Why does a child with a 40 °C fever, retro‑orbital pain and thrombocytopenia feel cold, and what is the appropriate immediate management?

Why a Child with 40°C Fever Feels Cold

This child is experiencing rigors (shivering and feeling cold) because the hypothalamic temperature set-point has been elevated by pyrogens, making the current body temperature feel "too cold" relative to the new set-point—this is the rising phase of fever and indicates the body is actively generating heat to reach the elevated set-point. 1, 2

Pathophysiology of Fever and Chills

The sensation of feeling cold despite a 40°C fever occurs through a specific thermoregulatory mechanism:

• Endogenous pyrogens reset the hypothalamic set-point upward by inhibiting warm-sensitive neurons in the preoptic area of the anterior hypothalamus, which normally facilitate heat loss and suppress heat production 1, 2

• When the set-point is elevated above current body temperature, the hypothalamus interprets the body as "too cold" and activates cold-defense mechanisms including vasoconstriction (decreasing heat loss) and shivering (increasing metabolic heat production) 1, 2

• The child subjectively feels cold because peripheral vasoconstriction reduces skin temperature and the central nervous system perceives a temperature deficit relative to the new elevated set-point 1

• This represents the ascending phase of fever, during which shivering can markedly increase heart rate and cardiac output 1

Clinical Context: Dengue Fever

Given the presentation of 40°C fever, retro-orbital pain, and thrombocytopenia, this clinical picture is highly consistent with dengue fever:

• Retro-orbital pain is a classic feature of dengue and other arboviral infections, distinguishing it from common bacterial infections 3

• Thrombocytopenia with high fever raises concern for dengue hemorrhagic fever or dengue shock syndrome, which can progress rapidly 3

• The combination of these three findings (high fever, retro-orbital pain, thrombocytopenia) should trigger immediate evaluation for dengue and other hemorrhagic fevers 3

Immediate Management Priorities

The immediate management must address both the fever mechanism and the underlying serious infection:

1. Assess for Shock and Severe Disease

• Evaluate for signs of shock immediately: altered consciousness, respiratory distress, signs of dehydration, persistent vomiting, or petechial/purpuric rash 3
• Check vital signs including blood pressure to identify early compensated shock 3
• Assess hydration status carefully, as dengue can cause plasma leakage leading to hypovolemic shock 3

2. Fever Management

• Treat fever aggressively with antipyretics (acetaminophen 15 mg/kg every 4-6 hours), as fever >38°C adversely influences recovery from illness 4, 5
• Avoid aspirin and NSAIDs due to thrombocytopenia and bleeding risk in suspected dengue 5
• Do NOT use aggressive external cooling (ice baths, cold immersion) in this context—the child has fever (regulated hyperthermia), not heat stroke (unregulated hyperthermia) 4

3. Diagnostic Workup

• Obtain complete blood count with differential to quantify thrombocytopenia and assess hematocrit (hemoconcentration suggests plasma leakage) 3, 6
• Check inflammatory markers (CRP, ESR) and comprehensive metabolic panel including liver function tests 6
• Blood culture before antibiotics if bacterial co-infection is suspected 6
• Dengue serology and/or PCR if available and epidemiologically appropriate 6

4. Supportive Care

• Ensure adequate hydration with oral fluids if the child can tolerate, or IV fluids if signs of dehydration or shock 3
• Monitor for warning signs of severe dengue: persistent vomiting, severe abdominal pain, bleeding, lethargy, liver enlargement, rising hematocrit with falling platelets 3

Critical Red Flags Requiring Immediate Intervention

Instruct parents to return immediately or activate emergency services if the child develops:

• Altered consciousness or severe lethargy 3
• Respiratory distress or hypoxia 3
• Signs of dehydration (decreased urine output, dry mucous membranes, poor skin turgor) 3
• Persistent vomiting preventing oral intake 3
• Petechial or purpuric rash suggesting hemorrhagic complications 3
• Severe abdominal pain which may indicate plasma leakage or hepatomegaly 3

Common Pitfalls to Avoid

• Do not dismiss the "feeling cold" as paradoxical—it is the expected physiologic response during the rising phase of fever and does not require aggressive external cooling 1, 2

• Do not use cold-water immersion or ice packs as recommended for heat stroke—this child has fever (regulated), not heat stroke (dysregulated), and such measures will cause extreme discomfort and shivering without benefit 4

• Do not delay evaluation for serious bacterial infection despite suspected viral etiology—the presence of one viral infection does not preclude coexisting bacterial infection 6

• Do not give aspirin or NSAIDs in the setting of thrombocytopenia and suspected dengue due to bleeding risk 5