Infectious Diseases Practice Questions

Q: Which of the following is the most common late toxic manifestation of diphtheria in a child?

Polyneuritis. ***Polyneuritis*** - **Polyneuritis** is the **most common late toxic manifestation** of diphtheria, typically appearing **2-6 weeks or more** after the onset of infection. - It results from the **diphtheria toxin's neurotoxic effects**, causing demyelination of peripheral nerves. - Clinical features include **cranial nerve palsies** (especially palatal and pharyngeal weakness), **limb weakness**, and **areflexia**. - It can persist for weeks to months and is the characteristic delayed complication. *Renal failure* - While diphtheria toxin can cause **acute tubular necrosis**, renal failure is **uncommon** and not a primary late toxic manifestation. - When kidney injury occurs, it is typically mild and occurs earlier in the acute phase rather than as a delayed complication. *Myocarditis* - **Myocarditis** is a serious complication of diphtheria occurring in **10-25% of cases**, typically appearing in **weeks 2-6**. - While it overlaps with the timing of late manifestations, it generally presents **earlier in that window** (often weeks 2-3) compared to polyneuritis. - It is a **major cause of mortality** in diphtheria, but **polyneuritis is more common as a late manifestation** presenting after week 3-4. - Clinical features include arrhythmias, heart failure, and conduction defects. *Septicemia* - **Septicemia** is not a direct toxic manifestation of *Corynebacterium diphtheriae*. - Diphtheria causes disease primarily through **localized infection and systemic toxin effects**, not through bloodstream invasion. - Secondary bacterial superinfection is possible but is not a characteristic manifestation of diphtheria toxicity.

Q: Oophoritis, Orchitis, Chipmunk cheeks seen in:

Mumps.. ***Mumps*** - **Mumps** is a viral infection that commonly presents with **bilateral parotid gland swelling**, leading to the characteristic "chipmunk cheeks" appearance. - It can also cause complications such as **oophoritis** (inflammation of the ovaries) in females and **orchitis** (inflammation of the testes) in males, which are key features seen in this clinical description. *Sialadenosis* - **Sialadenosis** refers to a non-inflammatory, non-neoplastic enlargement of the salivary glands, often the parotid glands. - While it can cause swollen glands, it is typically associated with systemic conditions like **diabetes** or **alcoholism** and does not cause oophoritis or orchitis. *Mucocele* - A **mucocele** is a common lesion of the oral mucosa that results from either rupture of a salivary gland duct and spillage of mucin into the surrounding soft tissues (extravasation type) or obstruction of a salivary gland duct (retention type). - It usually presents as a benign, fluid-filled swelling, most commonly on the **lower lip**, and is not associated with systemic inflammation or widespread glandular involvement. *Sialadenitis* - **Sialadenitis** is an inflammation of a salivary gland, often due to bacterial infection or duct obstruction (e.g., by salivary stones). - While it can cause painful swelling of the salivary glands, it typically affects only one gland and does not lead to complications like oophoritis or orchitis.

Q: If a mother has had measles, her newborn baby is immune to this disease for -

4 to 6 months. ***Correct: 4 to 6 months*** - Maternal antibodies, primarily **IgG**, are transferred across the placenta to the fetus, providing **passive immunity** to measles - This passive immunity typically lasts for a limited period, usually around **4 to 6 months**, as the maternal antibodies gradually degrade - This is why measles vaccination is typically scheduled at 9-12 months of age in most immunization protocols *Incorrect: 1 to 3 years* - A duration of 1 to 3 years is **too long** for maternally acquired passive immunity to last against measles - After the maternal antibody protection wanes, the child's own active immune system needs to develop through vaccination or natural exposure *Incorrect: 3 to 6 years* - This timeframe represents a significant **overestimation** of the longevity of maternally transferred measles antibodies - Long-term immunity beyond infancy is achieved through the infant's own immune response via vaccination, not passive transfer *Incorrect: 6 to 12 months* - While some infants may retain detectable maternal antibodies up to 9-12 months, the **most significant protective period** is generally 4-6 months - The efficacy of protection significantly wanes after the 6-month mark, making the infant increasingly vulnerable to measles infection

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: Raspberry tongue is a feature of

Scarlet fever. ***Scarlet fever*** - **Raspberry (or strawberry) tongue** is a classic sign of **scarlet fever**, characterized by an initial white coating that peels, revealing red, swollen papillae [1]. - This symptom is caused by the **erythrogenic toxins** produced by Group A Streptococcus bacteria, which are responsible for scarlet fever [1]. *Yellow fever* - Yellow fever is a **viral hemorrhagic disease** transmitted by mosquitoes, typically presenting with fever, muscle aches, and **jaundice**. - It does not present with characteristic tongue changes like a **raspberry tongue**. *Mamba's disease* - **Mamba's disease** is not a recognized medical condition; it does not exist in standard medical literature. - This option is a distractor, as such it is not associated with any specific clinical features, including tongue changes. *Katayama fever* - Katayama fever is an **acute manifestation of schistosomiasis** (snail fever) occurring shortly after exposure to contaminated water. - Symptoms usually include high fever, cough, hepatosplenomegaly, and eosinophilia, but **not a raspberry tongue**.

Question 1

Which of the following is the most common late toxic manifestation of diphtheria in a child?

Accepted Answer

Polyneuritis

Answer

Renal failure

Answer

Myocarditis

Answer

Septicemia

Question 2

Oophoritis, Orchitis, Chipmunk cheeks seen in:

Accepted Answer

Mumps.

Answer

Sialadenosis.

Answer

Mucocele.

Answer

Sialadenitis.

Question 3

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 4

If a mother has had measles, her newborn baby is immune to this disease for -

Accepted Answer

4 to 6 months

Answer

1 to 3 years

Answer

3 to 6 years

Answer

6 to 12 months

Question 5

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 6

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 7

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 8

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 9

Which of the following is Not characteristic of congenital Syphilis?

Accepted Answer

Ghon complex

Answer

Interstitial keratitis

Answer

Mulberry molars

Answer

Notched incisors

Question 10

Raspberry tongue is a feature of

Accepted Answer

Scarlet fever

Answer

Yellow fever

Answer

Mamba's disease

Answer

Katayama fever

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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