Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 491: Reye's Syndrome is caused by all except –

A. Influenza
B. RSV (Correct Answer)
C. Herpes
D. Adeno virus

Explanation: ***RSV*** - **Respiratory Syncytial Virus (RSV)** is not typically associated with Reye's Syndrome. While it can cause severe respiratory illness (bronchiolitis, pneumonia) in children, it does not have the direct link to mitochondrial dysfunction and hepatic encephalopathy characteristic of Reye's Syndrome. - Reye's Syndrome primarily occurs in children recovering from a **viral infection** (especially **influenza or varicella**) who are given **aspirin**, leading to acute encephalopathy and fatty liver. *Influenza* - **Influenza viruses (Type A and B)** are the most commonly associated viral infections with Reye's Syndrome, especially when aspirin is administered during recovery. - The combination of influenza infection and aspirin intake in children significantly increases the risk of this serious condition, which is why aspirin is contraindicated in children with febrile illnesses. *Herpes* - **Herpes simplex virus (HSV) infections** have been linked to Reye's Syndrome in some reported cases, particularly in infants and young children. - While less common than influenza or varicella-associated cases, herpes infection treated with aspirin can potentially precipitate Reye's Syndrome. *Adeno virus* - **Adenoviruses**, which cause respiratory infections and gastroenteritis, have also been implicated as a potential viral trigger for Reye's Syndrome in some reports. - The risk is heightened when salicylates (aspirin) are given to children recovering from an adenovirus infection, though this association is less established than with influenza or varicella.

Question 492: A 3-year-old boy presents with fever, throat pain, and difficulty swallowing. On examination, there is unilateral tonsillar swelling with deviation of the uvula. What is the most likely diagnosis?

A. Parapharyngeal abscess
B. Ludwig's angina
C. Peritonsillar abscess (Correct Answer)
D. Retropharyngeal abscess

Explanation: ***Peritonsillar abscess*** - This is the most common deep neck infection and typically presents with **unilateral tonsillar swelling**, **uvular deviation**, fever, and severe sore throat with difficulty swallowing (dysphagia) or speaking (muffled voice). - It usually develops as a complication of **acute tonsillitis**, where infection spreads from the tonsil into the peritonsillar space. *Parapharyngeal abscess* - While it can cause fever and severe throat pain, it typically presents with **trismus**, neck swelling below the angle of the mandible, and medial displacement of the lateral pharyngeal wall, rather than direct uvula deviation. - This type of abscess is located in the **parapharyngeal space**, which is lateral to the pharynx, and causes more diffuse swelling. *Ludwig's angina* - This is a rapidly spreading cellulitis of the **submandibular** and **sublingual spaces** and does not primarily involve the tonsils or cause uvular deviation. - Patients typically present with **symmetrical submental swelling**, painful swallowing, and tongue elevation, which can lead to airway obstruction. *Retropharyngeal abscess* - This abscess forms in the space behind the posterior pharyngeal wall and is more common in young children. - It often causes **neck stiffness**, muffled voice, stridor, and difficulty breathing, but less commonly presents with unilateral tonsillar swelling and uvular deviation.

Question 493: A 5-year-old unvaccinated child presents to the OPD with fever, red eyes, and a maculopapular rash. What is the most likely complication associated with this condition?

A. Acute myocarditis
B. Acute nephritis
C. Acute orchitis
D. Pneumonia (Correct Answer)

Explanation: ***Pneumonia*** - **Pneumonia** is the **most common and most likely complication of measles**, occurring in approximately **1-6% of measles cases** - The clinical presentation of **fever, red eyes (conjunctivitis), and maculopapular rash** in an **unvaccinated child** is classic for **measles (rubeola)** - Pneumonia may be due to **direct viral pneumonitis** from measles virus or **secondary bacterial infection** (most commonly *Streptococcus pneumoniae*, *Staphylococcus aureus*, or *Haemophilus influenzae*) - It is a major cause of **measles-related mortality**, particularly in young children and immunocompromised individuals *Acute myocarditis* - **Acute myocarditis** is an extremely rare complication of measles - While myocardial involvement can theoretically occur with severe viral infections, it is **not a recognized characteristic or common complication** of measles - This is not the most likely complication when compared to pneumonia, otitis media, or diarrhea *Acute nephritis* - **Acute nephritis** is not a characteristic complication of measles - It is more commonly associated with **post-streptococcal glomerulonephritis** following Group A Streptococcus infection - Kidney involvement in measles is not a well-documented or common complication *Acute orchitis* - **Acute orchitis** is a recognized complication of **mumps** virus infection, particularly in post-pubertal males (occurring in 20-30% of infected males) - It is **not associated with measles infection** - This is a classic distractor testing knowledge of viral exanthems and their specific complications

