Infectious Diseases Practice Questions

Q: A 7-month-old child presents with microcephaly. What is the most likely etiology for this clinical presentation?

Cytomegalovirus (CMV). **Explanation:** **Microcephaly** is a hallmark clinical feature of certain congenital infections, most notably **Cytomegalovirus (CMV)**. 1. **Why CMV is the correct answer:** CMV is the most common congenital infection worldwide. It characteristically causes central nervous system (CNS) insults during fetal development, leading to impaired brain growth and subsequent **microcephaly**. A high-yield diagnostic feature of CMV is **periventricular calcifications**, which helps differentiate it from other TORCH infections. 2. **Analysis of Incorrect Options:** * **Toxoplasma:** While congenital Toxoplasmosis affects the CNS, it more commonly presents with **macrocephaly** (due to obstructive hydrocephalus) and **diffuse intracerebral calcifications** (scattered throughout the parenchyma, not just periventricular). * **Rubella:** Congenital Rubella Syndrome (CRS) can cause microcephaly, but its "classic triad" consists of **cataracts, sensorineural hearing loss, and congenital heart disease** (PDA). CMV is statistically a more frequent cause of isolated microcephaly in clinical vignettes unless the triad is mentioned. * **Mumps:** Mumps is not a classic member of the TORCH group and is not typically associated with congenital malformations or microcephaly. **High-Yield Clinical Pearls for NEET-PG:** * **CMV:** Most common cause of non-syndromic sensorineural hearing loss (SNHL). Look for **periventricular calcifications**. * **Toxoplasmosis:** Look for the triad of **Chorioretinitis, Hydrocephalus, and Intracranial calcifications**. * **Zika Virus:** Currently the most "potent" viral cause of extreme microcephaly and fetal brain disruption sequence. * **Microcephaly Definition:** Head circumference < 3 Standard Deviations (SD) below the mean for age and sex.

Q: What is the correct indication for prophylaxis with varicella-zoster immunoglobulin in chicken-pox?

Given to a newborn contact. **Explanation:** The primary goal of **Varicella-Zoster Immunoglobulin (VZIG)** is to provide passive immunity to high-risk individuals who have been exposed to the virus but cannot mount an effective immune response or are at risk of severe complications. **Why Option B is Correct:** Neonates are at high risk for **Neonatal Varicella**, a potentially fatal condition. VZIG is specifically indicated for newborns if the mother develops chickenpox within **5 days before to 2 days after delivery**. In this window, the mother develops viremia but hasn't had enough time to transfer protective IgG antibodies to the fetus, leaving the newborn vulnerable. **Analysis of Incorrect Options:** * **Option A:** While VZIG should be given as soon as possible, the window for administration is up to **96 hours (4 days)** post-exposure (some guidelines extend this to 10 days), not strictly limited to 24 hours. * **Option C:** VZIG and the Varicella vaccine should **not** be given concurrently. Passive antibodies in VZIG can interfere with the replication of the live-attenuated virus in the vaccine, rendering it ineffective. If both are needed, they must be spaced apart. * **Option D:** VZIG is for **prophylaxis**, not treatment. Once the disease is established (rash appears), VZIG is ineffective; antiviral therapy (Acyclovir) is the treatment of choice for severe cases. **High-Yield Clinical Pearls for NEET-PG:** * **Indications for VZIG:** Immunocompromised individuals, pregnant women without immunity, and specific neonates (as described above). * **Post-exposure Prophylaxis (PEP):** In healthy susceptible children >12 months, the **Varicella Vaccine** is the preferred PEP if given within 3–5 days of exposure. * **Congenital Varicella Syndrome:** Occurs if the mother is infected in the first 20 weeks of pregnancy (presents with cicatricial skin scars, limb hypoplasia, and microcephaly).

Q: Papulovesicular oral lesions are seen in which condition?

