Infectious Diseases Practice Questions

Q: All of the following statements regarding measles are true except?

Rash appears first on the leg. **Explanation:** The correct answer is **A (Rash appears first on the leg)** because it is a false statement. In Measles (Rubeola), the characteristic maculopapular rash follows a **cephalocaudal progression**. It typically appears first behind the ears and along the hairline, spreading downwards to the face, neck, trunk, and finally reaching the extremities (legs) by the third day. **Analysis of other options:** * **Option B:** **Koplik spots** are pathognomonic for measles. They are small, bluish-white grains on an erythematous base found on the buccal mucosa opposite the lower second molars during the pre-eruptive (prodromal) stage. * **Option C:** **SSPE** is a rare, progressive, and fatal demyelinating disease of the central nervous system that occurs 5–10 years after a primary measles infection due to the persistence of a mutant virus. * **Option D:** Measles is caused by an **RNA virus** belonging to the genus *Morbillivirus* of the family *Paramyxoviridae*. **High-Yield Clinical Pearls for NEET-PG:** * **Infectivity:** Highly contagious from 4 days before to 5 days after the appearance of the rash. * **Vitamin A:** Supplementation is recommended for all children with acute measles to reduce mortality and prevent blindness. * **Isolation:** Respiratory isolation is required; the virus is transmitted via droplet nuclei. * **Most common complication:** Otitis media. * **Most common cause of death:** Pneumonia (secondary bacterial infection).

Q: Which is a common complication of mumps in children?

Aseptic meningitis. **Explanation:** Mumps is an acute viral infection caused by the **Rubulavirus** (Paramyxoviridae family). While parotitis is the hallmark clinical feature, the virus is highly neurotropic, making involvement of the central nervous system (CNS) very common. **1. Why Aseptic Meningitis is correct:** Aseptic meningitis is the **most common extra-salivary complication** of mumps in children. It occurs in up to 10% of clinical cases, though CSF pleocytosis (increased white cells) is found in nearly 50% of patients even without meningeal symptoms. It is typically benign, characterized by headache, fever, and neck stiffness, and carries a much better prognosis than other viral meningitides. **2. Analysis of Incorrect Options:** * **B. Pancreatitis:** While a classic complication, it is less common than meningitis in the pediatric population. It presents with epigastric pain and elevated serum amylase (though amylase is also elevated in parotitis). * **C. Pneumonia:** This is not a standard complication of mumps. Respiratory involvement is more characteristic of Measles or RSV. * **D. Encephalitis:** Mumps encephalitis is a rare (1 in 6,000 cases) but severe complication. It involves parenchymal damage and carries a higher risk of permanent sequelae compared to the more common aseptic meningitis. **Clinical Pearls for NEET-PG:** * **Orchitis:** The most common complication in **post-pubertal males** (up to 30%), usually unilateral; rarely leads to absolute sterility. * **Oophoritis:** Occurs in ~7% of post-pubertal females. * **Deafness:** Mumps is a classic cause of sudden, usually unilateral, **sensorineural hearing loss**. * **Diagnosis:** Most commonly clinical; IgM ELISA is the gold standard for serology. * **Prevention:** Live attenuated vaccine (Jeryl Lynn strain) as part of MMR.

Q: What is the most common extracutaneous site of involvement in varicella infection?