Question 494: Congenital Rubella Syndrome includes all except

A. SN deafness
B. Cataract
C. VSD
D. Intracerebral hemorrhage (Correct Answer)

Explanation: ***Intracerebral hemorrhage*** - This is not a typical manifestation of **Congenital Rubella Syndrome** (CRS). Symptoms of CRS primarily include sensory, cardiac, and ocular defects, not bleeding into the brain. *SN deafness* - **Sensorineural (SN) deafness** is a very common and characteristic symptom of **Congenital Rubella Syndrome**, often bilateral, due to damage to the organ of Corti. - It is one of the classic triad of manifestations of CRS. *Cataract* - **Cataracts** (clouding of the lens) are a prominent ocular defect in CRS, often leading to significant vision impairment or blindness. - Ocular defects like cataracts and **microphthalmia** are part of the classic clinical picture. *VSD* - **Ventricular Septal Defect (VSD)** is a common cardiac anomaly seen in CRS, caused by rubella virus infection during heart development. - Other common cardiac defects include **Patent Ductus Arteriosus (PDA)** and **Pulmonary Artery Stenosis**.

Question 495: The most effective treatment for extensive molluscum contagiosum in an immunocompetent child is:

A. Oral acyclovir
B. Cryotherapy
C. Topical imiquimod
D. Natural resolution (Correct Answer)

Explanation: ***Natural resolution*** - Molluscum contagiosum is a **self-limited viral infection** that typically resolves spontaneously within 6-12 months, or sometimes longer, even without intervention. - Given its benign nature and the potential for discomfort or scarring with aggressive treatments, **observational management** is often the most appropriate and effective "treatment" for extensive cases in immunocompetent children. *Oral acyclovir* - **Acyclovir** is an antiviral medication primarily effective against **herpes simplex virus (HSV)** and **varicella-zoster virus (VZV)**. - It has **no significant efficacy** against the **molluscum contagiosum virus (MCV)**, which belongs to the poxvirus family. *Cryotherapy* - **Cryotherapy** involves freezing the lesions with liquid nitrogen, which can be effective for individual lesions or a limited number of lesions. - For **extensive molluscum contagiosum**, cryotherapy would be **painful, time-consuming**, and potentially cause widespread scarring or hypopigmentation, making it impractical and not the most effective approach. *Topical imiquimod* - **Topical imiquimod** is an immune response modifier that stimulates the production of **cytokines**, such as interferon-alpha, which can help clear viral infections. - While it has been used off-label for molluscum, its efficacy is **variable**, and it can cause **significant local skin irritation** (redness, itching, burning), especially with extensive application, making it less suitable as the most effective treatment.

Question 496: A child presented at 18 months of age who has never been vaccinated before. Which vaccines will you administer?

