Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 741: The Roll Back Malaria programme focused mainly on

A. IEC campaigns for community awareness
B. Insecticide treated bed nets (Correct Answer)
C. Development of larvivorous fishes for eradication of larvae.
D. Presumptive treatment of malaria case

Explanation: ***Insecticide treated bed nets*** - The **Roll Back Malaria (RBM)** program, launched in 1998, focused significantly on key interventions including the promotion and distribution of **insecticide-treated nets (ITNs)**. - ITNs are highly effective in **preventing mosquito bites**, thus reducing malaria transmission, especially in vulnerable populations. *IEC campaigns for community awareness* - While **Information, Education, and Communication (IEC)** campaigns are crucial for health programs, they were a supportive component rather than the primary focus of RBM's core intervention strategy. - RBM emphasized **tangible interventions** with direct impact on disease transmission. *Development of larvivorous fishes for eradication of larvae* - The use of **larvivorous fish** is a form of biological control, which is typically part of **integrated vector management** but not the central pillar of RBM's strategy. - RBM prioritized interventions with **broad, immediate impact** across larger populations. *Presumptive treatment of malaria case* - **Presumptive treatment** (treating based on symptoms without laboratory confirmation) was an important aspect of early malaria control but not the main strategic thrust of the RBM initiative. - RBM's primary focus was on **prevention and rapid diagnosis/treatment** using effective antimalarials, and vector control strategies.

Question 742: The rodent that is the primary natural reservoir of plague in the Indian subcontinent is

A. Tatera indica (Correct Answer)
B. House mouse
C. Black rat
D. Brown rat

Explanation: ***Tatera indica*** - *Tatera indica*, also known as the **Indian gerbil**, is recognized as a significant **natural reservoir** for plague, specifically *Yersinia pestis*, in the Indian subcontinent. - These rodents play a crucial role in maintaining the **enzootic cycle** of plague in the region. *House mouse* - While **house mice** (*Mus musculus*) can be infected with plague, they are generally not considered the **primary natural reservoir** in endemic regions. - Their role in plague transmission is typically more peripheral compared to other rodent species. *Black rat* - The **black rat** (*Rattus rattus*) was historically a major vector for **epidemic plague** due to its close association with human dwellings. - However, it is primarily an **amplifying host** rather than a consistent natural reservoir maintaining the enzootic cycle in the **wild**. *Brown rat* - The **brown rat** (*Rattus norvegicus*) is also known to carry plague, but its ecological niche and geographical distribution make it less prominent as the **primary natural reservoir** in the Indian subcontinent compared to *Tatera indica*. - It is often associated with urban and suburban environments but is not the main long-term reservoir species in the wild.

Question 743: What is the best way to control the MRSA infection in the ward?

A. Fumigation of ward frequently
B. Washing hand before and after attending patients (Correct Answer)
C. Wearing masks during invasive procedures in ICU
D. Vancomycin given empirically to all the patients

Explanation: **Washing hand before and after attending patients** - **Hand hygiene** is the single most effective measure in preventing the transmission of **healthcare-associated infections**, including **MRSA**. - **Healthcare workers' hands** are the primary vehicle for spreading pathogens from one patient to another. *Fumigation of ward frequently* - **Fumigation** is generally not recommended for routine infection control and has limited efficacy against resistant organisms like **MRSA** in this context. - It does not address the primary mode of transmission, which is direct contact via **contaminated hands** or surfaces. *Wearing masks during invasive procedures in ICU is important.* - While important for preventing infections during **invasive procedures** and protecting against **aerosolized pathogens**, masks are not the primary strategy for controlling the spread of **MRSA** in routine ward settings. - **MRSA transmission** is predominantly contact-based, not airborne. *Vancomycin given empirically to all the patients* - **Empirical broad-spectrum antibiotic use** for all patients is a significant driver of **antibiotic resistance**, including **MRSA**. - It should be reserved for patients with suspected or confirmed **MRSA infections** based on clinical criteria and culture results, not as a general preventive measure.

Question 744: Which of the following is NOT a measure to prevent vertical transmission of HIV?

