Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 151: The SAFE strategy given by WHO forms the mainstream of the management of Trachoma. What does the S in the acronym represent?

A. Spectacles
B. Symbol
C. Symptom
D. Surgery (Correct Answer)

Explanation: ***Surgery*** - The 'S' in the WHO's SAFE strategy for Trachoma management stands for **Surgery**, which is essential for correcting **trichiasis** (in-turned eyelashes). - Surgery prevents irreversible vision loss by stopping the eyelashes from rubbing against and scarring the **cornea**. *Symptom* - Management of specific **symptoms** is generally an element of clinical treatment but does not represent a component of the comprehensive population-level intervention strategy known as SAFE. - The SAFE approach focuses on addressing the **infectious agent** (Antibiotics) and transmission factors (Facial cleanliness, Environmental improvement) for elimination. *Spectacles* - **Spectacles** are used for correcting refractive errors (like myopia or hyperopia) and are not a therapeutic measure for active **Chlamydia trachomatis** infection or trichiasis. - The goal of SAFE is elimination of the infectious cause and treatment of the blinding sequelae, not visual **refractive correction**. *Symbol* - A **symbol** is an abstract representation and does not constitute a concrete public health or clinical intervention necessary for the elimination of trachoma. - The other components (**Antibiotics**, **Facial cleanliness**, **Environmental improvement**) are tangible actions aimed at disease control and prevention.

Question 152: Which of the following is correctly matched for vectors and diseases? Vector: A. Louse, B. Mite, C. Flea, D. Tick. Disease: I. Scrub typhus, II. Endemic typhus, III. Rocky Mountain spotted fever, IV. Epidemic typhus.

A. A-IV, B-I, C-II, D-III (Correct Answer)
B. A-II, B-III, C-IV, D-I
C. A-IV, B-III, C-I, D-II
D. A-I, B-III, C-IV, D-II

Explanation: ***A-IV, B-I, C-II, D-III (Correct)*** - **Louse (A)** transmits **Epidemic typhus (IV)**, caused by *Rickettsia prowazekii*, typically occurring in overcrowded, unhygienic environments. - **Mite (B)** (chigger) transmits **Scrub typhus (I)**, caused by *Orientia tsutsugamushi*. - **Flea (C)** (rat flea) transmits **Endemic typhus (II)**, caused by *Rickettsia typhi*. - **Tick (D)** transmits **Rocky Mountain spotted fever (III)**, caused by *Rickettsia rickettsii*. *A-I, B-III, C-IV, D-II (Incorrect)* - Incorrectly matches Louse (A) with Scrub typhus (I); scrub typhus is transmitted by **mites** (chiggers), not lice. - Incorrectly matches Mite (B) with Rocky Mountain spotted fever (III); RMSF is transmitted by **ticks**, not mites. *A-II, B-III, C-IV, D-I (Incorrect)* - Incorrectly matches Louse (A) with Endemic typhus (II); endemic typhus is transmitted by **fleas** (rat flea), not lice. - Incorrectly matches Flea (C) with Epidemic typhus (IV); epidemic typhus is transmitted by **lice**, not fleas. *A-IV, B-III, C-I, D-II (Incorrect)* - While A-IV is correct (Louse-Epidemic typhus), this option incorrectly matches Mite (B) with Rocky Mountain spotted fever (III), which is transmitted by **ticks**. - Incorrectly matches Flea (C) with Scrub typhus (I); scrub typhus is transmitted by **mites**, not fleas.

Question 153: Which of the following is not classified under High-Risk Groups for HIV as per NACO guidelines?

