What Is Kawasaki Disease?

Kawasaki disease (also called Kawasaki syndrome) is a rare systemic inflammatory condition that usually occurs after or with an infection. The most common symptoms of fever, swollen lymph nodes, and a rash are seen most often in children under age 5, but heart problems and other complications can occur as well.

The main cause of Kawasaki disease remains unclear, though genetics, autoimmune response, and inflammation of the blood vessels may contribute to the disorder. There are no specific tests for Kawasaki disease and it is diagnosed on the basis of clinical features. It is highly treatable and most people make a full recovery.

This article discusses Kawasaki disease, its symptoms, and some of the possible causes. It explains how Kawasaki disease is treated along with some of the complications that can arise.

Kawasaki Disease Symptoms

Kawasaki disease can develop over the course of several weeks. Most of the time, the condition affects young children who are younger than five years old, but it can affect older children, and rarely, even adults.

Typically, the illness causes a high fever (over 100.4 F) that lasts for five days or more. It also includes at least four of the five signs of Kawasaki disease:

• Redness, swelling, and/or peeling of the skin on the hands and feet
• A rash on the back, abdomen, and/or chest
• Eye swelling or eye redness
• Swelling, redness, sores, or peeling of the mouth, lips, and/or throat
• Swollen lymph glands, especially on the neck

Children are likely to be irritable and may also develop a rash or peeling of the skin in the groin area. Sometimes Kawasaki disease is also associated with diarrhea, vomiting, joint pain or swelling, pain with urination, neck stiffness, or headaches.

When the disease affects the heart, symptoms can include shortness of breath, chest pain, loss of consciousness, or even a heart attack.

Kawasaki Disease Stages

There are three stages of Kawasaki disease. The acute stage, which typically lasts for a few weeks, is the stage when symptoms are noticeable. Treatment for Kawasaki disease is typically initiated during the acute stage.

The subacute stage is the recovery stage, and people may have persistent sore joints without other symptoms during this stage, which lasts for about a month.

The last stage is the convalescent stage. The convalescent stage lasts for several months, is characterized by mild symptoms or no symptoms, and lasts until all laboratory findings of abnormalities resolve.

Kawasaki Disease Cause

The cause of Kawasaki disease is not known, but there are some factors that make it more likely to occur. Kawasaki disease is not an infection, and it often develops during or after a mild viral or bacterial infection.

It is more common among people who have family members who have also had it. There is also geographic clustering, with the highest occurrence in Japan, followed by Korea, and then Taiwan. This familial tendency and geographic pattern has led experts to suggest that there may be a genetic predisposition to Kawasaki disease.

Inflammation

Kawasaki disease is associated with diffuse inflammation throughout the body that is believed to occur due to a high reactivity of the immune system.

It has been suggested that the inflammatory reaction could be an autoimmune response or an overreaction of the body's immune system to a trigger, such as an infection. The inflammation produces the fever, redness, swelling, and other symptoms.

Vasculitis

Many Kawasaki disease symptoms are attributed to vasculitis, or inflammation of the blood vessels. With Kawasaki syndrome, the inflammation is extensive, and it has a tendency to target the medium sized blood vessels of the body.

Vasculitis can affect blood vessels in the heart, potentially leading to life threatening blood clots and the possibility of long-term heart disease. One vascular complication of Kawasaki disease is the development of an aneurysm, which is an outpouching and weakening of a blood vessel.

Studies suggest that without treatment, about 25% of all children diagnosed with Kawasaki disease will develop a coronary (heart vessel) aneurysm. It's less than 5% in children treated with intravenous immunoglobulin (IVIG) within 10 days of their first symptoms.

How Kawasaki Disease Is Diagnosed

The diagnosis of Kawasaki disease is based on assessment of the clinical symptoms. While there are no specific tests that can confirm or rule out the disease, some diagnostic tests are used to help identify complications and guide treatment.

Laboratory Tests

A blood test or urine test can identify signs of inflammation. A complete blood count (CBC) may show leukocytosis (elevated white blood count).

Other laboratory signs of inflammation, including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and liver function tests may be abnormal in Kawasaki disease as well. A urine test may show sterile pyuria—white blood cells in the urine without evidence of an infection.

Imaging Tests

Kawasaki disease often causes swelling of the lymph nodes and it can cause swelling in other areas of the body, including the gallbladder. An imaging test such as a computerized tomography (CT) can help your child's doctor assess areas of concern.

Specialized Tests

Certain complications of Kawasaki disease need to be evaluated with specialized tests. For example, when there is a concern about dehydration due to vomiting or a decreased appetite, an electrolyte blood test can help identify early signs of dehydration that require treatment.

Vision changes caused by anterior uveitis, inflammation in the eye, can be diagnosed with an eye examination.

Heart Tests

If heart involvement is being considered, your child may need an electrocardiogram (EKG) or echocardiogram. An EKG is a noninvasive test that assesses the heart rate and rhythm. An echocardiogram is a noninvasive imaging test that can be used to visualize the anatomical structure of your heart in action as it moves.

An angiogram is an invasive test that can help your medical team visualize an abnormally shaped blood vessel, such as an aneurysm.

Kawasaki Disease Treatment

Kawasaki disease is treated in the hospital inpatient setting, and it typically takes days or weeks for the condition to resolve, even with treatment. The main treatment includes anti-inflammatory drugs to alleviate the inflammation and vasculitis. When there is an infection, targeted antibiotics or antivirals may be used to help resolve the infection.

In addition to medication that is used to reduce inflammation and treat any associated infection, children and adults with this condition may also receive IV fluids and other supportive treatments as needed.

Immune Suppression

Treatment of the Kawasaki disease with a combination of IVIG and aspirin helps prevent complications from developing.

The administration of IVIG is an infusion procedure in which immune proteins are injected into the vein to reduce the body's excessive and harmful immune response. Aspirin reduces inflammation and is used to bring down the fever.

Other treatments including corticosteroids or Remicade (infliximab) are used when the standard treatment is not effective.

Procedures

Serious heart and vascular problems may not improve with anti-inflammatory treatment and can persist after the acute phase of the condition resolves. These vascular complications may require treatment with an interventional procedure, such as surgery or catheterization. A catheter is a tube that is inserted to reach, and possibly repair, an anatomical defect.

The outcomes are good, but Kawasaki disease is still the most common cause of acquired heart disease in the United States.

Summary

Kawasaki disease is a potentially serious inflammatory disorder that most often affects children under age 5. The diagnosis often follows a bout of infection and Kawasaki disease has been associated with the COVID-19 virus in children.

There is no test for Kawasaki disease. However, a healthcare provider can identify Kawasaki disease through careful examination and the use of blood tests, imaging, and specific tests for any heart or vision changes.

Treatment with intravenous immunoglobulin (IVIG), aspirin, and corticosteroids is usually successful, but be sure to speak with a healthcare provider right away if your child develops signs of the condition.