June 24, 2025, 9:18 am | Read time: 5 minutes
At first glance, Kawasaki disease appears to be a harmless childhood illness characterized by fever, rash, and red eyes. However, this is precisely what makes it dangerous: If not promptly diagnosed and treated, it can cause serious damage to the heart, particularly to the coronary arteries that supply blood to the heart muscle.
Even though Kawasaki disease (also known as Kawasaki syndrome or mucocutaneous lymph node syndrome) is generally rare, it is still the most common acquired heart disease in childhood. FITBOOK editor Michel Winges explains what parents should watch for—and what is crucial in diagnosis and treatment.
Overview
What is Kawasaki Disease?
Kawasaki disease is an inflammatory vascular disease of unclear origin that primarily occurs in early childhood. It particularly affects medium-sized arteries, especially the coronary arteries, which supply the heart muscle.1 The disease usually begins suddenly with a high fever lasting at least five days. It is accompanied by symptoms such as red eyes, inflamed mucous membranes, skin rashes, and swelling of the hands and feet.
Origin of the Name
Kawasaki disease is named after a Japanese pediatrician, Dr. Tomisaku Kawasaki. He first described the disease in 1967 in Tokyo after observing unusual symptoms such as fever, rash, and swollen lymph nodes in several children that could not be attributed to any known illness. His discovery was initially controversial. However, he is now recognized as the first to identify the syndrome named after him as a distinct disease. Interestingly, the diagnostic criteria have changed little since Kawasaki’s initial description. The disease is still most frequently diagnosed in Japan, but the reasons for this are not yet fully understood.
Who is Affected?
Kawasaki syndrome primarily affects children between six months and five years old. Statistically, boys are about 50 percent more likely to be affected than girls. It is suspected that hormonal or immunological factors play a role, although the exact causes have not yet been conclusively determined.2
In Germany, the incidence rate is about five to ten new cases per 100,000 children under five years old, making it the most common acquired heart disease in childhood. Infants under six months are less frequently affected but often show atypical or incomplete courses, increasing the risk of complications.
Kawasaki Disease in Adults
Although Kawasaki disease is primarily considered a pediatric condition, it has been diagnosed in very rare cases in adults. Diagnosing adults is often challenging because the disease is rarely considered outside of childhood.3
Symptoms and Course of Kawasaki Syndrome
Kawasaki often begins unremarkably but can become dangerous. The disease typically progresses in three phases, with the main symptom being a high fever lasting at least five days that does not respond to antibiotics.4 Upon closer examination, a distinctive symptom complex emerges that differs from common childhood illnesses.
Acute Phase (Day 1 to Day 10)
- Sudden, high fever
- Dry, intensely red conjunctiva (without pus)
- Cracked, bright red lips (“lacquer lips”), strawberry tongue
- Swelling and redness of hands and feet
- Rash (usually on the trunk)
- Unilateral, painless swelling of the neck lymph nodes
Subacute Phase (Begins Around Day 10)
- Peeling of the skin on the fingertips and toes
- Thrombocytosis (high platelet count)
- Onset of possible changes in the coronary arteries (coronary aneurysms)
Convalescent Phase (From the Third Week)
- Reduction of symptoms
- Fatigue, slow normalization of blood values
- Heart complications remain possible
Not all children show the full range of symptoms. Particularly in infants, an “incomplete Kawasaki syndrome” may be present, which is often harder to recognize and carries an increased risk of complications.
How is the Diagnosis Made?
Kawasaki disease is primarily recognized by external signs, as there is no specific blood test for it. It is important that the child has a high fever for at least five days and at least four of five typical signs: red eyes without pus, red and cracked lips or a “strawberry tongue,” rash, swollen or red hands and feet, and swollen but painless lymph nodes in the neck. Blood tests often show elevated inflammation levels. An ultrasound examination of the heart (echocardiography) is particularly important to detect early problems in the heart vessels. Especially in small babies, careful and continuous observation is crucial, as not all symptoms may appear simultaneously.
How Dangerous is Kawasaki Syndrome?
The greatest danger lies in so-called coronary aneurysms—balloon-like enlargements of the coronary arteries that can occur due to a weakening of the vessel wall. They develop when the inflammation attacks and weakens the vessel walls. Without treatment, about a quarter of affected children develop coronary aneurysms. The risk: blood clots, circulatory disorders, or even a heart attack can occur—even in childhood.
While Kawasaki disease is generally rare, it is considered the most common acquired heart disease in childhood in industrialized countries. If the syndrome is detected and treated early, the risk of heart complications drops to less than five percent.
In the long term, the prognosis strongly depends on the timing of treatment. In most cases, children recover completely. In severe cases, especially with large aneurysms, lifelong cardiological follow-up may be necessary.
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The Treatment
It is crucial that treatment begins as early as possible—ideally within the first ten days after symptoms start. Intravenous immunoglobulins are used to help the body control the inflammation more quickly and prevent severe heart problems. Additionally, acetylsalicylic acid (ASA) is administered—first in high doses to combat fever and inflammation, later in lower doses to keep the blood thin. In difficult cases, when standard therapy is insufficient, corticosteroids or other medications may be necessary. It is important that the heart is regularly monitored by ultrasound to detect potential damage early.