Infectious Diseases Practice Questions

Q: In a 3-year-old child, the most common cause of hepatitis is:

Hepatitis A virus infection. ***Hepatitis A virus infection*** - **Hepatitis A virus (HAV)** is highly contagious and spreads primarily through the **fecal-oral route**, making it common in daycare settings or among young children. - In children, HAV infection is often **asymptomatic** or presents with mild, non-specific symptoms, but it is a frequent cause of acute hepatitis in this age group. *Perinatal* - **Perinatal transmission** typically refers to infections transmitted from mother to child around the time of birth, which is a common route for **Hepatitis B** and **Hepatitis C**, not generally HAV. - While possible, perinatal transmission is not the most common cause of hepatitis in a 3-year-old, as exposure usually occurs after birth in the general environment. *Pin prick* - **Pin prick injuries** or exposures to contaminated needles are routes for **blood-borne viruses** like **Hepatitis B** and **Hepatitis C**. - This mode of transmission is rare and atypical for a 3-year-old child and is not the primary route for the most common cause of hepatitis in this age group. *Saliva exchange* - While some viruses can be transmitted through **saliva exchange**, **Hepatitis A** is primarily transmitted via the **fecal-oral route**, not typically through saliva. - **Saliva exchange** is not a common or significant mode of transmission for hepatitis viruses that cause acute hepatitis in young children.

Q: An 8-year-old boy from an impoverished inner-city area has never been vaccinated appropriately. He develops fever, cough, and coryza. The next day, blue white spots develop on the buccal mucosa. On the third day, an erythematous, nonpruritic maculopapular rash develops on the face and spreads over the entire body. Which of the following is the most likely complication?

pneumonia. ***Pneumonia*** - This scenario describes **measles** (rubeola) with the classic triad of fever, cough, and coryza (the **3 Cs**), along with pathognomonic **Koplik spots** (blue-white spots on buccal mucosa) and the characteristic **maculopapular rash** spreading cephalocaudally from the face. - **Pneumonia** is the **most common serious complication** of measles, occurring in approximately **1-6% of cases**, and is the **leading cause of measles-related mortality** in children. - It can be either **viral pneumonia** (direct measles virus infection) or **secondary bacterial pneumonia** (especially *Streptococcus pneumoniae*, *Staphylococcus aureus*, *Haemophilus influenzae*). - This is particularly common in **unvaccinated, malnourished, and immunocompromised children** from impoverished areas, as described in this case. *Otitis media* - **Otitis media** is a common complication of measles, occurring in approximately **5-9% of cases**. - While frequent, it is **less common than pneumonia** and is generally less severe in terms of mortality risk. - It typically presents with ear pain and can lead to hearing complications if untreated. *Encephalitis* - **Measles encephalitis** is a rare but severe complication, occurring in approximately **1 in 1000 cases** (0.1%). - It typically develops **1-2 weeks after rash onset**, presenting with fever, headache, seizures, altered consciousness, and neurological deficits. - While serious with significant mortality and morbidity, it is **much less common** than pneumonia. *Bronchitis* - **Bronchitis** (cough, chest congestion) is typically part of the **initial prodromal phase** of measles itself rather than a distinct complication. - The respiratory symptoms (cough, coryza) are manifestations of the primary measles infection, not secondary complications.

Q: Child with generalized petechiae. CSF shows gram-negative diplococci. Treatment -

IV Ceftriaxone. ***IV Ceftriaxone*** - The presence of **generalized petechiae** and **gram-negative diplococci** in the CSF strongly suggests **meningococcal meningitis**, which is a severe infection requiring prompt and effective antibiotic treatment. - **Ceftriaxone** is a third-generation cephalosporin that has excellent penetration into the CSF and is a first-line treatment for bacterial meningitis caused by *Neisseria meningitidis*. *IV Penicillin G* - While **Penicillin G** can be effective against penicillin-susceptible strains of *Neisseria meningitidis*, there is increasing concern about penicillin resistance. - **Ceftriaxone** is generally preferred empirically due to its broader coverage and reliable efficacy against penicillin-resistant strains. *IV Penicillin V* - **Penicillin V** is an oral penicillin, and it is not suitable for the treatment of severe, invasive infections like **meningitis** due to inadequate systemic and CSF concentrations. - It is typically used for less severe infections like pharyngitis. *IV Cefotaxime* - **Cefotaxime** is also a third-generation cephalosporin with good CSF penetration and is an effective treatment for bacterial meningitis. - However, in many guidelines, **ceftriaxone** is often listed as the preferred agent due to its longer half-life, allowing for once-daily or twice-daily dosing, which is more convenient.

Q: Which of the following is Not characteristic of congenital Syphilis?

Ghon complex. ***Ghon complex*** - A **Ghon complex** (primary tubercular complex) is a characteristic feature of **primary tuberculosis**, not congenital syphilis. - It consists of a **calcified lesion** in the lung periphery (Ghon focus) and associated hilar lymph node calcification. - This represents a healed primary TB infection. *Interstitial keratitis* - **Interstitial keratitis** is a classic manifestation of **late congenital syphilis**, often appearing around puberty. - It involves inflammation of the **cornea, leading to photophobia and potentially blindness** if untreated. - Part of **Hutchinson's triad** (interstitial keratitis, Hutchinson's teeth, eighth nerve deafness). *Mulberry molars* - **Mulberry molars** (or Moon's molars) are a dental anomaly seen in **congenital syphilis**, characterized by irregularly shaped first molars with multiple, poorly formed cusps. - This is part of the **dental stigmata** of the disease. *Notched incisors* - **Notched incisors** (Hutchinson's teeth) are another pathognomonic sign of **congenital syphilis**. - They are characterized by **peg-shaped, widely spaced upper central incisors** with a crescent-shaped notch on the biting surface. - Also part of **Hutchinson's triad**.

