Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 681: Which of the following statements about leptospirosis is true?

A. Rats are prime reservoirs (Correct Answer)
B. Fluoroquinolones are the drug of choice
C. Person to person Transmission is common
D. Hepatorenal syndrome may occur in severe cases

Explanation: ***Rats are prime reservoirs*** - **Rats** and other wild and domestic animals (e.g., cattle, pigs, dogs, rodents) are the primary **reservoir hosts** for *Leptospira* bacteria, shedding the bacteria in their urine. - Humans become infected through contact with contaminated water or soil, or infected animal tissues/urine. *Fluoroquinolones are the drug of choice* - **Fluoroquinolones** are generally not the drug of choice for leptospirosis. - First-line treatment typically involves **doxycycline** for mild cases and **intravenous penicillin G** or **ceftriaxone** for severe disease. *Person to person Transmission is common* - **Person-to-person transmission** of leptospirosis is extremely rare and not considered a common route of infection. - The disease is usually acquired through environmental exposure to contaminated animal urine. *Hepatorenal syndrome may occur in severe cases.* - While **hepatic** (liver) and **renal** (kidney) dysfunction are characteristic of severe leptospirosis (Weil's disease), the term **hepatorenal syndrome** is a specific diagnosis describing acute kidney injury in patients with advanced liver cirrhosis. - The kidney and liver damage in leptospirosis are direct effects of the bacterial infection, rather than a secondary complication of liver cirrhosis.

Question 682: Which disease is NOT primarily transmitted by hard ticks?

A. KFD
B. Indian tick typhus
C. Tularemia
D. Relapsing fever (Correct Answer)

Explanation: ***Relapsing fever*** - Relapsing fever, particularly **epidemic louse-borne relapsing fever**, is primarily transmitted by the human body louse (*Pediculus humanus humanus*), not hard ticks. - While some forms of relapsing fever (endemic relapsing fever) *can* be transmitted by soft ticks, the most common association for public health concern regarding relapsing fever is with lice. *KFD* - **Kyasanur Forest Disease (KFD)** is a viral hemorrhagic fever transmitted by the bite of **hard ticks**, primarily *Haemaphysalis spinigera*. - The disease is endemic to certain regions of India and is a classic example of a hard tick-borne illness. *Indian tick typhus* - **Indian tick typhus** is a form of **spotted fever group rickettsiosis** caused by *Rickettsia conorii*, which is transmitted by **hard ticks**, including *Rhipicephalus sanguineus* (brown dog tick). - It is a well-known tick-borne disease in tropical and subtropical regions. *Tularemia* - While tularemia can be transmitted by various routes, **hard ticks** such as *Dermacentor* (dog ticks) and *Amblyomma* (lone star ticks) are important vectors for transmitting *Francisella tularensis*. - Tick bites are a significant mode of transmission for the **ulceroglandular form** of tularemia.

Question 683: Which of the following waterborne diseases is characterized by rice water stools?

A. Giardiasis
B. Typhoid fever
C. Cholera (Correct Answer)
D. Hepatitis A

Explanation: ***Typhoid fever*** - **Rice water stools** are a classic symptom of **cholera**, not typhoid fever. Typhoid fever is characterized by a **step-ladder fever pattern**, **bradycardia**, and abdominal pain, eventually leading to a rose-spot rash. - The causative agent of typhoid fever is **Salmonella typhi**, which primarily invades the gastrointestinal tract and then disseminates systemically. *Giardiasis* - Giardiasis is caused by the parasite **Giardia lamblia**, and its typical symptoms include **fatty**, **foul-smelling stools**, **bloating**, cramps, and weight loss, not rice water stools. - This infection is often acquired through the ingestion of **cysts** from contaminated water or food. *Cholera* - **Cholera** is the correct answer and is classically characterized by the production of **massive watery diarrhea** with **“rice water” stools**, which are gray, turbid, and flecked with mucus. - This severe dehydration is due to the action of **cholera toxin**, which causes electrolyte and fluid secretion into the intestinal lumen. *Hepatitis A* - **Hepatitis A** is primarily a **viral liver infection** characterized by **jaundice**, dark urine, fatigue, and nausea, and it does not typically present with diarrhea, especially not rice water stools. - It is transmitted via the **fecal-oral route**, often through contaminated food or water, but its primary target is the liver.

Question 684: Which of the following is not included in the Revised National Tuberculosis Control Programme (RNTCP)?

A. Chest X-rays are used as a diagnostic tool for tuberculosis.
B. Directly observed therapy (DOT) is a key strategy in tuberculosis control.
C. Active case finding is a strategy used in tuberculosis control. (Correct Answer)
D. Daily drug administration is part of the tuberculosis treatment regimen.