A. Men having sex with men (MSM)
B. Injecting drug users (IDUs)
C. Truck drivers (Correct Answer)
D. Female sex workers (FSW)

Explanation: ***Truck drivers*** - While considered a **Bridge Population** or a vulnerable group due to high mobility and potential for engaging in high-risk behavior, they are not categorized as a primary **High-Risk Group (HRG)** by NACO. - **Bridge Populations** facilitate the transmission of HIV between high-risk groups and the general population. ***Men having sex with men (MSM)*** - **MSM** is designated as a core **High-Risk Group (HRG)** due to a significantly higher prevalence of HIV compared to the general population. - The mode of transmission (anal intercourse) carries a higher risk and is considered a key factor in NACO's classification. ***Female sex workers (FSW)*** - **FSW** is classified as a core **High-Risk Group (HRG)** because of high exposure risk and the potential for greater onward transmission to the general population. - They are a major focus of targeted interventions under the National AIDS Control Programme (NACP). ***Injecting drug users (IDUs)*** - **IDUs** are a vital **High-Risk Group (HRG)** primarily due to the sharing of contaminated needles and syringes, leading to immediate blood-to-blood transmission (Parenteral route). - Targeted interventions focus on harm reduction strategies like Needle and Syringe Exchange Programmes (NSEP).

Question 154: According to WHO, which rapid molecular test is recommended as the initial diagnostic investigation for tuberculosis (TB) spine?

A. CBNAAT (Correct Answer)
B. X-ray
C. CT scan
D. Culture and sensitivity

Explanation: ***CBNAAT*** - The **WHO** strongly recommends **CBNAAT (GeneXpert or Truenat)** as the **initial rapid molecular diagnostic test** for extrapulmonary TB (EPTB), including **TB spine (Pott's disease)**, due to its rapid turnaround time and high sensitivity. - CBNAAT simultaneously detects **Mycobacterium tuberculosis** DNA and identifies resistance to **Rifampicin**, providing critical information for prompt treatment initiation, typically within 2 hours. - This rapid molecular test is preferred over traditional methods for initial diagnosis to enable early treatment decisions. *Incorrect: X-ray* - X-rays are imaging studies useful for detecting features like **vertebral destruction**, **paraspinal shadow**, and collapse leading to **gibbus deformity**, but they are not molecular diagnostic tests. - While X-rays are included in the diagnostic workup, they cannot confirm the presence of the organism or detect drug resistance, which is why they are not the WHO-recommended initial molecular test. *Incorrect: CT scan* - CT scans offer superior visualization of subtle bony changes, extent of destruction, and delineating **paraspinal cold abscesses**, often used for staging and guiding intervention. - Like X-ray, CT is an **imaging modality** that assists in identifying structural changes but is not a molecular diagnostic test and cannot provide microbiological confirmation or drug resistance information. *Incorrect: Culture and sensitivity* - **Culture (e.g., Lowenstein-Jensen, MGIT)** is considered the **gold standard** for definitive diagnosis and comprehensive Drug Susceptibility Testing (DST). - However, culture results are slow (taking 4–8 weeks), which delays crucial management decisions, leading the WHO to prioritize **rapid molecular tests** like CBNAAT for **initial diagnosis** over culture, though culture remains important for comprehensive DST.

Question 155: Which mosquito larva has no siphon and rests parallel to the water surface?

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

Explanation: ***Anopheles*** - **Anopheles** larvae lack a **siphon** (breathing tube) and breathe through spiracles located on the dorsal surface of the abdomen. - This absence of a siphon causes them to rest **parallel** to the water surface, which is a key identifying feature for species differentiation. *Aedes* - **Aedes** larvae possess a **siphon**, which is relatively shorter and stouter compared to *Culex*. - They hang down from the water surface at an angle, utilizing the siphon for air intake, not lying parallel to the surface. *Culex* - **Culex** larvae possess a long, distinct **siphon** (breathing tube) at the posterior end of the abdomen. - Due to the siphon, they rest at an **angle** (typically 45-60 degrees) to the water surface for breathing. *Mansonia* - **Mansonia** larvae have a modified, sharp **siphon** used to pierce the submerged **stems of aquatic plants** for oxygen extraction. - They remain attached to these plants underwater and do not float on or rest parallel to the water surface.