A. Stop breast feeding
B. Vaginal delivery
C. Administration of vitamin A (Correct Answer)
D. Treatment with zidovudine

Explanation: ***Administration of vitamin A*** - **Vitamin A supplementation** is important for general maternal and child health during pregnancy and lactation. - However, there is **no evidence** that vitamin A administration has any role in preventing **vertical transmission of HIV**. - It is **NOT part of PMTCT (Prevention of Mother-to-Child Transmission) protocols**. *Vaginal delivery* - **Vaginal delivery increases the risk** of HIV transmission compared to elective cesarean section. - **Elective cesarean section** (not vaginal delivery) is the preventive measure recommended for mothers with high or unknown viral loads. - Vaginal delivery may be acceptable only in mothers with **undetectable viral loads** on effective ART. *Stop breast feeding* - **Avoiding breastfeeding** (using replacement feeding) is a recognized strategy to prevent **postnatal HIV transmission** in resource-rich settings. - In resource-limited settings, WHO recommends **exclusive breastfeeding with maternal ART** as the safest option. - This is part of the comprehensive **PMTCT strategy**. *Treatment with zidovudine* - **Zidovudine (AZT)** is a cornerstone of **PMTCT protocols**. - Administration during pregnancy, labor, and to the newborn **significantly reduces vertical transmission risk**. - Now often part of combination **antiretroviral therapy (ART)** regimens for pregnant women with HIV.

Question 745: Which one of the following insecticides is most commonly used for ultra-low-volume fogging?

A. Abate
B. DDT
C. Paris green
D. Malathion (Correct Answer)

Explanation: ***Malathion*** - **Malathion** is a widely used organophosphate insecticide favored in **ultra-low-volume (ULV) fogging** due to its effectiveness against adult mosquitoes and its relatively rapid degradation in the environment. - Its properties allow for dispersion as fine aerosols, effectively covering large areas with minimal environmental residue. *Abate* - **Abate** (temephos) is primarily an **organophosphate larvicide**, used in standing water to control mosquito larvae. - It is not commonly used for ULV fogging, which targets adult mosquitoes. *DDT* - **DDT** (dichlorodiphenyltrichloroethane) is a persistent organochlorine insecticide that was once widely used but is now **restricted or banned** in most countries due to its environmental persistence and toxic effects. - It is not a common choice for ULV fogging in modern pest control. *Paris green* - **Paris green** (copper(II) acetoarsenite) is an inorganic compound historically used as an insecticide, particularly against **Anopheles larvae** in malarial control. - Due to its **high toxicity** (containing arsenic), it is rarely used today, and not suitable for ULV fogging.

Question 746: At what altitude is kala azar unlikely to occur?

A. 400 meters
B. 500 meters
C. 600 meters (Correct Answer)
D. 200 meters

Explanation: ***600 meters*** - Kala-azar, or **visceral leishmaniasis**, is primarily found in **low-lying areas** and is rarely reported at altitudes above 600 meters due to the specific ecological requirements of its **sand fly vector**. - The **Phlebotomus argentipes sand fly**, the main vector in the Indian subcontinent, prefers warm, humid climates and **lower altitudes**. *400 meters* - This altitude is within the **typical endemic range** for kala-azar, especially in regions like the Indian subcontinent. - The environmental conditions at 400 meters are generally conducive for the **survival and breeding** of the sand fly vector. *500 meters* - Similar to 400 meters, 500 meters is still considered within the **favorable altitude range** for kala-azar transmission. - The **sand fly vector** can thrive in the climate often found at this elevation. *200 meters* - This altitude represents a **highly endemic zone** for kala-azar, as it provides optimal conditions for the sand fly vector. - Lower altitudes are typically associated with increased **humidity and warmth**, favoring vector density and parasite transmission.

Question 747: Chemoprophylaxis is done for all except which of the following?

A. Malaria
B. Leprosy
C. Cholera (Correct Answer)
D. Taeniasis

Explanation: ***Cholera*** - **Chemoprophylaxis is generally not recommended for cholera** due to the rapid onset and short incubation period, making widespread prophylactic antibiotic use impractical and potentially contributing to **antibiotic resistance**. - WHO guidelines emphasize **prompt rehydration therapy**, improving sanitation/hygiene, and oral cholera vaccine rather than mass chemoprophylaxis. *Taeniasis* - **Chemoprophylaxis is not a standard practice** for taeniasis prevention. Control measures focus on **proper cooking of pork**, meat inspection, and improved sanitation. - While **praziquantel** is effective for **treatment** of established infection, routine prophylactic use is not recommended in public health practice. *Malaria* - **Malaria chemoprophylaxis is a cornerstone of prevention** for travelers to endemic areas and can be used in certain high-risk populations within endemic regions (e.g., pregnant women, children). - Drugs like **mefloquine, doxycycline, and atovaquone-proguanil** are commonly prescribed to prevent infection. *Leprosy* - **Post-exposure chemoprophylaxis** with a single dose of **rifampicin** is a recommended WHO strategy for close contacts of individuals with newly diagnosed multibacillary leprosy to reduce the risk of developing the disease. - The aim is to **prevent new cases** and interrupt transmission within high-risk groups.

