What Is Kawasaki Disease?

The cause of Kawasaki disease is not known. Microorganisms and toxins like that of scarlet fever have been suspected, but none has been identified to date.

• It is common for Kawasaki disease to occur after a preceding infection, such as tonsillitis, ear infection, pneumonia, urine infection, or gastrointestinal infection.
• Genetic factors (genetic variants in some patients) and the immune system (for example, autoimmune disease) seem to play roles in the disease, which is characterized by immune activation.

Who develops Kawasaki disease?

• Kawasaki disease typically affects children under 5 years of age. Only rarely does it affect children over 8 years of age, in which case it is sometimes referred to as atypical Kawasaki disease.
• The disease is more common in those of Japanese or Korean descent.

The usual symptoms and signs of Kawasaki disease include

• prolonged fever (about 5 days),
• reddening of the eyes without pus (pinkeye),
• cracked and inflamed lips and mucous membranes of the mouth with an inflamed strawberry tongue,
• ulcerative gum disease (gingivitis),
• swollen lymph nodes in the neck (cervical lymphadenopathy),
• joint pain often on both sides of the body,
• irritability,
• cough and runny nose, and
• a rash that is raised and bright red, with cracking and peeling skin (desquamation), especially on the palms and soles.

The rash appears in a glove-and-sock fashion over the skin of the hands and feet. The rash becomes hard, swollen (edematous), and then peels off.

What are the unusual signs and symptoms of Kawasaki disease?

Most of the common symptoms described above will resolve without complications, even if untreated. Less common findings include

• inflammation of the lining of the heart (pericarditis),
• joints (arthritis), or
• covering of the brain and spinal cord (meningitis), and
• the other heart problems listed below in the section on serious complications.

The outlook (prognosis) for an individual affected is primarily determined by the seriousness of any heart complications.

They are the same condition. Kawasaki disease is also referred to as Kawasaki syndrome. It was first described in the late 1960s in Japan by the renowned pediatrician Tomisaku Kawasaki.

No. Kawasaki disease is not believed to be a contagious illness. However, Kawasaki disease symptoms and signs often start after the patient has had an acute infection with something else. The cause of the preceding illness may be something contagious.

Children with Kawasaki disease can develop inflammation of the arteries of various parts of the body.

• This inflammation of the arteries is called vasculitis. Arteries that can be affected include the arteries that supply blood to the heart muscle (the coronary arteries).
• Vasculitis can cause weakening of the blood vessels and lead to areas of vessel widening (aneurysms).
• The weakening occurs because of the destruction of the elastic tissue in the walls of the blood vessels.
• Coronary artery aneurysms occur because of such injury to the blood vessels in Kawasaki disease.

Because of the potential for heart injury and coronary artery aneurysms, special tests are performed to examine the heart.

• Children are typically evaluated with an electrocardiogram (EKG) and an ultrasound test of the heart (echocardiogram).
• Monitoring for this problem is crucial throughout life as it can develop as a late aftereffect of Kawasaki disease.
• Other arteries that can become inflamed include the arteries of the lungs, neck, and abdomen.
• These effects can lead to breathing problems, headaches, and abdominal pain, respectively.
• Blood tests to measure the degree of inflammation (such as C-reactive protein, or CRP, and erythrocyte sedimentation rate, or ESR) are often used to monitor the activity of the disease.

Children affected by Kawasaki disease are hospitalized.

• Kawasaki disease is treated with high doses of aspirin (salicylic acid) to reduce inflammation and to mildly thin the blood to prevent blood clot formation. This is one of the few times when children may take aspirin.
• Also used in treatment is gamma globulin administered through the vein (intravenous immunoglobulin or IVIG), together with fluids. This treatment has been shown to decrease the chance of developing coronary aneurysms in the coronary arteries, especially when used early in the illness.
• Sometimes cortisone medications are given. Persisting joint pains are treated with anti-inflammatory drugs, such as ibuprofen (Advil) or naproxen (Aleve).
• Plasma exchange (plasmapheresis) has been reported as effective in patients who were not responding to aspirin and gamma globulin. Plasmapheresis is a procedure whereby the patient's plasma is removed from the blood and replaced with protein-containing fluids. By taking out portions of the patient's plasma, the procedure also removes antibodies and proteins that are felt to be part of the immune reaction that is causing the inflammation of the disease.
• Treatments being investigated include doxycycline, statin drugs (Lipitor, Mevacor, others), anakinra (Kineret), and cyclosporine (Neoral).

Kawasaki disease is typically self-limited and generally resolves on its own after four to eight weeks, and with early treatment, full recovery is usual.

Kawasaki disease that is not responding to the traditional cornerstones of treatment, aspirin and gamma globulin infusions, can be deadly.

• Rarely, Kawasaki disease can cause death from blood clots forming in abnormal areas of widening (aneurysms) of the heart arteries (coronary arteries) and myocarditis (inflammation of heart muscle). Aneurysms of the arteries to the heart (coronary arteries) can occur early or late, even when the children are adults so follow-up is recommended for those patients diagnosed with the disease.
• Those children with larger aneurysms have a worse prognosis because of this risk. Such aneurysms can lead to blood clots, heart attacks (myocardial infarction), and internal bleeding. Those whose echocardiograms do not demonstrate widening of the coronary arteries throughout life do best. Those with any signs of aneurysm changes require very close monitoring. Children less than 6 months of age and those with high levels of inflammation on blood testing are at the highest risk.
• The earlier the diagnosis is made and treatment is begun the better the outcome.
• Researchers are searching for methods of detecting which children are at risk for the development of aneurysms of the coronary arteries. Further research is underway to investigate a variety of criteria for atypical variants of Kawasaki disease that do not have classical presentations.

Because the cause of Kawasaki disease has not been determined, there are no measures known that can prevent the disease. Early evaluation and treatment can decrease the chance of long-term problems and/or complications.

Another disease recently noted to have almost identical signs and symptoms to Kawasaki disease has been linked to the COVID-19 (coronavirus) pandemic. The new disease seems more virulent than Kawasaki disease. The CDC named the disease (as of May 14, 2020) multisystem inflammatory syndrome in children or MIS-C. The following is the case definition for MIS-C provided by the CDC:

• An individual under 21 years of age with fever, laboratory evidence of inflammation, and evidence of clinically severe illness requiring hospitalization with multisystem (>2) organ involvement (cardiac, renal, respiratory, hematologic, gastrointestinal, dermatologic, or neurological); and
• no alternative plausible diagnoses; and
• positive for current or recent SARS-CoV-2 infection by reverse-transcriptase polymerase chain reaction, serology, or antigen test; or COVID-19 exposure within the 4 weeks prior to the onset of symptoms.

The CDC noted the fever should be at least 100.4 F (38 C) for at least 24 hours or a subjective fever lasting 24 hours. The main differences between MIS-C and Kawasaki disease are a more rapid and serious advancement of symptoms, especially fever and multisystem organ problems like cardiac and respiratory problems along with a current or recent infection with SARS-CoV-2. Some children suffer a rapid heartbeat and may develop cardiac and/or respiratory arrest.