Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 41: Which statement is not true regarding Yellow Fever?

A. It is an exotic disease.
B. The incubation period is 2-6 days.
C. The vaccine is a live attenuated 17D strain.
D. The vaccine is valid for 6 years. (Correct Answer)

Explanation: **Explanation:** The correct answer is **D** because the validity of the Yellow Fever vaccine certificate has been updated by the WHO under the International Health Regulations (IHR). 1. **Why Option D is the correct answer (False statement):** Previously, the Yellow Fever vaccination certificate was valid for 10 years. However, since **July 11, 2016**, the WHO has mandated that a single dose of the Yellow Fever vaccine provides **life-long protection**. Therefore, the certificate is now valid for the duration of the life of the person vaccinated, starting 10 days after vaccination. 2. **Analysis of other options (True statements):** * **Option A:** It is an **exotic disease** in India. While the vector (*Aedes aegypti*) is present, the disease itself is not endemic, and strict quarantine laws are in place to prevent its entry. * **Option B:** The intrinsic incubation period in humans is typically **3 to 6 days**, making the "2-6 days" range accurate. * **Option C:** The vaccine is a **live attenuated** preparation using the **17D strain** (grown in chick embryos). It is highly effective and safe. **High-Yield Clinical Pearls for NEET-PG:** * **Vector:** *Aedes aegypti* (Urban cycle) and *Haemagogus* (Sylvan/Jungle cycle). * **Vaccination Dose:** 0.5 ml, subcutaneous. * **Contraindications:** Infants <6 months, egg allergy, and symptomatic HIV/immunocompromised states. * **Quarantine:** The Indian Aircraft Public Health Rules specify a quarantine period of **6 days** for unvaccinated travelers coming from endemic zones. * **Cold Chain:** The vaccine is highly heat-sensitive and must be stored between **-30°C and +5°C**.

Question 42: Which one of the following diseases is communicable?

A. Rickets
B. Amoebiasis (Correct Answer)
C. Diabetes
D. Cancer

Explanation: **Explanation:** The core concept in this question is the classification of diseases into **Communicable (Infectious)** and **Non-Communicable (Chronic/Degenerative)**. **Why Amoebiasis is the Correct Answer:** Amoebiasis is a communicable disease caused by the protozoan parasite *Entamoeba histolytica*. It is transmitted via the **fecal-oral route**, primarily through contaminated food or water containing mature cysts. Because the infectious agent can be transmitted from an infected person (or reservoir) to a susceptible host, it is classified as a communicable disease. **Analysis of Incorrect Options:** * **Rickets (Option A):** This is a **nutritional deficiency** disorder caused by a lack of Vitamin D, calcium, or phosphate. It cannot be transmitted from one person to another. * **Diabetes (Option B):** This is a **metabolic/lifestyle disorder** characterized by chronic hyperglycemia. It results from genetic predisposition and environmental factors, not an infectious agent. * **Cancer (Option D):** This is a **non-communicable disease** characterized by uncontrolled cellular proliferation. While certain viruses (like HPV or HBV) can cause cancer, the disease "Cancer" itself is not considered communicable in the traditional sense. **NEET-PG High-Yield Pearls:** * **Infective stage of *E. histolytica*:** Quadrinucleate cyst. * **Diagnostic hallmark:** Presence of ingested RBCs (erythrophagocytosis) in trophozoites (indicates invasive amoebiasis). * **Commonest extra-intestinal site:** Liver (Amoebic Liver Abscess), typically presenting with "anchovy sauce" pus. * **Drug of choice:** Metronidazole or Tinidazole (followed by a luminal amoebicide like Diloxanide furoate to eradicate cysts).

Question 43: Leprosy is not targeted for global eradication because?

A. No effective vaccine is available
B. It is highly infectious but has low pathogenicity
C. Only humans act as a reservoir
D. It has a long incubation period (Correct Answer)

