What is the treatment for a young child under 5 years old diagnosed with Kawasaki disease?

Treatment of Kawasaki Disease in Young Children Under 5 Years

All children diagnosed with Kawasaki disease should be treated immediately with intravenous immunoglobulin (IVIG) 2 g/kg as a single infusion plus high-dose aspirin (80-100 mg/kg/day divided into four doses), ideally within the first 10 days of fever onset. 1

Initial Treatment Protocol

Primary Therapy

• IVIG 2 g/kg should be administered as a single infusion over 10-12 hours 1
• High-dose aspirin 80-100 mg/kg/day divided into four doses for anti-inflammatory effect 1
• This combination reduces coronary artery abnormalities from 15-25% (untreated) to approximately 5% for any abnormality and 1% for giant aneurysms 1

Timing Considerations

• Treatment should be initiated as soon as the diagnosis is established, even before day 5 of fever if classic features are present 1
• Children presenting after day 10 should still receive treatment if they have ongoing systemic inflammation (ESR elevated or CRP >3.0 mg/dL) with persistent fever or coronary artery abnormalities 1
• Do not withhold treatment in children presenting late if inflammation markers remain elevated 1

Aspirin Management Algorithm

Acute Phase

• Continue high-dose aspirin (80-100 mg/kg/day) until 48-72 hours after defervescence OR until day 14 of illness with 48-72 hours afebrile 1

Convalescent Phase

• Transition to low-dose aspirin (3-5 mg/kg/day) as a single daily dose for antiplatelet effect 1
• Continue for 6-8 weeks if no coronary abnormalities are detected 1
• Continue indefinitely if coronary artery abnormalities are present 1

Critical Aspirin Precautions

• Administer annual influenza vaccination to children on long-term aspirin therapy due to Reye's syndrome risk 1
• Instruct parents to contact physician immediately if influenza or varicella symptoms develop 1
• Avoid ibuprofen as it antagonizes aspirin's antiplatelet effect 1

Treatment for Incomplete Kawasaki Disease

Children under 5 years with incomplete (atypical) Kawasaki disease face paradoxically higher rates of coronary aneurysms if untreated, making prompt recognition critical 1

Diagnostic Algorithm for Incomplete Disease

• Children with ≥5 days of fever plus 2-3 clinical criteria should undergo laboratory assessment (CRP, ESR) 1
• If CRP ≥3.0 mg/dL or ESR elevated with compatible clinical features, treat with IVIG and aspirin 1
• Perform echocardiography in all suspected cases; coronary abnormalities with ≥3 clinical features confirms diagnosis and mandates treatment 1
• Infants with ≥7 days of unexplained fever should have laboratory assessment even without KD features; perform echo if inflammation markers are elevated 1

Management of Treatment-Resistant Disease

Approximately 10-15% of patients fail to respond to initial IVIG (persistent or recurrent fever >36 hours after completion) 1, 2

Second-Line Therapy

• Administer a second dose of IVIG 2 g/kg for persistent fever beyond 36 hours after initial treatment 1, 2
• Continue high-dose aspirin throughout 1

Third-Line Options for Multiple IVIG Failures

• Intravenous methylprednisolone pulse therapy 2, 3
• Infliximab (anti-TNF therapy) 2, 3
• Cyclosporine or methotrexate may be considered for patients failing multiple IVIG doses and steroids 4, 2

Cardiac Monitoring Requirements

Acute Phase Echocardiography

• Perform baseline echocardiography at diagnosis to assess for coronary artery dilation, aneurysms, decreased ventricular function, valvular regurgitation, or pericardial effusion 1
• Obtain follow-up echo at 2 weeks and 6-8 weeks after disease onset 1

Long-Term Surveillance

• Frequency and intensity of cardiovascular monitoring depend on presence and severity of coronary abnormalities at diagnosis 5
• Children with persistent coronary abnormalities require lifelong cardiology follow-up 1

Critical Pitfalls to Avoid

• Do not delay treatment waiting for all classic criteria to appear simultaneously; features may evolve over time and careful history-taking is essential 1
• Do not dismiss incomplete presentations in infants <1 year, as they have the highest risk of coronary complications 1
• Do not mistake initial symptoms for antibiotic reactions (rash after treatment for presumed cervical lymphadenitis), partially treated UTI (sterile pyuria), or viral meningitis (CSF pleocytosis in young infants) 1
• Do not withhold IVIG based on risk scores alone; all diagnosed patients should receive treatment regardless of predicted risk 1