Question 156: Match the following: Vector/agent : 1. Louse - 2. Tick - 3. Mite - 4. Poxvirus Diseases caused : A. Epidemic typhus - B. Rocky Mounted Spotted Fever (RMSF) - C. Scrub typhus - D. Molluscum contagiosum

A. 1-B, 2-A, 3-C, 4-D
B. 1-D, 2-B, 3-C, 4-A
C. 1-C, 2-B, 3-A, 4-D
D. 1-A, 2-B, 3-C, 4-D (Correct Answer)

Explanation: ***1-A, 2-B, 3-C, 4-D*** - **1-A (Louse - Epidemic typhus):** Epidemic typhus is caused by *Rickettsia prowazekii*, transmitted to humans via the bite or feces of the **human body louse** (*Pediculus humanus corporis*). This is a classic louse-borne rickettsial disease. - **2-B (Tick - Rocky Mountain Spotted Fever):** RMSF is caused by *Rickettsia rickettsii* and transmitted by **hard ticks**, primarily *Dermacentor* species. It is the most severe tick-borne rickettsial illness in the United States. - **3-C (Mite - Scrub typhus):** Scrub typhus is caused by *Orientia tsutsugamushi*, transmitted by the bite of infected **larval mites** (chiggers) of the *Leptotrombidium* genus. It is endemic in the Asia-Pacific region. - **4-D (Poxvirus - Molluscum contagiosum):** Molluscum contagiosum is a benign viral skin infection caused by the **Molluscum contagiosum virus**, a member of the Poxviridae family. It spreads through direct contact, not via arthropod vectors. *1-B, 2-A, 3-C, 4-D* - The match **1-B** is incorrect: **Louse** transmits **Epidemic typhus (A)**, not Rocky Mountain Spotted Fever (B), which is tick-borne. - The match **2-A** is incorrect: **Tick** transmits **Rocky Mountain Spotted Fever (B)**, not Epidemic typhus (A), which is louse-borne. *1-D, 2-B, 3-C, 4-A* - The match **1-D** is incorrect: **Louse** is an arthropod vector for **Epidemic typhus (A)**, while **Molluscum contagiosum (D)** is a viral disease spread by direct contact, not lice. - The match **4-A** is incorrect: **Poxvirus** causes **Molluscum contagiosum (D)**, while **Epidemic typhus (A)** is a rickettsial infection transmitted by lice, not a poxvirus disease. *1-C, 2-B, 3-A, 4-D* - The match **1-C** is incorrect: **Louse** transmits **Epidemic typhus (A)**, not **Scrub typhus (C)**, which is transmitted by larval mites. - The match **3-A** is incorrect: **Mites** transmit **Scrub typhus (C)**, not **Epidemic typhus (A)**, which is a louse-borne disease.

Question 157: Which is the type of mosquito shown below?

A. Culex mosquito
B. Aedes mosquito (Correct Answer)
C. Anopheles mosquito
D. Haemagogus mosquito

Explanation: The provided image is a mosquito. Based on the characteristics visible, particularly the **striped legs and body**, it appears to be an **Aedes mosquito**. Here's an explanation of why each option might be correct or incorrect (*Note: The options provided in the input were null, so I'm generating options based on common mosquito types*): ***Aedes mosquito*** - Recognizable by its **black and white striped patterns** on the legs and body. - This genus is a significant vector for diseases like **dengue**, **chikungunya**, and **Zika fever**. *Anopheles mosquito* - Anopheles mosquitoes often have **dark and pale scales on their wings**, creating a spotted appearance, which isn't distinct here. - They typically rest with their **abdomen raised at an angle** to the surface, differing from the posture seen. *Culex mosquito* - Culex mosquitoes usually have a **more uniform brownish body** and **unmarked wings**. - They tend to rest with their **body parallel to the surface**, but lack the distinct striped pattern seen in the image. *Haemagogus mosquito* - Haemagogus mosquitoes are known for their **bright metallic blue or purple coloration**, which is not present in the image. - They are primarily forest-dwelling and can also transmit yellow fever.

Question 158: The insect shown in the figure is a vector of which of these diseases?