Explanation: ***Active case finding is a strategy used in tuberculosis control*** - **This is the correct answer** - Traditional RNTCP primarily relied on **passive case finding**, where symptomatic patients self-report to health facilities - While active case finding (systematic screening of high-risk groups) is now emphasized in NTEP (National TB Elimination Programme), it was **not a major strategy in the original RNTCP framework** - The classic RNTCP approach focused on identifying patients who presented with symptoms rather than actively seeking cases in the community *Directly observed therapy (DOT) is a key strategy in tuberculosis control* - **DOT is a cornerstone** of RNTCP/NTEP to ensure treatment adherence - A trained provider directly observes the patient taking anti-TB medications - This prevents treatment default and reduces drug resistance *Chest X-rays are used as a diagnostic tool for tuberculosis* - **Chest X-rays are integral** to RNTCP for screening and diagnosis of pulmonary TB - Used in conjunction with sputum microscopy/molecular tests like CBNAAT - Helps identify lung involvement and assess disease severity *Daily drug administration is part of the tuberculosis treatment regimen* - **RNTCP/NTEP uses daily drug regimens** for most TB categories (replaced older intermittent regimens) - Daily dosing improves treatment efficacy and patient adherence - Part of the standardized treatment protocols under the programme

Question 685: All of the following diseases can be eradicated, EXCEPT:

A. Guinea worm
B. Polio
C. Tuberculosis (Correct Answer)
D. Measles

Explanation: ***Tuberculosis*** - **Tuberculosis** is extremely difficult to eradicate due to its airborne transmission, ability to lie **latent** in carriers, and the emergence of **drug-resistant strains**. - Widespread reservoirs of infection and the lack of a fully effective vaccine make complete eradication highly challenging. *Guinea worm* - Guinea worm disease (Dracunculiasis) is close to eradication due to its unique life cycle, which involves only **human hosts** and **copepods (water fleas)** as intermediate hosts. - Eradication efforts focus on simple interventions like **filtering drinking water** and preventing contaminated water consumption. *Polio* - Polio is targeted for eradication due to the availability of effective **oral and inactivated vaccines** and the fact that the poliovirus has no animal reservoir, only infecting humans. - Global vaccination campaigns have dramatically reduced its incidence, with only a few endemic countries remaining. *Measles* - Measles is a prime candidate for eradication because humans are the virus's only natural host, and a highly effective, **live-attenuated vaccine** provides long-lasting immunity. - High vaccination coverage can interrupt transmission and has led to elimination in many regions.

Question 686: Which of the following is a reservoir for measles?

A. Man (Correct Answer)
B. Soil
C. Fomites
D. Monkey

Explanation: ***Man*** - Humans are the **natural and sole reservoir** for the measles virus (**Morbillivirus**). - The virus is highly contagious and spreads directly from person to person via respiratory droplets. *Soil* - Soil is a reservoir for certain **bacterial or fungal pathogens** (e.g., *Clostridium tetani*, *Histoplasma capsulatum*), but not for measles virus. - Viruses, especially those causing human-specific diseases like measles, do not typically survive or replicate in soil. *Fomites* - Fomites are **inanimate objects** that can harbor pathogens and contribute to transmission. - While measles virus can survive on fomites for a short period, they are a mode of transmission, not a reservoir where the virus multiplies or is maintained. *Monkey* - Monkeys are reservoirs for some viruses (e.g., simian immunodeficiency virus), but not for the **measles virus**. - Measles is a **human-specific disease**, and while some closely related viruses can affect primates, monkeys do not naturally harbor or transmit human measles.

Question 687: In the context of a viral outbreak, what is the first step that public health officials should take?

A. Immunization
B. Notification (Correct Answer)
C. Isolation
D. Verification of diagnosis

Explanation: ***Correct: Notification*** - **Notification** is the **first and essential step** in public health outbreak management as mandated by the International Health Regulations (IHR) and national disease surveillance systems - Immediate notification to public health authorities triggers the entire surveillance and response mechanism, enabling coordinated investigation, resource mobilization, and implementation of control measures - Without notification, the public health system cannot mount an organized response, and individual isolation efforts remain uncoordinated and potentially ineffective - Notification activates the epidemic response teams who then conduct verification, implement isolation, and coordinate other control measures *Incorrect: Isolation* - While **isolation** is a critical containment measure, it cannot be the first step before cases are identified and reported through the surveillance system - Isolation is implemented **after** notification and during/after case verification as part of the coordinated public health response - Premature isolation without proper notification leads to fragmented, uncoordinated responses and missed opportunities for comprehensive outbreak control *Incorrect: Verification of diagnosis* - **Verification of diagnosis** is essential but occurs **after** notification to health authorities - The verification process (epidemiological investigation and laboratory confirmation) is conducted by public health teams mobilized through the notification system - While clinical suspicion may exist, formal verification requires coordinated investigation that follows notification *Incorrect: Immunization* - **Immunization** is a preventive and control measure implemented in later stages of outbreak response - Vaccine deployment requires significant planning, availability, and logistics that can only be coordinated after the outbreak is officially reported and verified - Ring vaccination or mass immunization campaigns are organized interventions that follow the initial notification and assessment phases

Question 688: Which of the following statements about measles is incorrect?

