Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 561: A 30-year-old man has been bitten by a stray dog. What is the recommended post-exposure prophylaxis for rabies?

A. Antibiotic therapy
B. Tetanus booster
C. Administration of anti-rabies immunoglobulin only
D. Immediate wound washing, rabies vaccination, and anti-rabies immunoglobulin (Correct Answer)

Explanation: ***Immediate wound washing, rabies vaccination, and anti-rabies immunoglobulin*** - **Immediate and thorough washing of the wound** with soap and water for at least 15 minutes is the first critical step to reduce the viral load at the bite site. - **Rabies vaccination** is essential for active immunization, stimulating the body's immune system to produce antibodies over 2-4 weeks. - **Rabies immunoglobulin (RIG)** provides immediate passive immunity by directly supplying antibodies, protecting the patient while vaccine-induced immunity develops. - For **Category III exposures** (transdermal bites from suspected rabid animals like stray dogs), **both vaccine and RIG are mandatory** as per WHO guidelines. *Antibiotic therapy* - While sometimes indicated for **secondary bacterial infections** that can develop from animal bites, antibiotics do not prevent rabies virus infection. - They are not considered a primary component of **rabies post-exposure prophylaxis (PEP)** unless there are signs of bacterial infection. *Tetanus booster* - A **tetanus booster** may be necessary depending on the patient's vaccination status, as animal bites can pose a risk for tetanus. - However, it addresses **tetanus risk** and does not provide any protection against the rabies virus. *Administration of anti-rabies immunoglobulin only* - **Rabies immunoglobulin (RIG)** alone provides only temporary passive immunity without stimulating long-term antibody production. - RIG must always be given **in conjunction with the rabies vaccine** for complete and lasting protection against the virus.

Question 562: What is the most effective prevention strategy against rabies after an exposure has occurred?

A. Administration of rabies immunoglobulin
B. Immediate wound washing and vaccination (Correct Answer)
C. Antibiotic prophylaxis
D. Observation for signs of infection

Explanation: ***Immediate wound washing and vaccination*** - **Immediate and thorough wound washing** with soap and water or a virucidal agent significantly reduces the viral load at the site of exposure, greatly lowering the risk of infection. - Subsequently, **rabies vaccination (Post-Exposure Prophylaxis - PEP)** stimulates active immunity against the virus, preventing its replication and spread to the central nervous system. - This combination is the **cornerstone of rabies post-exposure management** and is required for all exposure categories according to WHO guidelines. *Administration of rabies immunoglobulin* - **Rabies immunoglobulin (RIG)** provides passive immunity by supplying preformed antibodies, offering immediate but short-term protection. - While critical for Category III exposures (severe bites, multiple bites, or bites on high-risk areas), RIG alone is insufficient without subsequent vaccination to induce long-lasting active immunity. - RIG is an adjunct to, not a replacement for, wound washing and vaccination. *Antibiotic prophylaxis* - **Antibiotic prophylaxis** is used to prevent bacterial infections that can result from animal bites, but it has no effect on the rabies virus itself. - Rabies is a viral disease, so antibiotics are ineffective against the pathogen causing rabies. *Observation for signs of infection* - **Observation for signs of infection** is a passive approach that delays intervention, which is dangerous in rabies due to its rapid progression once symptoms appear. - Once rabies symptoms manifest, the disease is almost universally fatal, making immediate post-exposure treatment essential.

Question 563: What was the mainstay of diagnosis in the Revised National Tuberculosis Control Program (RNTCP) for pulmonary tuberculosis?

A. Sputum smear microscopy for AFB (Correct Answer)
B. Chest X-Ray imaging
C. Physical examination findings
D. Molecular diagnostic tests (e.g., PCR)

