Infectious Diseases Practice Questions

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).

Q: What is helpful in a child with severe falciparum malaria with high parasitemia?

Exchange transfusion. **Explanation:** Severe falciparum malaria is a medical emergency characterized by high parasite density (hyperparasitemia) and multi-organ dysfunction. **Why Exchange Transfusion is correct:** Exchange transfusion is considered an adjunctive therapy in severe malaria, particularly when parasitemia exceeds **10-15%** or if there are signs of organ failure (e.g., cerebral malaria, ARDS, or renal failure). The procedure works by: 1. **Rapidly reducing parasite load:** Physically removing infected red blood cells (RBCs). 2. **Improving Rheology:** Removing rigid, parasitized RBCs that cause microvascular sequestration and replacing them with flexible donor cells, thereby improving tissue perfusion. 3. **Reducing Toxicity:** Clearing parasite-derived toxins, cytokines, and free hemoglobin. **Why other options are incorrect:** * **IV Corticosteroids:** Previously used for cerebral malaria to reduce brain edema, clinical trials (like those by Warrell et al.) proved they are **contraindicated**. They increase the risk of secondary infections and gastrointestinal bleeding without improving survival. * **Hyperbaric Oxygen:** There is no established clinical evidence or physiological basis for its use in treating the pathophysiology of malaria. **NEET-PG High-Yield Pearls:** * **WHO Criteria for Hyperparasitemia:** >10% in low-transmission areas or >20% in high-transmission areas. * **Drug of Choice:** IV **Artesunate** is the gold standard for severe malaria (superior to Quinine). * **Common Complication in Children:** Hypoglycemia and severe anemia are more frequent in pediatric severe malaria compared to adults. * **Blackwater Fever:** Characterized by massive intravascular hemolysis and hemoglobinuria, often associated with Quinine use.

Q: Excessive crying is a known side effect following which vaccination?

DPT. **Explanation:** The correct answer is **DPT (Diphtheria, Pertussis, and Tetanus)**. **Why DPT is the correct answer:** Excessive crying (defined as persistent, inconsolable crying lasting for 3 hours or more) is a well-documented systemic adverse event following immunization (AEFI) specifically associated with the **whole-cell Pertussis (wP)** component of the DPT vaccine. This reaction typically occurs within 2–24 hours of administration. It is thought to be caused by the local inflammatory response and systemic effects of the endotoxins present in the *Bordetella pertussis* bacteria. While distressing to parents, it is usually self-limiting and not a contraindication to future doses, though acellular pertussis (aP) vaccines are associated with a significantly lower incidence of this side effect. **Why other options are incorrect:** * **Polio (OPV/IPV):** Generally very well tolerated. The most serious (though rare) side effect of OPV is Vaccine-Associated Paralytic Poliomyelitis (VAPP), not excessive crying. * **BCG:** Typically causes local reactions such as a papule, ulcer, and eventual scarring at the injection site. Systemic reactions like persistent crying are rare. * **Measles:** Common side effects include fever and a transient rash occurring 5–12 days after vaccination, rather than immediate excessive crying. **High-Yield Clinical Pearls for NEET-PG:** * **Persistent Inconsolable Crying:** Occurs in approximately 1% of children receiving the wP vaccine. * **Absolute Contraindications to Pertussis vaccine:** Encephalopathy (e.g., coma, seizures) within 7 days of a previous dose. * **Triple Response:** DPT is also associated with local pain, swelling, and redness at the injection site. * **Switching to DTaP:** If a child experiences severe reactions to DTwP, the acellular version (DTaP) is preferred for subsequent doses.

Q: A 9-year-old girl presents with a 2-day history of sore throat. Physical examination reveals pharyngeal erythema with yellowish exudates over swollen palatine tonsils. A Gram stain of the exudate shows gram-positive cocci in chains. She is treated with penicillin. What is the most likely complication prevented by prompt treatment?

Carditis. **Explanation:** The clinical presentation of sore throat, pharyngeal exudates, and Gram-positive cocci in chains is diagnostic of **Acute Pharyngitis** caused by **Group A Streptococcus (GAS)**, specifically *Streptococcus pyogenes*. **Why Carditis is correct:** Prompt antibiotic treatment (within 9 days of symptom onset) is primarily aimed at preventing **Acute Rheumatic Fever (ARF)**. ARF is a nonsuppurative, immune-mediated complication caused by molecular mimicry between streptococcal M-proteins and human cardiac tissue. **Carditis** is the most serious manifestation of ARF and can lead to permanent valvular damage. Notably, while antibiotics prevent ARF, they do **not** prevent Post-Streptococcal Glomerulonephritis (PSGN). **Why other options are incorrect:** * **Hepatitis:** This is not a recognized complication of *S. pyogenes* infection. * **Meningitis:** While GAS can rarely cause meningitis via hematogenous spread or local extension, it is not the primary complication targeted by routine penicillin therapy for pharyngitis. * **Otitis:** Otitis media is a common *suppurative* complication of streptococcal pharyngitis. While penicillin reduces its incidence, the most critical "preventable" systemic sequela emphasized in medical exams is the life-altering carditis associated with ARF. **High-Yield NEET-PG Pearls:** * **Jones Criteria:** Used for diagnosing ARF (Major: Carditis, Polyarthritis, Chorea, Erythema marginatum, Subcutaneous nodules). * **ASO Titre:** Elevated Anti-Streptolysin O (ASO) titers indicate recent streptococcal infection. * **Drug of Choice:** Penicillin remains the gold standard for GAS pharyngitis due to 100% sensitivity. * **PSGN vs. ARF:** Antibiotics prevent ARF but **not** PSGN. PSGN can follow both skin (impetigo) and throat infections, whereas ARF follows **only** pharyngeal infections.

