Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 141: What is the recommended prophylaxis for health personnel working in a plague ward?

A. Vaccine
B. Tetracycline throughout the duty
C. A course of tetracycline (Correct Answer)
D. Vaccine and Erythromycin

Explanation: **Explanation:** The correct answer is **C. A course of tetracycline**. **Medical Concept:** Plague, caused by *Yersinia pestis*, is a highly infectious disease. Health personnel working in plague wards are at high risk of exposure to pneumonic plague, which spreads via respiratory droplets. For post-exposure prophylaxis (PEP) or for those in close contact with patients, **chemoprophylaxis** is the gold standard. A short course (usually 7 days) of **Tetracycline** (or Doxycycline) is recommended to prevent the onset of the disease. **Analysis of Options:** * **A. Vaccine:** Plague vaccines (killed or live attenuated) are primarily used for pre-exposure prophylaxis in high-risk laboratory workers. They are **not** effective for immediate protection in an outbreak or ward setting because they take time to induce immunity and do not protect against pneumonic plague effectively. * **B. Tetracycline throughout the duty:** Chemoprophylaxis is administered as a fixed **course** (7 days) rather than indefinitely throughout the duty period to minimize toxicity and the risk of antibiotic resistance. * **D. Vaccine and Erythromycin:** Erythromycin is not the first-line drug for plague prophylaxis. Tetracyclines and Sulfonamides are preferred. As mentioned, the vaccine has no role in immediate post-exposure management. **High-Yield Pearls for NEET-PG:** * **Drug of Choice (DOC) for Treatment:** Streptomycin (Gentamicin is an alternative). * **DOC for Prophylaxis:** Tetracycline or Doxycycline. * **Vector:** Rat flea (*Xenopsylla cheopis*). * **Quarantine Period:** 6 days (International Health Regulations). * **Diagnostic Test:** Wayson stain (shows characteristic "safety-pin" appearance).

Question 142: What is the current Global strategy for malaria control called?

A. Modified plan of operation
B. Malaria Eradication Programme
C. Malaria Control Programme
D. Roll Back Malaria (Correct Answer)

Explanation: **Explanation:** **Roll Back Malaria (RBM)** is the correct answer as it represents the current global strategic framework for addressing malaria. Launched in **1998** by the WHO, UNICEF, UNDP, and the World Bank, its primary goal is to coordinate international action to reduce the malaria burden through evidence-based interventions like Long-Lasting Insecticidal Nets (LLINs), Indoor Residual Spraying (IRS), and Artemisinin-based Combination Therapy (ACT). **Analysis of Incorrect Options:** * **Modified Plan of Operation (MPO):** Launched in India in **1977**, this was a specific national strategy introduced after the resurgence of malaria in the mid-70s. It shifted the focus from total eradication to "effective control." * **Malaria Eradication Programme:** This refers to the **Global Malaria Eradication Programme (GMEP)** launched by the WHO in **1955**. It was eventually abandoned in 1969 due to the emergence of drug resistance (Chloroquine) and insecticide resistance (DDT). * **Malaria Control Programme:** This is a generic term. While India started the National Malaria Control Programme (NMCP) in **1953**, it is not the name of the current "Global Strategy." **High-Yield Clinical Pearls for NEET-PG:** * **National Framework for Malaria Elimination (NFME) 2016–2030:** India’s current roadmap aiming for a malaria-free country by **2030**. * **World Malaria Day:** Observed on **April 25th**. * **Drug of Choice:** ACT is the mainstay for *P. falciparum*; Chloroquine remains the drug of choice for *P. vivax* (provided there is no resistance). * **E-2025 Initiative:** A WHO initiative supporting 25 countries that have the potential to eliminate malaria by 2025.

Question 143: What is the drug of choice for Falciparum Malaria?

