Dengue in Children
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Direct answer
Defervescence, not the fever itself, is the dangerous moment in dengue: as fever settles over days three to seven, plasma leakage begins, and the child with abdominal pain, persistent vomiting, restlessness, tender hepatomegaly, mucosal bleeding or a rising haematocrit with falling platelets has entered the critical 24-48 hours when shock can develop. Dengue haemorrhagic fever requires all four of fever, haemorrhagic manifestations (positive tourniquet test counts), platelets at or below 100,000 per microlitre and plasma leakage shown by a haematocrit rise of 20 per cent or more, effusion or ascites; grade III-IV shock with pulse pressure 20 mmHg or less needs rapid isotonic crystalloid resuscitation. Management is fluid choreography — oral rehydration for warning-sign-free cases, careful isotonic intravenous fluid during the leak phase, and active de-escalation during recovery — while aspirin and NSAIDs are avoided and platelets are transfused only for bleeding.
What you must remember
- Three phases: febrile (2-7 days), critical (24-48 hours around defervescence when capillary leakage peaks), recovery (reabsorption, convalescent rash, bradycardia, haemodilution).
- Warning signs mandating immediate review: abdominal pain, persistent vomiting, clinical fluid accumulation (right pleural effusion, ascites), mucosal bleeding, lethargy or restlessness, tender hepatomegaly, and rising haematocrit with falling platelets.
- DHF 1997 criteria: fever plus haemorrhage (positive tourniquet test is sufficient) plus platelets ≤100,000/microlitre plus leakage (haematocrit rise ≥20 per cent, or effusion/ascites/hypoalbuminaemia); grades I-II without and III-IV with shock — grade III: pulse pressure ≤20 mmHg with palpable pulse; grade IV: impalpable pulse, unrecordable blood pressure.
- Tests by day: NS1 antigen in the first five days, IgM ELISA from about day five; a negative early test excludes nothing — serial haematocrit and platelet trends carry more weight than any single report.
- Fluid plans: Plan A — oral fluids and paracetamol at home; Plan B — isotonic crystalloid at maintenance-plus for warning signs; Plan C — immediate 10-20 mL/kg isotonic bolus for shock, repeated with reassessment, colloid if refractory, then judicious maintenance.
- Monitoring bundle: hourly pulse and blood pressure (narrowing pulse pressure is the earliest shock signal), haematocrit every 6-12 hours, urine output at least 0.5-1 mL/kg/hour, mental state; over-transfusion in recovery floods the lungs.
- Absolute avoidances: aspirin and NSAIDs (bleeding and Reye risk — paracetamol alone), platelet transfusion for the count alone, prophylactic antibiotics, and discharge at defervescence without observation.
- Recovery physiology: the leak stops, extravascular fluid returns to circulation — falling haematocrit with stable haemodynamics and diuresis means recovery, not bleeding; reduce intravenous fluids promptly.
A five-day admission in one paragraph
A nine-year-old presents on day four of fever with retro-orbital pain, myalgia and a positive tourniquet test; platelets are 90,000 and haematocrit 36 per cent. Fever settles that evening — the exact hour the family relaxes is the hour to intensify observation. Overnight she vomits twice, has right-sided abdominal pain and becomes quietly restless: haematocrit climbs to 44 (a 22 per cent rise), platelets fall to 55,000, and a chest film shows a right pleural effusion — warning signs becoming severe. Start Plan B isotonic crystalloid, monitor hourly, and confiscate the grandmother's NSAIDs. If the pulse pressure narrows to 18 mmHg with cool extremities, give the first 20 mL/kg crystalloid bolus over 15-30 minutes and reassess, repeating once rather than flooding blindly. By day six urine output surges, the haematocrit drifts down and a confluent convalescent rash with sinus bradycardia appears — cut the intravenous rate, let the child eat, and discharge only after 24 hours of stable haemodynamics off fluids. Nothing in this paragraph needed platelet transfusion; everything needed a blood pressure cuff.
Where students slip
The national obsession is the platelet count, but the exam's obsession is the haematocrit — leakage, not thrombocytopenia, kills, and a normal platelet count on day three means nothing about day five. Second: discharging at defervescence, precisely when the critical phase begins — a child with falling fever is a child to examine more often. Third: interpreting a recovering child's falling haematocrit as gastrointestinal bleeding and transfusing whole blood — with a well-perfused, diuresing child, haemodilution is the expected physiology.
Frequently asked questions
What are the warning signs of severe dengue?
Abdominal pain, persistent vomiting, fluid accumulation, mucosal bleeding, lethargy or restlessness, tender hepatomegaly, and rising haematocrit with falling platelets — any one demands immediate clinical review.
What four criteria define dengue haemorrhagic fever?
Fever, haemorrhagic manifestations (a positive tourniquet test qualifies), platelet count at or below 100,000 per microlitre, and objective plasma leakage such as a haematocrit rise of 20 per cent or more.
How is dengue shock resuscitated?
Rapid isotonic crystalloid 10-20 mL/kg over 15-30 minutes with reassessment, colloid for refractory shock, then titrated maintenance as perfusion recovers.
Why are aspirin and NSAIDs contraindicated in dengue?
They impair platelet function and increase bleeding risk, and aspirin adds Reye syndrome risk in children; paracetamol is the only antipyretic used.
When does NS1 antigen testing become unhelpful?
After about day five, when antigen levels fall and IgM becomes the better test — a negative NS1 never overrides the clinical picture.