Central Nervous System (CNS). **Explanation:** Varicella-Zoster Virus (VZV) is a highly neurotropic alpha-herpesvirus. While primary varicella (chickenpox) is characterized by a generalized pruritic vesicular rash, the **Central Nervous System (CNS)** is the most frequent site of extracutaneous involvement. The most common CNS manifestation in children is **acute cerebellar ataxia** (presenting with nystagmus and unsteady gait), whereas **encephalitis** is a more severe but rarer complication seen more frequently in adults. **Analysis of Options:** * **Central Nervous System (CNS) (Correct):** Due to the virus's inherent neurotropism, neurological complications (ataxia, encephalitis, or aseptic meningitis) occur more frequently than involvement of other organ systems. * **Lungs:** Varicella pneumonia is the most serious complication in adults and pregnant women, but it is statistically less common than CNS involvement across the general population. * **Liver:** While subclinical elevation of liver enzymes is common, clinically significant hepatitis is rare except in immunocompromised individuals. * **Heart:** Myocarditis is an extremely rare complication of VZV infection. **NEET-PG High-Yield Pearls:** * **Most common complication in children:** Secondary bacterial infection of skin lesions (usually *S. pyogenes* or *S. aureus*). * **Most common CNS complication in children:** Acute Cerebellar Ataxia (good prognosis). * **Most serious complication in adults:** Varicella Pneumonia. * **Tzanck Smear:** Shows multinucleated giant cells with Cowdry type A intranuclear inclusion bodies (common to VZV and HSV). * **Congenital Varicella Syndrome:** Characterized by cicatricial skin scarring, limb hypoplasia, and chorioretinitis if infection occurs in the first 20 weeks of gestation.

Q: Which of the following is NOT a manifestation of congenital rubella?

Rash appears first on the trunk. **Explanation:** The correct answer is **A (Rash appears first on the trunk)** because in Rubella (German Measles), the characteristic maculopapular rash typically **begins on the face** and spreads cephalocaudally (downward) to the trunk and extremities. A rash starting on the trunk is more characteristic of Roseola Infantum (Exanthem Subitum). **Analysis of Options:** * **Pre-auricular lymphadenopathy (B):** This is a hallmark clinical feature of Rubella. Tender lymphadenopathy involving the **post-auricular, suboccipital, and posterior cervical nodes** often precedes the rash by 5–10 days. * **Arthralgia (C):** Joint pain and arthritis are common manifestations, especially in adolescent girls and adult women infected with Rubella. It usually involves the small joints of the hands. * **Retinopathy (D):** "Salt and pepper" retinopathy is the most common ocular manifestation of **Congenital Rubella Syndrome (CRS)**. While it usually does not affect vision, it is a critical diagnostic clue. **High-Yield Clinical Pearls for NEET-PG:** * **Gregg’s Triad (CRS):** 1. Cataracts (or glaucoma), 2. Sensorineural hearing loss (most common), 3. Congenital heart disease (Patent Ductus Arteriosus is most common; Peripheral Pulmonary Artery Stenosis is also seen). * **Forchheimer spots:** Small, red petechiae on the soft palate seen during the prodromal phase. * **Blueberry Muffin Rash:** Seen in neonates with CRS due to extramedullary hematopoiesis. * **Timing:** The risk of fetal malformation is highest (up to 85%) if the mother is infected during the **first trimester** (especially the first 8 weeks).

Q: A 10-month-old unimmunized child presents with fever and a diffuse maculopapular rash on day 4 of illness. The rash starts on the face and spreads downwards. The child also has postauricular lymphadenopathy. What is the most likely diagnosis?

Measles. **Explanation:** The clinical presentation of a high-grade fever followed by a **maculopapular rash on day 4** that spreads **cephalocaudally** (face downwards) in an **unimmunized** child is classic for **Measles (Rubeola)**. In Measles, the rash typically appears 3–4 days after the onset of prodromal symptoms (cough, coryza, conjunctivitis) and coincides with the peak of the fever. **Why the other options are incorrect:** * **Rubella (German Measles):** While Rubella also features a cephalocaudal rash and postauricular lymphadenopathy, the rash typically appears on **day 1** of illness, and the systemic symptoms (fever) are much milder than in Measles. * **Varicella (Chickenpox):** The rash is **pleomorphic** (macules, papules, and vesicles present simultaneously) and follows a **centripetal** distribution (trunk to extremities), unlike the downward spread in this case. * **Roseola Infantum (Exanthema Subitum):** Characteristically, the fever is very high for 3–5 days and **subsides abruptly** just as the rash appears ("fever falls, rash appears"). The rash starts on the trunk, not the face. **High-Yield Clinical Pearls for NEET-PG:** * **Koplik Spots:** Pathognomonic for Measles; seen on the buccal mucosa opposite the lower second molars during the prodromal stage. * **Vitamin A:** Supplementation is mandatory in Measles management to reduce morbidity and mortality (specifically preventing blindness and pneumonia). * **Complications:** The most common complication is **Otitis Media**; the most common cause of death is **Pneumonia**; the most delayed complication is **SSPE** (Subacute Sclerosing Panencephalitis). * **Infectivity:** Maximum during the prodromal stage (4 days before to 5 days after the appearance of the rash).