A. Chloroquine
B. Mefloquine
C. Artemisinin-based Combination Therapy (ACT) (Correct Answer)
D. Proguanil

Explanation: **Explanation:** The current National Drug Policy for Malaria in India (NVBDCP guidelines) mandates **Artemisinin-based Combination Therapy (ACT)** as the first-line treatment for all cases of *Plasmodium falciparum* malaria. The underlying medical concept is to combat widespread drug resistance and ensure rapid parasite clearance. ACTs combine a fast-acting artemisinin derivative (which reduces the parasite biomass quickly) with a long-acting partner drug (which eliminates remaining parasites and prevents recrudescence). **Analysis of Options:** * **Chloroquine (A):** While it remains the drug of choice for *P. vivax* in most regions, it is no longer used for *P. falciparum* due to high levels of chloroquine resistance (CQR) globally and across India. * **Mefloquine (B):** This is primarily used for chemoprophylaxis in travelers or as a partner drug within an ACT (e.g., Artesunate + Mefloquine). It is not used as a monotherapy for treatment due to neuropsychiatric side effects and resistance. * **Proguanil (C):** This is a folate antagonist used mainly for prophylaxis (often in combination with Atovaquone) rather than the acute treatment of falciparum malaria. **High-Yield Clinical Pearls for NEET-PG:** 1. **ACT Regimen in India:** The standard ACT used is **Artesunate (3 days) + Sulphadoxine-Pyrimethamine (1 day)**. 2. **North-East Exception:** In North-Eastern states (where SP resistance is high), the recommended ACT is **Artemether + Lumefantrine**. 3. **Gametocidal Action:** A single dose of **Primaquine (0.75 mg/kg)** is added on Day 2 to all *P. falciparum* cases to prevent transmission (except in pregnancy/infancy). 4. **Severe Malaria:** The drug of choice is **Intravenous (IV) Artesunate** for at least 24 hours, regardless of the species.

Question 144: Which mosquito species is recognized as the principal secondary vector for Zika virus transmission globally?

A. Aedes polynesiensis
B. Aedes albopictus (Correct Answer)
C. Aedes australis
D. Aedes mitchellae

Explanation: ***Aedes albopictus*** - This mosquito, commonly known as the **Asian tiger mosquito**, is recognized as the **principal secondary vector** for Zika virus transmission globally. - It is a competent vector capable of transmitting **Zika**, **Dengue**, and **Chikungunya** viruses across multiple continents including Asia, Europe, Africa, and the Americas. - While *Aedes aegypti* remains the primary vector, *Aedes albopictus* plays a significant role in Zika transmission, particularly in temperate regions where *Ae. aegypti* is less prevalent. - Its adaptability to diverse climates and ability to breed in natural and artificial water containers make it epidemiologically important. *Aedes polynesiensis* - This species is primarily known as a vector for **lymphatic filariasis** (*Wuchereria bancrofti*) in Pacific islands. - While it was involved in Zika virus transmission during the **French Polynesia outbreak (2013-2014)**, it is geographically restricted and not considered a principal vector for global Zika transmission. - Its role is limited to specific Pacific island populations. *Aedes australis* - This species is endemic to Australia and transmits **Ross River virus** and other Australian arboviruses. - It is **not** a recognized vector for Zika virus transmission. - Its geographical distribution and host preferences exclude it from the Zika transmission cycle. *Aedes mitchellae* - This species is not documented in major public health literature as a vector for Zika virus. - It belongs to a mosquito species complex with no established role in arboviral transmission to humans. - Epidemiologically insignificant for Zika virus transmission.

Question 145: What is the usual method of collecting a sample of urine to detect UTI?