Herpangina. **Explanation:** The correct answer is **Herpangina**. This condition is primarily caused by **Coxsackievirus A** (and occasionally Coxsackievirus B or Echoviruses). It is characterized by the sudden onset of fever, sore throat, and the pathognomonic finding of small **papulovesicular lesions** (1–2 mm) that rapidly ulcerate. These lesions are specifically localized to the **posterior oropharynx**, including the anterior tonsillar pillars, soft palate, and uvula. **Analysis of Options:** * **Measles (Rubeola):** Characterized by **Koplik spots**, which are bluish-white specks on an erythematous base found on the buccal mucosa opposite the lower molars. They are macules, not vesicles. * **Rubella (German Measles):** Associated with **Forchheimer spots**, which are small, red petechiae on the soft palate. These are vascular changes, not vesicular lesions. * **Hand, Foot, and Mouth Disease (HFMD):** While also caused by Coxsackievirus A16 and featuring oral vesicles, the question asks for the condition defined by these lesions. In HFMD, vesicles are typically found on the **buccal mucosa and tongue** (anterior oral cavity), accompanied by a characteristic rash on the palms and soles. **High-Yield Clinical Pearls for NEET-PG:** * **Herpangina vs. HFMD:** Herpangina involves the **posterior** pharynx; HFMD involves the **anterior** mouth plus extremities. * **Etiology:** Both are Enteroviruses, most commonly **Coxsackievirus A**. * **Differential Diagnosis:** Unlike Herpetic Gingivostomatitis (HSV-1), Herpangina does **not** involve the gums (gingiva) and lacks the diffuse swelling seen in primary herpes. * **Seasonality:** These infections typically peak in summer and autumn months.

Q: A rash with retro-auricular origin is typically seen in which of the following conditions?

Rubeola. **Explanation:** The correct answer is **Rubeola (Measles)**. In Rubeola, the characteristic maculopapular rash typically appears on the 4th day of fever. It follows a classic **cephalocaudal progression**, starting behind the ears (**retro-auricular**) and along the hairline, then spreading downwards to the face, neck, trunk, and finally the extremities. This specific anatomical starting point is a hallmark clinical feature used to differentiate it from other exanthematous illnesses. **Analysis of Options:** * **Rubella (German Measles):** While the rash also starts on the face and spreads downwards, it is typically lighter (pinkish), non-confluent, and disappears much faster ("3-day measles"). The most characteristic feature of Rubella is **post-auricular and suboccipital lymphadenopathy**, rather than just the rash origin. * **Chickenpox (Varicella):** The rash typically starts on the **trunk** (centripetal distribution) and is pleomorphic (macules, papules, vesicles, and crusts present simultaneously). * **Mumps:** This is a viral infection primarily affecting the parotid glands. It presents with **parotid swelling** and does not typically present with a generalized maculopapular rash. **High-Yield Clinical Pearls for NEET-PG:** * **Koplik Spots:** Pathognomonic for Measles; seen on the buccal mucosa opposite the lower 2nd molars *before* the rash appears. * **Vitamin A:** Supplementation is mandatory in Measles management to reduce morbidity and mortality. * **Complications:** The most common complication is Otitis Media; the most common cause of death is Pneumonia; the most dreaded late complication is SSPE (Subacute Sclerosing Panencephalitis). * **Infectivity:** Measles is most infectious during the prodromal (catarrhal) stage.

Q: Which of the following is FALSE regarding Poliomyelitis?

Bilateral and symmetrical involvement. **Explanation:** Poliomyelitis is an acute viral infection caused by the Poliovirus (an enterovirus), primarily affecting the anterior horn cells of the spinal cord. **Why Option B is the Correct (False) Statement:** The hallmark of paralytic poliomyelitis is **asymmetrical** and **random** involvement of muscles. It typically affects one limb more than the other (most commonly the legs) and rarely presents with perfect symmetry. If a patient presents with acute flaccid paralysis that is bilateral and symmetrical, clinicians should prioritize a diagnosis of Guillain-Barré Syndrome (GBS) over Polio. **Analysis of Other Options:** * **Option A (Descending paralysis):** While Polio is often described as affecting proximal muscles more than distal ones, the paralysis characteristically spreads in a **descending** fashion (starting from the hip/shoulder and moving downwards). * **Option C (Non-progressive condition):** Once the febrile illness subsides and the paralysis is established (usually within 48–72 hours), the paralysis is **static and non-progressive**. Any further "progression" after the fever touches baseline is unlikely to be Polio. * **Option D (LMN type paralysis):** Because the virus destroys the **anterior horn cells** (the final common pathway of the motor system), it results in classic **Lower Motor Neuron (LMN)** signs: flaccidity, loss of deep tendon reflexes, and eventual muscle atrophy. **High-Yield Clinical Pearls for NEET-PG:** * **Most common presentation:** Asymptomatic/Inapparent infection (>90-95%). * **CSF Findings:** Albuminocytologic dissociation is **absent** (unlike GBS). There is initial pleocytosis. * **Diagnosis:** Isolation of the virus from **stool samples** (two samples collected 24 hours apart) is the gold standard for AFP surveillance. * **Prognosis:** Maximum recovery occurs within the first 6 months; paralysis persisting beyond 60 days is usually permanent.

