Kawasaki disease is a syndrome of unknown cause that results in a fever and mainly affects children under 5 years of age. It is a form of vasculitis, where blood vessels become inflamed throughout the body. The fever typically lasts for more than five days and is not affected by usual medications. Other common symptoms include large lymph nodes in the neck, a rash in the genital area, lips, palms, or soles of the feet, and red eyes. Within three weeks of the onset, the skin from the hands and feet may peel, after which recovery typically occurs. In some children, coronary artery aneurysms form in the heart.While the specific cause is unknown, it is thought to result from an excessive immune system response to an infection in children who are genetically predisposed. It does not spread between people. Diagnosis is usually based on a persons signs and symptoms. Other tests such as an ultrasound of the heart and blood tests may support the diagnosis. Diagnosis must take into account many other conditions that may present similar features, including scarlet fever and juvenile rheumatoid arthritis. An emerging Kawasaki-like disease temporally associated with COVID-19 appears to be a distinct syndrome.Typically, initial treatment of Kawasaki disease consists of high doses of aspirin and immunoglobulin. Usually, with treatment, fever resolves within 24 hours and full recovery occurs. If the coronary arteries are involved, ongoing treatment or surgery may occasionally be required. Without treatment, coronary artery aneurysms occur in up to 25% and about 1% die.
However, a Cochrane review published in 2017 (updated in 2022) found that, in children, the use of corticosteroids in the acute phase of KD was associated with improved coronary artery abnormalities, shorter hospital stays, a decreased duration of clinical symptoms, and reduced inflammatory marker levels. Patient populations based in Asia, people with higher risk scores, and those receiving longer steroid treatment may have greater benefit from steroid use. Prognosis
With early treatment, rapid recovery from the acute symptoms can be expected, and the risk of coronary artery aneurysms is greatly reduced. Untreated, the acute symptoms of Kawasaki disease are self-limited (i.e. the patient will recover eventually), but the risk of coronary artery involvement is much greater, even many years later. Many cases of myocardial infarction in young adults have now been attributed to Kawasaki disease that went undiagnosed during childhood. Overall, about 2% of patients die from complications of coronary vasculitis.Laboratory evidence of increased inflammation combined with demographic features (male sex, age less than six months or greater than eight years) and incomplete response to IVIG therapy create a profile of a high-risk patient with Kawasaki disease. The likelihood that an aneurysm will resolve appears to be determined in large measure by its initial size, in which the smaller aneurysms have a greater likelihood of regression. Other factors are positively associated with the regression of aneurysms, including being younger than a year old at the onset of Kawasaki disease, fusiform rather than saccular aneurysm morphology, and an aneurysm location in a distal coronary segment.