Infectious Diseases Practice Questions

Q: A child presents with complaints of oliguria, abdominal distension, and diarrhea. On examination, there is deep jaundice. Hepatomegaly was present, measuring 4 cm below the costal margin. Conjugated bilirubin in blood was 38 mg/dL, and there were urine urobilinogen and bile pigments. Hemoglobin was 4 g/dL and serum creatinine was 3 mg/dL. Which of the following tests is of least importance to diagnose this case?

Serum ceruloplasmin. The clinical presentation describes a child with **acute fulminant illness** characterized by the triad of **severe jaundice (conjugated hyperbilirubinemia), acute kidney injury (oliguria, high creatinine), and severe anemia (Hb 4 g/dL).** ### Why Serum Ceruloplasmin is the Least Important **Serum ceruloplasmin** is the screening test for **Wilson Disease**. While Wilson disease can present with acute liver failure and Coombs-negative hemolytic anemia, it typically occurs in older children (rarely under 5 years) and is characterized by **unconjugated hyperbilirubinemia** (due to hemolysis) and low alkaline phosphatase. In this acute, febrile-sounding presentation with multi-organ involvement (renal + hepatic), Wilson disease is the least likely diagnosis compared to acute infections or hematologic crises. ### Evaluation of Other Options * **G6PD level & Reticulocyte count:** The patient has severe anemia (4 g/dL) and jaundice. A G6PD deficiency trigger (infection/drugs) can cause a **hemolytic crisis** leading to hemoglobinuric acute tubular necrosis (renal failure). Reticulocyte count is essential to confirm hemolysis. * **Leptospiral antibody level:** This is a high-yield diagnosis for this triad. **Weil’s Disease (Leptospirosis)** classically presents with fever, diarrhea, hepatorenal syndrome (jaundice + oliguria), and hemorrhage/anemia. ### NEET-PG High-Yield Pearls * **Weil’s Syndrome Triad:** Jaundice, Renal Failure, and Hemorrhage (Leptospirosis). * **Conjugated Hyperbilirubinemia (>20% of total):** Always pathological; suggests hepatocellular damage or biliary obstruction, not simple hemolysis. * **Wilson Disease Presentation:** Suspect in any child >5 years with unexplained liver disease or neurological symptoms. The gold standard for diagnosis is a **liver biopsy** for copper content, though ceruloplasmin is the initial screen.

Q: A child patient presents to the outpatient department with a history of black central arch rashes on their body. What is your diagnosis?

Meningococcemia. ### Explanation **Correct Option: A. Meningococcemia** The hallmark clinical sign of Meningococcemia (caused by *Neisseria meningitidis*) is a rapidly progressing petechial or purpuric rash. These lesions often undergo central necrosis due to **disseminated intravascular coagulation (DIC)** and perivascular inflammation, leading to a characteristic **"black central arch"** or "gunmetal grey" appearance. This represents skin infarction and is a medical emergency, often progressing to Waterhouse-Friderichsen syndrome (adrenal hemorrhage). **Why other options are incorrect:** * **B. Dengue Hemorrhagic Fever:** While it presents with petechiae and ecchymosis due to thrombocytopenia, the classic rash is described as **"islands of white in a sea of red"** (convalescent rash). It typically lacks the necrotic black centers seen in meningococcemia. * **C. Leptospirosis:** Presents with conjunctival suffusion (pathognomonic), calf tenderness, and jaundice (Weil’s disease). While a petechial rash can occur, it is not the defining feature. * **D. Scrub Typhus:** The characteristic skin finding is an **Eschar**—a painless ulcer with a black crust at the site of the chigger bite—rather than generalized black central arch rashes. **NEET-PG High-Yield Pearls:** * **DOC for Prophylaxis:** Rifampicin (Close contacts); Ceftriaxone is preferred for pregnant women. * **DOC for Treatment:** Ceftriaxone or Cefotaxime. * **Glass Test:** Petechiae and purpura in meningococcemia are **non-blanching** (do not disappear when pressed with a glass). * **Most common serogroup in India:** Historically Serogroup A, though W-135 and Y are emerging globally.

Q: A 8-year-old boy presented with swelling on both sides of the face, below the ears, of 4 days duration. The swelling first started on the left side and then, 3 days later, appeared on the right side. Immunization to this disease can be achieved by which of the following vaccinations?

