Severe Dengue

Severe dengue is dengue virus infection with severe plasma leakage causing shock or fluid accumulation with respiratory distress, severe bleeding, or severe organ impairment. It follows the febrile phase, typically on days 3 to 7, as fever falls (critical phase).

• Transmission by Aedes aegypti and A. albopictus; outbreaks occur in coastal Kenya (Mombasa, Lamu) and the north east.
• Risk factors: secondary infection with a different serotype, infancy, older age, pregnancy, obesity, comorbid diabetes, hypertension, asthma and sickle cell disease.

Initial high fever with severe headache, retro orbital pain, myalgia, arthralgia and rash; the critical phase brings persistent vomiting, severe abdominal pain, mucosal bleeding, lethargy, restlessness, liver enlargement and fluid accumulation.

• Shock: cold clammy extremities, narrow pulse pressure (under 20 mmHg), weak rapid pulse, delayed capillary refill, hypotension late.
• Organ involvement: AST or ALT over 1000 U/L, impaired consciousness, myocarditis, acute kidney injury.
• Differential diagnosis: malaria, chikungunya, typhoid, leptospirosis, meningococcaemia, sepsis, Rift Valley fever, yellow fever, other viral haemorrhagic fevers, measles, acute HIV infection, rickettsiosis, influenza.
• Complications: refractory shock, haemorrhage (gastrointestinal, uterine), fluid overload and respiratory failure, acute liver failure, encephalopathy, myocarditis, haemophagocytic syndrome, death.

Combine epidemiology, warning signs and laboratory tests.

• Days 1 to 5: NS1 antigen or dengue RNA PCR; after day 5: IgM and IgG serology.
• Full blood count: leucopenia, thrombocytopenia (under 100 x 10^9/L), rising haematocrit (20 percent or more over baseline); liver enzymes, albumin, creatinine, lactate, glucose, coagulation profile.
• Chest radiograph or ultrasound for pleural effusion and ascites; malaria test; blood cultures.

Careful fluid titration guided by haematocrit, vital signs and urine output.

• Supportive: admit to a high dependency unit, monitor vital signs every 1 to 4 hours, haematocrit every 4 to 6 hours, urine output target 0.5 mL/kg/h or more, glucose; oxygen; avoid intramuscular injections, aspirin and NSAIDs; bed rest.
• Pharmacological: paracetamol 10 to 15 mg/kg every 6 hours (adults 1 g every 6 hours, maximum 3 g daily). Shock: Ringer lactate or 0.9 percent sodium chloride 10 to 20 mL/kg (adults 500 mL) over 15 to 30 minutes, reassess; repeat once or twice. If shock persists with falling haematocrit, give red cells 5 to 10 mL/kg (or whole blood 10 to 20 mL/kg) because of occult bleeding. If haematocrit stays high, give colloid (albumin 5 percent 10 mL/kg) or a second crystalloid bolus. After stabilisation, give crystalloid 5 to 7 mL/kg/h for 1 to 2 hours, then 3 to 5 mL/kg/h for 2 to 4 hours, then 2 to 3 mL/kg/h, and reduce as leakage resolves. Stop IV fluids at 24 to 48 hours of critical phase. Platelet transfusion only for severe bleeding. Furosemide 0.5 to 1 mg/kg IV for fluid overload once shock has resolved. Vitamin K 10 mg IV for liver dysfunction with coagulopathy. Proton pump inhibitor (omeprazole 40 mg IV daily) for gastrointestinal bleeding.
• Procedures: mechanical ventilation for respiratory failure; renal replacement therapy for acute kidney injury; pleural drainage only for refractory effusion.
• Special groups: pregnancy, give isotonic crystalloid in small boluses with reassessment, with obstetric and haematology input, and keep blood available for delivery; infants, 10 mL/kg boluses with care; elderly and cardiac disease, cautious fluids; obesity, dose by ideal weight.
• Red flags: persistent vomiting, abdominal pain, mucosal bleeding, lethargy, narrow pulse pressure, rising haematocrit with falling platelets, oliguria, hepatomegaly, ascites.
• Follow-up: monitor for 24 to 48 hours after fever resolution; discharge when afebrile for 48 hours without antipyretics, haemodynamically stable, platelets rising (over 50 x 10^9/L), good appetite and urine output.