Infectious Diseases — MCQs

Consider the following strategies pertaining to National Anti-Malaria Programme: 1. Early case detection and prompt treatment with ACT (Artemisinin Combination Therapy) 2. Indoor Residual Spraying (IRS) in areas with API ≥2 3. Distribution and promotion of Long Lasting Insecticidal Nets (LLINs) Which of the above strategies is/are being used in India?

Q206

Effective disinfection of a typhoid patient's faecal matter can be done with

Q207

Consider the following : 1. Hepatitis A outbreak 2. Polio outbreak 3. Gonorrhoea outbreak through prostitution Which of the above-listed outbreaks is/are classified under propagated epidemics?

Q208

Asymptomatic endometrial tuberculosis leading to infertility is categorized in which diagnostic category of DOTS?

Q209

With reference to quarantine measures to prevent the spread of a disease, which of the following statements is/are correct? 1. In addition to human beings, quarantine measures are at times also applied to an aircraft or a train or a container etc. 2. The duration of the quarantine period is equivalent to the minimum incubation period for the disease Select the correct answer using the code given below:

Q210

To control Mansonia mosquitoes, the most effective method is:

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 201: Match List-I with List-II and select the correct answer using the code given below the Lists:

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

Explanation: ***A→4 B→3 C→2 D→1*** - A **symposium** (A) is characterized by a "discussion among the speakers" (4), where experts present different aspects of a topic, followed by interaction. - A **panel discussion** (B) involves a "series of speeches on a selected subject" (3) by panel members in front of an audience, often with interaction moderated by a chairperson. - A **workshop** (C) typically focuses on "arriving at a plan of action to solve the problem" (2) through practical, hands-on activities and collaborative problem-solving. - **Role-play** (D) is a technique where a "situation is dramatized" (1) by participants acting out roles to understand different perspectives or practice new skills. *A→1 B→3 C→2 D→4* - This option incorrectly matches "Symposium" with "Situation is dramatized" and "Role-play" with "Discussion among the speakers". - Role-play is about dramatizing a situation, while a symposium involves discussion among speakers. *A→1 B→2 C→3 D→4* - This option misaligns multiple matches, particularly with "Symposium" (A) and "Workshop" (C). - A workshop is about action plans, and a symposium is about discussions among speakers, not the other way around. *A→4 B→2 C→3 D→1* - This option incorrectly matches "Panel discussion" with "Arriving at a plan of action to solve the problem" and "Workshop" with "Series of speeches on a selected subject". - Workshops focus on action plans, and panel discussions involve a series of speeches.

Question 202: The use of condoms for protection against sexually transmitted diseases qualifies as

A. Primordial prevention
B. Health promotion
C. Secondary prevention
D. Specific protection (Correct Answer)

Explanation: ***Specific protection*** - **Specific protection** involves measures aimed at preventing particular diseases by reducing exposure to their causes or by enhancing resistance against them. - Using condoms directly acts against the transmission of **sexually transmitted infections (STIs)**, thus making it a form of specific protection. *Primordial prevention* - **Primordial prevention** focuses on addressing underlying social and economic conditions that contribute to disease risk. - It targets **root causes** before risk factors for a disease even develop in the population. *Health promotion* - **Health promotion** is a broader concept that includes educational and environmental efforts to support healthy lifestyles and reduce overall disease risk. - While condom use could be part of a health promotion campaign, the act itself is a more targeted intervention. *Secondary prevention* - **Secondary prevention** involves early detection and prompt treatment of existing health problems to prevent their progression or complications. - This would include activities like **STI screening** and starting treatment after diagnosis, not preventing initial transmission.