MMR. **Explanation:** The clinical presentation of bilateral facial swelling below the ears, starting on one side and progressing to the other, is a classic description of **Parotitis**, the hallmark of **Mumps**. Mumps is an acute viral infection caused by the *Rubulavirus* (Paramyxoviridae family). **Why MMR is correct:** The **MMR (Measles, Mumps, and Rubella)** vaccine is a live-attenuated vaccine that provides effective immunity against the Mumps virus. In the National Immunization Schedule (India) and IAP guidelines, it is typically administered in two doses (at 9 months as MR/MMR and 15 months as MMR). **Why other options are incorrect:** * **BCG (Bacillus Calmette-Guérin):** A live bacterial vaccine used to prevent severe forms of Tuberculosis (miliary and meningeal TB). * **Hepatitis B:** A subunit vaccine (HBsAg) used to prevent viral hepatitis caused by the Hepatitis B virus. * **Polio:** Administered as OPV (Sabin - live) or IPV (Salk - inactivated) to prevent poliomyelitis. **High-Yield Clinical Pearls for NEET-PG:** * **Most common complication in children:** Aseptic meningitis. * **Most common complication in post-pubertal males:** Epididymo-orchitis (usually unilateral; rarely leads to sterility). * **Other complications:** Pancreatitis (look for elevated serum amylase), Oophoritis, and Sensorineural hearing loss (usually unilateral). * **Infectivity:** Patients are most infectious from 2 days before to 5 days after the onset of parotid swelling. * **Diagnosis:** Primarily clinical; however, IgM antibodies or PCR can confirm the diagnosis.

Q: What is the approximate percentage of HIV transmission from an infected mother to her child?

20% – 30%. **Explanation:** The transmission of HIV from an infected mother to her child is known as **Vertical Transmission** or Mother-to-Child Transmission (MTCT). In the absence of any medical intervention (antiretroviral therapy, elective cesarean section, or avoidance of breastfeeding), the risk of transmission is approximately **20% to 30%**. **Breakdown of Transmission Timing:** * **In-utero (Transplacental):** ~5%–10% * **Intrapartum (During delivery):** ~10%–15% (Most common route) * **Postpartum (Breastfeeding):** ~5%–20% (Cumulative risk) **Analysis of Options:** * **Option A (20% – 30%):** Correct. This represents the standard global average for vertical transmission in non-interventional settings. * **Option B (10% – 20%):** Incorrect. This range is too low for a mother who is breastfeeding without treatment, though it may approximate the risk if breastfeeding is strictly avoided. * **Option C (70% – 80%):** Incorrect. HIV is not transmitted to every fetus; the placental barrier and maternal immune factors provide significant protection. * **Option D (100%):** Incorrect. Transmission is never guaranteed; even without treatment, the majority of infants born to HIV-positive mothers are born HIV-negative. **High-Yield Clinical Pearls for NEET-PG:** 1. **Prevention of Parent-to-Child Transmission (PPTCT):** With effective HAART (Highly Active Antiretroviral Therapy) and a suppressed maternal viral load, the risk can be reduced to **<1%–2%**. 2. **Most Common Route:** The **intrapartum period** (exposure to maternal blood and vaginal secretions) carries the highest risk. 3. **Diagnosis in Infants:** HIV DNA PCR (Nucleic Acid Test) is the gold standard for infants <18 months. Antibody tests (ELISA) are unreliable due to the persistence of maternal IgG antibodies. 4. **Prophylaxis:** In India, the NACP guidelines recommend **Nevirapine** syrup for the infant for at least 6 weeks.

Q: Raspberry tongue is seen in which of the following conditions?