Explanation: ### Explanation The goal of **eradication** is the permanent reduction to zero of the worldwide incidence of an infection. Leprosy is currently targeted for **elimination** (defined as a prevalence of <1 case per 10,000 population) rather than eradication due to several biological and epidemiological hurdles. **Why Option D is Correct:** The primary barrier to eradication is the **long and variable incubation period** (average 3–5 years, but can extend up to 20 years). This makes it extremely difficult to track transmission chains, identify all active cases simultaneously, and ensure that the "reservoir" is truly empty. By the time a case is clinically detected, the individual may have already transmitted the bacilli to others years prior. **Analysis of Incorrect Options:** * **Option A:** While a specific vaccine (like BCG, which offers partial protection) is not 100% effective, the absence of a vaccine is not the primary reason for not targeting eradication. Diseases like Smallpox were eradicated primarily through vaccination, but others (like Dracunculiasis) are targeted for eradication through behavioral and environmental changes without a vaccine. * **Option B:** Leprosy actually has **high infectivity but low pathogenicity**. While many are exposed, only about 5% of people develop clinical disease. However, this high subclinical infection rate makes it harder, not easier, to eradicate. * **Option C:** This is factually incorrect. While humans are the primary reservoir, **extra-human reservoirs** exist (e.g., Nine-banded armadillos in the Americas and certain primates), which complicates eradication efforts as the disease can persist outside human populations. **High-Yield NEET-PG Pearls:** * **Agent:** *Mycobacterium leprae* (Acid-fast, obligate intracellular). * **Most Common Site:** Peripheral nerves and skin. * **Infectivity:** Highest in Multibacillary (MB) cases; nasal discharge is the most common route of exit. * **Classification:** Ridley-Jopling (Immunological) vs. WHO (Operational/Therapeutic). * **Current Strategy:** National Leprosy Eradication Programme (NLEP) in India aims for "Leprosy Mukt Bharat" (Leprosy Free India) by 2027.

Question 44: About yaws, all are true except:

A. Caused by T. pallidum subspecies pertenue
B. Transmitted non-venereally
C. Secondary yaws can involve bones
D. Later stages can involve heart and nerves (Correct Answer)

Explanation: **Explanation:** Yaws is a chronic, non-venereal treponematosis caused by **Treponema pallidum subspecies pertenue**. It primarily affects children in tropical regions and is characterized by skin, bone, and joint involvement. **Why Option D is the correct answer (The "Except"):** Unlike venereal syphilis, yaws **does not** involve the cardiovascular system (heart) or the central nervous system (nerves). It is strictly a disease of the skin, bone, and cartilage. The late stage of yaws is characterized by destructive lesions like **gangosa** (rhinopharyngitis mutilans) and **goundou** (exostosis of the maxilla), but visceral involvement is absent. **Analysis of other options:** * **Option A:** Correct. The causative agent is *T. pallidum pertenue*. It is morphologically indistinguishable from the agent of syphilis. * **Option B:** Correct. Yaws is transmitted via **direct skin-to-skin contact** with the exudate of early lesions. It is not sexually transmitted. * **Option C:** Correct. Secondary yaws is characterized by generalized skin eruptions and **osteoperiostitis** (involving long bones and fingers, leading to "sabre tibia" or polydactylitis). **NEET-PG High-Yield Pearls:** * **Endemicity:** Found in humid, tropical "hotspots." India was declared **Yaws-free** by the WHO in 2016 (the first country to be so certified under the 2012 roadmap). * **Diagnosis:** Serological tests (VDRL, TPHA) are positive but cannot distinguish yaws from syphilis. * **Treatment:** A single dose of **Azithromycin** (30 mg/kg) is the current WHO-recommended treatment (Morgues strategy). Benzathine Penicillin is the alternative. * **Key Lesion:** The initial lesion is called the **"Mother Yaw"** (frambesioma).

Question 45: What is the national helpline number for HIV/AIDS?

A. 1081
B. 1091
C. 1097 (Correct Answer)
D. 1100

Explanation: **Explanation:** **Correct Answer: C. 1097** The National AIDS Control Organization (NACO) established **1097** as the dedicated national toll-free helpline number for HIV/AIDS in India. This 24/7 service provides confidential counseling, information on HIV prevention, testing centers (ICTC), and treatment facilities (ART centers). It is a crucial tool for reducing stigma and increasing awareness under the National AIDS Control Programme (NACP). **Analysis of Incorrect Options:** * **A. 1081:** This is not a standard national medical helpline. (Note: 108 is the emergency ambulance service in many Indian states). * **B. 1091:** This is the **Women Helpline** number, dedicated to women in distress or facing violence. * **D. 1100:** This is typically used for **Chief Minister’s Helplines** or municipal grievance redressal in various states (e.g., Andhra Pradesh, Himachal Pradesh). **High-Yield Clinical Pearls for NEET-PG:** * **NACP Phase V (2021-2026):** Currently active, focusing on the "95-95-95" targets (95% aware of status, 95% on ART, 95% virally suppressed). * **Red Ribbon Express:** A specialized awareness train launched by NACO to spread HIV/AIDS education across rural India. * **ICTC (Integrated Counseling and Testing Centre):** The first point of contact for HIV diagnosis. * **Link Worker Scheme:** A community-based intervention targeting high-risk groups in rural areas. * **National Toll-free TB Helpline:** 1800-11-6666 (Nikshay Sampark).