A. Starting stream collection
B. Early morning sample
C. Midstream catch (Correct Answer)
D. Suprapubic catheter

Explanation: ***Midstream catch*** - This technique is the *standard, non-invasive method* for routine urine culture as it minimizes **contamination** from bacteria residing in the distal urethra and periurethral area. - By discarding the initial urine (starting stream) and collecting the middle portion, the sample is more representative of the urine contained within the **bladder**. *Early morning sample* - While an early morning sample is often preferred for optimal concentration (e.g., detecting **proteinuria** or **casts**), it is not the methodology for *minimizing contamination*. - The collection technique (midstream) is more critical than the time of day for ensuring a reliable sample for **UTI culture**. *Suprapubic catheter* - Suprapubic aspiration (SPA) provides an **uncontaminated specimen** (often considered the gold standard), but it is an invasive procedure requiring a needle insertion into the bladder. - It is reserved for specific situations, such as neonates or patients with ambiguous results, and is not the **usual** collection method. *Starting stream collection* - The starting stream is most likely to be contaminated with **urethral flora** (e.g., *Staphylococcus epidermidis* or environmental organisms). - Collecting the starting stream significantly increases the chance of **false positive** culture results, confusing the diagnosis of a true **UTI**.

Question 146: Identify A and B in the image of the mosquito larvae given

A. A-Anopheles, B-Culex (Correct Answer)
B. A-Culex, B-Anopheles
C. A-Culex, B-Aedes
D. A-Anopheles, B-Mansonia

Explanation: ***A-Anopheles, B-Culex*** - Larva A is identified as **Anopheles** because it rests **parallel** to the water surface and lacks a respiratory **siphon**, breathing through palmate hairs on its abdominal segments. - Larva B is identified as **Culex** as it hangs at an **angle** to the water surface and breathes through a long, narrow respiratory **siphon**. *A-Culex, B-Aedes* - This is incorrect as larva A exhibits the characteristics of **Anopheles** (no siphon, parallel resting), not **Culex**. - While **Aedes** larvae also hang at an angle, larva B's long siphon is more typical of **Culex**; **Aedes** larvae usually have a shorter, stouter siphon. *A-Culex, B-Anopheles* - This option incorrectly reverses the identities. Larva A is **Anopheles** and larva B is **Culex** based on their distinct resting postures and respiratory structures. - The key differentiating feature is the presence of a **siphon** in B (**Culex**) and its absence in A (**Anopheles**). *A-Anopheles, B-Mansonia* - Although the identification of A as **Anopheles** is correct, larva B is not **Mansonia**. - **Mansonia** larvae are unique as they attach to the roots of aquatic plants to obtain oxygen and do not hang from the surface, unlike the larva shown in B.

Question 147: Under IDSP, which diseases are included under sentinel surveillance?

A. HIV + HBV (Correct Answer)
B. Measles + Diphtheria
C. Malaria + Dengue
D. HIV + TB

Explanation: ***HIV + HBV***- **Sentinel surveillance** under IDSP is utilized for diseases where continuous monitoring of specific, defined sites (sentinel sites) provides crucial incidence or prevalence trends, such as **HIV** and **Hepatitis B Virus (HBV)**.- This method is essential for monitoring these diseases as it provides reliable data on prevalence and long-term trends, often focusing on high-risk or specific population groups.*HIV + TB*- While **HIV** is included in sentinel surveillance, **Tuberculosis (TB)** is primarily monitored through **passive surveillance** using mandatory case notification to track incidence and treatment outcomes.- TB is a reportable disease utilizing a robust notification system (e.g., Nikshay portal in India), which differs from the specialized, site-specific sampling used for sentinel surveillance.*Malaria + Dengue*- **Malaria** and **Dengue** are typically included in **syndromic and presumptive surveillance** streams under IDSP due to their potential for rapid outbreaks and the need for immediate, widespread reporting.- Monitoring for these vector-borne diseases focuses on early detection of outbreaks involving fever in defined geographical areas, rather than long-term prevalence trends at specialized sentinel sites.*Measles + Diphtheria*- These diseases are **vaccine-preventable diseases** and are monitored using **enhanced surveillance** protocols to achieve elimination/eradication targets.- Enhanced surveillance requires immediate investigation and reporting of every suspected case to track coverage gaps and initiate immediate public health measures, differing from the sentinel approach.

