Infectious Diseases Practice Questions

Q: Which of the following diseases is not effectively prevented by maternal antibodies transferred during pregnancy?

Whooping cough (Pertussis). ***Whooping cough (Pertussis)*** - **Maternal antibodies** against pertussis are **poorly transferred** across the placenta, offering **limited protection** to the neonate. - Infants remain highly vulnerable to pertussis, necessitating early vaccination or **cocooning strategies** (vaccinating close contacts). *Mumps* - Maternal antibodies provide **effective passive immunity** to the infant for several months, protecting against mumps. - This protection wanes, making **childhood vaccination (MMR)** crucial. *Rubella* - **Maternal antibodies** against rubella are **effectively transferred**, providing good protection to the infant during the first 6-12 months of life. - This is particularly important as congenital rubella syndrome can cause severe birth defects. *Measles* - Infants born to mothers with measles immunity receive **strong passive maternal antibody protection**, which typically lasts until 6-9 months of age. - This initial protection is why the first dose of the **MMR vaccine** is usually given around 12 months.

Q: Rubella is known to cause all of the following conditions except:

Glaucoma. ***Glaucoma*** - While rubella can cause **ocular defects** such as **cataracts** and **pigmentary retinopathy**, glaucoma is not a typical congenital manifestation of rubella syndrome. - **Congenital glaucoma** is more commonly associated with other genetic syndromes or developmental anomalies. *Microcephaly* - **Microcephaly** is a recognized neurological complication of congenital rubella syndrome, resulting from impaired brain development due to viral infection. - The rubella virus can interfere with the **proliferation and migration** of neuronal cells during fetal development. *VSD* - **Ventricular septal defect (VSD)** is a common congenital heart defect associated with congenital rubella syndrome. - Other cardiac anomalies seen include **patent ductus arteriosus (PDA)** and **pulmonary artery stenosis**. *Conduction defects* - **Conduction defects** and other **cardiac arrhythmias** can occur in congenital rubella syndrome due to direct viral damage to the developing cardiac conduction system. - This can manifest as **bradyarrhythmias** or various degrees of **heart block**.

Q: Treatment for meningitis caused by Streptococcus pneumoniae in children is typically given for how many days?

10 days. ***10 days*** - The standard duration for treating **bacterial meningitis** caused by *Streptococcus pneumoniae* in children is **10 days**. - This duration is crucial to ensure complete eradication of the bacteria and prevent relapse or long-term neurological sequelae. *5 days* - A 5-day course is generally **too short** for *Streptococcus pneumoniae* meningitis; it might lead to treatment failure or recurrence. - Shorter courses, such as 5-7 days, are sometimes used for less resistant organisms or in specific cases of **meningococcal meningitis**. *7 days* - While 7 days might be sufficient for some causes of bacterial meningitis, such as **meningococcal meningitis** or particular strains of *Haemophilus influenzae*, it is generally considered insufficient for **pneumococcal meningitis**. - *Streptococcus pneumoniae* often requires a longer course due to its potential for resistance and the severity of the infection. *21 days* - A 21-day course is typically reserved for more difficult-to-treat or **intracranial infections** like **tuberculous meningitis** or certain fungal meningitis cases. - It is generally **unnecessary** and could increase the risk of antibiotic-related side effects for uncomplicated *Streptococcus pneumoniae* meningitis.

Q: Koplik spots are characteristic of which viral infection?

Pathognomonic sign of measles. ***Correct Answer: Pathognomonic sign of measles*** - **Koplik spots** are considered an **enanthem** (a rash on mucous membranes) and are **pathognomonic** for **measles (rubeola)**, meaning their presence is diagnostic of the disease. - These spots typically appear on the **buccal mucosa** opposite the molars as small white spots with red halos, preceding the characteristic skin rash. - They serve as an important early clinical marker for the diagnosis of measles. *Incorrect: Not typically seen in measles* - This statement is completely incorrect; **Koplik spots are highly characteristic** and pathognomonic for measles. - Their presence is virtually diagnostic of measles infection. *Incorrect: Seen 2-3 days after cutaneous rashes* - This is incorrect regarding timing; Koplik spots typically **appear 1-3 days BEFORE the onset of the generalized maculopapular rash**. - Their presence helps in the **early diagnosis** of measles, before the widespread skin eruption develops. *Incorrect: Seen in the incubation period of measles* - This is incorrect. The **incubation period** (typically **10-12 days** after exposure) is asymptomatic - no signs or symptoms are present. - Koplik spots appear during the **prodromal stage**, which follows the incubation period and is characterized by fever, cough, coryza, and conjunctivitis (the 3 C's). - The prodromal stage precedes the full-blown maculopapular rash by 1-3 days.

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.

Question 1

Which of the following diseases is not effectively prevented by maternal antibodies transferred during pregnancy?

Accepted Answer

Whooping cough (Pertussis)

Answer

Mumps

Answer

Rubella

Answer

Measles

Question 2

Rubella is known to cause all of the following conditions except:

Accepted Answer

Glaucoma

Answer

Conduction defects

Answer

VSD

Answer

Microcephaly

Question 3

Treatment for meningitis caused by Streptococcus pneumoniae in children is typically given for how many days?

Accepted Answer

10 days

Answer

5 days

Answer

7 days

Answer

21 days

Question 4

Prophylaxis with cotrimoxazole is recommended in all situations except for which of the following?

Accepted Answer

All symptomatic HIV infected children > 5 years of age irrespective of CD4

Answer

All HIV infected infants less than 1 year age irrespective of symptoms or CD4 counts

Answer

All HIV exposed infants till HIV infection can be ruled out

Answer

As secondary prophylaxis after initial treatment for Pneumocystis jirovecii pneumonia

Question 5

Koplik spots are characteristic of which viral infection?

Accepted Answer

Pathognomonic sign of measles

Answer

Seen in the incubation period of measles

Answer

Seen 2-3 days after cutaneous rashes

Answer

Not typically seen in measles

Question 6

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 7

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

Accepted Answer

Hilar adenopathy

Answer

Abscess

Answer

Consolidation

Answer

CNS tuberculosis

Question 8

What is the most common cause of infantile diarrhea?

Accepted Answer

Rotavirus

Answer

Adenovirus

Answer

Reovirus

Answer

Norovirus

Question 9

Koplik spots are pathognomonic of which of the following?

Accepted Answer

Measles

Answer

Diphtheria

Answer

Donovanosis

Answer

Gonorrhoea

Question 10

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

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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