Kawasaki disease causes inflammation of blood vessels throughout the body in children who are under 5 years old.
The cause of Kawasaki disease is unknown but may be triggered by an infection.
Children typically have fever, rash, and a red strawberry tongue, and some develop heart complications that rarely can be fatal.
The diagnosis is based on established criteria.
Children are given immune globulin and aspirin.
With prompt treatment, nearly all children recover.
Kawasaki disease causes inflammation in the walls of blood vessels (vasculitis) throughout the body. 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 are under 5 years of age. Rarely, infants under 4 months of age, adolescents, and adults can develop the disease. Boys are affected slightly more often than girls.
The illness is more common among children of Japanese descent, but it occurs worldwide. In the United States, 4,000 to 5,500 cases of Kawasaki disease occur every year. Kawasaki disease occurs year-round but most often in spring or winter.
The cause of Kawasaki disease is unknown, but evidence suggests an infection triggers an abnormal immune system response in children who have an increased chance of developing the illness because of the genes they have.
Symptoms of Kawasaki Disease
© Springer Science+Business Media
The illness begins with fever that is usually above 100.4° F (38° C) and lasts at least 5 days . The child's temperature does not return to normal even when medications that lower the temperature (such as acetaminophen and ibuprofen) are given. Within a day or two, the eyes become red but do not have 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 rash may look like hives or may look like the rash caused by measles or scarlet fever. The child has a red throat; reddened, dry, cracked lips; and a red tongue that looks somewhat like a strawberry. 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.
Complications of Kawasaki disease
If children are not treated, heart problems may develop, usually beginning 1 to 4 weeks after the illness starts. A few children develop the most serious heart problem, a bulge in the wall of a coronary artery (coronary artery aneurysm). These aneurysms can rupture or cause a blood clot, leading to a heart attack and sudden death. Treatment greatly reduces the risk of heart complications.
Other problems may include vomiting, diarrhea, and painful inflammation of the tissues lining the brain (meningitis), ears, eyes, liver, joints, urethra, and gallbladder. These problems eventually resolve without causing permanent damage.
Diagnosis of Kawasaki Disease
Established criteria
Electrocardiogram and ultrasound of the heart
Laboratory tests
Doctors diagnose Kawasaki disease when children have had a fever for at least 5 days and 4 out of 5 defined symptoms (see sidebar How Do Doctors Diagnose Kawasaki Disease?).
Blood and urine tests, chest x-rays, and cultures of the blood and of samples taken from the throat are also done to rule out other disorders that cause similar symptoms (such as measles, scarlet fever, juvenile idiopathic arthritis, and multisystem inflammatory syndrome in children [MIS-C]).
Doctors who specialize in treating children's heart disorders (pediatric cardiologists) or infectious diseases are often consulted.
Once doctors suspect Kawasaki disease, children have an electrocardiogram (ECG) and an ultrasound of the heart (echocardiogram) 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 echocardiogram results are abnormal, doctors may do a stress test. If an aneurysm is found, children may have heart catheterization.
Treatment of Kawasaki Disease
Immune globulin and aspirin
Treatment for Kawasaki disease is started as soon as possible. Treatment given within the first 10 days of symptoms significantly reduces the risk of coronary artery damage and makes the fever, rash, and discomfort go away faster.
Initially, immune globulin is 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 ofaspirin is lowered. The lower dose of aspirin is given for at least 8 weeks from the beginning of the illness until imaging tests of the heart are repeated. If doctors do not see any coronary artery aneurysms or signs of inflammation, aspirin may be stopped. However, if doctors do see coronary artery abnormalities, children need to continue to take aspirin for a long time.
Because aspirin use slightly increases the risk of a very rare but life-threatening disorder called Reye syndrome in children who have the flu or chickenpox, doctors recommend giving children who need long-term treatment with aspirin the flu shot (influenza vaccination) every year and the varicella (chickenpox) vaccineat the appropriate ages. If children are exposed to or contract the flu or chickenpox, doctors may give the medication dipyridamole instead ofaspirin temporarily to lessen the risk of Reye syndrome.
Children with large coronary aneurysms also may be treated with medications that prevent the blood from clotting (anticoagulants).
Prognosis for Kawasaki Disease
With treatment, children recover completely if their coronary arteries are not affected. For children with coronary artery problems, the outcome varies with the severity of the disease. However, with early treatment, almost no children with Kawasaki disease in the United States die.
Without treatment, Kawasaki disease is fatal in some children. Fatalities can be sudden and unpredictable.
About two-thirds of the aneurysms go away within 1 year. Large aneurysms are more likely to remain and require more treatment. However, even when aneurysms go away, children may have an increased risk of heart problems in adulthood.
