Infectious Diseases Practice Questions

Q: Which vaccine is recommended at 2 years of age according to the latest Indian Academy of Pediatrics (IAP) guidelines?

Booster of Typhoid Conjugate Vaccine. ***Booster of Typhoid Conjugate Vaccine*** - As per the latest IAP immunization guidelines, a **booster dose** of the **Typhoid Conjugate Vaccine** is recommended at **2 years of age** after the primary series given during infancy. - This booster provides continued protection against **typhoid fever**, which remains a significant health concern in India. *MMR* - The first dose of **MMR (Measles, Mumps, Rubella)** vaccine is typically given at **9 months**, with a second dose around **15-18 months** of age. - While important, it is usually completed before or at 18 months, not specifically at 2 years. *Pneumococcal conjugate* - The primary series of **Pneumococcal Conjugate Vaccine (PCV)** is administered in infancy, with doses typically at 6 weeks, 14 weeks, and a booster at 9 months. - While it protects against **pneumococcal infections**, a specific dose at 2 years is not a standard recommendation per IAP guidelines. *Varicella* - The first dose of **Varicella vaccine** is recommended around **15 months** of age, with a second dose typically given between **4 and 6 years**. - Therefore, 2 years of age falls between the usual schedule for the primary and booster doses of Varicella vaccine.

Q: What is the most common presentation of tuberculosis (TB) in children?

Hilar adenopathy. ***Hilar adenopathy*** - **Hilar adenopathy** is the most common radiographic finding in children with **primary tuberculosis**, reflecting lymph node involvement. - This is often accompanied by a small parenchymal lesion, forming the **Ghon complex**. *Abscess* - While TB can cause abscesses (e.g., cold abscesses in bone or soft tissue), it's not the **most common initial presentation** of primary childhood TB. - Abscess formation suggests a more **advanced or extrapulmonary** manifestation. *Consolidation* - **Consolidation** can be seen in adult-type or progressive primary TB, but it is less frequent than hilar adenopathy as the **initial presentation** in children. - It indicates **pneumonia-like changes** due to parenchymal inflammation. *CNS tuberculosis* - **Central Nervous System (CNS) tuberculosis** (e.g., tuberculous meningitis or tuberculoma) is a severe, extrapulmonary form of TB. - It is a **serious complication** rather than the most common initial presentation in children.

Q: What is the most common cause of infantile diarrhea?

Rotavirus. ***Rotavirus*** - **Rotavirus** is the **classic and most common cause** of severe, dehydrating **diarrhea** in infants and young children worldwide, especially in unvaccinated populations. - It remains the **standard answer** in medical examinations and textbooks. - While **rotavirus vaccine introduction** (Universal Immunization Program in India) has significantly reduced its prevalence in vaccinated populations, it continues to be a major pathogen in areas with incomplete vaccine coverage. - Presents with **watery diarrhea, vomiting, fever**, and can lead to severe dehydration. *Adenovirus* - **Adenovirus** (especially serotypes 40 and 41) can cause **gastroenteritis**, but it is a **less common cause** of infantile diarrhea compared to rotavirus. - It often presents with **respiratory symptoms** in addition to diarrhea. - Accounts for approximately **5-10%** of viral gastroenteritis cases. *Reovirus* - **Reovirus** is a family of viruses, and while some members can infect humans, they are **rarely associated** with significant or widespread diarrheal disease. - It is **not considered a common cause** of infantile diarrhea in clinical practice. *Norovirus* - **Norovirus** is a **very common cause of gastroenteritis** in older children and adults, often in outbreak settings (schools, cruise ships). - While it can affect infants and has increased in relative frequency in highly vaccinated populations, **rotavirus historically and classically predominated** as the leading cause of severe infantile diarrhea. - Norovirus causes more **sporadic cases** in infancy compared to rotavirus.

Q: Koplik spots are pathognomonic of which of the following?

Measles. ***Measles*** - **Koplik spots** are small, white spots with a bluish-white center on an erythematous base, found on the buccal mucosa opposite the molars. - They are a **pathognomonic sign** of measles (rubeola) and typically appear 1-2 days before the generalized maculopapular rash. *Diphtheria* - Characterized by the formation of a **thick, grayish membrane (pseudomembrane)** in the throat and tonsils, which can cause respiratory obstruction. - It is caused by **_Corynebacterium diphtheriae_** and does not present with Koplik spots. *Donovanosis* - This is a chronic, progressive **genital ulcerative disease** caused by **_Klebsiella granulomatis_**. - It presents with **beefy-red, granulomatous lesions** on the genitals or perineum and has no association with oral lesions like Koplik spots. *Gonorrhea* - A **sexually transmitted infection** caused by **_Neisseria gonorrhoeae_**, primarily affecting the urethra, cervix, rectum, and pharynx. - Oral manifestations can include pharyngitis, but **Koplik spots are not a feature** of gonorrhea.

Q: A patient presents with clustered, white lesions on the buccal mucosa, typically near the upper molars. These lesions are pathognomonic for measles. What are these lesions called?

