What is Kawasaki disease?
Kawasaki disease is a serious pediatric illness that causes inflammation of the blood vessels and can damage the coronary arteries of the heart. While its symptoms can mimic many infectious and non-infectious diseases, such as scarlet fever, toxic shock syndrome and measles, it was first recognized as a separate illness in 1967 by Dr. Tomisaku Kawasaki, a Japanese pediatrician. This illness is now the most common cause of acquired heart disease in children in developed nations, and it is diagnosed in approximately 3,500-5,000 children in the U.S. each year. Early detection and diagnosis is critical, as 1 in 4 children with this illness develop heart complications without proper treatment.
Kawasaki disease is often characterized by the following symptoms: fever, rash, swelling of the hands and feet, redness of the eyes, irritation and inflammation of the lips, mouth and throat, and swollen lymph nodes in the neck. The immediate effects of this disease are rarely serious; however, in some cases long-term heart complications such as coronary artery disease may result.
Who gets Kawasaki disease?
Kawasaki disease occurs most commonly among children of Asian ancestry, but it affects children of all racial and ethnic groups. There are about 3,500-5,000 reported cases per year in the U.S. and over 8,000 per year in Japan. This illness commonly affects children under 5 years of age, and the average age is 2 years old. Boys develop this illness more often than girls.
In recent years this illness has occurred in small, local outbreaks and most often in late winter or early spring, but it occurs throughout the year. It is not contagious and does not appear to be hereditary, and it is unusual for more than one child in a family to develop this illness. Because the illness sometimes occurs in outbreaks, it most likely occurs when a specific infectious agent (virus) infects a non-immune child who is genetically susceptible. There is no proven environmental trigger.
How is Kawasaki disease diagnosed?
The diagnosis of Kawasaki disease cannot be made by a single test. There is no true diagnostic laboratory test available. Like other complex diseases (diabetes, cancer, etc.), multiple genetic factors are involved and are only beginning to be identified. A physician will make the diagnosis after carefully examining the child searching for evidence of at least 4 of the 5 clinical features, reviewing a laboratory workup, and eliminating the possibilities of other diseases that can cause similar symptoms.
Kawasaki disease can be diagnosed as "classic" or "typical" when a child has had a fever and at least 4 of the clinical features in combination with changes in the laboratory blood tests, such as an elevated erythrocyte sedimentation rate (ESR) and/or C-reactive protein (CRP) tests.
However, a diagnosis of "atypical" or "incomplete" Kawasaki disease can also be made if a child (often an infant) has a fever plus fewer than four of the clinical features, together with other diagnostic criteria. This is often extremely difficult to diagnose and may result in overdiagnosis or underdiagnosis of Kawasaki disease.