A. Filaria (Correct Answer)
B. Leishmaniasis
C. Yellow fever
D. Malaria

Explanation: ***Filaria (Lymphatic Filariasis)*** - The image shows a **mosquito** with characteristics consistent with **Culex** species (likely *Culex quinquefasciatus*), which is the primary vector for **lymphatic filariasis** in endemic regions - Lymphatic filariasis is caused by filarial worms (*Wuchereria bancrofti, Brugia malayi*) transmitted through infected mosquito bites - *Culex* mosquitoes have a characteristic blunt abdomen and parallel resting posture *Leishmaniasis* - Transmitted by **sandflies** (*Phlebotomus* and *Lutzomyia* species), not mosquitoes - Sandflies are much smaller, hairy, and have distinctive wing positioning *Yellow fever* - While transmitted by mosquitoes, specifically ***Aedes aegypti*** - *Aedes* mosquitoes have distinctive **white markings** on legs and body (lyre-shaped pattern on thorax) - The mosquito in the image lacks these characteristic *Aedes* features *Malaria* - Transmitted by ***Anopheles*** mosquitoes - *Anopheles* have a distinctive **resting posture** with abdomen raised at an angle (approximately 45°) to the surface - The mosquito shown has a **parallel resting posture**, ruling out *Anopheles*

Question 159: The image given below is symbolic of:

A. Biomedical waste
B. Contraceptive efficacy labels
C. Nuclear toxicity labels
D. Pesticide toxicity labels (Correct Answer)

Explanation: ***Pesticide toxicity labels*** - The image displays the **hazard symbols** and **labels**, particularly the **skull and crossbones** and the words "POISON," "DANGER," and "CAUTION" on color-coded diamonds. - These are internationally recognized symbols used to indicate different levels of **toxicity** and **hazard** associated with chemical substances, most notably in **pesticides**. *Biomedical waste* - Biomedical waste symbols typically involve a **biohazard symbol**, which is a **three-crescent circle** in a black or red color, without other text or skull imagery. - While it indicates hazard, it specifies biological risks, not chemical toxicity as depicted. *Contraceptive efficacy labels* - Contraceptive efficacy is usually indicated by **numerical percentages** or **descriptive terms** (e.g., "highly effective," "moderately effective"), not hazard symbols. - These labels are found on product packaging or informational materials to inform users about the effectiveness of a contraceptive method. *Nuclear toxicity labels* - Nuclear toxicity or **radioactivity labels** feature a **trefoil symbol** (a three-bladed propeller shape) in black on a yellow background. - This symbol is distinct from the skull and crossbones or the "POISON" warnings for chemical toxicity shown in the image.

Question 160: Identify the component of NACP as shown in the image:

A. Ayush
B. ICTC
C. PPTCT (Correct Answer)
D. Blood transfusion

Explanation: ***PPTCT*** - The image depicts a family (father, mother, and child) within the **red ribbon** symbol for HIV/AIDS awareness. This strongly represents the concept of **Prevention of Parent-to-Child Transmission (PPTCT)**, which aims to prevent HIV transmission from an infected mother to her baby. - PPTCT programs include **HIV testing for pregnant women**, antiretroviral therapy for HIV-positive mothers, and safe infant feeding practices. *Ayush* - **AYUSH** refers to traditional Indian systems of medicine (Ayurveda, Yoga, Unani, Siddha, and Homoeopathy) and is not directly represented by the family-and-ribbon imagery in the context of HIV prevention. - While AYUSH may be integrated into some health programs, it is not the primary visual representation for HIV transmission prevention in families. *ICTC* - **Integrated Counseling and Testing Centres (ICTC)** provide voluntary counseling and testing for HIV but primarily focus on individual diagnosis and counseling, not explicitly on preventing transmission within a family unit as depicted. - While ICTC is a component of NACP, the image's emphasis on parents and child more directly aligns with PPTCT. *Blood transfusion* - Measures related to **blood transfusion safety** focus on screening donated blood for HIV to prevent transmission through blood products. - The image does not show any elements related to blood donation, blood bags, or transfusion procedures, making this option less likely.

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