Q: A 10-year-old child presents to the OPD with fever, neck rigidity, convulsions, and signs of meningeal irritation. Cerebrospinal fluid (CSF) examination shows normal glucose, slightly elevated proteins, and appears clear on gross examination. What is the most probable diagnosis?

Viral meningitis. ### Explanation The clinical presentation of fever, neck rigidity, and convulsions indicates **meningitis**. The key to differentiating the etiology lies in the **CSF analysis**. **1. Why Viral Meningitis is Correct:** Viral (Aseptic) meningitis typically presents with a **clear CSF appearance**. The biochemical markers are characteristic: * **Glucose:** Normal (Viruses do not consume glucose). * **Proteins:** Normal to slightly elevated (usually <100 mg/dL). * **Cell count:** Predominantly lymphocytic pleocytosis (though neutrophils may appear very early). The combination of meningeal signs with normal glucose and clear CSF is the classic "textbook" description of a viral etiology. **2. Why Other Options are Incorrect:** * **Bacterial Meningitis:** CSF is typically **turbid/purulent**. It shows **markedly low glucose** (hypoglycorrhachia), significantly elevated proteins, and a high polymorphonuclear (neutrophil) count. * **Tubercular Meningitis (TBM):** CSF is often clear or "cobweb" appearance. However, TBM is characterized by **very low glucose** and **very high protein** levels. The clinical course is usually more subacute/chronic compared to viral meningitis. * **Sub-arachnoid Hemorrhage:** While it causes signs of meningeal irritation (chemical meningitis), the CSF would be **grossly bloody or xanthochromic** (yellowish) rather than clear, with a high RBC count. **Clinical Pearls for NEET-PG:** * **Most common cause of viral meningitis:** Enteroviruses (Coxsackie, Echovirus). * **Mumps Meningitis:** Unique among viral causes as it can sometimes show *low* CSF glucose. * **CSF Glucose Rule:** Normal CSF glucose is approximately **2/3rd (60-70%)** of the simultaneous blood glucose level. * **Latex Agglutination Test:** Useful for rapid diagnosis of bacterial meningitis if the patient has already received prior antibiotics (partially treated meningitis).

Q: What is the most common complication of measles in children?

Otitis media. **Explanation:** Measles (Rubeola) is a highly contagious viral infection that leads to generalized immunosuppression, predisposing children to secondary bacterial infections. **Why Otitis Media is the correct answer:** While pneumonia is the most common cause of measles-related *death* in children, **Otitis Media** is statistically the **most common complication** overall. It occurs in approximately 5–10% of cases. The virus causes inflammation of the respiratory tract and Eustachian tube dysfunction, allowing secondary bacterial pathogens (like *S. pneumoniae*) to infect the middle ear. **Analysis of Incorrect Options:** * **A. Subacute sclerosing panencephalitis (SSPE):** This is a fatal, progressive degenerative neurological disorder. While it is a classic association, it is a **rare, late complication** occurring years after the initial infection (incidence ~1 in 10,000 to 100,000). * **B. Pulmonary hypertension:** This is not a recognized direct complication of measles. However, giant cell pneumonia (Hecht pneumonia) is a severe respiratory complication, especially in immunocompromised patients. * **D. Oophoritis:** This is a classic complication of **Mumps**, not Measles. **High-Yield Clinical Pearls for NEET-PG:** * **Most common complication:** Otitis Media. * **Most common cause of death:** Pneumonia. * **Most common neurological complication:** Post-measles encephalitis (Acute Disseminated Encephalomyelitis). * **Pathognomonic sign:** Koplik spots (found on the buccal mucosa opposite the lower 2nd molars). * **Vitamin Supplementation:** Vitamin A reduces morbidity and mortality in all children with acute measles. * **First sign of recovery:** Fading of the rash in the same order it appeared, often leaving behind "branny desquamation" and brownish staining.