Question 148: Which of the following is the National Deworming Day?

A. 11th January
B. 10th February (Correct Answer)
C. 10th August
D. 10th March

Explanation: ***10th February*** - The **National Deworming Day (NDD)** is observed annually on **February 10th** across India as the primary national observance to combat **Soil-Transmitted Helminths (STH)** infections - This day involves mass administration of **Albendazole** to children and adolescents (typically 1-19 years) through schools and Anganwadi centres - This is the officially recognized date for the **first annual round** of the national campaign *10th August* - While this date is used for deworming, it serves as the designated date for the **second round** or **follow-up dose** in states using a biannual strategy - This is not the primary National Deworming Day; **February 10th** remains the nationally recognized date for the official observance *10th March* - This date is incorrect and not officially associated with the **National Deworming Day** in India - The official campaign date is fixed to ensure standardized, synchronized provision of **Albendazole** nationwide *11th January* - **January 11th** is not the recognized date for either the first or second round of the **National Deworming Day** campaign - The program's schedule is intentionally set in February and August to maximize coverage and minimize disruption to academic schedules

Question 149: Which of the following is the vector responsible for transmitting Orientia tsutsugamushi?

A. Mite (Correct Answer)
B. Flea
C. Tick
D. Louse

Explanation: ***Mite***- *Orientia tsutsugamushi*, the causative agent of **scrub typhus**, is transmitted to humans by the bite of the **larval stage** (chiggers) of mites belonging to the Trombiculidae family, such as *Leptotrombidium deliense*. - Mites are crucial in the infectious cycle because they maintain the pathogen through **transovarial transmission**, acting as both the **vector** and the **reservoir**. *Tick* - Ticks are the vectors for other rickettsial diseases, most notably **Rocky Mountain spotted fever** (*Rickettsia rickettsii*) and tularaemia. - Tick-borne infections typically involve different reservoirs (e.g., small mammals, deer) and produce distinct clinical syndromes from scrub typhus. *Louse* - Lice (specifically the body louse) are the vectors for **epidemic typhus** (*Rickettsia prowazekii*) and trench fever. - Transmission of louse-borne pathogens involves scratching infectious feces into the skin, which is not the mechanism for *Orientia tsutsugamushi*. *Flea* - Fleas, particularly the oriental rat flea, transmit **murine typhus** (*Rickettsia typhi*) and **plague** (*Yersinia pestis*). - This type of vector is typically associated with peridomestic rodents, contrasting with the outdoor, vegetation-associated exposure risk characteristic of **scrub typhus**.

Question 150: Hand washing during COVID-19 is what level of prevention?

A. Secondary prevention
B. Tertiary prevention
C. Primary prevention (Correct Answer)
D. Primordial prevention

Explanation: ***Primary prevention***- Hand washing is a crucial public health measure that provides **specific protection** by removing SARS-CoV-2 from the skin surface, thereby preventing the entry and establishment of the disease.- This level of prevention focuses on actions taken *before* the onset of disease to reduce the incidence of infection, aligning with efforts like **vaccination** and health education.*Primordial prevention*- This is the earliest stage, aimed at preventing the emergence and establishment of **environmental or social conditions** that may lead to the development of risk factors (e.g., discouraging unhealthy lifestyle trends globally).- It addresses pre-existing **underlying determinants** of health, whereas hand washing directly targets an infectious agent.*Secondary prevention*- This level involves actions aimed at early diagnosis and prompt treatment of an existing condition to halt progression (e.g., large-scale **testing/screening** of asymptomatic cases for COVID-19).- Actions taken at this stage occur *after* the infection has begun but before significant symptoms or complications arise.*Tertiary prevention*- This level focuses on measures taken when the disease has already fully developed, aiming to reduce the severity of **complications**, limit disability, and provide **rehabilitation** (e.g., physical therapy for post-COVID syndrome).- It deals with the management and recuperation phase of established illness, which is not applicable to preventive hygiene practices.

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