Kawasaki Disease

Overview

Kawasaki disease is an acute systemic vasculitis affecting small and medium-sized vessels predominantly affecting children under 5 years old. It is the leading cause of acquired heart disease in children in developed countries. Kawasaki is often self-limiting, but 20–25% risk of coronary artery aneurysms if untreated ¹.

Anatomy & Physiology

Affects medium-sized muscular arteries, especially coronary arteries. Inflammation involves intima, media, and adventitia of vessels.

Aetiology & Risk Factors

• Unknown cause; likely infectious trigger in genetically susceptible host.
• Suggested triggers: viral infections (e.g. coronavirus, adenovirus), bacterial toxins.
• Risk factors
  • Age < 5 years
  • Asian descent, especially Japanese (2)
  • Male gender
  • Family history of KD

Pathophysiology

• Trigger (e.g., infection) → activates innate immune response
• Cytokine release (e.g. IL-1, IL-6, TNF-α) → systemic inflammation and endothelial injury
• Inflammatory cells infiltrate vascular walls → necrotising arteritis
• Medium-sized arteries (notably coronary) are weakened → aneurysm formation
• Resolution may occur, or in severe cases → thrombosis or myocardial infarction

Clinical Manifestations

Classic (complete) KD:

• High grade fever with 4 of the following:
  • Conjuctivitis (bilateral non purulent)
  • Rash
    • Polymorphous
    • Maculopapular
  • Erythema and oedema of hands or feet
  • Adenopathy (cervical lymphadenopathy)
  • Mucous membranes
    • Dry cracked lips
    • Red tongue
    • Strawberry tongue
• Other findings: Irritability, arthritis, aseptic meningitis, sterile pyuria
• Cardiac: Coronary artery aneurysms (days 7–10), myocarditis, pericardial effusion

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Diagnosis

Clinical diagnosis; no single definitive test.
High grade fever ≥ 5 days (essential) plus ≥4 of 5 principal features:

• Conjunctivitis (bilateral, non-exudative)
• Rash (polymorphous, usually trunk/extremities)
• Oral mucosal changes (cracked lips, strawberry tongue, red oropharynx)
• Extremity changes (erythema, oedema, desquamation)
• Cervical lymphadenopathy (usually unilateral, >1.5 cm)

Investigations:

• ↑ ESR and CRP (often markedly elevated)
• ↑ Platelets (especially after day 7), ↑ WBCs, normocytic anemia
• ↑ ALT/AST, hypoalbuminemia
• Sterile pyuria
• Echocardiogram: baseline and repeat at 2 and 6 weeks to assess coronary arteries
• ECG to detect arrhythmias

Differential diagnosis:

• Scarlet fever (Group A Strep)
• Measles
• Stevens-Johnson syndrome
• Toxic shock syndrome
• Systemic JIA (especially in incomplete KD)
  

Classification

• Classic KD: Fever ≥5 days + ≥4/5 clinical features.
• Incomplete KD: <4 features but compatible lab and echo findings.
• Atypical KD: Unusual presentations (e.g., renal failure, hepatitis, CNS involvement).

Treatment

• IVIG 2 g/kg over 10–12 hours — within first 10 days of illness (3)
• Aspirin: high-dose during acute phase → low-dose until inflammation resolves or longer if coronary changes persist
• Corticosteroids or infliximab in IVIG-resistant cases
• Close cardiology follow-up for coronary monitoring

Complications and Prognosis

Complication

• Cardiac:
  • Coronary artery aneurysms (seen in ~25% if untreated, ~5% with IVIG)
  • Myocarditis, pericarditis, arrhythmia
• Thrombosis and MI from aneurysms
• Recurrent KD (~3%)
• Long-term risk of atherosclerosis

Prognosis

• Excellent if treated early with IVIG.
• Coronary aneurysm regression possible, especially if small.
• Long-term cardiac surveillance may be needed.

References

1. McCrindle BW, Rowley AH, Newburger JW, et al. Diagnosis, treatment, and long-term management of Kawasaki disease: A scientific statement. Circulation. 2017;135(17):e927–e999.
2. Kato H, Sugimura T, Akagi T, et al. Long-term consequences of Kawasaki disease. A 10- to 21-year follow-up study. Circulation. 1996;94(6):1379–1385.
3. Newburger JW, Takahashi M, Gerber MA, et al. Diagnosis, treatment, and long-term management of Kawasaki disease: A statement for health professionals. Pediatrics. 2004;114(6):1708–1733.
4. Singh S, Agarwal S, Bhattad S, et al. Management of Kawasaki disease. Indian J Pediatr. 2016;83(1):77–84.