Dengue fever in children

Overview

Dengue is a mosquito-borne viral infection that has become a major public health problem in tropical and subtropical cities, including in South Asia, where cases typically peak after the monsoon (Park). Most infections are mild, but dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS) are leading causes of admission and death among children in endemic areas. Good outcomes depend on spotting plasma leakage early and giving just enough fluid.

Aetiology

• Dengue virus: an RNA flavivirus (family Flaviviridae) with four serotypes, DENV-1, 2, 3 and 4.
• Infection with one serotype gives lifelong immunity to that serotype but only brief, partial cross-protection against the others.

Transmission

• Aedes aegypti (and Aedes albopictus): a day-biting, domestic mosquito that breeds in clean stored water, water tanks, flower pots, discarded tyres and plastic containers that collect rain.
• The mosquito picks up the virus from a person during the viraemia (about 2-7 days, matching the fever).
• After an extrinsic incubation of 8-10 days in the mosquito, it stays infective for life and can pass the virus to its eggs (transovarial transmission).
• Humans are the main amplifying host. There is no direct person-to-person spread.

Pathogenesis

• Secondary infection with a different serotype is the main risk factor for severe disease. Non-neutralising antibodies from the first infection help the new virus enter monocytes (antibody-dependent enhancement), releasing cytokines and vasoactive substances.
• The result is increased capillary permeability with plasma leakage into pleural and peritoneal spaces, haemoconcentration and, if severe, shock.
• Haemostasis is disturbed: thrombocytopenia, vasculopathy and coagulopathy, sometimes DIC.

Clinical features

Incubation: Park gives 3-10 days (commonly 5-6); Akbar gives 1-7 days.

Dengue fever (classical)

• Sudden high fever (often 39-40 °C), severe headache, pain behind the eyes, muscle, joint and bone pains ("breakbone fever"), flushed face, nausea, vomiting, abdominal pain.
• Rash: early flushing, then a maculopapular or scarlatiniform rash around days 3-4.
• Fever may be biphasic (saddle-back): a brief remission then a second spike.
• Infants and young children often have only a non-specific fever with rash, resembling other viral illnesses.
• Mild bleeding (petechiae, gum or nose bleeds) can occur.

The three phases of dengue

Warning signs (need admission)

• Abdominal pain or tenderness
• Persistent vomiting
• Clinical fluid accumulation (effusion, ascites)
• Mucosal bleeding (gums, nose, gut)
• Lethargy or restlessness
• Liver enlargement over 2 cm
• Rising haematocrit with a rapid fall in platelets
• Low urine output (no urine for 4-6 hours)

Dengue shock

• Early (compensated) shock: tachycardia, cold extremities, delayed capillary refill, weak pulse, restlessness, while the child is often alert and the systolic pressure is normal.
• The diastolic pressure rises towards the systolic: a narrow pulse pressure of 20 mmHg or less (for example 100/80) means shock in a child.
• Late: hypotension, then unrecordable pressure; acidosis, DIC, major bleeding and organ failure.

Classification

WHO criteria for DHF (Park, Akbar)

All of:

1. Fever of 2-7 days (or biphasic).
2. Haemorrhagic tendency: positive tourniquet test, petechiae, bruising, mucosal or gut bleeding.
3. Thrombocytopenia: platelets 100,000/mm3 or less.
4. Plasma leakage: haematocrit rise of 20% or more from baseline, or pleural effusion, ascites or low albumin.

Grades

Grades III and IV = dengue shock syndrome.

Newer WHO terms group cases as dengue without warning signs, dengue with warning signs and severe dengue (severe leakage with shock or breathlessness, severe bleeding, or severe organ damage such as hepatitis, encephalitis or myocarditis).

Tourniquet test

• Inflate a BP cuff midway between systolic and diastolic pressure for 5 minutes.
• Positive: 10 or more petechiae per square inch (2.5 × 2.5 cm); in DHF usually 20 or more.

Investigations

Differential diagnosis

Other dengue-like viral fevers, influenza and other viral respiratory illnesses, and early malaria (Akbar); typhoid in a child with prolonged fever.

Management

Dengue fever without warning signs (home care)

• Paracetamol for fever and pain, at least 6 hours apart; tepid sponging.
• Do not give aspirin, ibuprofen or other NSAIDs, or steroids: they worsen bleeding and gastritis.
• Plenty of oral fluids: ORS, juices, soups.
• Daily review (temperature, fluid intake, urine output, warning signs, haematocrit and platelets).
• Tell parents to return at once if warning signs appear, especially as the fever falls.

Admission

Admit children with warning signs, any feature of DHF or shock, inability to drink, infants, and those with high-risk conditions (for example haemoglobin disorders, heart disease, obesity).

DHF without shock (grades I-II)

Park's WHO-based scheme:

1. Start IV crystalloid (normal saline or Ringer's lactate) at about 6 ml/kg/hour for 1-2 hours.
2. If improving (haematocrit falls, pulse and blood pressure stable, urine output rises): reduce stepwise to 3 ml/kg/hour and stop after about 24 hours.
3. If not improving: increase to 10 ml/kg/hour; then consider colloid (for example dextran) or blood if the haematocrit falls (bleeding).

Dengue shock (grades III-IV)

• Emergency: oxygen, rapid IV crystalloid bolus (larger volumes in profound shock), reassessing after each bolus.
• Change to colloid if shock persists despite crystalloid with a high haematocrit.
• If the haematocrit falls while shock persists, suspect internal bleeding and give fresh whole blood about 10 ml/kg.
• Monitor vital signs, urine output and haematocrit frequently; reduce fluids as soon as the child stabilises.
• Correct electrolytes and acidosis; manage DIC.

Platelets and blood

• Prophylactic platelet transfusion is not recommended, even with very low counts, if there is no significant bleeding.
• Transfuse red cells or whole blood for significant bleeding or refractory shock with a falling haematocrit.

Complications

• Shock and multi-organ failure; DIC; severe bleeding (gut).
• Fluid overload: respiratory distress, pulmonary oedema.
• Encephalopathy or encephalitis, febrile convulsions, hyperpyrexia.
• Hepatitis and liver failure, myocarditis.
• Electrolyte disturbance, hypoglycaemia.

Prognosis

• Dengue fever: excellent.
• DHF: good with early recognition and careful fluids; delayed or wrong treatment raises mortality. Akbar notes that untreated shock can carry very high mortality (40-50%).

Prevention

• Vector control is the main method: remove or cover stored water, empty containers and tyres, cover water tanks, and use chemical control during outbreaks.
• Personal protection against daytime bites: long sleeves, repellents, screens and bed nets (also for daytime sleep), especially for patients during the febrile phase so mosquitoes do not pick up the virus.
• National dengue guidance in Pakistan changes with each season; check the current national guideline and WHO dengue guidance (checked 8 Nov 2026).

Quick revision

• Flavivirus, DENV 1-4; Aedes aegypti, day-biter, clean stored water.
• Second infection with a new serotype raises DHF risk.
• Critical phase at defervescence (days 3-7); leak lasts 24-48 hours.
• Warning signs: abdominal pain, vomiting, fluid, mucosal bleeding, lethargy, big liver.
• DHF: fever, bleeding tendency, platelets 100,000 or less, haematocrit up 20% or more.
• DSS = grades III-IV; pulse pressure 20 mmHg or less.
• NS1 or PCR early; IgM from day 5.
• Paracetamol only; oral fluids; IV crystalloid titrated to haematocrit and vitals; avoid overload.

Written by The House Job from standard references (Basis of Paediatrics by Pervez Akbar; Park's Preventive and Social Medicine).

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