Q: Forschheimer spots are seen on which of the following locations?

Uvula. **Explanation:** **Forschheimer spots** are a classic clinical sign associated with **Rubella (German Measles)**. They are characterized by small, pinpoint, reddish-pink spots (petechiae) located on the **soft palate and uvula**. These spots appear during the prodromal phase or on the first day of the rash in approximately 20% of Rubella patients. While characteristic, they are not pathognomonic as they can occasionally be seen in Scarlet fever or Infectious Mononucleosis. **Analysis of Options:** * **A. Uvula (Correct):** This is the anatomical site for Forschheimer spots, specifically involving the soft palate and the uvula. * **B. Trunk:** While the Rubella rash (exanthem) typically starts on the face and spreads to the trunk, Forschheimer spots are an *enanthem* (mucosal rash) and are not found on the skin of the trunk. * **C. Dorsal aspect of hand:** This is not a site for specific enanthems. However, Gottron papules (seen in Dermatomyositis) are typically found on the dorsal aspect of interphalangeal joints. * **D. Penis:** This is not a site for Forschheimer spots. Genital lesions are more characteristic of STIs like Syphilis (Chancre) or HSV. **Clinical Pearls for NEET-PG:** * **Koplik Spots vs. Forschheimer Spots:** Koplik spots (Measles) are bluish-white spots on an erythematous base located on the buccal mucosa opposite the lower molars. Forschheimer spots (Rubella) are reddish petechiae on the soft palate/uvula. * **Rubella Triad (Congenital):** Cataract, Sensorineural hearing loss, and PDA (Patent Ductus Arteriosus). * **Rash Progression:** Rubella rash is known for its rapid spread and disappearance within 3 days ("3-day measles").

Q: Which of the following complications has been associated with the adverse effects of rotavirus vaccine?

Intussusception. **Explanation:** The correct answer is **D. Intussusception.** **Why Intussusception is the correct answer:** Rotavirus vaccines (such as Rotarix and RotaTeq) are live-attenuated oral vaccines. Historically, the first-generation vaccine (Rotashield) was withdrawn in 1999 due to a significant association with **intussusception** (telescoping of one segment of the intestine into another). While current vaccines have a much lower risk profile, a small but statistically significant risk (approximately 1 to 5 cases per 100,000 vaccinated infants) remains. The risk is highest within the first **7 days** following the first dose. Consequently, the vaccine is contraindicated in infants with a prior history of intussusception or uncorrected congenital malformations of the GI tract (like Meckel’s diverticulum). **Why other options are incorrect:** * **A. Guillain-Barré syndrome:** This is primarily associated with the **Influenza vaccine** and *Campylobacter jejuni* infections, not rotavirus. * **B. Hemolytic anemia:** This is not a recognized side effect of the rotavirus vaccine. It is more commonly associated with drugs (e.g., dapsone in G6PD deficiency) or infections. * **C. Febrile seizures:** While common after DPT or MMR vaccines, they are not a characteristic adverse effect of the oral rotavirus vaccine. **High-Yield Clinical Pearls for NEET-PG:** * **Age Limits:** To minimize the risk of intussusception, the WHO/IAP recommends the first dose be given after 6 weeks and the series completed by **8 months** of age. * **Vaccine Types:** Rotarix (Monovalent, 2 doses) and RotaTeq/Rotavac (Pentavalent, 3 doses). * **Contraindications:** History of intussusception, SCID (Severe Combined Immunodeficiency), and acute gastroenteritis.

Q: An 8-year-old child presents with a 3-day history of high-grade fever, vomiting, headache, and decreased responsiveness. Examination reveals a distressed child in shock, with maculopapular and ecchymotic rashes, bleeding from venipuncture sites, and hepatomegaly. Investigations show PCV = 65%, WBC = 4000, platelets = 25,000, and mildly prolonged PT. Chest X-ray reveals a left-sided pleural effusion. What is the most likely diagnosis?