Koplik spots. ***Koplik spots*** - These are pathognomonic for **measles (rubeola)** and appear as small, **white or bluish-white lesions** on an erythematous base on the buccal mucosa. - They typically precede the characteristic rash of measles by 1-2 days, making them a crucial early diagnostic sign. *Leukoplakia* - Refers to **thickened, white patches** on the mucous membranes that cannot be scraped off and are often precancerous. - These lesions are usually associated with chronic irritation (e.g., tobacco use) and are not a feature of viral infections like measles. *Kaposi spots* - This term is **not typically used** to describe oral lesions, particularly in the context of measles. - Kaposi sarcoma involves **purple or brown skin lesions** associated with HHV-8 infection, commonly seen in immunocompromised individuals. *None of the options* - This option is incorrect because **Koplik spots** accurately describe the buccal mucosal lesions pathognomonic for measles.

Q: A 12-year-old boy develops a sore throat of 4-day duration. On examination, a yellow-grayish patch is seen over both tonsils, and a foul smell is coming from his mouth. Which non-suppurative complication is most commonly associated with streptococcal throat infections?

Acute rheumatic fever. ***Acute rheumatic fever*** - **Acute rheumatic fever (ARF)** is a serious **non-suppurative complication** of streptococcal pharyngitis, primarily caused by **Group A Streptococcus (GAS)** [1]. - It involves **inflammatory lesions** of the heart, joints, brain, and subcutaneous tissues [2]. *Acute glomerulonephritis* - This is also a **non-suppurative complication** of streptococcal infection but is typically less common than acute rheumatic fever following pharyngitis. - **Acute post-streptococcal glomerulonephritis** is more frequently associated with **streptococcal skin infections (impetigo)** than pharyngeal infections. *Scarlet fever* - **Scarlet fever** is a **toxin-mediated disease** that is a direct manifestation of a streptococcal infection, not a non-suppurative complication. - It presents with a characteristic **rash**, **strawberry tongue**, and fever, making it a different category of streptococcal sequela. *Both acute rheumatic fever and acute glomerulonephritis* - While both can be non-suppurative complications, **acute rheumatic fever** is the **most commonly associated** non-suppurative complication specifically with **streptococcal throat infections** [1]. - **Acute glomerulonephritis** has a stronger association with **skin infections** and is less common after pharyngitis compared to acute rheumatic fever.

Q: All of the following are contraindications to the pertussis-containing vaccine except which of the following?

No known allergies. ***No known allergies*** - The absence of known allergies is **not a contraindication** to vaccination; rather, it suggests an individual is less likely to experience an **allergic reaction**. - This option describes a **normal and healthy** patient profile, suitable for vaccination. *Uncontrolled epilepsy* - **Uncontrolled epilepsy** represents an **unstable neurological condition** and is a **contraindication** to pertussis vaccination per current guidelines. - Progressive or unstable neurological disorders are contraindications because vaccination might be **temporally associated** with neurological deterioration, making it difficult to determine causality. - Once epilepsy is **controlled and stable**, pertussis vaccination may be reconsidered. *Anaphylactic reaction to previous dose* - A confirmed **anaphylactic reaction** to a prior dose of any vaccine component is an **absolute contraindication** to further doses. - Re-exposure could lead to a **severe and life-threatening** allergic response. *Progressive encephalopathy* - **Progressive encephalopathy** without an identified cause occurring within 7 days after a previous dose of pertussis vaccine is an **absolute contraindication**. - Vaccination in this context could exacerbate the condition or confuse the diagnosis of the underlying encephalopathy.

Q: What is the most common cause of acute epiglottitis in children in the post-Hib vaccination era?

Streptococcus pyogenes (Group A Strep). ***Streptococcus pyogenes (Group A Strep)*** - In the **post-Hib vaccination era**, *Streptococcus pyogenes* has emerged as **one of the most common causes** of acute epiglottitis in children. - With the dramatic reduction in H. influenzae type B cases due to widespread vaccination, Group A Streptococcus now accounts for a significant proportion of bacterial epiglottitis cases. - Other common causes in the current era include *Streptococcus pneumoniae* and *Staphylococcus aureus*. *Hemophilus influenzae type B* - While H. influenzae type B was the **predominant cause in the pre-vaccination era**, its incidence has **declined by over 95%** since the introduction of the Hib vaccine. - Cases now occur primarily in **unvaccinated or incompletely vaccinated children** and are relatively rare in populations with high vaccination coverage. - The question specifically asks about the post-Hib vaccination era, making this no longer the most common cause. *Para influenza virus type I and II* - **Parainfluenza viruses**, particularly types I and II, are the **leading cause of croup** (laryngotracheobronchitis), not epiglottitis. - Croup primarily affects the **subglottic region** and presents with a characteristic **barking cough**, whereas epiglottitis involves the supraglottic structures and presents with drooling, dysphagia, and the "tripod position." *Streptococcus pneumoniae* - *Streptococcus pneumoniae* is also a **common cause of acute epiglottitis in the post-Hib era**, along with Group A Streptococcus. - While S. pneumoniae can cause epiglottitis, Group A Strep is generally cited more frequently in recent literature as a leading bacterial cause in the current era. - Both organisms have become more prominent as etiologic agents following the decline of H. influenzae type B.

