Kawasaki Disease: Causes, Symptoms and Treatment

What is Kawasaki Disease?

Kawasaki disease (also known as Kawasaki syndrome or mucocutaneous lymph node syndrome) is an acute, self-limiting systemic vasculitis -- an inflammation of blood vessels -- that primarily affects children under the age of five. It was first described in 1967 by Japanese pediatrician Tomisaku Kawasaki. Today, it is recognized as the leading cause of acquired heart disease in children in developed countries. The most dangerous complication is involvement of the coronary arteries, which can lead to aneurysms -- abnormal bulging or widening of the vessel walls.

Causes

The exact cause of Kawasaki disease remains unknown. Current evidence suggests an interplay between genetic predisposition and an infectious trigger that provokes an abnormal immune response. Key factors under investigation include:

• Infections: Various viruses and bacteria (e.g., adenoviruses, staphylococci) have been proposed as potential triggers.
• Genetic predisposition: Children of Asian descent, particularly from Japan and Korea, are disproportionately affected.
• Immune dysregulation: Excessive activation of the immune system leads to widespread vascular inflammation.

Symptoms

Kawasaki disease typically progresses through three clinical phases. Diagnosis is based on the presence of fever and characteristic principal features:

Principal Diagnostic Criteria

• Prolonged high fever lasting five or more days (above 38.5 °C / 101.3 °F), unresponsive to antibiotics
• Conjunctivitis: Bilateral, non-purulent (without discharge) reddening of the eyes
• Changes of the lips and oral mucosa: Red, cracked lips, strawberry tongue, reddened throat lining
• Skin rash: Polymorphous erythematous rash on the trunk
• Changes of the extremities: Redness and swelling of the hands and feet, followed by peeling of the fingertips
• Cervical lymphadenopathy: Enlarged lymph nodes in the neck (usually unilateral, diameter greater than 1.5 cm)

Additional Possible Symptoms

• Irritability and restlessness
• Abdominal pain, diarrhea, vomiting
• Joint pain (arthralgia)
• Cardiac arrhythmias or myocarditis (inflammation of the heart muscle)

Diagnosis

There is currently no specific laboratory test for Kawasaki disease. Diagnosis is made clinically and requires fever lasting at least five days plus at least four of the five principal criteria. The following investigations support the diagnosis:

• Blood tests and inflammatory markers: Elevated CRP, ESR, and leukocytosis indicate systemic inflammation.
• Echocardiography: Ultrasound examination of the heart to assess the coronary arteries; this is the most critical diagnostic tool.
• Urinalysis: Sterile pyuria (white blood cells in urine without bacterial infection) may be present.
• ECG: To evaluate potential cardiac arrhythmias.

Children who do not fulfill all criteria may still have incomplete Kawasaki disease, which should be treated equally promptly.

Treatment

Early treatment is essential to prevent complications, particularly coronary artery aneurysms. Standard therapy includes:

Intravenous Immunoglobulin (IVIG)

High-dose intravenous immunoglobulin (2 g/kg body weight as a single infusion) is the most effective treatment and significantly reduces the risk of coronary artery aneurysms. It should be administered within the first 10 days of illness.

Aspirin (Acetylsalicylic Acid)

Aspirin is used at high doses during the acute phase for its anti-inflammatory effect and later continued at low doses as an antiplatelet agent to reduce the risk of thrombosis in patients with existing aneurysms.

Additional Treatment Options

• Corticosteroids: Used as an adjunct in cases resistant to IVIG.
• Infliximab or ciclosporin: Considered in refractory cases.
• Anticoagulation therapy: Indicated for large coronary aneurysms to prevent clot formation.

Prognosis and Outlook

With timely treatment, most children recover fully. Without therapy, approximately 20-25% of patients develop coronary artery aneurysms, which may lead to heart attacks. Children with persistent coronary artery changes require long-term cardiac follow-up. Mortality in developed countries is below 0.1%.

References

1. Newburger J. W. et al. - Diagnosis, Treatment, and Long-Term Management of Kawasaki Disease: A Scientific Statement for Health Professionals from the American Heart Association. Circulation, 2004; updated 2017.
2. McCrindle B. W. et al. - Kawasaki Disease: A Comprehensive Review of Pathophysiology and Recommended Therapy. Journal of the American College of Cardiology, 2020.
3. World Health Organization (WHO) - Kawasaki disease overview and global epidemiology. www.who.int