Overview

Kawasaki disease is a rare but serious illness that primarily affects young children. It causes inflammation in the walls of blood vessels throughout the body and is the leading cause of acquired heart disease in children in developed countries. Although most common in children under five years of age, older children and, very rarely, adults can also develop the condition.

The disease is named after Dr. Tomisaku Kawasaki, who first described it in Japan in 1967. Despite decades of research, the exact cause of Kawasaki disease remains unknown. However, early diagnosis and treatment are critical to prevent serious complications, especially those involving the heart.

Early Symptoms

Kawasaki disease develops in three distinct stages, each with its own set of symptoms. Recognizing these signs early can help ensure timely treatment.

Acute Phase (Week 1-2)

  • Persistent fever above 102.2°F (39°C) lasting more than five days

  • Bloodshot eyes without discharge (conjunctival injection)

  • Red, cracked lips and a "strawberry tongue" (red with enlarged taste buds)

  • Swelling and redness in the hands and feet

  • Rash, particularly on the torso and genital area

  • Swollen lymph nodes in the neck

Subacute Phase (Week 2-4)

  • Peeling skin around the nails, hands, and feet

  • Joint pain and swelling

  • Diarrhea, vomiting, or abdominal pain

  • Irritability and fatigue

Convalescent Phase (Week 4+)

  • Symptoms begin to resolve

  • Beau's lines (horizontal ridges on nails)

  • Gradual return to normal energy levels

Causes and Risk Factors

The precise cause of Kawasaki disease is still unclear. However, experts believe it involves a combination of genetic susceptibility and environmental triggers.

Possible Factors Include:

  • Immune System Response: An exaggerated immune reaction to an infection may trigger the disease.

  • Genetics: Certain gene variants (such as in the ITPKC gene) increase risk.

  • Ethnicity: It is more common in children of East Asian descent, particularly Japanese and Korean.

  • Age: 80% of cases occur in children younger than five.

  • Sex: Boys are more frequently affected than girls.

  • Family History: A child with a sibling or parent who had Kawasaki disease is at greater risk.

Kawasaki disease is not contagious and does not spread from person to person.

Diagnosis

There is no specific test to diagnose Kawasaki disease. Healthcare providers rely on clinical criteria and supportive tests to make the diagnosis.

Typical Diagnostic Steps:

  • Physical Exam: To identify the key signs (fever, rash, swelling, etc.)

  • Blood Tests: To assess white blood cell count, platelet levels, and markers of inflammation (e.g., ESR, CRP)

  • Urine Tests: To rule out other possible infections

  • Echocardiogram (ECG): To check for heart involvement, especially coronary artery abnormalities

  • Electrocardiogram (EKG): To monitor heart rhythm and detect possible myocarditis

Treatment Options

Prompt treatment within 10 days of symptom onset significantly reduces the risk of long-term heart problems.

Primary Treatments Include:

  • Intravenous Immunoglobulin (IVIG): A high-dose IV infusion of antibodies that reduces inflammation and the risk of heart complications.

  • Aspirin Therapy: Initially given in high doses to reduce inflammation and fever, then in lower doses to prevent clot formation.

Additional or Adjunctive Treatments:

  • Corticosteroids: May be used in children who don't respond to IVIG or are at high risk for complications.

  • Anti-inflammatory Drugs: Such as infliximab in select cases.

  • Ongoing Monitoring: Regular echocardiograms may be required for months or even years if coronary artery changes are found.

Possible Complications

If left untreated, Kawasaki disease can cause serious and potentially life-threatening complications:

  • Coronary Artery Aneurysms: Abnormal bulging of blood vessels that can lead to blood clots or heart attacks.

  • Myocarditis: Inflammation of the heart muscle.

  • Heart Valve Problems: Especially mitral or aortic regurgitation.

  • Arrhythmias: Irregular heart rhythms that can disrupt blood flow.

Even with treatment, around 5% of children may develop coronary artery complications and require long-term cardiac care.

Kawasaki and MIS-C

Since the COVID-19 pandemic, a related condition called Multisystem Inflammatory Syndrome in Children (MIS-C) has emerged. MIS-C shares many features with Kawasaki disease but tends to affect older children and may involve more severe cardiac involvement. Both conditions are thought to involve immune system overreactions and benefit from similar treatment strategies like IVIG and steroids.

Living With Kawasaki Disease

Most children recover completely from Kawasaki disease with appropriate treatment. However, follow-up care is crucial to monitor for any lasting cardiac effects.

Recovery Tips and Considerations:

  • Follow-Up Appointments: Children need regular cardiac check-ups for at least a year after diagnosis.

  • Emotional Support: Irritability and fatigue may linger, requiring patience from caregivers.

  • Activity Restrictions: In cases with coronary artery involvement, physical activity may need to be limited.

  • Medication Management: Long-term low-dose aspirin may be required to prevent clot formation.

When to See a Doctor

You should contact a healthcare provider if your child experiences:

  • A fever lasting more than five days

  • Rash and red eyes

  • Swollen hands or feet

  • Cracked lips or red tongue

  • Signs of irritability and lethargy

Prompt diagnosis and treatment can drastically reduce the chances of complications.

Summary

Kawasaki disease is an acute, self-limiting vasculitis that primarily affects children. Early treatment is critical to avoid complications, especially involving the heart. Though the cause remains unknown, effective therapies like IVIG and aspirin allow most children to recover fully. Ongoing research and awareness continue to improve outcomes and understanding of this condition.