Q: What is the most common viral disease affecting the parotid glands?

Mumps. **Explanation:** The correct answer is **Mumps**. Mumps is an acute viral infection caused by the **Rubulavirus** (a Paramyxovirus). Its hallmark clinical feature is **nonsuppurative parotitis** (swelling of the parotid glands), which occurs in approximately 95% of symptomatic cases. The virus has a specific tropism for glandular and nervous tissue. **Why the other options are incorrect:** * **Measles (Rubeola):** Caused by a Morbillivirus, it primarily presents with the triad of cough, coryza, and conjunctivitis, followed by Koplik spots and a maculopapular rash. It does not typically involve the salivary glands. * **Rubella (German Measles):** Characterized by retroauricular and suboccipital lymphadenopathy and a 3-day rash. While it involves lymph nodes, it does not cause parotid swelling. * **Varicella (Chickenpox):** Caused by the Varicella-Zoster virus, it presents with a centripetal, pleomorphic rash ("dewdrop on a rose petal"). It does not target the parotid glands. **High-Yield Clinical Pearls for NEET-PG:** * **Transmission:** Respiratory droplets; most infectious 48 hours before the onset of parotitis. * **Complications:** * **Orchitis:** Most common complication in post-pubertal males (usually unilateral; rarely leads to sterility). * **Aseptic Meningitis:** Most common neurological complication. * **Pancreatitis:** A classic association to remember for exams. * **Oophoritis:** Seen in 5% of post-pubertal females. * **Prevention:** Live attenuated vaccine (Jeryl Lynn strain is most common) administered as part of the MMR vaccine.

Q: A previously healthy child develops bacterial meningitis. Assuming no specific contraindications, which of the following is the drug of choice?

Ceftriaxone. **Explanation:** The primary goal in treating bacterial meningitis is the rapid administration of bactericidal antibiotics that achieve high concentrations in the cerebrospinal fluid (CSF). **Why Ceftriaxone is the Correct Answer:** Ceftriaxone (a 3rd-generation cephalosporin) is the drug of choice for empirical treatment of bacterial meningitis in children. It covers the most common pathogens—*Streptococcus pneumoniae* and *Neisseria meningitidis*. Its advantages include excellent CSF penetration, a long half-life (allowing once or twice daily dosing), and high efficacy against penicillin-resistant strains of *S. pneumoniae*. **Why the Other Options are Incorrect:** * **Erythromycin:** This is a macrolide that is primarily bacteriostatic and has very poor penetration into the blood-brain barrier (BBB), making it ineffective for CNS infections. * **Penicillin V:** This is an oral penicillin with low bioavailability and poor CSF penetration; it is never used for meningitis. * **Penicillin G:** While historically used for meningococcal meningitis, increasing resistance in *S. pneumoniae* and the requirement for very frequent dosing make it a second-line agent compared to Ceftriaxone. **High-Yield Clinical Pearls for NEET-PG:** * **Empirical Therapy:** In children >1 month, the standard regimen is **Ceftriaxone + Vancomycin** (to cover highly resistant *S. pneumoniae*). * **Neonatal Meningitis (<1 month):** The common organisms are *GBS, E. coli,* and *Listeria*. The drug of choice is **Ampicillin + Cefotaxime** (or Gentamicin). * **Avoid Ceftriaxone in Neonates:** It can displace bilirubin from albumin, increasing the risk of **kernicterus**, and can precipitate with intravenous calcium. * **Steroids:** Dexamethasone should be given *before* or with the first dose of antibiotics to reduce the risk of hearing loss, especially in *H. influenzae* type b meningitis.