Q: Which of the following statements is true about erythema infectiosum?

It is caused by parvovirus B19.. ***It is caused by parvovirus B19.*** - **Parvovirus B19** is the definitive etiological agent of erythema infectiosum, also known as fifth disease. - This viral infection is common in **children** and presents with a characteristic rash. *The rash appears on the head and neck.* - The classic **slapped-cheek rash** does appear on the face (cheeks), but the more characteristic **lacy, reticular rash** typically appears on the **trunk and extremities**. - The neck is not a primary site of involvement, and this option is incomplete as it doesn't mention the distinctive truncal and extremity distribution. *The rash appears during the febrile phase.* - In erythema infectiosum, the **rash typically appears after the fever has subsided** (if fever was present at all). - The prodromal symptoms (mild fever, malaise) resolve before the characteristic slapped-cheek rash emerges. - By the time the rash appears, the patient is usually feeling better and is in the convalescent phase. *It primarily affects adults.* - Erythema infectiosum primarily affects **children**, particularly those of school age (5-15 years). - While adults can contract the infection, it is far more common in childhood.

Q: Which of the following is the MOST COMMON manifestation of congenital rubella syndrome?

Sensory neural hearing loss. ***Sensorineural hearing loss*** - **Sensorineural hearing loss** is the **most common manifestation** of congenital rubella syndrome, affecting **60-90% of infected infants**, and is often the **only manifestation** present. - It can be **unilateral or bilateral** and is typically **permanent**, ranging from mild to profound. - It is the **most frequent sequela** and may be the sole defect in many cases. *Cataract* - While **cataracts** are a classic component of the congenital rubella syndrome **triad** (cataracts, cardiac defects, deafness), they occur in **30-50% of cases**. - They are **less common** than sensorineural hearing loss. - Other ocular manifestations include **retinopathy**, **glaucoma**, and **microphthalmia**. *Congenital heart disease* - **Congenital heart disease**, particularly **patent ductus arteriosus (PDA)** and **peripheral pulmonary artery stenosis**, is a classic manifestation. - It occurs in **40-60% of cases**, making it **less common** than hearing loss. - Cardiovascular defects are part of the classic triad but not the most frequent finding. *None of the options* - This option is incorrect because **sensorineural hearing loss** is the well-established **most common manifestation** of congenital rubella syndrome. - It is the **single most frequent defect** identified in affected children.

Question 1

Which vaccine is recommended at 2 years of age according to the latest Indian Academy of Pediatrics (IAP) guidelines?

Accepted Answer

Booster of Typhoid Conjugate Vaccine

Answer

MMR

Answer

Pneumococcal conjugate

Answer

Varicella

Question 2

What is the most common presentation of tuberculosis (TB) in children?

Accepted Answer

Hilar adenopathy

Answer

Abscess

Answer

Consolidation

Answer

CNS tuberculosis

Question 3

What is the most common cause of infantile diarrhea?

Accepted Answer

Rotavirus

Answer

Adenovirus

Answer

Reovirus

Answer

Norovirus

Question 4

Koplik spots are pathognomonic of which of the following?

Accepted Answer

Measles

Answer

Diphtheria

Answer

Donovanosis

Answer

Gonorrhoea

Question 5

A patient presents with clustered, white lesions on the buccal mucosa, typically near the upper molars. These lesions are pathognomonic for measles. What are these lesions called?

Accepted Answer

Koplik spots

Answer

Leukoplakia

Answer

Kaposi spots

Answer

None of the options

Question 6

A 12-year-old boy develops a sore throat of 4-day duration. On examination, a yellow-grayish patch is seen over both tonsils, and a foul smell is coming from his mouth. Which non-suppurative complication is most commonly associated with streptococcal throat infections?

Accepted Answer

Acute rheumatic fever

Answer

Acute glomerulonephritis

Answer

Scarlet fever

Answer

Both acute rheumatic fever and acute glomerulonephritis

Question 7

All of the following are contraindications to the pertussis-containing vaccine except which of the following?

Accepted Answer

No known allergies

Answer

Uncontrolled epilepsy

Answer

Anaphylactic reaction to previous dose

Answer

Progressive encephalopathy

Question 8

What is the most common cause of acute epiglottitis in children in the post-Hib vaccination era?

Accepted Answer

Streptococcus pyogenes (Group A Strep)

Answer

Hemophilus influenzae type B

Answer

Para influenza virus type I and II

Answer

Streptococcus pneumoniae

Question 9

Which of the following statements is true about erythema infectiosum?

Accepted Answer

It is caused by parvovirus B19.

Answer

The rash appears on the head and neck.

Answer

The rash appears during the febrile phase.

Answer

It primarily affects adults.

Question 10

Which of the following is the MOST COMMON manifestation of congenital rubella syndrome?

Accepted Answer

Sensory neural hearing loss

Answer

None of the options

Answer

Congenital heart disease

Answer

Cataract

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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