Scarlet fever. **Explanation:** **Scarlet Fever (Correct Answer):** Scarlet fever is caused by **Group A Streptococcus (Streptococcus pyogenes)** producing **Erythrogenic (Pyrogenic) toxins**. The "Raspberry tongue" is a classic clinical sign that evolves in stages. Initially, the tongue has a white coating with red, hypertrophied papillae projecting through it (**White Strawberry Tongue**). By day 4 or 5, the white coat desquamates, leaving a bright red, denuded surface with prominent papillae, known as the **Red Strawberry or Raspberry Tongue**. **Analysis of Incorrect Options:** * **Vitiligo:** This is an autoimmune skin disorder characterized by the loss of melanocytes, leading to depigmented white patches. It does not affect the tongue in this inflammatory manner. * **Vitamin B12 deficiency:** This typically causes a **"Beefy red tongue"** or Hunter’s glossitis, where the tongue appears smooth and shiny due to the atrophy of lingual papillae (atrophic glossitis), rather than the prominent papillae seen in Scarlet fever. * **Impetigo:** Also caused by *S. pyogenes* or *S. aureus*, this is a superficial skin infection characterized by "honey-colored crusts." It does not typically involve the tongue. **NEET-PG High-Yield Pearls:** * **Dick Test:** Historically used to determine susceptibility to Scarlet fever. * **Schultz-Charlton Reaction:** A diagnostic test where antitoxin injected into the skin causes blanching of the Scarlet fever rash. * **Pastia’s Lines:** Pink or red lines in skin creases (axilla/groin) seen in Scarlet fever. * **Differential Diagnosis:** Strawberry tongue is also a major diagnostic criterion for **Kawasaki Disease**.

Q: Congenital rubella causes all EXCEPT:

Hydrocephalus. **Explanation:** Congenital Rubella Syndrome (CRS) is caused by the transplacental transmission of the Rubella virus, typically during the first trimester. The classic clinical presentation is defined by **Gregg’s Triad**, which includes sensorineural deafness, eye anomalies, and congenital heart disease. **Why Hydrocephalus is the correct answer:** Hydrocephalus is **not** a feature of Congenital Rubella. Instead, the hallmark neurological finding in CRS is **Microcephaly** (small head size due to impaired brain growth). Hydrocephalus is more characteristically associated with **Congenital Toxoplasmosis** (part of the classic triad: hydrocephalus, chorioretinitis, and intracranial calcifications). **Analysis of Incorrect Options:** * **A. Deafness:** Sensorineural hearing loss is the **most common** manifestation of CRS, occurring in about 80% of affected infants. * **B. Cataract:** Ocular defects are common, with "pearlescent" nuclear cataracts and "salt-and-pepper" retinopathy being high-yield findings. * **C. Cardiac defects:** The most characteristic lesion is **Patent Ductus Arteriosus (PDA)**, followed by peripheral pulmonary artery stenosis. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad:** Cataract, Deafness, and PDA. * **Skin manifestation:** "Blueberry muffin" rash (due to extramedullary hematopoiesis). * **Radiology:** "Celery stalking" appearance (longitudinal radiolucent striations in the metaphysis of long bones). * **Timing:** Risk is highest (up to 90%) if maternal infection occurs before 11 weeks of gestation. * **Diagnosis:** Detection of Rubella-specific IgM in the newborn or persistence of IgG titers beyond 6–12 months.

Q: Which of the following is NOT a complication of mumps?

Hepatitis. **Explanation:** Mumps is an acute viral illness caused by the **Rubulavirus** (Paramyxoviridae family), primarily characterized by painful swelling of the parotid glands. While the virus is systemic and can affect various glandular and neurological tissues, **Hepatitis (Option D)** is not a recognized or typical complication of mumps. Liver involvement is extremely rare, making it the correct answer for this "except" type question. **Analysis of Complications:** * **Orchitis (Option A):** This is the most common complication in post-pubertal males (occurring in up to 30-40% of cases). It is usually unilateral and can lead to testicular atrophy, though permanent infertility is rare. * **Oophoritis (Option B):** Occurring in about 5-7% of post-pubertal females, it presents with pelvic pain and tenderness but rarely affects fertility. * **Encephalitis (Option C):** Neurological involvement is common. While **aseptic meningitis** is the most frequent neurological complication, true encephalitis (direct brain parenchyma involvement) occurs in about 1 in 1,000 cases and is a significant cause of mumps-related morbidity. **High-Yield Clinical Pearls for NEET-PG:** * **Pancreatitis:** Mumps is a classic viral cause of acute pancreatitis. * **Deafness:** Mumps is a leading cause of **sudden onset sensorineural hearing loss** (usually unilateral) in children. * **Most common complication in children:** Aseptic meningitis. * **Most common complication in post-pubertal males:** Orchitis. * **Incubation Period:** 14–21 days. * **Infectivity:** Patients are most infectious from 2 days before to 5 days after the onset of parotitis.

Q: A 10-year-old child presents with a 10-day history of continuous fever, accompanied by a soft, enlarged spleen. What is the most likely diagnosis?