Question 748: The re-evaluation of a case of acute flaccid paralysis for residual paralysis for the purpose of AFP surveillance is done after how many days?

A. 60 days (Correct Answer)
B. 90 days
C. 6 months
D. 1 year

Explanation: ***60 days*** - The 60-day mark is crucial for **AFP surveillance** as it helps distinguish between transient paralysis and **residual paralysis**, which is more indicative of serious conditions like polio. - This period allows sufficient time for most cases of non-polio AFP to resolve, making persistent paralysis at this point a strong indicator for further investigation. *90 days* - While 90 days might be relevant for some long-term follow-ups, it is not the standard timeframe for re-evaluating **residual paralysis** within the established **AFP surveillance** guidelines. - The primary classification for an **AFP case** as having residual paralysis, or not, is definitively made at 60 days post-onset. *6 months* - Six months is a much longer timeframe than required for the initial determination of **residual paralysis** in **AFP surveillance**. - By this point, immediate public health response for potential polio cases would be significantly delayed, missing a critical window for intervention. *1 year* - A one-year re-evaluation is far beyond the scope of immediate **AFP surveillance** objectives, which aim for rapid detection and response. - This duration would not facilitate timely public health actions to prevent potential polio outbreaks.

Question 749: A 25-year-old female has been diagnosed with tuberculosis and has a history of previous TB treatment (relapse case). What is the treatment regimen recommended under the current National Tuberculosis Elimination Programme (NTEP) for this previously treated patient?

A. 2 months of H, R, Z, E daily or thrice weekly + 4 months of H, R, E daily or thrice weekly (Correct Answer)
B. 2 months of H, R, S, Z, E thrice weekly + 1 month of H, R, Z, E thrice weekly + 5 months of H, R thrice weekly
C. 3 months of H, R, Z, E thrice weekly + 3 months of H, R thrice weekly
D. 3 months of H, R, S, Z, E thrice weekly + 1 month of H, R thrice weekly + 6 months of continuation phase (incomplete regimen)

Explanation: ***2 months of H, R, Z, E daily or thrice weekly + 4 months of H, R, E daily or thrice weekly*** - This is the **current NTEP-recommended regimen for previously treated TB cases** (including relapse, treatment after failure, and treatment after loss to follow-up). - The key difference from new cases is the **addition of ethambutol (E) throughout the continuation phase** (4 months of HRE instead of HR) to account for potential drug resistance. - Total treatment duration is **6 months** under current guidelines. *2 months of H, R, Z, E thrice weekly + 4 months of H, R thrice weekly* - This is the regimen for **newly diagnosed drug-sensitive pulmonary TB**, not for previously treated cases. - Previously treated cases require **ethambutol in the continuation phase** (HRE, not just HR) due to higher risk of drug resistance. *2 months of H, R, S, Z, E thrice weekly + 1 month of H, R, Z, E thrice weekly + 5 months of H, R thrice weekly* - This represents the **old Category II regimen under RNTCP** (pre-2020), which is no longer recommended. - Streptomycin (S) has been **removed from standard regimens** due to injectable-related toxicity and the shift to all-oral regimens under NTEP. *3 months of H, R, Z, E thrice weekly + 3 months of H, R thrice weekly* - This regimen does not match either current or previous standard TB treatment protocols. - The duration and drug combinations do not align with NTEP guidelines for any category of TB patients.

Question 750: What term describes an infection or infectious disease that is transmissible under natural conditions from vertebrate animals to humans?

A. Epizootic
B. Epornithic
C. Zoonoses (Correct Answer)
D. Exotic

Explanation: ***Zoonoses*** - A **zoonosis** is an infectious disease that can be **transmitted naturally from vertebrate animals to humans**. - Examples include rabies, Lyme disease, and influenza, where animals act as natural hosts or reservoirs for the pathogen. *Epizootic* - **Epizootic** refers to a disease event in an **animal population** that is analogous to an **epidemic in humans**, indicating a sudden and widespread outbreak. - It describes the prevalence pattern of a disease within an animal population, not the transmission across species to humans. *Epornithic* - **Epornithic** is a term specifically used for an outbreak of disease within a **bird population**, similar to how epizootic refers to animals in general. - This term does not describe the transmission of disease from animals to humans, but rather the incidence within birds. *Exotic* - **Exotic** refers to something originating in or characteristic of a distant foreign country, often implying something unusual or introduced from outside. - It does not specifically describe a type of infectious disease or its transmissibility from animals to humans.

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