Q: A 3-year-old child presents with fever, malaise, and oral ulcers, making swallowing difficult. What is the most likely diagnosis?

Acute herpetic gingivostomatitis. ### Explanation **Correct Answer: C. Acute herpetic gingivostomatitis** **1. Why it is correct:** Acute herpetic gingivostomatitis is the most common clinical manifestation of **primary Herpes Simplex Virus Type 1 (HSV-1)** infection in children, typically occurring between ages 6 months and 5 years. The clinical triad of **high-grade fever, malaise, and painful oral ulcers** (often involving the gingiva, tongue, and buccal mucosa) is classic. The pain is often severe enough to cause drooling and refusal to swallow, leading to dehydration—a common reason for hospitalization in this age group. **2. Why the other options are incorrect:** * **Aphthous stomatitis:** These are "canker sores." While painful, they are typically **not associated with systemic symptoms** like high fever or malaise. They are usually solitary or few in number and do not involve the diffuse gingival edema seen in primary herpes. * **Herpes labialis:** This represents **reactivation** (secondary infection) of HSV-1. It is characterized by localized "cold sores" or vesicular lesions on the vermilion border of the lips. It lacks the diffuse intraoral involvement and severe systemic toxicity seen in primary gingivostomatitis. **3. NEET-PG High-Yield Pearls:** * **Etiology:** HSV-1 is the most common cause; HSV-2 is rare in the oral cavity. * **Diagnosis:** Primarily clinical. If testing is required, **Tzanck smear** shows multinucleated giant cells and Cowdry type A inclusion bodies. * **Treatment:** Supportive (hydration/analgesia). Oral **Acyclovir** is effective if started within 72 hours of onset. * **Differential:** Hand-Foot-Mouth Disease (Coxsackie A16) also presents with oral ulcers but is distinguished by the presence of vesicular rashes on the palms and soles.

Q: Which of the following is TRUE about measles, EXCEPT?

It is not infective before the rash appears.. **Explanation:** The correct answer is **D**, as the statement is false. Measles is highly contagious and is infective **4 days before to 4 days after** the appearance of the rash. The period of maximum infectivity occurs during the prodromal stage (catarrhal stage) due to high viral shedding in respiratory secretions through coughing and sneezing. **Analysis of other options:** * **Option A:** **Koplik spots** are pathognomonic for measles. They appear on the buccal mucosa opposite the lower second molars during the **prodromal stage**, usually 1–2 days before the rash, and disappear shortly after the rash starts. * **Option B:** In measles, the fever typically **increases (spikes)** with the onset of the rash and then gradually subsides. This is a distinguishing feature from Roseola Infantum, where the fever drops *before* the rash appears. * **Option C:** Under the National Immunization Schedule (NIS) in India, the first dose of the Measles-Rubella (MR) vaccine is administered at **9 completed months** (up to 12 months) to avoid interference from maternal antibodies. **High-Yield Clinical Pearls for NEET-PG:** * **Agent:** RNA Paramyxovirus (Genus *Morbillivirus*). * **Rash Pattern:** Maculopapular, starts behind the ears (retro-auricular), spreads cephalocaudally, and disappears with **brownish discoloration/desquamation**. * **Vitamin A:** Supplementation is mandatory in all children with measles to prevent complications like blindness and reduce mortality. * **Complications:** Most common is **Otitis Media**; most common cause of death is **Pneumonia**; most serious late complication is **SSPE** (Subacute Sclerosing Panencephalitis).

Q: What is the most common complication of mumps?