Enteric fever. **Explanation:** The clinical presentation of **continuous fever** lasting for more than a week, associated with a **soft, enlarged spleen**, is a classic hallmark of **Enteric Fever** (Typhoid/Paratyphoid). 1. **Why Enteric Fever is correct:** In the first week of Enteric fever, the temperature rises in a "step-ladder" fashion, becoming continuous by the second week. Splenomegaly typically appears at the end of the first week or during the second week. Crucially, the spleen in Enteric fever is **soft and mildly tender**, unlike the firm/hard spleen seen in chronic infections or malignancies. 2. **Why other options are incorrect:** * **Malaria:** Characterized by intermittent fever with chills and rigors (paroxysms), rather than a continuous fever pattern. The spleen in malaria becomes firm over time. * **Hodgkin’s Disease:** Usually presents with painless, rubbery lymphadenopathy. While it can cause fever (Pel-Ebstein type) and splenomegaly, the spleen is typically firm, and the fever is rarely the sole presenting symptom for only 10 days. * **Meningitis:** Presents with acute onset high-grade fever, headache, vomiting, and signs of meningeal irritation (neck stiffness). Splenomegaly is not a standard feature. **NEET-PG High-Yield Pearls:** * **Gold Standard Diagnosis:** Bone marrow culture (most sensitive); Blood culture (positive in 1st week). * **Widal Test:** Significant only after the 2nd week (look for a four-fold rise in titers). * **Relative Bradycardia (Faget’s sign):** Pulse rate is slower than expected for the degree of fever; a key diagnostic clue. * **Rose Spots:** Faint, salmon-colored macules on the trunk (seen in the 2nd week).

Question 1

A child presents with complaints of oliguria, abdominal distension, and diarrhea. On examination, there is deep jaundice. Hepatomegaly was present, measuring 4 cm below the costal margin. Conjugated bilirubin in blood was 38 mg/dL, and there were urine urobilinogen and bile pigments. Hemoglobin was 4 g/dL and serum creatinine was 3 mg/dL. Which of the following tests is of least importance to diagnose this case?

Accepted Answer

Serum ceruloplasmin

Answer

G6PD level in blood

Answer

Reticulocyte count

Answer

Leptospiral antibody level

Question 2

A child patient presents to the outpatient department with a history of black central arch rashes on their body. What is your diagnosis?

Accepted Answer

Meningococcemia

Answer

Dengue hemorrhagic fever

Answer

Leptospirosis

Answer

Scrub typhus

Question 3

Which vaccine is contraindicated in an HIV-positive child?

Accepted Answer

Oral Polio Vaccine (OPV)

Answer

Measles, Mumps, and Rubella (MMR) vaccine

Answer

Rabies vaccine

Answer

Influenza vaccine

Question 4

A 8-year-old boy presented with swelling on both sides of the face, below the ears, of 4 days duration. The swelling first started on the left side and then, 3 days later, appeared on the right side. Immunization to this disease can be achieved by which of the following vaccinations?

Accepted Answer

MMR

Answer

BCG

Answer

Hepatitis B

Answer

Polio

Question 5

A lactating woman has sputum positive TB. The neonate is 3 months old. What is the recommended chemoprophylaxis?

Accepted Answer

INH 5mg/kg for 6 months

Answer

INH 3mg/kg for 3 months

Answer

INH 5mg/kg for 3 months

Answer

INH 3mg/kg for 6 months

Question 6

What is the approximate percentage of HIV transmission from an infected mother to her child?

Accepted Answer

20% – 30%

Answer

10% – 20%

Answer

70% – 80%

Answer

100%

Question 7

Raspberry tongue is seen in which of the following conditions?

Accepted Answer

Scarlet fever

Answer

Vitiligo

Answer

Vitamin B12 deficiency

Answer

Impetigo

Question 8

Congenital rubella causes all EXCEPT:

Accepted Answer

Hydrocephalus

Answer

Deafness

Answer

Cataract

Answer

Cardiac defects

Question 9

Which of the following is NOT a complication of mumps?

Accepted Answer

Hepatitis

Answer

Orchitis

Answer

Oophoritis

Answer

Encephalitis

Question 10

A 10-year-old child presents with a 10-day history of continuous fever, accompanied by a soft, enlarged spleen. What is the most likely diagnosis?

Accepted Answer

Enteric fever

Answer

Malaria

Answer

Hodgkin's disease

Answer

Meningitis

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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