Explanation: ***Sputum smear microscopy for AFB*** - **Sputum smear microscopy for acid-fast bacilli (AFB)** was the primary diagnostic tool under RNTCP due to its **cost-effectiveness**, speed, and accessibility in resource-limited settings, allowing for rapid identification of infectious cases. - It was crucial for defining **smear-positive pulmonary tuberculosis**, which guided direct observation treatment short-course (DOTS) strategies within the RNTCP. - **Note**: Under the current **National Tuberculosis Elimination Program (NTEP)** launched in 2020, **CBNAAT (GeneXpert MTB/RIF)** is now the first-line diagnostic test, though sputum microscopy remains important. *Chest X-Ray imaging* - While helpful for identifying **pulmonary infiltrates** and other signs suggestive of TB, a chest X-ray alone **cannot confirm active infection** or mycobacterial presence. - It is often used as a **screening tool** and to assess the extent of disease but was not considered the definitive diagnostic mainstay without microbiological confirmation. *Physical examination findings* - Physical examination can reveal **non-specific signs** such as rales or diminished breath sounds, but these are not diagnostic of tuberculosis. - It is used for **initial assessment** and to guide further investigation, but **lacks the specificity** to confirm TB. *Molecular diagnostic tests (e.g., PCR, CBNAAT)* - **Molecular tests** like CBNAAT/GeneXpert are highly sensitive and specific for detecting *Mycobacterium tuberculosis* and drug resistance. - Under RNTCP, their **higher cost** and need for advanced infrastructure limited their widespread use as the *primary* diagnostic mainstay, though they were being scaled up. - Under the current **NTEP**, CBNAAT is now the **first-line diagnostic test** for all presumptive TB cases.

Question 564: Which is a critical component of the Directly Observed Treatment, Short-course (DOTS) strategy under the National Tuberculosis Elimination Programme (NTEP), formerly known as RNTCP?

A. Self-administration of drugs
B. Hospitalization of all tuberculosis patients
C. Observation of patients taking their medication (Correct Answer)
D. Use of traditional medicine in treatment

Explanation: ***Observation of patients taking their medication*** - The core principle of **DOTS** is the direct observation of patients by a health worker or trained volunteer as they swallow their anti-TB medications. - This directly addresses issues of **non-adherence** to treatment, which is a major cause of treatment failure and the development of drug resistance. - DOTS remains a cornerstone strategy under **NTEP** (formerly RNTCP) for ensuring treatment completion. *Self-administration of drugs* - This approach is precisely what **DOTS** aims to overcome, as it can lead to inconsistent medication intake and an increased risk of treatment failure. - While patient education is part of the overall strategy, unsupervised self-administration is not a core component of **DOTS**. *Hospitalization of all tuberculosis patients* - **DOTS** emphasizes outpatient treatment to make care accessible and cost-effective, reserving hospitalization for severe cases or those with complications. - Widespread hospitalization would be financially unsustainable and impractical for the large number of TB patients, particularly in resource-limited settings. *Use of traditional medicine in treatment* - The **NTEP** and **DOTS** strategy primarily rely on evidence-based, WHO-approved anti-TB regimens, not traditional medicine. - While traditional practices may exist, they are not a recognized or critical component of the official **DOTS** treatment protocol for active TB.

Question 565: In the case of an outbreak of waterborne diseases, what immediate action should public health officials prioritize?

A. Boiling water
B. Chlorination of water supply (Correct Answer)
C. Providing antibiotics
D. Issuing health advisories

Explanation: ***Chlorination of water supply*** - **Chlorination** is a rapid and effective method to disinfect large volumes of water, immediately killing most **pathogenic microorganisms** responsible for waterborne diseases. - This action directly addresses the **source of transmission** by purifying the contaminated water, preventing further spread of the outbreak. *Boiling water* - While effective for individual use, recommending **boiling water** for a widespread outbreak is not feasible for an entire community's water supply. - It serves as a **temporary measure** for individuals but does not solve the root cause of the contaminated public water system. *Providing antibiotics* - **Antibiotics** are a treatment for symptomatic individuals and do not prevent the spread of the disease through the water source itself. - Widespread prophylactic antibiotic use can also contribute to **antibiotic resistance** and is not the primary immediate public health intervention for a waterborne outbreak. *Issuing health advisories* - **Health advisories** are crucial for informing the public and guiding individual protective measures, but they do not directly interrupt the transmission cycle from the contaminated water supply. - This is an important **communicative step**, but it must be coupled with direct actions to purify the water.

Question 566: A 30-year-old man presents with fever, night sweats, and weight loss. Acid-fast bacilli are found in his sputum. What is the primary mode of transmission of the causative agent?