Dengue hemorrhagic fever. The correct answer is **Dengue Hemorrhagic Fever (DHF)**. ### **Why it is correct:** The clinical presentation and laboratory findings perfectly match the **WHO criteria for DHF**: 1. **High-grade fever** and constitutional symptoms. 2. **Hemorrhagic manifestations:** Ecchymotic rashes and bleeding from venipuncture sites. 3. **Thrombocytopenia:** Platelet count 20% from baseline) and the presence of **pleural effusion** and **hepatomegaly** confirm plasma leakage into the third space. ### **Why other options are incorrect:** * **Meningococcemia with DIC:** While it causes shock and purpura, it does not typically cause significant hemoconcentration (high PCV) or pleural effusion. WBC count is usually high (leukocytosis), whereas Dengue typically shows leukopenia. * **Leptospirosis:** Presents with conjunctival suffusion, jaundice, and renal failure. While it can cause bleeding (Weil’s disease), it does not explain the massive plasma leakage seen here. * **Complicated Malaria:** Can cause shock (Algid malaria) and thrombocytopenia, but the hallmark is severe anemia (low PCV), not hemoconcentration (high PCV). ### **NEET-PG High-Yield Pearls:** * **Dengue Grading:** DHF is graded I to IV. Grades III and IV (presence of shock) are termed **Dengue Shock Syndrome (DSS)**. * **Critical Phase:** Occurs during defervescence (day 3–7). This is when plasma leakage and shock are most likely to occur. * **Fluid Management:** Isotonic crystalloids (Ringer’s Lactate) are the gold standard for resuscitation. * **Diagnosis:** NS1 antigen (Day 1–5); IgM/IgG ELISA (after Day 5).

Question 1

A 16-month-old boy presents with fever, irritability, and lethargy. Examination reveals nuchal rigidity. He is unvaccinated. CSF Gram stain shows an organism that grows on chocolate agar but not blood agar. The patient has received empirical antibiotics. Which of the following statements regarding the treatment of this condition is FALSE?

Accepted Answer

Fluoroquinolones can be used for treatment.

Answer

Corticosteroids have no role in the treatment of this disease.

Answer

First-line therapy includes ceftriaxone or cefotaxime.

Answer

The duration of therapy is 1-2 weeks.

Question 2

Which of the following sexually transmitted diseases can cause fetal abnormalities?

Accepted Answer

Treponema pallidum

Answer

Herpes simplex virus

Answer

Hepatitis B virus

Answer

Neisseria gonorrhoeae

Question 3

A 7-month-old child presents with microcephaly. What is the most likely etiology for this clinical presentation?

Accepted Answer

Cytomegalovirus (CMV)

Answer

Toxoplasma

Answer

Rubella

Answer

Mumps

Question 4

What is the correct indication for prophylaxis with varicella-zoster immunoglobulin in chicken-pox?

Accepted Answer

Given to a newborn contact

Answer

Should be given within 24 hours of exposure

Answer

Can be given concurrently with the varicella vaccine

Answer

Administered in established chicken-pox disease

Question 5

Papulovesicular oral lesions are seen in which condition?

Accepted Answer

Herpangina

Answer

Measles

Answer

Rubella

Answer

Hand foot and mouth disease

Question 6

A rash with retro-auricular origin is typically seen in which of the following conditions?

Accepted Answer

Rubeola

Answer

Rubella

Answer

Chickenpox

Answer

Mumps

Question 7

Which of the following is FALSE regarding Poliomyelitis?

Accepted Answer

Bilateral and symmetrical involvement

Answer

Descending paralysis

Answer

Non-progressive condition

Answer

Lower Motor Neuron (LMN) type paralysis

Question 8

Forschheimer spots are seen on which of the following locations?

Accepted Answer

Uvula

Answer

Trunk

Answer

Dorsal aspect of hand

Answer

Penis

Question 9

Which of the following complications has been associated with the adverse effects of rotavirus vaccine?

Accepted Answer

Intussusception

Answer

Guillain-Barré syndrome

Answer

Hemolytic anemia

Answer

Febrile seizures

Question 10

An 8-year-old child presents with a 3-day history of high-grade fever, vomiting, headache, and decreased responsiveness. Examination reveals a distressed child in shock, with maculopapular and ecchymotic rashes, bleeding from venipuncture sites, and hepatomegaly. Investigations show PCV = 65%, WBC = 4000, platelets = 25,000, and mildly prolonged PT. Chest X-ray reveals a left-sided pleural effusion. What is the most likely diagnosis?

Accepted Answer

Dengue hemorrhagic fever

Answer

Meningococcemia with DIC

Answer

Leptospirosis

Answer

Complicated malaria

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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