Kawasaki disease and follow-up

Kawasaki Disease (Mucocutaneous Lymph Node Syndrome)

Kawasaki disease is an acute, self-limiting systemic vasculitis of medium-sized muscular arteries. It has an extraordinary predilection for the coronary arteries, representing the leading cause of acquired paediatric heart disease in Australia and other developed nations. Approximately 85% of cases occur in children between 6 months and 5 years of age.

Classical Diagnostic Criteria

Kawasaki diagnosis is clinical and can be made with at least four days of fever plus compatible features under the RCH pathway. Experienced assessment can recognise earlier or incomplete disease. Do not wait rigidly for five days when concern is high; involve paediatrics/cardiology and assess coronary involvement.

1. Bilateral Non-Exudative Conjunctival Injection: Painless, diffuse erythema of the bulbar conjunctiva that characteristically spares the limbus (the avascular border surrounding the iris). There is no purulent discharge or corneal ulceration.
2. Oral Cavity and Lip Changes: Erythema, severe drying, cracking, and bleeding fissures of the lips; diffuse erythema of the oropharyngeal mucosa; and a prominent "strawberry tongue" (hyperplastic fungiform papillae protruding through a denuded or erythematous lingual coating).
3. Polymorphous Cutaneous Rash: Widespread maculopapular, erythema multiforme-like, or scarlatiniform eruption predominantly involving the trunk, extremities, and groin; characteristically non-vesicular.
4. Extremity Changes:
   • Acute phase: Marked erythema of the palms and soles with indurative, painful, non-pitting oedema of the dorsum of hands and feet (infant refuses to bear weight).
   • Convalescent phase: Characteristic sheet-like periungual desquamation (peeling around the fingernails and toenails) beginning 2 to 3 weeks after fever onset.
5. Cervical Lymphadenopathy: Typically unilateral, involving the anterior cervical chain, with at least one node measuring $\ge 1.5\text{ cm}$ in diameter; firm, non-fluctuant, and minimally tender.

Incomplete (Atypical) Kawasaki Disease

• Frequently encountered in young infants under 6 months of age, who paradoxically face the highest risk of developing giant coronary aneurysms.
• Incomplete Kawasaki disease: Consider persistent unexplained fever with fewer features, especially in infants. Laboratory and echocardiographic assessment supports the pathway; consult paediatrics/cardiology without waiting rigidly for a calendar threshold.

Cardiac Complications and Management

• Coronary Artery Aneurysms: Untreated Kawasaki disease results in coronary artery aneurysms in 20% to 25% of children. Aneurysms predispose to acute coronary thrombosis, myocardial infarction, and sudden cardiac death. Giant aneurysms (internal diameter $> 8\text{ mm}$ or Z-score $\ge 10$) carry the highest lifetime risk of thrombosis and stenosis.
• First-Line Pharmacotherapy:
  • Intravenous Immunoglobulin (IVIG): Administered as a single high-dose infusion of $2\text{ g/kg}$ over 10 to 12 hours. Must be initiated within the first 10 days of fever onset (and at any time thereafter if fever or systemic inflammation persists). Early IVIG reduces the incidence of coronary artery abnormalities from 25% to under 3% to 5%.
  • Aspirin (Oral): Dual dosing phases in Australia:
• Kawasaki treatment: Senior paediatric/cardiology management includes IVIG 2 g/kg and low-dose aspirin; RCH uses 5 mg/kg daily for thrombosis prevention. Higher acute aspirin doses have not demonstrated improved coronary outcomes, so a mandatory high-dose-then-low-dose regimen is not universal Australian practice. High-risk patients may receive adjunct corticosteroids.
  • Aspirin: RCH uses 5 mg/kg daily, with duration guided by coronary findings and cardiology; avoid a mandatory high-dose acute regimen.
• Transthoracic Echocardiography: Performed at diagnosis (baseline), repeated at 2 weeks, and at 6 to 8 weeks post-presentation to measure coronary internal luminal diameters and calculate body surface area-adjusted Z-scores.

Kawasaki follow-up example

A child has four days of fever, conjunctival injection, oral changes, rash and extremity changes. Arrange senior paediatric/cardiology assessment and echocardiography; do not wait for a fifth fever day if the clinical picture is compelling. Incomplete disease can occur without every feature, especially in younger infants. Treat under the pathway, assess response and arrange coronary follow-up. Persistent fever after initial IVIG needs specialist reassessment of inflammation and alternative diagnoses. Explain aspirin use and bleeding precautions, and check timing of subsequent live vaccines after IVIG using the current immunisation guidance.

Fever response after treatment

If fever returns after initial Kawasaki treatment, reassess with the specialist team for ongoing inflammation, coronary involvement, treatment resistance and alternative diagnoses. Do not automatically repeat the same medicines without reviewing response and risks. Families need a clear follow-up schedule and instructions for deterioration, chest symptoms, persistent fever or poor intake. Echocardiographic assessment and later surveillance are determined by disease course; a normal first scan does not remove every follow-up requirement. Coordinate vaccination advice after IVIG, particularly the timing of live vaccines, using the current Handbook and the dose/indication received.

Primary references (checked 7 October 2026): RCH Kawasaki disease; RCH meningitis/encephalitis.