Q: Subdural effusions in association with acute bacterial meningitis are:

A common occurrence. **Explanation:** Subdural effusion is a frequent complication of acute bacterial meningitis, particularly in infants. It occurs due to increased capillary permeability and the leakage of fluid into the potential space between the dura and the arachnoid mater during the inflammatory process. **Why Option D is Correct:** Studies indicate that subdural effusions occur in approximately **30–50% of infants** with bacterial meningitis (most commonly associated with *Streptococcus pneumoniae* and *Haemophilus influenzae* type b). Because they occur in nearly half of the cases, they are classified as a **common occurrence**. Most are asymptomatic and resolve spontaneously without intervention. **Why Other Options are Incorrect:** * **Option A:** Effusions are a physiological consequence of the inflammatory response to the infection itself, not a sign of antibiotic failure or inadequate treatment. * **Option B:** While subdural *hematomas* can be seen in bleeding disorders, subdural *effusions* (sterile fluid) are inflammatory in origin and not related to coagulopathies. * **Option C:** Most effusions are benign and asymptomatic. They are rarely fatal unless they become infected (subdural empyema) or cause significant mass effect leading to herniation, which is uncommon. **High-Yield Clinical Pearls for NEET-PG:** * **Most common organisms:** *S. pneumoniae* and *H. influenzae*. * **Clinical Signs:** Suspect effusion if there is a bulging fontanelle, rapidly increasing head circumference, or persistent fever despite 48–72 hours of appropriate antibiotics. * **Diagnosis:** Transillumination of the skull (in infants) or Neuroimaging (CT/MRI). * **Management:** Most require **observation only**. Surgical aspiration (subdural tap) is indicated only if there are signs of increased intracranial pressure (e.g., vomiting, seizures) or suspected empyema.

Q: A fetogram of a stillborn infant is shown below. What is the most likely diagnosis?

Congenital syphilis. ***Congenital syphilis*** - Characteristic **skeletal abnormalities** on fetogram include **periostitis**, **osteochondritis**, and **metaphyseal irregularities** affecting long bones. - **Wimberger sign** (bilateral destruction of the proximal medial tibial metaphysis) is pathognomonic for congenital syphilis on radiographic imaging. *Congenital varicella syndrome* - Primarily causes **limb defects**, **cortical atrophy**, and **cicatricial skin lesions** rather than distinctive bone changes. - Skeletal manifestations are typically **limb hypoplasia** and **shortened extremities**, not the periostitis seen in syphilis. *Congenital lupus* - Mainly presents with **cardiac conduction defects** (complete heart block) and **cutaneous manifestations** (neonatal lupus rash). - Does not typically cause the characteristic **bone lesions** or **periostitis** visible on fetogram imaging. *Congenital CMV infection* - Radiographic findings include **intracranial calcifications**, **microcephaly**, and **growth restriction** rather than bone abnormalities. - Skeletal involvement is rare and does not produce the **metaphyseal changes** and **periostitis** characteristic of syphilis.

Question 1

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

Question 2

What is helpful in a child with severe falciparum malaria with high parasitemia?

Accepted Answer

Exchange transfusion

Answer

IV corticosteroids

Answer

Hyperbaric oxygen

Answer

All the above

Question 3

Excessive crying is a known side effect following which vaccination?

Accepted Answer

DPT

Answer

Polio

Answer

BCG

Answer

Measles

Question 4

A 9-year-old girl presents with a 2-day history of sore throat. Physical examination reveals pharyngeal erythema with yellowish exudates over swollen palatine tonsils. A Gram stain of the exudate shows gram-positive cocci in chains. She is treated with penicillin. What is the most likely complication prevented by prompt treatment?

Accepted Answer

Carditis

Answer

Hepatitis

Answer

Meningitis

Answer

Otitis

Question 5

DPT vaccine is contraindicated in which of the following conditions?

Accepted Answer

Evolving neurological illness

Answer

Family history of convulsions and neurological illness

Answer

Acute upper respiratory infection

Answer

Malnutrition

Question 6

A 10-year-old child presents to the OPD with fever, neck rigidity, convulsions, and signs of meningeal irritation. Cerebrospinal fluid (CSF) examination shows normal glucose, slightly elevated proteins, and appears clear on gross examination. What is the most probable diagnosis?

Accepted Answer

Viral meningitis

Answer

Bacterial meningitis

Answer

Tubercular meningitis

Answer

Sub-arachnoid hemorrhage

Question 7

What is the most common complication of measles in children?

Accepted Answer

Otitis media

Answer

Subacute sclerosing panencephalitis (SSPE)

Answer

Pulmonary hypertension

Answer

Oophoritis

Question 8

Which of the following is true about cerebral malaria in children?

Accepted Answer

Quinine is the drug of choice and hypoglycemia is a common complication.

Answer

Hypoglycemia is a common complication.

Answer

Cerebral malaria in children has a good prognosis.

Answer

Cerebral malaria is caused by Plasmodium vivax.

Question 9

Subdural effusions in association with acute bacterial meningitis are:

Accepted Answer

A common occurrence

Answer

The result of inadequate treatment

Answer

Indicative of a bleeding disorder

Answer

Usually fatal

Question 10

A fetogram of a stillborn infant is shown below. What is the most likely diagnosis?

Accepted Answer

Congenital syphilis

Answer

Congenital varicella syndrome

Answer

Congenital lupus

Answer

Congenital CMV infection

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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