Infectious Diseases Practice Questions

Q: Subacute sclerosing panencephalitis is associated with which virus?

Measles. **Explanation:** **Subacute Sclerosing Panencephalitis (SSPE)**, also known as Dawson disease, is a rare, progressive, and fatal neurodegenerative condition caused by a **persistent, aberrant infection of the Measles virus** (Rubeola) [1]. 1. **Why Measles is Correct:** SSPE occurs due to a mutated measles virus that lacks the 'M' (matrix) protein, preventing the virus from budding. Instead, it spreads directly from cell to cell via syncytia formation, evading the immune system. It typically manifests 7–10 years after an initial measles infection, especially in children infected before the age of two [1]. 2. **Why Incorrect Options are Wrong:** * **Mumps:** Primarily causes parotitis and orchitis; its neurological complication is typically acute aseptic meningitis, not a chronic panencephalitis. * **Exanthema Subitum (Roseola Infantum):** Caused by HHV-6. While it can cause febrile seizures, it is not associated with SSPE. * **Erythema Infectiosum (Fifth Disease):** Caused by Parvovirus B19. It is associated with aplastic crisis and hydrops fetalis, not chronic CNS degeneration. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Stages:** Characterized by behavioral changes (Stage 1), **myoclonic jerks** (Stage 2), and eventual vegetative state/decorticate rigidity. * **EEG Finding:** Pathognomonic **periodic, high-voltage slow-wave complexes** (Radermecker complexes). * **CSF Analysis:** Shows significantly **elevated anti-measles antibody titers** (intrathecal synthesis) and oligoclonal bands [2]. * **Diagnosis:** Brain biopsy shows **Cowdry type A** intranuclear inclusion bodies in neurons and glial cells. * **Prevention:** The most effective strategy is universal vaccination with the **MMR vaccine** [1].

Q: Which type of meningitis typically presents with normal glucose levels in the cerebrospinal fluid?

Coxsackie meningitis. The correct answer is **Coxsackie meningitis**. This is a form of **Viral Meningitis** (Aseptic Meningitis) [1]. In viral meningitis, the blood-brain barrier remains relatively intact, and the glucose transport mechanisms are not compromised. Furthermore, viruses do not consume glucose for metabolism. Therefore, a hallmark of viral meningitis (like that caused by Enteroviruses such as Coxsackie A and B) is a **normal CSF glucose level** (typically >60% of plasma glucose). **Analysis of Incorrect Options:** * **Tuberculous Meningitis (A):** Characteristically presents with **very low glucose** (hypoglycorrhachia) and markedly elevated protein [2]. The bacilli interfere with glucose transport and consume it during their slow metabolic processes. * **Cryptococcal Meningitis (B):** As a fungal infection, it typically results in **low glucose** levels. The yeast cells and the associated inflammatory response consume glucose. * **Listerial Meningitis (D):** *Listeria monocytogenes* is a gram-positive bacterium. Bacterial meningitis is defined by **low glucose** levels because bacteria consume glucose and the inflammatory response impairs its entry into the CSF [1]. **NEET-PG High-Yield Pearls:** * **CSF Glucose Rule:** Normal = Viral; Low = Bacterial, Fungal, or Tubercular. * **Cell Predominance:** Viral meningitis shows **Lymphocytic pleocytosis** (though early stages may show neutrophils). Bacterial shows **Neutrophilic** predominance [1]. * **Coxsackie Virus:** Part of the *Enterovirus* family, which is the most common cause of viral meningitis worldwide. * **Mumps Meningitis:** A rare viral exception that can sometimes present with *low* CSF glucose, mimicking bacterial patterns.

Q: Which of the following is NOT typically seen in Dengue fever?

Hepato-splenomegaly. ### Explanation In Dengue fever, the hallmark clinical features are related to capillary leak and bone marrow suppression. While **Hepatomegaly** (enlargement of the liver) is a common finding and a recognized "warning sign" in Dengue Hemorrhagic Fever (DHF), **Splenomegaly is rare**. The presence of significant hepato-splenomegaly should prompt a clinician to consider alternative diagnoses such as Malaria, Enteric fever, or Kala-azar. **Analysis of Options:** * **A. Hemorrhagic tendencies:** These are common due to thrombocytopenia and vascular dysfunction. Manifestations include petechiae, ecchymosis, and mucosal bleeding (e.g., epistaxis) [1]. * **B. High grade fever:** Dengue typically presents with a sudden-onset, high-grade fever (often "saddleback" or biphasic) accompanied by retro-orbital pain and severe myalgia ("break-bone fever") [1]. * **C. Circulatory problems:** Plasma leakage due to increased capillary permeability can lead to hemoconcentration, pleural effusion, ascites, and in severe cases, Dengue Shock Syndrome (DSS) [1]. * **D. Hepato-splenomegaly:** As noted, while the liver is often tender and enlarged, the spleen is typically not involved. **Clinical Pearls for NEET-PG:** * **Vector:** *Aedes aegypti* (Day biter; breeds in clean stagnant water). * **Warning Signs:** Abdominal pain, persistent vomiting, mucosal bleed, lethargy, and **Hepatomegaly >2 cm**. * **Lab Findings:** Leukopenia (early sign), Thrombocytopenia, and rising Hematocrit (indicates plasma leak). * **Tourniquet Test:** Positive if >10–20 petechiae per square inch; used as a screening tool for capillary fragility [1]. * **NS1 Antigen:** Best for early diagnosis (Days 1–5). IgM/IgG ELISA is used after Day 5.

