Kawasaki disease causes inflammation of blood vessels (vasculitis) throughout the body.
Kawasaki disease causes inflammation in the walls of blood vessels throughout the body. The cause is unknown, but evidence suggests a virus or other infectious organism triggers an abnormal immune system response in genetically predisposed children. Inflammation of blood vessels in the heart causes the most serious problems. The inflammation also can spread to other parts of the body such as the pancreas and kidneys.
Most children with Kawasaki disease range in age from 1 to 8 years, although infants and adolescents can be affected. Roughly twice as many boys as girls are affected. The illness is more common among children of Japanese descent. Several thousand cases of Kawasaki disease are estimated to occur in the United States every year.
The illness begins with fever—usually above 102° F (38.9° C)—which rises and falls over 1 to 3 weeks. Within a day or two, the eyes become red but without any discharge. Within 5 days, a red, often patchy rash usually appears over the trunk, around the diaper area, and on mucous membranes, such as the lining of the mouth or vagina. The child has a red throat; reddened, dry, cracked lips; and a strawberry-red tongue. Also, the palms and soles turn red or purplish red, and the hands and feet often swell. The skin on the fingers and toes begins to peel about 10 days after the illness starts. The lymph nodes in the neck are often swollen and slightly tender. The illness may last from 2 to 12 weeks or longer.
About 50% of children develop problems involving the heart, such as a rapid or irregular heart beat, usually beginning 1 to 4 weeks after the illness starts. If untreated, half of the children with heart problems (about 1 in 5 overall) develop the most serious heart problem, a bulge in the wall of a coronary artery (coronary artery aneurysm). These aneurysms can rupture or provoke a blood clot, leading to a heart attack and sudden death.
Other problems include painful inflammation of the tissues lining the brain (meningitis), ears, eyes, liver, joints, urethra, and gallbladder. These symptoms eventually resolve without causing permanent damage.
Doctors diagnose Kawasaki disease when children have at least 4 out of 5 predefined symptoms (see How Do Doctors Diagnose Kawasaki Disease?). Blood tests and cultures of the blood and throat are also done to rule out other disorders that cause similar symptoms (such as measles, scarlet fever, and juvenile idiopathic arthritis). Doctors who specialize in treating children's heart disorders (pediatric cardiologists) or infectious diseases are often consulted.
Once Kawasaki disease is diagnosed, children have electrocardiography (ECG) and ultrasonography of the heart (echocardiography) to look for coronary artery aneurysms, leaking heart valves, inflammation of the sac that surrounds the heart (pericarditis), or inflammation of the heart muscle (myocarditis). Sometimes abnormalities do not appear right away, so these tests are repeated 2 to 3 weeks, 6 to 8 weeks, and perhaps 6 to 12 months after symptoms began. If ECG or echocardiography tests are abnormal, doctors may do a stress test (see Stress Testing). If an aneurysm is seen during echocardiography, children may have heart catheterization (see Cardiac Catheterization and Coronary Angiography).
Children recover completely if their coronary arteries are not affected within the first 8 weeks of illness. For children with coronary artery problems, the outcome varies with the severity of disease, but with early treatment, almost no children with Kawasaki disease in the United States die. Without treatment, the death rate is about 1%. Of the children who die, death nearly always occurs in the first 6 months but can occur as long as 10 years later. About two thirds of the aneurysms resolve within 1 year. Large aneurysms are less likely to resolve. However, even when aneurysms resolve, children have an increased risk of heart problems in adulthood.
Treatment given within the first 10 days of symptoms significantly reduces the risk of coronary artery damage and speeds the resolution of fever, rash, and discomfort. For 1 to 4 days, high doses of immune globulin are given by vein, and high doses of aspirin are given by mouth. As soon as the child has no fever for 4 to 5 days, the dose of aspirin is lowered and continued until at least 8 weeks from the beginning of illness. If there are no coronary artery aneurysms and signs of inflammation are gone, aspirin may be stopped. However, children with coronary artery abnormalities require continuous and long-term treatment with aspirin.
Because aspirin use increases the risk of Reye syndrome (see Reye Syndrome) in children who have influenza or chicken pox, doctors give children on long-term aspirin therapy an annual influenza vaccination (by injection, not by nasal spray). If children are exposed to or contract influenza or chickenpox, dipyridamole is sometimes temporarily used instead of aspirin to lessen the risk of Reye syndrome.
Children with large coronary aneurysms may be treated with drugs that prevent the blood from clotting (anticoagulants) such as warfarin or dipyridamole.
Last full review/revision October 2012 by Elizabeth J. Palumbo, MD