Orchitis and oophoritis. **Explanation:** Mumps is an acute viral infection caused by the **Rubulavirus** (Paramyxoviridae family), primarily characterized by the painful swelling of the parotid glands. **Why Orchitis and Oophoritis are correct:** Epididymo-orchitis is the **most common extra-salivary complication** of mumps in post-pubertal males, occurring in approximately 20-30% of cases. It is usually unilateral and can lead to testicular atrophy, though permanent sterility is rare. Oophoritis (inflammation of the ovaries) occurs in about 5% of post-pubertal females. The virus has a predilection for glandular tissue and the central nervous system. **Analysis of Incorrect Options:** * **B. Encephalitis:** While CNS involvement is common (often presenting as asymptomatic pleocytosis or viral meningitis), true encephalitis is a rare but severe complication (<1% of cases). * **C. Pneumonia:** Unlike other paramyxoviruses like Measles or RSV, mumps rarely involves the lower respiratory tract. * **D. Myocarditis:** This is an extremely rare complication of mumps, usually presenting with transient ECG changes rather than clinical heart failure. **High-Yield Clinical Pearls for NEET-PG:** * **Most common complication in children:** Aseptic meningitis. * **Most common cause of acute pancreatitis in children:** Mumps virus. * **Neurological sequelae:** Mumps is a classic cause of **sudden onset sensorineural deafness** (usually unilateral). * **Diagnosis:** Elevated **Serum Amylase** is a key biochemical marker due to parotid and pancreatic involvement. * **Prevention:** Live attenuated vaccine (Jeryl Lynn strain) as part of the MMR vaccine.

Question 1

All of the following statements regarding measles are true except?

Accepted Answer

Rash appears first on the leg

Answer

Koplik spots are seen on the buccal mucosa

Answer

Long-term complications may be seen in the form of Subacute Sclerosing Panencephalitis (SSPE)

Answer

Caused by an RNA virus

Question 2

Which is a common complication of mumps in children?

Accepted Answer

Aseptic meningitis

Answer

Pancreatitis

Answer

Pneumonia

Answer

Encephalitis

Question 3

What is the most common extracutaneous site of involvement in varicella infection?

Accepted Answer

Central Nervous System (CNS)

Answer

Heart

Answer

Lungs

Answer

Liver

Question 4

Which of the following is NOT a manifestation of congenital rubella?

Accepted Answer

Rash appears first on the trunk

Answer

Pre-auricular lymphadenopathy

Answer

Arthralgia

Answer

Retinopathy

Question 5

A 10-month-old unimmunized child presents with fever and a diffuse maculopapular rash on day 4 of illness. The rash starts on the face and spreads downwards. The child also has postauricular lymphadenopathy. What is the most likely diagnosis?

Accepted Answer

Measles

Answer

Rubella

Answer

Varicella

Answer

Roseola infantum

Question 6

What is the most common viral disease affecting the parotid glands?

Accepted Answer

Mumps

Answer

Measles

Answer

Rubella

Answer

Varicella

Question 7

A previously healthy child develops bacterial meningitis. Assuming no specific contraindications, which of the following is the drug of choice?

Accepted Answer

Ceftriaxone

Answer

Erythromycin

Answer

Penicillin V

Answer

Penicillin G

Question 8

A 3-year-old child presents with fever, malaise, and oral ulcers, making swallowing difficult. What is the most likely diagnosis?

Accepted Answer

Acute herpetic gingivostomatitis

Answer

Aphthous stomatitis

Answer

Herpes labialis

Answer

None of the above

Question 9

Which of the following is TRUE about measles, EXCEPT?

Accepted Answer

It is not infective before the rash appears.

Answer

Koplik spots appear in the prodromal stage.

Answer

Fever stops after the onset of the rash.

Answer

The vaccine is given at 9 months of age.

Question 10

What is the most common complication of mumps?

Accepted Answer

Orchitis and oophoritis

Answer

Encephalitis

Answer

Pneumonia

Answer

Myocarditis

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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