Q: A 29-year-old man presents with fever, myalgia, headache, nausea, and a rash on his wrists, ankles, and body after a hiking trip where he experienced numerous insect bites. Examination reveals a blood pressure of 90/60 mmHg, pulse of 100/min, and respirations of 20/min. He has multiple macules, some with hemorrhagic centers consistent with petechiae. A clinical diagnosis of Rocky Mountain Spotted Fever (RMSF) is made. What is the most common central nervous system (CNS) presentation in this condition?

Encephalitis. **Explanation:** **Rocky Mountain Spotted Fever (RMSF)**, caused by *Rickettsia rickettsii*, is a systemic vasculitis. The pathogen infects the vascular endothelial cells, leading to increased capillary permeability, microvascular leakage, and inflammatory responses across various organ systems, including the Central Nervous System (CNS) [2]. **1. Why Encephalitis is Correct:** CNS involvement is a hallmark of severe RMSF due to widespread microvascular injury in the brain. **Encephalitis** is the most common CNS manifestation, presenting as altered mental status, confusion, lethargy, or even coma. It occurs in approximately 25–35% of patients. Pathologically, this is characterized by "typhus nodules" (glial nodules) and perivascular mononuclear infiltration. [2] **2. Why Incorrect Options are Wrong:** * **A & C (Hemiplegia/Paraplegia):** While focal neurological deficits can occur due to localized vasculitis or stroke-like events, they are much less common than global cerebral dysfunction (encephalitis). * **B (Cranial nerve abnormalities):** These are rare complications (e.g., deafness or ocular palsies) and do not represent the primary or most frequent CNS presentation compared to the diffuse involvement seen in encephalitis. **3. Clinical Pearls for NEET-PG:** * **The Classic Triad:** Fever, headache, and a centripetal rash (starts on wrists/ankles and spreads to the trunk) [1]. * **The Rash:** Typically appears on day 3–5; it starts as maculopapular and often becomes **petechial** (a sign of severe microvascular damage). * **Treatment:** **Doxycycline** is the drug of choice for all ages, including children, as the benefit of treating this potentially fatal disease outweighs the risk of dental staining. * **Laboratory findings:** Look for hyponatremia and thrombocytopenia in the clinical vignette.

Question 1

Subacute sclerosing panencephalitis is associated with which virus?

Accepted Answer

Measles

Answer

Mumps

Answer

Exanthema subitum

Answer

Erythema infectiosum

Question 2

In AIDS patients with a CD4 count >75 lymphocytes/mm
³, cotton wool spots on eye examination suggest infection by which of the following organisms?

Accepted Answer

Cytomegalovirus (CMV)

Answer

Toxoplasma gondii

Answer

Cryptococcus neoformans

Answer

Acanthamoeba

Question 3

Which type of meningitis typically presents with normal glucose levels in the cerebrospinal fluid?

Accepted Answer

Coxsackie meningitis

Answer

Tuberculous meningitis

Answer

Cryptococcal meningitis

Answer

Listerial meningitis

Question 4

What is the treatment of choice for tropical splenomegaly?

Accepted Answer

Proguanil

Answer

Chloroquine for 6 months

Answer

Mefloquine for 3 months

Answer

Pyrimethamine + sulphadoxine for 1 month

Question 5

A 34-year-old male presents with headache, nausea, vomiting, and intermittent focal seizures. The patient is diagnosed with neurocysticercosis. What is the typical duration for antiparasitic drug therapy in the management of neurocysticercosis?

Accepted Answer

15-30 days

Answer

60-90 days

Answer

3-4 months

Answer

6 months

Question 6

Which of the following is NOT typically seen in Dengue fever?

Accepted Answer

Hepato-splenomegaly

Answer

Hemorrhagic tendencies

Answer

High grade fever

Answer

Circulatory problems

Question 7

What constitutes a complicated urinary tract infection (UTI)?

Accepted Answer

A urinary tract infection that occurs in the presence of underlying structural, medical, or neurological disease.

Answer

A urinary tract infection in the absence of underlying renal or neurological disease.

Answer

More than three symptomatic urinary tract infections within 12 months, despite clinical therapy.

Answer

Recurrent urinary tract infections caused by a different pathogen at any time.

Question 8

A 29-year-old man presents with fever, myalgia, headache, nausea, and a rash on his wrists, ankles, and body after a hiking trip where he experienced numerous insect bites. Examination reveals a blood pressure of 90/60 mmHg, pulse of 100/min, and respirations of 20/min. He has multiple macules, some with hemorrhagic centers consistent with petechiae. A clinical diagnosis of Rocky Mountain Spotted Fever (RMSF) is made. What is the most common central nervous system (CNS) presentation in this condition?

Accepted Answer

Encephalitis

Answer

Hemiplegia

Answer

Cranial nerve abnormalities

Answer

Paraplegia

Question 9

A young female presents with myalgia, fever, headache, diarrhea, and an erythematous rash which first appeared in the groin. What is the most likely diagnosis?

Accepted Answer

Toxic shock syndrome

Answer

Toxic epidermal necrolysis

Answer

Staphylococcal scalded skin syndrome

Answer

Epidermolysis bullosa

Question 10

A patient is found to be HIV positive on routine check-up. They have no symptoms and a CD4 count of 800 cells/mm³. What is the recommended management for this patient?

Accepted Answer

Tenofovir plus lamivudine plus efavirenz for lifelong treatment.

Answer

No treatment is required.

Answer

Zidovudine plus stavudine for 28 days.

Answer

Tenofovir plus zidovudine plus lamivudine for lifelong treatment.

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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