A. Secondary attack rate is 90%
B. Maximum incidence in 6 months to 3 years age group
C. Best age for immunization is 9-12 months
D. Secondary attack rate is 30% (Correct Answer)

Explanation: ***Secondary attack rate is 30%*** - Measles is highly contagious, and its **secondary attack rate** is much higher than 30%, often reaching **90% or more** among susceptible household contacts. - A 30% secondary attack rate would be exceptionally low for a disease with measles's known **high transmissibility**. *Maximum incidence in 6 months to 3 years age group* - This statement is correct as **maternal antibodies wane** around 6 months, making infants susceptible, and young children in this age range are often actively exposed in community settings. - Peak incidence occurs in this age group, particularly in **unvaccinated or under-vaccinated populations**. *Best age for immunization is 9-12 months* - This is the **recommended age** for measles vaccination under India's **Universal Immunization Programme (UIP)**. - Immunizing at this age ensures that waning maternal antibodies do not interfere with vaccine efficacy while providing timely protection during the high-risk period. *Secondary attack rate is 90%* - This statement is correct. Measles is one of the **most contagious infectious diseases**, with a secondary attack rate among susceptible household contacts often **exceeding 90%**. - Its high transmissibility is due to its **airborne spread** and long communicable period.

Question 689: In the context of malaria management, surveillance every fortnight is part of which specific programme?

A. Urban malaria scheme
B. National malaria control programme
C. Modified plan of operation (Correct Answer)
D. Malaria eradication programme

Explanation: ***Modified plan of operation*** - The Modified Plan of Operation (MPO), launched in **1977**, introduced **active surveillance every fortnight** with house-to-house visits and presumptive treatment - This was the **defining characteristic** of MPO, aimed at containing perennial malaria transmission in areas where eradication failed - Objective: Reduce the Slide Positive Incidence Rate (SPIR) to **less than 2%**, indicating a strategy of control rather than eradication - Fortnightly surveillance distinguished MPO from all previous malaria programmes in India *Urban malaria scheme* - Focuses on malaria control specifically in **urban areas** with anti-larval operations and targeted case management - Does **not mandate fortnightly surveillance** as its defining characteristic - Part of broader malaria control efforts rather than a programme defined by specific surveillance frequency *National malaria control programme* - Initiated in **1953**, focused on reducing morbidity and mortality through **indoor residual spraying (IRS)** - Did **not implement fortnightly surveillance** as its primary strategy - Later replaced by National Malaria Eradication Programme (NMEP) in 1958 due to initial success *Malaria eradication programme* - Launched in **1958**, aimed for complete elimination through extensive residual insecticide spraying - Used **passive case detection** rather than active fortnightly house-to-house surveillance - Did not specify fortnightly surveillance with presumptive treatment like the MPO did after disease resurgence

Question 690: Which of the following diseases is primarily transmitted by body lice?

A. Plague
B. Endemic typhus
C. Chiggerosis
D. Trench fever (Correct Answer)

Explanation: ***Trench fever*** - **Trench fever** is caused by the bacterium *Bartonella quintana* and is classically transmitted by the **body louse** acquiring the bacteria from an infected human. - The disease is characterized by relapsing fevers, bone pain (especially in the shins), headache, and rash, and it gained prominence during World War I due to poor hygiene and louse infestations among soldiers. *Plague* - **Plague**, caused by *Yersinia pestis*, is primarily transmitted by the bite of infected **fleas**, usually from rodents to humans. - While human-to-human transmission can occur in pneumonic plague, lice are not the primary vector for bubonic or septicemic forms. *Endemic typhus* - **Endemic (murine) typhus** is caused by *Rickettsia typhi* and is transmitted by the **rat flea** (*Xenopsylla cheopis*), not body lice. - It occurs primarily in areas with rodents and their fleas, typically presenting with fever, headache, and a rash. *Chiggerosis* - **Chiggerosis** (also known as trombiculiasis or scrub itch) is caused by the bite of **chigger mites** (larval mites of the family Trombiculidae), which burrow into the skin. - These mites are not body lice and do not transmit bacterial infections like trench fever; their bites cause intensely itchy papules.

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