Question 46: The National AIDS Control Programme was initiated in which year?

A. 1977
B. 1980
C. 1987 (Correct Answer)
D. 1990

Explanation: **Explanation:** The correct answer is **1987 (Option C)**. The **National AIDS Control Programme (NACP)** was launched by the Ministry of Health and Family Welfare, Government of India, in **1987**, shortly after the first AIDS case was reported in India (Chennai, 1986). Initially, the program focused on increasing awareness and screening blood for transfusion. In 1992, the National AIDS Control Organization (NACO) was established to implement and oversee the program's subsequent phases (NACP I to NACP V). **Analysis of Incorrect Options:** * **1977 (Option A):** This year is significant for the launch of the **Expanded Programme on Immunization (EPI)** in India and the global eradication of Smallpox (last case in Somalia). * **1980 (Option B):** This marks the year the World Health Assembly officially declared the **Global Eradication of Smallpox**. * **1990 (Option D):** While HIV surveillance was intensified during this period, it does not mark the inception of the national program. **High-Yield Clinical Pearls for NEET-PG:** * **First Case in India:** Reported in **1986** in female sex workers in Chennai. * **NACO Establishment:** **1992** (coinciding with the launch of NACP-I). * **ART Initiative:** Free Antiretroviral Therapy (ART) was launched on **April 1, 2004**. * **Current Phase:** India is currently under **NACP Phase V** (2021–2026), aiming for the "95-95-95" targets. * **Red Ribbon Express:** A mobile bus/train exhibition used for HIV/AIDS awareness in India.

Question 47: Which of the following is NOT included in the Revised National Tuberculosis Control Program (RNTCP)?

A. Active case finding (Correct Answer)
B. Directly observed treatment
C. X-ray as a diagnostic tool
D. All of the above

Explanation: **Explanation:** The **Revised National Tuberculosis Control Program (RNTCP)**, now renamed the **National Tuberculosis Elimination Program (NTEP)**, was traditionally built on the foundation of **Passive Case Finding**. This means the program relied on symptomatic patients (chest symptomatics) voluntarily reporting to health facilities for diagnosis. 1. **Why Option A is Correct:** Under the original RNTCP guidelines, **Active Case Finding (ACF)**—where health workers proactively screen the community to identify cases—was not a core component. The strategy focused on "quality diagnosis and treatment" for those who sought care. Note: While the newer NTEP has introduced ACF for vulnerable populations, in the context of classic RNTCP questions, passive case finding remains the hallmark. 2. **Why Option B is Incorrect:** **Directly Observed Treatment Short-course (DOTS)** is the heart of RNTCP. It ensures treatment adherence by having a provider or trained person observe the patient swallowing their medication. 3. **Why Option C is Incorrect:** While Sputum Smear Microscopy was the primary diagnostic tool, **Chest X-ray** has always been included in the RNTCP diagnostic algorithm, specifically for smear-negative patients who remain symptomatic after a course of antibiotics. **High-Yield Clinical Pearls for NEET-PG:** * **Case Finding Strategy:** RNTCP = Passive Case Finding; NTEP = Moving towards Active Case Finding. * **Goal of NTEP:** To eliminate TB in India by **2025** (5 years ahead of the global SDG goal of 2030). * **Diagnostic Gold Standard:** Rapid molecular tests like **CBNAAT (GeneXpert)** or TrueNat have now replaced microscopy as the initial diagnostic tool under current NTEP guidelines. * **Nikshay:** The web-based surveillance system for monitoring TB patients in India.

Question 48: Screening for which of the following viral infections in blood donors is compulsory?

A. HIV
B. HBV
C. HCV
D. All of these (Correct Answer)

Explanation: **Explanation:** In India, the **Drugs and Cosmetics Act (1940)** and its subsequent amendments mandate the screening of all donated blood units to ensure transfusion safety and prevent **Transfusion-Transmitted Infections (TTIs)**. **Why the correct answer is "All of these":** The mandatory screening protocol in India requires every unit of blood to be tested for **five specific pathogens** before it can be issued for clinical use. These include: 1. **HIV (Human Immunodeficiency Virus):** Types 1 and 2. 2. **HBV (Hepatitis B Virus):** Specifically testing for Hepatitis B Surface Antigen (HBsAg). 3. **HCV (Hepatitis C Virus):** Testing for anti-HCV antibodies. 4. **Syphilis:** Testing for *Treponema pallidum*. 5. **Malaria:** Testing for *Plasmodium* species. **Analysis of Options:** * **HIV, HBV, and HCV** are all highly infectious, blood-borne viruses that can lead to chronic, life-threatening conditions. Because they share common transmission routes and have significant "window periods," universal screening is the only way to safeguard the blood supply. Therefore, selecting only one (Options A, B, or C) would be incomplete. **High-Yield Clinical Pearls for NEET-PG:** * **Window Period:** This is the time between infection and the point when laboratory tests can detect the pathogen. **NAT (Nucleic Acid Testing)** is increasingly used in advanced centers to reduce this window period, though it is not yet universally mandatory in all government blood banks. * **Mandatory Tests:** Remember the "Big 5": HIV, HBV, HCV, Syphilis, and Malaria. * **Hepatitis B:** It is the most common TTI globally. * **Professional Donors:** Under Indian law, blood donation must be **voluntary and non-remunerated**; professional (paid) blood donation is strictly banned to reduce the risk of TTIs.

