Infectious Diseases Practice Questions

Q: At what age is the MMR vaccination typically given?

18 months. **Explanation:** In the context of the National Immunization Schedule (NIS) in India, the **MMR (Measles, Mumps, Rubella)** vaccine is typically administered as a booster dose at **18 months** (specifically between 16–24 months). Under the current Universal Immunization Programme (UIP), the **MR (Measles-Rubella)** vaccine has replaced the standalone Measles vaccine, given as a first dose at 9 months and a second dose at 16–24 months. However, in private practice (IAP guidelines), the MMR vaccine is the standard. **Analysis of Options:** * **A. Birth:** Vaccines given at birth include BCG, OPV-0, and Hepatitis B. Live viral vaccines like MMR are not given at birth due to the presence of maternal antibodies which neutralize the vaccine virus. * **B. 6 months:** No MMR/MR vaccine is scheduled here. The earliest a Measles-containing vaccine is given is 6 months *only* during outbreaks (known as the "zero dose"), which does not count toward the primary series. * **C. 1 year:** While some international schedules start MMR at 12 months, the Indian NIS/IAP focus is on the 9-month and 16–24 month windows. * **D. 18 months (Correct):** This aligns with the second dose/booster recommendation in India to ensure long-term immunity and cover primary vaccine failures from the first dose. **High-Yield Clinical Pearls for NEET-PG:** * **Route:** MMR is administered **Subcutaneously (SC)**. * **Adverse Effect:** The most common side effect is a transient fever and rash occurring 7–10 days after vaccination. * **Contraindication:** It is a live vaccine; hence, it is contraindicated in **pregnancy** and **severely immunocompromised** patients. However, it *can* be given to asymptomatic HIV-infected children. * **Vitamin A:** Always remember that Vitamin A supplementation is co-administered with Measles-containing vaccines in the NIS to reduce complications.

Q: What is the most common cause of neonatal meningitis?

E. coli. **Explanation:** Neonatal meningitis (occurring within the first 28 days of life) is primarily caused by pathogens colonizing the maternal birth canal. Globally, the most common causative organisms are **Group B Streptococcus (GBS)** and **Escherichia coli (E. coli)**. In the context of the Indian subcontinent and many NEET-PG clinical scenarios, **Gram-negative bacilli**, specifically **E. coli**, are frequently cited as the leading cause of neonatal meningitis and sepsis. E. coli possesses the **K1 capsular antigen**, which allows it to evade host immune responses and cross the blood-brain barrier effectively. **Analysis of Options:** * **B. E. coli (Correct):** It is the most common Gram-negative cause and a leading cause overall in the neonatal period. * **A. Staphylococcus:** While *S. aureus* or *Coagulase-negative Staphylococci (CONS)* can cause late-onset sepsis in NICU settings (especially with indwelling catheters), they are not the most common cause of primary meningitis. * **C. H. influenzae:** This was a leading cause in children aged 3 months to 5 years but has significantly declined due to the Hib vaccine. It is rare in the neonatal period. * **D. Pneumococcus (*S. pneumoniae*):** This is the most common cause of bacterial meningitis in infants **older than 3 months**, children, and adults, but not in neonates. **High-Yield Pearls for NEET-PG:** 1. **Age-wise Etiology:** * 0–28 days: GBS, E. coli, Listeria. * 3 months–5 years: *S. pneumoniae*, *N. meningitidis*. 2. **Listeria monocytogenes:** A notable cause of neonatal meningitis associated with maternal consumption of unpasteurized milk/cheese; it is inherently resistant to cephalosporins (requires Ampicillin). 3. **Clinical Presentation:** Neonatal meningitis often presents with non-specific signs like bulging fontanelle, temperature instability, refusal to feed, or seizures. 4. **CSF Findings:** High protein, low glucose, and pleocytosis (increased WBCs).

Q: A mother brings her 9-month-old baby, concerned that no BCG scar has appeared, although the baby received the BCG vaccine at birth. What is the next best step?