Question 203: Match List-I with List-II and select the correct answer using the code given below the Lists: List-I (Vectors): A. Hard ticks B. Sandflies C. Louse D. Soft ticks List-II (Diseases): 1. Oriental sore 2. Epidemic typhus 3. Tularemia 4. Relapsing fever

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

Explanation: ***A→3 B→1 C→2 D→4*** - **Hard ticks** (A) are primary vectors for **tularemia** (3), transmitting *Francisella tularensis* through their bite during blood feeding. - **Sandflies** (B) transmit **oriental sore** (1), the cutaneous form of **leishmaniasis** caused by *Leishmania tropica* and other species. *A→4 B→1 C→3 D→2* - Incorrectly matches **hard ticks** with **relapsing fever**, which is specifically transmitted by **soft ticks** (*Ornithodoros* species). - Misassociates **louse** with **tularemia**, when **body lice** are established vectors for **epidemic typhus**. *A→1 B→2 C→3 D→4* - Wrongly pairs **hard ticks** with **oriental sore**, which requires **sandfly** vectors for transmission of *Leishmania* parasites. - Incorrectly matches **sandflies** with **epidemic typhus**, a louse-borne disease caused by *Rickettsia prowazekii*. *A→2 B→4 C→1 D→3* - Mismatches **hard ticks** with **epidemic typhus**, which is transmitted by **body lice**, not tick species. - Incorrectly associates **soft ticks** with **tularemia**, when they are specific vectors for **relapsing fever** caused by *Borrelia* species.

Question 204: The larvae of which one of the following mosquitoes cannot successfully be killed by spreading oil on the surface of its breeding water sources?

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

Explanation: ***Mansonoides*** - The larvae of *Mansonoides* mosquitoes attach to the underwater stems and roots of **aquatic vegetation** for oxygen. - This adaptation means they do not surface to breathe, rendering **surface oiling ineffective** against them. *Aedes* - *Aedes* larvae are **surface breathers**, obtaining oxygen from the air-water interface. - Oiling the water surface forms a film that **prevents oxygen uptake**, suffocating the larvae. *Culex* - *Culex* larvae are also **surface breathers** and, like *Aedes*, rely on the air-water interface for oxygen. - An oil film on the water surface will **block their access to atmospheric oxygen**, leading to their demise. *Anopheles* - *Anopheles* larvae are **surface dwellers** that lie parallel to the water surface, using their **spiracles** to breathe air. - An oil layer effectively **obstructs these spiracles**, preventing respiration and killing the larvae.

Question 205: Consider the following strategies pertaining to National Anti-Malaria Programme: 1. Early case detection and prompt treatment with ACT (Artemisinin Combination Therapy) 2. Indoor Residual Spraying (IRS) in areas with API ≥2 3. Distribution and promotion of Long Lasting Insecticidal Nets (LLINs) Which of the above strategies is/are being used in India?

A. 2 and 3 only
B. 1, 2 and 3 (Correct Answer)
C. 1 and 2 only
D. 1 only

Explanation: ***1, 2 and 3*** - The **National Anti-Malaria Programme (NAMP)** in India utilizes all three strategies as core components for malaria control and elimination. - **Early case detection and prompt treatment with ACT** are crucial for reducing the parasite reservoir and preventing severe disease. **Indoor Residual Spraying (IRS)** is used for vector control, especially in high-burden areas (API ≥2), and **Long Lasting Insecticidal Nets (LLINs)** provide personal protection against mosquito bites. *2 and 3 only* - This option is incorrect because it excludes **early case detection and prompt treatment with ACT**, which is a fundamental and critical strategy in malaria control. - Effective **case management** is essential for reducing transmission and morbidity/mortality, alongside vector control methods like IRS and LLINs. *1 and 2 only* - This option is incorrect as it omits the **distribution and promotion of Long Lasting Insecticidal Nets (LLINs)**, which are a highly effective and widely implemented tool for preventing mosquito bites and reducing malaria transmission, particularly in endemic areas. - **LLINs** are a cost-effective intervention promoting personal protection, empowering communities in malaria prevention efforts. *1 only* - This option is incorrect because relying solely on **early case detection and prompt treatment** is insufficient for comprehensive malaria control. - Effective malaria control requires a multi-pronged approach that also incorporates **vector control strategies** like IRS and LLINs to reduce human-vector contact.