A. BCG and OPV
B. Pentavalent vaccine alone
C. DPT, OPV and MMR (Correct Answer)
D. MMR, OPV, Rotavirus

Explanation: ***DPT, OPV and MMR*** - Among the given options, **DPT, OPV, and MMR** represent the **most comprehensive combination** for an unvaccinated 18-month-old child. - **DPT** provides protection against Diphtheria, Pertussis, and Tetanus (in modern practice, **Pentavalent vaccine** containing DPT+Hib+Hepatitis B is preferred). - **OPV** is essential for polio protection as part of catch-up immunization. - **MMR** (Measles, Mumps, Rubella) is critical at this age, as the first dose is typically given at 9-12 months. - **Note:** A complete catch-up schedule would also include **Hepatitis B vaccine** (if not using Pentavalent), **BCG** (if never given), and **Hib vaccine**, but this option covers the maximum number of essential vaccines among the choices provided. *BCG and OPV* - While both **BCG** and **OPV** should be part of catch-up vaccination at 18 months, this combination alone is **grossly incomplete**. - It misses critical vaccines like **DPT/Pentavalent**, **Hepatitis B**, and **MMR**. - BCG should still be given at 18 months if the child was never vaccinated, despite being ideally administered at birth. *Pentavalent vaccine alone* - **Pentavalent vaccine** (DPT+Hib+Hepatitis B) is actually preferred in modern Indian immunization practice over standalone DPT. - However, giving only Pentavalent would miss **MMR** and adequate **polio vaccination** (OPV/IPV), both of which are critical at this age. - A catch-up schedule requires multiple vaccines, not just one. *MMR, OPV, Rotavirus* - **MMR** and **OPV** are indeed essential for an 18-month-old in catch-up vaccination. - However, **Rotavirus vaccine** is **contraindicated** at this age—it must be started by 14 weeks and completed by 8 months of age (maximum age for last dose varies by vaccine brand but typically 24-32 weeks). - This combination also misses **DPT/Pentavalent** and **Hepatitis B**, making it incomplete.

Question 497: Which vaccine is contraindicated in a 6-month-old infant whose sibling is on chemotherapy for leukemia?

A. Oral polio vaccine (Correct Answer)
B. Hepatitis B
C. Rotavirus vaccine
D. DPT

Explanation: ***Oral polio vaccine*** - The **oral polio vaccine (OPV)** is a live attenuated vaccine containing weakened but live viruses. - It is **absolutely contraindicated** in individuals with immunocompromised household contacts (like a sibling on **chemotherapy**) due to the risk of **vaccine-associated paralytic poliomyelitis (VAPP)** from shedding of the live vaccine virus. - The shed virus can be transmitted to and cause disease in immunocompromised contacts. - This is the primary reason most countries have switched to **inactivated polio vaccine (IPV)**. *Hepatitis B* - The **Hepatitis B vaccine** is an inactivated (non-live) recombinant vaccine. - It poses no risk of transmitting live virus to an immunocompromised individual. - It is safe to administer to an infant with an immunocompromised household contact. *Rotavirus vaccine* - The **Rotavirus vaccine** is also a live attenuated vaccine, and there is a **relative contraindication** when household contacts are severely immunocompromised. - The vaccine virus can be shed in stool for several days after vaccination. - However, compared to OPV, the risk of serious disease transmission is considered much lower, and some guidelines allow its use with precautions (strict hand hygiene, avoiding diaper changes by immunocompromised contacts). - In the context of this question, **OPV has a stronger absolute contraindication** than rotavirus vaccine. *DPT* - The **DPT vaccine** (Diphtheria, Pertussis, Tetanus) is an **inactivated vaccine** containing toxoids and killed bacterial components. - It is safe to administer to an infant with an immunocompromised household contact as there is no risk of shedding live pathogens.

Question 498: Hutchinson's triad includes?

A. Conductive deafness, malformed incisors, interstitial keratitis
B. Interstitial keratitis, malformed molars, conductive deafness
C. Interstitial keratitis, malformed incisors, conductive deafness
D. Interstitial keratitis, Hutchinson's incisors, sensorineural deafness (Correct Answer)