Reassure the mother. ***Reassure the mother*** - The absence of a characteristic **BCG scar** up to 9 months later is common and does not indicate **vaccination failure** if the vaccine was properly administered and documented. - Standard vaccination protocols generally recommend **no re-vaccination** or immediate investigation solely based on the lack of a scar in an otherwise healthy infant. *Give the BCG vaccine immediately* - **Re-vaccination** without evidence of non-conversion (which is not routinely assessed) is not standard practice and carries the risk of increased **local adverse reactions**. - Current public health policies consider a single documented BCG dose adequate protection, regardless of the subsequent **cutaneous reaction**. *Do the Mantoux test & wait for the result* - The **Mantoux test (TST)** is not recommended solely for assessing BCG efficacy or scar absence in asymptomatic children due to difficulties in defining a protective threshold. - Finding a negative TST result does not currently mandate **re-vaccination**, as international guidelines prioritize coverage reliability over scar/TST status. *Refer the baby for a chest X-ray & further evaluation* - Extensive investigations, including a **chest X-ray**, are reserved for children presenting with signs or symptoms highly suggestive of **active tuberculosis disease**. - Performing aggressive workups on an asymptomatic child solely for an absent scar constitutes an excessive response and is not supported by clinical guidelines.

Q: A 5-year-old girl is brought to the clinic with a fever, cough, red eyes, running nose, and rash. The appearance of the child is shown below. What is the diagnosis? ![img-36.jpeg](img-36.jpeg)

Measles. ***Measles*** - The clinical presentation of fever with the classic triad of **cough, coryza, and conjunctivitis** (the "3 Cs") is highly suggestive of measles (rubeola). - The image shows **Koplik's spots** (small white spots on the buccal mucosa), which are pathognomonic for measles and appear before the characteristic maculopapular rash. *Mumps* - Mumps is primarily characterized by **parotitis**, a painful swelling of the salivary glands, which is not described in this patient. - The classic prodrome of the "3 Cs" and Koplik's spots are absent in mumps. *Chickenpox* - The rash in chickenpox (varicella) is **vesicular**, often described as a "dewdrop on a rose petal," and appears in crops. This is different from the maculopapular rash of measles. - While a fever and malaise can occur, the prominent upper respiratory symptoms and conjunctivitis of measles are not typical of chickenpox. *Erythema infectiosum* - Caused by **Parvovirus B19**, this condition is characterized by a distinctive "**slapped-cheek**" rash on the face. - It is followed by a **lacy, reticular rash** on the trunk and extremities, which is inconsistent with the patient's presentation.

Q: An 8-year-old child presented with a sudden onset of high-grade fever, seizures, and loss of consciousness. On examination, the child had anemia, hypoglycemia, and no focal neurological deficits. What is the probable diagnosis?

Cerebral malaria. ***Cerebral malaria***- This diagnosis is strongly suggested by the sudden onset of high-grade fever, seizures, and loss of consciousness in a child, coupled with systemic complications like **anemia** and significant **hypoglycemia**.- Cerebral malaria, caused by *Plasmodium falciparum*, is a medical emergency where **hypoglycemia** results from high glucose consumption by parasites and impaired hepatic gluconeogenesis; **anemia** is also a key feature. *Tubercular meningitis*- Tuberculous meningitis typically presents with an **insidious, subacute onset** (over weeks) of fever, headache, and altered sensorium, not the sudden, explosive presentation described.- While it can cause neurological deficits, it is less commonly associated with the acute, severe systemic triad of high fever, profound **hypoglycemia**, and **anemia** seen here.*Viral meningitis*- Viral meningitis is usually associated with a milder clinical course and typically lacks the profound systemic complications like severe **anemia** and significant **hypoglycemia** that often precipitate seizures and coma in this age group.- Though high fever and seizures can occur, the presence of severe systemic features points away from typical viral etiologies and towards a systemic parasitic infection.*Fungal meningitis*- Fungal meningitis (e.g., *Cryptococcus*) is typically an **indolent or chronic infection** developing over weeks to months, primarily affecting **immunocompromised patients** (e.g., HIV/AIDS), which is unlikely in an otherwise healthy 8-year-old.- It rarely presents as an acute febrile illness with subsequent rapid onset of **anemia** and severe **hypoglycemia** leading to loss of consciousness.

Q: A 7-year-old child with a history of ear infection is complaining of lockjaw and limb spasm/fever/neck rigidity. Choose the most appropriate diagnosis:

