A 6-year-old boy from Delhi presents with fever, myalgia, and rash on day 4 of illness. Platelet count is 80,000/μL. Which of the following is NOT a recognized feature of dengue fever in children?

Explanation

## Dengue Fever in Children — Clinical Features ### Correct Answer Rationale **Dengue shock syndrome (DSS) is NOT exclusive to primary dengue infection.** In fact, DSS is significantly more common and severe in secondary dengue infection (due to antibody-dependent enhancement), though it can occur in primary infection as well. This is a key distinction that examiners test frequently. ### Why the Other Options Are Correct | Feature | Evidence | |---------|----------| | **Thrombocytopenia after defervescence** | Platelet nadir occurs during the critical phase (days 3–7), typically after fever subsides; this is pathognomonic for dengue [cite:Park 26e] | | **Hepatomegaly > splenomegaly** | Hepatomegaly is present in ~60% of dengue cases in children; splenomegaly is less frequent [cite:Nelson Textbook of Pediatrics] | | **Tourniquet test positivity** | A positive tourniquet test (≥20 petechiae in a 2.5 cm circle after 1 min at mean arterial pressure) indicates increased capillary fragility and correlates with bleeding manifestations | ### Key Pathophysiology **Key Point:** Secondary dengue (especially with different serotype) carries 15–80× higher risk of severe dengue due to **antibody-dependent enhancement (ADE)**. Non-neutralizing antibodies from the first infection enhance viral uptake into macrophages, leading to higher viremia and more severe systemic inflammation. **High-Yield:** DSS can occur in both primary and secondary dengue, but is **more common, earlier, and more severe in secondary infection**. This is why dengue in endemic areas with multiple circulating serotypes is particularly dangerous. ### Clinical Pearl In a child with dengue presenting with shock, always ask: "Is this the first dengue infection or a second one?" Secondary dengue with DSS is a medical emergency requiring aggressive fluid resuscitation and close monitoring for complications. ### Mnemonic: Dengue Severity Markers — **CRASH** - **C**ritical phase (days 3–7, post-defervescence) - **R**ising hematocrit (>20% increase = plasma leakage) - **A**lert for thrombocytopenia (<100,000) - **S**hock (hypotension, narrow pulse pressure) - **H**emorrhage (GI bleed, mucosal bleeding)