Question 206: Effective disinfection of a typhoid patient's faecal matter can be done with

A. 2% phenol
B. 5% formalin
C. 5% cresol
D. 2% bleaching powder (Correct Answer)

Explanation: ***2% bleaching powder*** - **Bleaching powder** (calcium hypochlorite) is a strong oxidizing agent that effectively disinfects faecal matter by destroying microbial cell structures. - A **2% solution** provides sufficient concentration of free chlorine to kill *Salmonella Typhi* and other pathogens in faeces. *2% phenol* - While **phenol** is an antiseptic and disinfectant, a 2% solution may not be strong enough for the effective and rapid disinfection of heavily contaminated faecal matter. - **Phenol** acts by denaturing proteins and disrupting cell membranes, but higher concentrations or longer contact times are generally needed for spore-forming or highly resistant organisms, though *Salmonella Typhi* is not spore-forming. *5% formalin* - **Formalin** (a solution of formaldehyde) is a powerful disinfectant and fixative, but it is typically used for sterilizing medical equipment or preserving biological specimens. - Its **strong fumes** and irritating nature make it less suitable for routine, large-scale disinfection of faecal matter due to safety concerns and logistical challenges. *5% cresol* - **Cresol** is a phenolic disinfectant that is more potent than phenol and is effective against a broad spectrum of microorganisms. - While effective, **cresol** is typically used in higher concentrations (like 5%) for disinfecting surfaces or specific wastes, and its pungent odor and potential toxicity might make it a less practical choice for general faecal disinfection compared to bleaching powder.

Question 207: Consider the following : 1. Hepatitis A outbreak 2. Polio outbreak 3. Gonorrhoea outbreak through prostitution Which of the above-listed outbreaks is/are classified under propagated epidemics?

A. 2 and 3 only (Correct Answer)
B. 1 and 2 only
C. 1 only
D. 1, 2 and 3

Explanation: ***2 and 3 only*** - A **propagated epidemic** is characterized by person-to-person transmission, leading to a gradual increase in cases over time, often forming multiple waves. - **Polio outbreaks** spread through person-to-person transmission via the fecal-oral route (contact with infected feces or oral secretions), making it a classic propagated epidemic. - **Gonorrhea outbreaks through prostitution** involve direct person-to-person transmission via sexual contact, clearly fitting the propagated epidemic pattern. - These outbreaks show progressive spread through the population with characteristic secondary and tertiary waves. *1, 2 and 3* - This option incorrectly includes **Hepatitis A outbreak**, which is typically a **common source epidemic**, not a propagated epidemic. - While Hepatitis A can be transmitted person-to-person via the fecal-oral route, most **outbreaks** are linked to a contaminated common source (water, food) and follow a common source pattern with a single sharp peak. - Common source epidemics have a characteristic sharp rise and fall, unlike the gradual progressive spread of propagated epidemics. *1 and 2 only* - This option incorrectly includes **Hepatitis A outbreak** (typically common source, not propagated) while excluding gonorrhea outbreak. - It also incorrectly excludes **gonorrhea outbreak**, which is clearly a propagated epidemic due to person-to-person sexual transmission. *1 only* - This option incorrectly suggests only Hepatitis A is a propagated epidemic, when in fact Hepatitis A outbreaks are typically **common source epidemics**. - It incorrectly excludes **Polio** and **Gonorrhea outbreaks**, both of which are true propagated epidemics involving progressive person-to-person transmission.

Question 208: Asymptomatic endometrial tuberculosis leading to infertility is categorized in which diagnostic category of DOTS?

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

Explanation: ***Category III*** - Category III of the DOTS classification includes **newly diagnosed pulmonary smear-negative** and all forms of **extra-pulmonary tuberculosis**, provided they are not severe. - Endometrial tuberculosis, leading to infertility, is an **extra-pulmonary site** and is generally considered less severe compared to disseminated forms, thus falling into Category III. *Category II* - Category II is reserved for **previously treated cases** of tuberculosis, including relapse, treatment failure, or return after default. - This patient is described as having **asymptomatic** endometrial tuberculosis, implying a new diagnosis, not a retreatment case. *Category IV* - Category IV is used for cases of **chronic tuberculosis**, where the patient remains smear-positive after completing a retreatment regimen, often indicating drug-resistant TB. - This scenario describes a new diagnosis of extra-pulmonary TB, with no mention of prior treatment failures or chronic infection. *Category I* - Category I applies to **newly diagnosed pulmonary smear-positive** tuberculosis cases and severe forms of extra-pulmonary tuberculosis. - Asymptomatic endometrial tuberculosis, in this context, is neither pulmonary smear-positive nor typically considered a severe or life-threatening form of extra-pulmonary TB.

