parasites. - They transmit the parasite through their **saliva** when they bite humans, typically during **dusk and dawn**. - This is the most significant pathogenic association among the options. *Incorrect: Mansonia mosquitoes lay their eggs in rafts.* - **Mansonia mosquitoes** lay their eggs in **clusters attached to underwater parts of aquatic plants**, not in rafts. - **Culex mosquitoes** are the ones that lay their eggs in **raft-like formations** on water surfaces. *Incorrect: Culex mosquitoes are primarily vectors for West Nile virus.* - While **Culex mosquitoes** can transmit West Nile virus, in the **Indian context** they are primarily known as vectors for **lymphatic filariasis** (Wuchereria bancrofti) and **Japanese encephalitis**. - West Nile virus is more relevant in Western countries and is not the primary disease association for Culex in India. *Incorrect: Aedes mosquitoes are known for their distinctive black and white striped markings.* - While **Aedes aegypti** and **Aedes albopictus** do have **black and white striped markings**, this is a **morphological characteristic** rather than a primary **pathogenic association**. - The question asks about pathogenic mosquitoes, and Aedes is better characterized by its **disease transmission** (dengue, Zika, chikungunya, yellow fever) rather than its appearance. - As a pathogenic mosquito, its **daytime biting behavior** and **urban breeding habits** are more relevant than its markings.

Question 629: Which of the following statements about influenza infectivity is correct?

A. Communicable period is 1 day before to 5-7 days after the onset of symptoms
B. All of the options are correct. (Correct Answer)
C. There can be subclinical cases of influenza.
D. The primary source of infection is a clinical case.

Explanation: ***All of the options are correct.*** - All statements provided accurately describe aspects of influenza infectivity and epidemiology. - The **communicable period**, the **primary source of infection**, and the potential for **subclinical cases** are all characteristic features of influenza. *Communicable period is 1 day before to 5-7 days after the onset of symptoms* - This statement is accurate, as influenza is transmissible **before symptom onset** and for several days afterward, which contributes to its rapid spread. - Peak viral shedding often occurs just before and in the first few days of symptomatic illness. - Adults typically shed virus from 1 day before to 5-7 days after symptom onset (can be longer in children and immunocompromised individuals). *The primary source of infection is a clinical case.* - This is correct, as **symptomatic individuals (clinical cases) are the PRIMARY source** of influenza virus transmission to others. - Respiratory droplets produced by coughing, sneezing, or talking from an infected person are the main mode of spread. - While subclinical cases can transmit, clinical cases with overt symptoms produce more respiratory droplets and are the major drivers of transmission. *There can be subclinical cases of influenza.* - This statement is correct; many individuals infected with influenza virus experience **mild or asymptomatic infections** (subclinical cases). - These subclinical cases can still transmit the virus, though typically to a lesser extent than symptomatic cases, further complicating control efforts.

Question 630: Under NTEP, what is the honorarium given to a DOTS provider after the completion of treatment?

A. 150 INR
B. 500 INR (Correct Answer)
C. 1000 INR
D. 250 INR

Explanation: ***500 INR*** - Under the **National Tuberculosis Elimination Programme (NTEP)**, a **DOTS provider** receives an honorarium of **INR 500** upon the successful completion of tuberculosis treatment for a **new TB patient**. - This incentive, revised from the earlier amount of INR 250, aims to recognize the crucial role of DOTS providers in ensuring treatment adherence and successful outcomes. - The increased honorarium reflects the government's commitment to incentivizing community participation in TB elimination. *150 INR* - This amount is **significantly lower than the stipulated honorarium** for a DOTS provider upon treatment completion under current NTEP guidelines. - The correct incentive for successful completion of treatment is INR 500 for new TB cases. *250 INR* - This was the **earlier honorarium amount** under the previous NTEP guidelines, which has since been **revised upward**. - Under the current NTEP incentive structure, the honorarium for treatment completion has been increased to INR 500. *1000 INR* - This amount is **higher than the designated honorarium** for a DOTS provider upon treatment completion under NTEP. - While this figure may apply to other incentive schemes or different milestones, the standard honorarium for new TB case completion is INR 500.

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