Q: Best method to diagnose HIV in an infant?

PCR. ***PCR*** - **Polymerase Chain Reaction (PCR)** detects **HIV nucleic acids** (DNA or RNA) directly, which is crucial for infants because maternal antibodies can persist for up to 18 months, interfering with antibody-based tests. - PCR allows for early diagnosis, often within the first few weeks or months of life, facilitating timely intervention. *ELISA* - **Enzyme-linked immunosorbent assay (ELISA)** detects HIV antibodies. - In infants, ELISA can be misleading due to the presence of **maternal HIV antibodies** transferred across the placenta, making it unreliable for diagnosing active infection. *Western blot* - **Western blot** is used to confirm positive ELISA results in adults by detecting specific HIV proteins. - Like ELISA, it relies on the detection of **antibodies** and is therefore not reliable in infants due to maternally transmitted antibodies. *All of the options* - This option is incorrect because **ELISA** and **Western blot** are antibody-based tests that are unreliable in infants due to the presence of **maternal antibodies**. - Only **PCR** directly detects the virus itself, making it the preferred diagnostic method in this age group.

Q: Reye's syndrome in children is commonly associated with aspirin use during which type of infection?

Influenza virus. ***Influenza virus*** - Reye's syndrome is a rare but severe condition characterized by **acute encephalopathy and fatty liver infiltration** that predominantly affects children recovering from viral infections - **Aspirin use during influenza** is one of the two most strongly documented associations with Reye's syndrome, leading to contraindication of aspirin in children with febrile illnesses - The incidence of Reye's syndrome dropped dramatically after public health warnings against aspirin use in children with influenza-like illnesses *Varicella (Chickenpox)* - Varicella is the **other major viral infection** strongly associated with Reye's syndrome when aspirin is used - Both influenza and varicella are considered the two primary precipitating viral infections - In competitive exam context, when both are options, understanding the equal significance is important, though influenza is often cited first in classical teaching *HIV* - **HIV is a chronic infection** and not an acute febrile viral illness where aspirin would typically be used for symptomatic relief - Reye's syndrome is specifically associated with **acute viral illnesses** (influenza and varicella) where aspirin might be administered for fever control - No established association between HIV infection and Reye's syndrome *Measles virus* - While measles is an acute viral infection, the **documented association with Reye's syndrome is significantly weaker** compared to influenza and varicella - The major contraindication for aspirin in pediatric febrile illness specifically emphasizes **influenza and varicella** - Not considered one of the primary precipitating infections for Reye's syndrome

Question 1

Which of the following is true about Diphtheria EXCEPT:

Accepted Answer

Faucial diphtheria is more dangerous than laryngeal diphtheria

Answer

Laryngeal diphtheria mandates tracheotomy

Answer

Myocarditis may be a complication

Answer

Child is more toxic with faucial diphtheria

Question 2

In a 3-year-old child, the most common cause of hepatitis is:

Accepted Answer

Hepatitis A virus infection

Answer

Perinatal

Answer

Pin prick

Answer

Saliva exchange

Question 3

For the prevention of parent to child transmission of HIV, the NACO's recommendation is to give -

Accepted Answer

Tenofovir + Lamivudine + Dolutegravir (TLD regimen) to mother and Nevirapine syrup to newborn for 6 weeks

Answer

Zidovudine monotherapy to mother during pregnancy and labor only

Answer

Efavirenz monotherapy to mother throughout pregnancy and breastfeeding

Answer

Nevirapine single dose to mother in labor and single dose to newborn

Question 4

Which of the following statements concerning sensorineural hearing loss in children with bacterial meningitis are TRUE?

Accepted Answer

Prompt institution of antimicrobial therapy appears not to influence the incidence

Answer

It occurs rarely (less than 5% of cases)

Answer

Its onset often is late in the clinical course, after discontinuation of antimicrobial therapy

Answer

It occurs more commonly when Haemophilus influenza type B rather than Streptococcus pneumoniae is the causative organism of the meningitis

Question 5

An 8-year-old boy from an impoverished inner-city area has never been vaccinated appropriately. He develops fever, cough, and coryza. The next day, blue white spots develop on the buccal mucosa. On the third day, an erythematous, nonpruritic maculopapular rash develops on the face and spreads over the entire body. Which of the following is the most likely complication?

Accepted Answer

pneumonia

Answer

encephalitis

Answer

bronchitis

Answer

otitis media

Question 6

Symptomatic neonatal CNS involvement is most commonly seen in which group of congenital intrauterine infections?

Accepted Answer

CMV and toxoplasmosis

Answer

Rubella and toxoplasmosis

Answer

CMV and syphilis

Answer

Rubella and HSV

Question 7

Child with generalized petechiae. CSF shows gram-negative diplococci. Treatment -

Accepted Answer

IV Ceftriaxone

Answer

IV Penicillin G

Answer

Oral Penicillin V

Answer

IV Cefotaxime

Question 8

Which of the following is Not characteristic of congenital Syphilis?

Accepted Answer

Ghon complex

Answer

Interstitial keratitis

Answer

Mulberry molars

Answer

Notched incisors

Question 9

Best method to diagnose HIV in an infant?

Accepted Answer

PCR

Answer

ELISA

Answer

Western blot

Answer

All of the options

Question 10

Reye's syndrome in children is commonly associated with aspirin use during which type of infection?

Accepted Answer

Influenza virus

Answer

Varicella (Chickenpox)

Answer

HIV

Answer

Measles virus

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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