A. Ingestion of contaminated food
B. Inhalation of respiratory droplets (Correct Answer)
C. Contact with infected blood
D. Vector-borne transmission

Explanation: ***Inhalation of respiratory droplets*** - The presence of **acid-fast bacilli in sputum**, along with symptoms like fever, night sweats, and weight loss, is highly suggestive of **pulmonary tuberculosis**. - **Tuberculosis** is primarily spread when an infected person coughs, sneezes, or talks, releasing airborne droplets containing *Mycobacterium tuberculosis* that can be inhaled by others. *Ingestion of contaminated food* - While some mycobacterial infections can be acquired through contaminated food (e.g., *Mycobacterium bovis* via unpasteurized dairy), the presence of **acid-fast bacilli in sputum** indicates a respiratory source. - This mode of transmission is typically associated with **gastrointestinal infections**, not primary pulmonary disease presenting in this manner. *Contact with infected blood* - Transmission via **blood contact** is characteristic of bloodborne pathogens like HIV, Hepatitis B, or Hepatitis C. - Tuberculosis is not transmitted through direct contact with infected blood, making this an unlikely mode for the described clinical scenario. *Vector-borne transmission* - **Vector-borne diseases** involve an animal or insect (e.g., mosquitoes, ticks) transmitting a pathogen to humans (e.g., malaria, Lyme disease). - This mode of transmission is not applicable to **tuberculosis**, which is spread directly from person to person via respiratory secretions.

Question 567: What is the standard treatment protocol for new, drug-sensitive pulmonary tuberculosis (formerly Category I) under the National Tuberculosis Elimination Programme (NTEP)?

A. 2 months of HRZE followed by 4 months of HR (Correct Answer)
B. 3 months of HRZE followed by 3 months of HR
C. 6 months of HRZE continuously
D. 2 months of HRZE followed by 6 months of HR

Explanation: ***2 months of HRZE followed by 4 months of HR*** - The standard treatment for **new, drug-sensitive pulmonary tuberculosis** (formerly Category I TB) under NTEP involves an intensive phase of **2 months of HRZE** (Isoniazid, Rifampicin, Pyrazinamide, Ethambutol). - This is followed by a continuation phase of **4 months of HR** (Isoniazid, Rifampicin), totaling a **6-month regimen**. - This protocol applies to newly diagnosed TB patients with **no history of previous anti-TB treatment** and **no drug resistance**. *3 months of HRZE followed by 3 months of HR* - This protocol does not align with the standard NTEP recommendations for new, drug-sensitive TB cases. - The initial intensive phase for newly diagnosed TB is **2 months, not 3 months**, as per current guidelines. *6 months of HRZE continuously* - Continuous use of **all four drugs (HRZE)** for 6 months is not the standard regimen for new, drug-sensitive TB. - **Pyrazinamide (Z) and Ethambutol (E)** are typically discontinued after the initial 2-month intensive phase to reduce toxicity and simplify the continuation phase. *2 months of HRZE followed by 6 months of HR* - While the intensive phase **(2 months of HRZE)** is correct, the continuation phase of **6 months of HR is longer than the standard 4 months**. - This would result in an unnecessary 8-month total treatment duration, increasing pill burden, costs, and potential adverse effects without additional clinical benefit for drug-sensitive TB.

Question 568: In a hospital outbreak of yellow fever, which strategy would be most effective in controlling the spread of the virus?

A. Vector control through mosquito eradication (Correct Answer)
B. Isolation of infected individuals
C. Mass vaccination of the population
D. Antiviral therapy administration