Tetanus. ***Tetanus*** - The striking combination of **lockjaw (trismus)** and generalized **limb spasms** is the hallmark clinical presentation of **Tetanus**, caused by the neurotoxin from *Clostridium tetani*. - The presence of **fever** and **neck rigidity** alongside an antecedent **ear infection** (potential portal of entry) strongly supports this diagnosis. - Tetanus causes sustained muscle contractions due to the inhibition of inhibitory neurons, leading to characteristic trismus, risus sardonicus, and opisthotonus. - Note: This is distinct from metabolic **tetany** (hypocalcemia), which causes carpopedal spasm without fever or lockjaw. *Incorrect: Meningitis* - While meningitis causes **fever** and **neck rigidity** (nuchal rigidity), it does not typically present with severe **lockjaw (trismus)** or sustained generalized **muscle spasms**. - Meningitis usually presents with headache, photophobia, altered consciousness, and positive Kernig's/Brudzinski's signs. *Incorrect: Bezold abscess* - A Bezold abscess is a deep neck abscess complicating mastoiditis, causing localized symptoms like neck pain, swelling, and **torticollis** (fixed head tilt). - It does not cause neuromuscular hyperexcitability resulting in **lockjaw** and widespread **limb spasms**. *Incorrect: Sinus thrombosis* - Lateral sinus thrombosis is a complication of otitis media presenting with **picket-fence fever**, headache, and signs of raised intracranial pressure. - It does not cause the characteristic muscle spasms and lockjaw seen in this presentation.

Q: An HIV-positive mother with a viral load of 1200 copies/mL delivers a baby. What is the most appropriate antiretroviral prophylaxis for the newborn?

Nevirapine + Zidovudine for 6 weeks. ***Nevirapine + Zidovudine for 6 weeks*** - This combination is the recommended regimen for **high-risk newborns** in resource-limited settings, defined by a maternal viral load (MVL) greater than 1000 copies/mL or if maternal treatment was **suboptimal/absent**. - The dual prophylaxis provides comprehensive coverage to minimize the risk of **mother-to-child transmission (MTCT)**, which is elevated due to the high viral load (1200 copies/mL). *Nevirapine for 6 weeks* - **Nevirapine monotherapy** is reserved for **low-risk newborns** (MVL < 1000 copies/mL) or when the mother received adequate **antiretroviral therapy (ART)**. - Given the MVL of 1200 copies/mL, the risk is high, making dual therapy necessary. *Nevirapine for 12 weeks* - Extended NVP prophylaxis (12 weeks) is sometimes used if the infant is **breastfed and at high risk**, but current standard guidelines for non-breastfed infants with this MVL recommend 6 weeks of dual therapy. - **Duration of 12 weeks** is typically not the initial prophylaxis choice for a non-breastfed infant born to a mother with a high viral load. *Zidovudine for 4 weeks* - **Zidovudine monotherapy** for 4 weeks is considered inadequate given the mother's high viral load of **1200 copies/mL**. - This regimen (4 weeks of ZDV) is primarily reserved for **low-risk newborns** in settings where dual therapy is not feasible, or for term infants born to mothers with **fully suppressed viral loads** who received continuous ART.

Q: A 6-week-old child with tuberous sclerosis, and on vigabatrin has been brought for vaccination. Which of the following vaccine should be given?

A. ***Correct Option A (DTaP/Pentavalent Vaccine)*** - At **6 weeks of age**, the child is due for the first dose of **DPT (Diphtheria, Pertussis, Tetanus)** or Pentavalent vaccine as per the Indian National Immunization Schedule - **Tuberous sclerosis is NOT an immunocompromising condition** and does not contraindicate any routine vaccines - **Vigabatrin is NOT immunosuppressive** - it is an antiepileptic drug used specifically for infantile spasms in tuberous sclerosis and does not affect vaccine response or safety - All routine vaccines including inactivated and live vaccines can be safely administered to children with tuberous sclerosis on vigabatrin *Incorrect Option B (BCG Vaccine)* - BCG vaccine is administered **at birth** (or as early as possible in the neonatal period), not at 6 weeks of age - By 6 weeks, the child should have already received BCG - Even if BCG was delayed, tuberous sclerosis and vigabatrin are NOT contraindications for BCG vaccination - The misconception that these children are immunocompromised is incorrect *Incorrect Option C (Varicella/Live Vaccine)* - Varicella vaccine is not part of the routine immunization schedule at 6 weeks in India - It is typically given at 15 months of age or later - Even though it is a live vaccine, it would NOT be contraindicated in this child as tuberous sclerosis and vigabatrin do not cause immunosuppression *Incorrect Option D (Other Vaccine Formulation)* - This does not represent the standard vaccine indicated at 6 weeks of age - At 6 weeks, the priority is to administer the first dose of DPT/Pentavalent vaccine along with OPV/IPV, Hepatitis B, Hib, Rotavirus, and PCV as per the immunization schedule

Q: A child presents with the ocular findings shown in the image below. Identify the most likely underlying illness:

