Kawasaki Disease

What is Kawasaki disease?

Kawasaki disease is the most common form of vasculitis that primarily affects children. The disease produces irritation and inflammation of many tissues of the body, including the hands, feet, whites of the eyes, mouth, lips, and throat. High fever and swelling of the lymph nodes in the neck also are characteristic of this illness. While most children completely recover, the main threat from Kawasaki disease comes from its effect on the heart and blood vessels. Heart-related complications can be seen as early as two weeks after onset of the disease and can be temporary or may affect the child long-term. The heart, particularly the coronary arteries, is affected in as many as one of five children who develop Kawasaki disease. Infants less than one year of age are usually the most seriously ill and are at the greatest risk for cardiac involvement. The risk of developing coronary artery disease later in life is not yet known.

Another name for Kawasaki disease is mucocutaneous lymph node syndrome.

How often does it occur?

Kawasaki disease is fairly common in the U.S. According to the American Heart Association, the illness is a major cause of heart disease in children. About 5,000 children are hospitalized in the U.S. each year. Kawasaki disease, together with acute rheumatic fever, is the leading cause of acquired heart disease in children in the U.S. and Japan.

Who is affected by Kawasaki disease?

Kawasaki disease occurs more often in Japan than in any other country. In the U.S., children of Asian or Asian American heritage are affected more often than other races, although Kawasaki disease can occur in any racial or ethnic group.

The vast majority of children who develop Kawasaki disease are under age five. The average age child seen with the illness is two years old. It occurs in boys twice as often as in girls.

What causes Kawasaki disease?

It is not clear what causes Kawasaki disease. Scientists believe a virus or bacteria may be responsible, but current research is still underway. Kawasaki disease does not appear to be contagious, nor does it appear to be hereditary.

It is rare for more than one child in a family to develop the disease. As a result, less than 2 percent of persons with Kawasaki disease develop the disease more than once.

Why is Kawasaki disease a concern?

Kawasaki disease can be a very uncomfortable illness, since it causes fever, as well as irritation and inflammation in many tissues of the body. However, these symptoms usually run their course and resolve within a few weeks. The primary concern with Kawasaki disease is heart and blood vessel involvement.

The coronary arteries are the vessels that provide the heart muscle with an oxygen-rich blood supply. Kawasaki disease can weaken the wall of one or more of the coronary arteries, causing it to bulge or balloon out. This weakened, ballooned area is called an aneurysm.

Blood clots can form in the ballooned area and possibly block the blood flow through the coronary artery. When this happens, the heart muscle will no longer receive an adequate supply of oxygen-rich (red) blood, and the heart muscle can be damaged. On rare occasions, the aneurysm can also burst.

The illness may also cause the heart muscle (myocardium) to be irritated and inflamed, as well as the membrane covering the heart (pericardium). Irregular heart rhythms and heart valve problems may also occur with Kawasaki disease.

In most cases, the effects on the heart caused by Kawasaki disease are temporary, and resolve within five or six weeks. However, coronary artery problems may sometimes persist for longer periods of time.

What are the symptoms of Kawasaki disease?

The following are the most common symptoms of Kawasaki disease and generally lasting 10-14 days. However, each child may experience symptoms differently. Symptoms may include:

• Moderate to high fever (101 degrees F to 104 degrees F) that lasts for at least five days and has not responded to treatment, and that rises and falls for up to three weeks

• Irritability

• Swollen lymph glands in the neck

• Spotty, bright red rash on the back, chest, abdomen, and/or groin

• Bloodshot eyes

• Sensitivity to light

• Swollen, coated tongue

• Dry, red, cracked lips

• Dark red interior surfaces of the mouth

• Red, swollen palms of hands and soles of feet

• Peeling skin around the nail beds, hands, or feet

• Swollen, painful joints

The symptoms of Kawasaki disease may resemble other conditions or medical problems. Always consult your child's health care provider for a diagnosis.

How is Kawasaki disease diagnosed?

Your child's health care provider will obtain a medical history, and perform a physical examination. Several of the above mentioned symptoms need to be present for your child's health care provider to consider Kawasaki's disease as the cause for the illness.

Diagnostic tests may also include:

• Electrocardiogram (ECG or EKG). A test that records the electrical activity of the heart, shows abnormal rhythms (arrhythmias or dysrhythmias), and detects heart muscle damage.

• Echocardiogram (echo). A procedure that evaluates the structure and function of the heart by using sound waves recorded on an electronic sensor that produce a moving picture of the heart and heart valves.

• X-ray. A diagnostic test which uses invisible X-ray energy beams to produce images of internal tissues, bones, and organs onto film.

• Complete blood count (CBC). A measurement of size, number, and maturity of different blood cells in a specific volume of blood. The health care provider will look for an elevation in the numbers of white blood cells which normally multiply in the presence of infection and may notice elevated platelet levels with Kawasaki disease as well.

• Erythrocyte sedimentation rate (ESR or sed rate). A measurement of how quickly red blood cells fall to the bottom of a test tube. When swelling and inflammation are present, the blood's proteins clump together and become heavier than normal. Thus, when measured, they fall and settle faster at the bottom of the test tube. Generally, the faster the blood cells fall, the more severe the inflammation.

• Urinalysis. Testing of a urine sample for protein, red blood cells, white blood cells, or casts to indicate kidney disease associated with several rheumatic diseases.

Treatment for Kawasaki disease

Specific treatment for Kawasaki disease will be determined by your child's health care provider based on:

• Your child's age, overall health, and medical history

• Extent of the disease

• Your child's tolerance for specific medications, procedures, or therapies

• Expectations for the course of the disease

• Your opinion or preference

Prior to the diagnosis of Kawasaki disease by your child's health care provider, the goal of treatment is to provide comfort for your child. Fever reduction and increasing fluids are very helpful. Acetaminophen or ibuprofen is often used for fever.

Once the diagnosis of Kawasaki disease is made, your child's health care provider may prescribe aspirin to help decrease the inflammation that the illness produces, as well as to prevent clots from forming. However, always check with your child's health care provider before giving your child aspirin. Some children benefit from an intravenous (IV) medication called gamma globulin that may decrease the risk of the heart being affected. Your child may need to stay in the hospital for a few days if IV gamma globulin is prescribed.

Can Kawasaki disease be prevented?

Currently, there is no known way to prevent Kawasaki disease.

Long-term outlook after having Kawasaki disease

About 80 percent of all children have a full recovery after Kawasaki disease resolves. If an aneurysm of the coronary arteries (heart's arteries) is detected, echocardiograms will be repeated periodically, sometimes for several years after the illness. Additional treatment may be necessary including blood thinners in order to prevent clots from forming within the dilated (aneurysmal) coronary (heart's) arteries. Some heart problems may not be evident right away, so it is important to keep follow-up appointments with your child's health care provider, even if your child is feeling well.

There is a risk for early coronary artery disease after having Kawasaki disease, including early heart attacks because of intrinsic abnormalities within the coronary arteries themselves. Thus, preventive measures such as heart-healthy living habits and regular follow-up with a cardiologist should be continued throughout the lifespan.

Consult your child's health care provider regarding the specific outlook for your child.