Explanation: ***Vector control through mosquito eradication*** - Yellow fever is a **mosquito-borne illness**, primarily transmitted by Aedes aegypti mosquitoes, making vector control the cornerstone of outbreak management. - In a hospital outbreak, this includes **eliminating breeding sites, using insecticides, installing screens, and deploying mosquito traps** to interrupt the transmission cycle. - Vector control directly addresses the **source of transmission** and provides sustained protection for all susceptible individuals in the facility. *Isolation of infected individuals* - While yellow fever is not directly transmitted person-to-person, isolation of viremic patients **does play an important role** in outbreak control. - Isolating infected patients in **screened rooms or under bed nets prevents mosquitoes from biting them** and becoming infected vectors, which is recommended by WHO guidelines. - However, this is a **complementary measure** rather than the most effective primary strategy, as it doesn't address existing infected mosquitoes or prevent bites to susceptible individuals. *Mass vaccination of the population* - **Vaccination is highly effective for prevention** and is crucial for long-term control of yellow fever. - However, in an ongoing outbreak, protective immunity takes **10-30 days to develop** after vaccination, making it less immediately effective compared to vector control for acute outbreak containment. - Ring vaccination may be employed as part of outbreak response but requires time to achieve protective immunity. *Antiviral therapy administration* - There is currently **no specific antiviral treatment for yellow fever**; management is primarily supportive (fluid resuscitation, management of hemorrhagic manifestations, organ support). - Without specific antivirals available, this approach cannot effectively control viral spread during an outbreak.

Question 569: The WHO's '3 by 5' initiative aimed to:

A. Reduce child mortality by threefold by 2005
B. Provide antiretroviral treatment to 3 million people by 2005 (Correct Answer)
C. Decrease tuberculosis deaths by threefold by 2005
D. Achieve 100% immunization coverage in 5 years

Explanation: ***Provide antiretroviral treatment to 3 million people by 2005*** - The '3 by 5' initiative was a highly publicized **World Health Organization (WHO)** campaign launched in 2003. - Its primary goal was to bring **antiretroviral treatment (ART)** to 3 million people living with HIV/AIDS in low- and middle-income countries by the end of 2005. *Reduce child mortality by threefold by 2005* - While child mortality reduction is a significant global health goal, it was addressed by other initiatives like the **Millennium Development Goals (MDGs)**, not specifically the '3 by 5' WHO campaign. - The '3 by 5' initiative had a specific focus on **HIV/AIDS treatment access**. *Decrease tuberculosis deaths by threefold by 2005* - **Tuberculosis (TB)** control is a major public health priority, but it was not the direct focus of the '3 by 5' initiative. - WHO has specific programs for TB control, such as the **Stop TB Partnership**, but these are distinct from the '3 by 5' campaign. *Achieve 100% immunization coverage in 5 years* - Achieving high immunization coverage is a key component of **global health efforts**, often led by GAVI and WHO's Expanded Programme on Immunization (EPI). - However, the '3 by 5' initiative was specifically targeted at expanding access to **HIV/AIDS treatment**, not general immunization.

Question 570: What is the aim of the '100% condom use program'?

A. Transmission of non-communicable diseases
B. Transmission of sexually transmitted infections (Correct Answer)
C. Unwanted industrial pollution
D. Spread of oral diseases

Explanation: ***Transmission of sexually transmitted infections*** * The **'100% condom use program'** aims to reduce the incidence and prevalence of **sexually transmitted infections (STIs)** by promoting consistent and correct condom use during every sexual act. * This strategy is particularly effective in populations with high-risk sexual behaviors or in settings like commercial sex work, where STI transmission rates can be elevated. *Transmission of non-communicable diseases* * Non-communicable diseases such as **diabetes**, heart disease, or cancer are not transmitted through sexual contact and therefore are not targeted by condom use programs. * Condoms primarily provide a physical barrier against pathogen exchange, which is irrelevant for the prevention of non-infectious conditions. *Unwanted industrial pollution* * Industrial pollution is an environmental concern related to manufacturing and waste, completely unrelated to sexual health or disease transmission. * This option is entirely out of context and has no connection to public health initiatives involving condom use. *Spread of oral diseases* * While some oral infections can be transmitted through oral sexual contact, the primary and overarching aim of a **'100% condom use program'** is broad prevention of **all STIs**, not exclusively oral diseases. * Comprehensive oral hygiene practices and dental care are the main interventions for preventing the spread of routine oral diseases.

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Communicable Disease Control Principles

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HIV/AIDS Control Program

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Tuberculosis Control

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Leprosy Elimination

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Emerging and Re-emerging Infections

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Hospital-Acquired Infections

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Integrated Disease Surveillance Project

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