Pertussis. ***Pertussis (Whooping Cough)*** - The image shows **subconjunctival hemorrhage**, which is a **classic complication** of pertussis in children - Pertussis causes severe **paroxysmal coughing fits** that dramatically increase intrathoracic and intravascular pressure - This elevated pressure leads to rupture of conjunctival blood vessels, resulting in subconjunctival hemorrhages and facial petechiae - These hemorrhages are well-recognized **diagnostic clues** for pertussis, especially when accompanied by the characteristic whooping cough - This is a **primary manifestation** of the disease process, not merely an incidental finding *Trachoma* - Trachoma, caused by *Chlamydia trachomatis*, presents with **chronic follicular conjunctivitis** and progressive scarring - Classic features include follicles on upper tarsal conjunctiva, conjunctival scarring, trichiasis, and pannus formation - While it causes conjunctival inflammation, **acute subconjunctival hemorrhage is NOT a typical feature** of trachoma - Trachoma is a chronic, scarring disease rather than an acute hemorrhagic condition *Tetanus* - Tetanus is a neurological disorder characterized by **muscle rigidity** and **spasms**, beginning with trismus (lockjaw) - Ocular manifestations are limited to **risus sardonicus** (facial muscle spasm) and potential ophthalmoplegia - Does NOT cause subconjunctival hemorrhage as a direct manifestation *Measles* - Measles presents with **maculopapular rash**, fever, the three C's (cough, coryza, conjunctivitis), and **Koplik spots** - The conjunctivitis in measles is typically a **bilateral, non-hemorrhagic inflammation** with watery discharge - Does NOT typically cause prominent subconjunctival hemorrhage as shown in the image

Question 1

At what age is the MMR vaccination typically given?

Accepted Answer

18 months

Answer

Birth

Answer

6 months

Answer

1 year

Question 2

What is the most common cause of neonatal meningitis?

Accepted Answer

E. coli

Answer

Staphylococcus

Answer

H. influenzae

Answer

Pneumococcus

Question 3

A mother brings her 9-month-old baby, concerned that no BCG scar has appeared, although the baby received the BCG vaccine at birth. What is the next best step?

Accepted Answer

Reassure the mother

Answer

Do the Mantoux test & wait for the result

Answer

Refer the baby for a chest X-ray & further evaluation

Answer

Give the BCG vaccine immediately

Question 4

An unvaccinated 5-year-old child of a migrant worker family was brought to the casualty with fever and a characteristic skin rash. Upon eye examination, Bitot's spot was seen. What is the appropriate management?

Accepted Answer

Isolate and give nutritional supply with vitamin A supplement

Answer

Only measles vaccine

Answer

Institutional Isolation, nutritional management with vitamin A supplement

Answer

Give measles vaccine and vitamin A supplement

Question 5

A 5-year-old girl is brought to the clinic with a fever, cough, red eyes, running nose, and rash. The appearance of the child is shown below. What is the diagnosis? ![img-36.jpeg](img-36.jpeg)

Accepted Answer

Measles

Answer

Chickenpox

Answer

Mumps

Answer

Erythema infectiosum

Question 6

An 8-year-old child presented with a sudden onset of high-grade fever, seizures, and loss of consciousness. On examination, the child had anemia, hypoglycemia, and no focal neurological deficits. What is the probable diagnosis?

Accepted Answer

Cerebral malaria

Answer

Tubercular meningitis

Answer

Viral meningitis

Answer

Fungal meningitis

Question 7

A 7-year-old child with a history of ear infection is complaining of lockjaw and limb spasm/fever/neck rigidity. Choose the most appropriate diagnosis:

Accepted Answer

Tetanus

Answer

Meningitis

Answer

Bezold abscess

Answer

Sinus thrombosis

Question 8

An HIV-positive mother with a viral load of 1200 copies/mL delivers a baby. What is the most appropriate antiretroviral prophylaxis for the newborn?

Accepted Answer

Nevirapine + Zidovudine for 6 weeks

Answer

Zidovudine for 4 weeks

Answer

Nevirapine for 6 weeks

Answer

Nevirapine for 12 weeks

Question 9

A 6-week-old child with tuberous sclerosis, and on vigabatrin has been brought for vaccination. Which of the following vaccine should be given?

Accepted Answer

A

Answer

B

Answer

C

Answer

D

Question 10

A child presents with the ocular findings shown in the image below. Identify the most likely underlying illness:

Accepted Answer

Pertussis

Answer

Tetanus

Answer

Measles

Answer

Trachoma

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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