Question 209: With reference to quarantine measures to prevent the spread of a disease, which of the following statements is/are correct? 1. In addition to human beings, quarantine measures are at times also applied to an aircraft or a train or a container etc. 2. The duration of the quarantine period is equivalent to the minimum incubation period for the disease Select the correct answer using the code given below:

A. 1 only (Correct Answer)
B. Neither 1 nor 2
C. 2 only
D. Both 1 and 2

Explanation: **Statement Analysis:** **Statement 1 - CORRECT:** Quarantine measures are indeed applied beyond human beings to various entities including **aircraft, trains, ships, and containers**. This is a standard practice under International Health Regulations (IHR 2005) to prevent the spread of disease vectors or contaminated goods. For example, during outbreaks of vector-borne diseases, aircraft from affected areas may be disinfected, and containers with potentially contaminated goods can be quarantined for inspection. **Statement 2 - INCORRECT:** The duration of quarantine is equivalent to the **maximum incubation period**, NOT the minimum. This is a fundamental principle of quarantine - it must extend through the longest possible incubation period to ensure that anyone exposed will develop symptoms before release. If quarantine were based on the minimum incubation period, individuals infected later in their exposure could still become infectious after being released from quarantine, defeating its purpose. ***Correct Answer: 1 only*** - **Only statement 1 is correct** - quarantine applies to multiple entities beyond humans - **Statement 2 is incorrect** - quarantine duration is based on maximum, not minimum incubation period - This ensures effective disease containment and prevents asymptomatic spread post-quarantine *Incorrect: 2 only* - Statement 2 is fundamentally flawed regarding quarantine duration principles *Incorrect: Both 1 and 2* - While statement 1 is correct, statement 2 contains a critical error about incubation period *Incorrect: Neither 1 nor 2* - Statement 1 is clearly correct as per international health regulations

Question 210: To control Mansonia mosquitoes, the most effective method is:

A. Avoidance of water collections
B. Larvicidal insecticides
C. Removal of water plants (Correct Answer)
D. Oiling of water

Explanation: ***Correct: Removal of water plants*** - **Mansonia** mosquitoes have a unique biological adaptation where their **larvae and pupae attach to the roots and stems of aquatic plants** (like *Pistia*, *Eichhornia*, water lettuce) to obtain oxygen through a specialized respiratory siphon - **Removal of aquatic vegetation** is the **most effective control method** because it eliminates the attachment sites essential for larval and pupal respiration - Without host plants, the larvae and pupae cannot obtain oxygen and die, making this the **gold standard** for Mansonia control - This method provides long-term control by eliminating the breeding habitat *Incorrect: Larvicidal insecticides* - While larvicidal insecticides are effective for many mosquito species, they are **less effective for Mansonia** mosquitoes - Since Mansonia larvae remain submerged and attached to plant roots (not coming to the surface for air), conventional larvicides have difficulty reaching them - The larvae's unique oxygen-obtaining mechanism makes them relatively resistant to surface-applied larvicides *Incorrect: Avoidance of water collections* - **Mansonia** mosquitoes breed in large, permanent water bodies with extensive aquatic vegetation (ponds, marshes, swamps) - These are natural habitats that cannot be easily eliminated - Unlike container-breeding mosquitoes (e.g., *Aedes*), avoidance of water collections is impractical and ineffective for Mansonia control *Incorrect: Oiling of water* - **Oiling the water surface** creates a film that prevents mosquito larvae from accessing atmospheric oxygen at the surface - This method works for species like **Anopheles** and **Culex** whose larvae breathe from the water surface - It is **completely ineffective against Mansonia** because their larvae obtain oxygen directly from **aquatic plant roots beneath the surface**, not from atmospheric air

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