Explanation: ***Interstitial keratitis, Hutchinson's incisors, sensorineural deafness*** - This triad of symptoms is pathognomonic for **congenital syphilis** and is known as **Hutchinson's triad**. - **Interstitial keratitis** causes inflammation of the cornea with photophobia and lacrimation, typically appearing between 5-20 years of age. - **Hutchinson's incisors** are characteristic notched, peg-shaped central incisors with a screwdriver appearance. - **Sensorineural deafness** (8th cranial nerve deafness) affects the inner ear and typically manifests in late childhood. *Conductive deafness, malformed incisors, interstitial keratitis* - This option incorrectly specifies **conductive deafness** instead of sensorineural deafness. - The hearing loss in Hutchinson's triad is **sensorineural**, resulting from damage to the cochlea or auditory nerve due to congenital syphilis infection. *Interstitial keratitis, malformed molars, conductive deafness* - This option has two errors: **malformed molars** instead of Hutchinson's incisors, and **conductive deafness** instead of sensorineural. - While **Moon's molars (mulberry molars)** are a stigma of congenital syphilis, they are NOT part of Hutchinson's triad. - The classical triad specifically includes **Hutchinson's incisors**, not molars. *Interstitial keratitis, malformed incisors, conductive deafness* - This option correctly mentions malformed incisors but incorrectly specifies **conductive deafness**. - The type of hearing loss in Hutchinson's triad is **sensorineural**, not conductive, as it results from damage to the inner ear structures or auditory nerve.

Question 499: How long should a child be isolated after being diagnosed with bacterial meningitis to prevent further transmission?

A. Till 12 hrs after admission
B. Till cultures become negative
C. Till 24 hours after starting antibiotics (Correct Answer)
D. Till antibiotics course is complete

Explanation: ***Till 24 hours after starting antibiotics*** - This duration is crucial because, after **24 hours of effective antibiotic therapy**, the bacterial load in the nasopharynx (the primary site of transmission) is significantly reduced. - At this point, the child is generally considered **non-infectious**, and the risk of airborne transmission to others is minimal. *Till 12 hrs after admission* - This period is generally too short to ensure the child is non-infectious, as it may not be enough time for antibiotics to adequately reduce the bacterial load. - Active shedding of bacteria through respiratory droplets can still occur, posing a risk of transmission. *Till cultures become negative* - Waiting for cultures to become negative is an overly stringent and impractical approach to isolation, as it can take several days for culture results. - Clinical guidelines prioritize a more immediate and practical strategy for isolation based on antibiotic efficacy and reduced transmission risk. *Till antibiotics course is complete* - Isolating for the entire course of antibiotics is usually unnecessary and excessive, as the child is typically no longer contagious long before the full course is finished. - Prolonged isolation can create logistical challenges and is not based on the infectious period for bacterial meningitis.

Question 500: Which vaccination schedule is correct for PCV (Pneumococcal Conjugate Vaccine)?

A. 6, 10, 14 weeks, booster at 12 months (Correct Answer)
B. 2, 4, 6 months
C. 6, 10, 14 weeks
D. 2, 4, 6 months, booster at 15 months

Explanation: ***6, 10, 14 weeks, booster at 12 months*** - This is the **standard recommended schedule** for PCV (3+1 schedule) as per **IAP (Indian Academy of Pediatrics) guidelines**. - The initial three doses at 6, 10, and 14 weeks provide **primary immunity**, while the booster at 12 months significantly **enhances and extends protection** against invasive pneumococcal disease. - This schedule is included in the **Universal Immunization Programme (UIP)** in India. *2, 4, 6 months* - This schedule follows the **US CDC** pattern primarily used for DTaP, Hib, and PCV in the United States. - It **lacks the critical booster dose** at 12 months as per Indian guidelines and uses months instead of weeks for the primary series. - Not the standard schedule tested in **Indian Medical PG exams**. *6, 10, 14 weeks* - This provides the **primary series** but omits the crucial **booster dose** typically given at 12 months. - Without the booster, **long-term protection against pneumococcal disease** may be insufficient, leading to waning immunity. - An incomplete vaccination schedule. *2, 4, 6 months, booster at 15 months* - This follows the **US CDC schedule** with a delayed booster. - Indian guidelines recommend the primary series at **6, 10, 14 weeks** (not months) with booster at **12 months** (not 15 months). - Not aligned with **IAP/NTAGI recommendations** for India.

Practice by Chapter

Vaccine-Preventable Diseases

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Immunization Schedule

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Common Childhood Infections

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Pediatric HIV

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Congenital Infections

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Fever in Infants and Children

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Meningitis and Encephalitis

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Respiratory Tract Infections

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Gastrointestinal Infections

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Parasitic Infections

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Tuberculosis in Children

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Opportunistic Infections

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