Question 49: Targeted intervention for HIV is recommended for which of the following groups, except?

A. Commercial sex workers
B. Migrant laborers
C. Street children
D. Industrial workers (Correct Answer)

Explanation: **Explanation:** Targeted Intervention (TI) is a core component of the **National AIDS Control Programme (NACP)**. It focuses on providing prevention and care services to specific populations who are at a higher risk of acquiring and transmitting HIV due to their behavior or social circumstances. **Why Industrial Workers is the correct answer:** Under NACP guidelines, Targeted Interventions are specifically designed for **High-Risk Groups (HRGs)** and **Bridge Populations**. While industrial workers may face occupational health hazards, they are not classified as a high-risk or bridge population for HIV unless they specifically fall into categories like migrant labor. General industrial workers are considered part of the "general population" and are covered under general awareness programs rather than specific TI projects. **Analysis of Incorrect Options:** * **Commercial Sex Workers (CSWs):** They are classified as a **Core High-Risk Group (HRG)**. TIs for CSWs focus on 100% condom use, STI screening, and behavior change communication. * **Migrant Laborers:** They are classified as a **Bridge Population**. They often live away from families and may visit sex workers, potentially "bridging" the infection from high-risk groups to the general population (their spouses in rural areas). * **Street Children:** They are categorized as a **Vulnerable Population**. Due to their lack of supervision and high risk of substance abuse or sexual exploitation, they are included in targeted outreach. **High-Yield NEET-PG Pearls:** * **Core HRGs:** Female Sex Workers (FSW), Men who have Sex with Men (MSM), and Injecting Drug Users (IDU). * **Bridge Populations:** Migrants and Long-distance Truckers. * **Components of TI:** Condom promotion, Treatment of STIs, Behavior Change Communication (BCC), and creating an enabling environment. * **NACP Phase V (Current):** Aims to reduce new HIV infections and AIDS-related deaths by 80% by 2030.

Question 50: Kyasanur forest disease is transmitted by:

A. Mite
B. Tick (Correct Answer)
C. Mosquito
D. None

Explanation: **Explanation:** **Kyasanur Forest Disease (KFD)**, commonly known as "Monkey Fever," is a viral hemorrhagic fever endemic to the Western Ghats of India (primarily Karnataka). It is caused by the Kyasanur Forest Disease Virus (KFDV), a member of the family *Flaviviridae*. 1. **Why Tick is Correct:** The primary vector for KFD is the **hard tick**, specifically ***Haemaphysalis spinigera***. Humans typically contract the disease through the bite of an infected nymphal tick or through contact with an infected animal (monkeys are the common amplifying hosts). The transmission cycle involves ticks, wild rodents, and monkeys. 2. **Why Other Options are Incorrect:** * **Mite:** Mites are vectors for diseases like **Scrub Typhus** (*Leptotrombidium* mite). * **Mosquito:** Mosquitoes transmit a wide range of viral diseases such as Dengue, Chikungunya, and Malaria, but they play no role in the transmission of KFD. **High-Yield Clinical Pearls for NEET-PG:** * **Reservoirs:** Wild rodents and monkeys (Langurs and Bonnet Macaques). A sudden increase in monkey deaths in a forest area is a classic sentinel sign of a KFD outbreak. * **Seasonality:** Most cases occur during the dry season (January to June) when human activity in forests increases and nymphal tick activity is high. * **Clinical Presentation:** Characterized by sudden onset high fever, severe headache, myalgia, and hemorrhagic manifestations. A "biphasic" fever pattern is often noted. * **Prevention:** A **formalin-inactivated KFDV vaccine** is used in endemic areas for individuals aged 7–65 years. * **Diagnosis:** Confirmed via PCR (early stage) or ELISA (IgM) for antibodies.

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Communicable Disease Control Principles

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Vector-Borne Diseases

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Water-Borne Diseases

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Air-Borne Diseases

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Zoonotic Diseases

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Sexually Transmitted Infections

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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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