Kawasaki Syndrome

What Is It?

Kawasaki syndrome is a rare illness that typically strikes children younger than age 5. It is also known as mucocutaneous lymph node syndrome. Kawasaki syndrome is a mysterious illness of unknown cause, although some scientists suspect that the cause may be a type of bacterium (such as staphylococcus or streptococcus). Kawasaki syndrome was first identified among Japanese children in 1967, and within nine years, the illness had been reported in American children living in Hawaii. Although researchers assume that the Kawasaki syndrome could have been caused by an infection that was carried between Japan and Hawaii, there has been no confirmation that Kawasaki syndrome can be transmitted via contact between people. Recent evidence suggests that inherited (genetic) factors may also be important, but the cause of Kawasaki syndrome remains a mystery.

Kawasaki syndrome makes children ill by triggering inflammation in many different parts of the body. In the heart, this inflammation can take the form of myocarditis (inflammation of heart muscle), pericarditis (inflammation of membranes covering the heart) or valvulitis (inflammation of the heart valves). Kawasaki syndrome can cause a type of meningitis (inflammation of membranes covering the brain and spinal cord), and it can cause inflammation in the skin, eyes, lungs, lymph nodes, joints and mouth. However, the most dangerous problem related to Kawasaki syndrome is the threat of vasculitis (blood vessel inflammation), especially in the body's medium-sized arteries. This vasculitis can be especially dangerous when it damages the heart's coronary arteries, causing an abnormal widening (dilation) or bulge (aneurysm) in these vessels. In rare cases, artery damage related to Kawasaki syndrome can significantly interfere with the heart's blood supply, even to the point of causing a heart attack in a very young child.

In the United States and other industrialized nations, Kawasaki syndrome is now the most common cause of heart disease that is not present at birth in children. According to U.S. government statistics, 1,262 cases of Kawasaki syndrome were reported between 1994 and 1997, with an average of 315 cases each year. Approximately 80% were younger than 5 years old, and boys were affected more often than girls.

Symptoms

Because there is no test available to confirm that a person has Kawasaki syndrome, doctors define the condition by the combination of problems that it produces. The typical person with this disease has a high fever (usually 104° Fahrenheit or above) for at least five days. This fever usually occurs together with at least four of the following additional symptoms:

• Conjunctivitis of both eyes (bloodshot eyes)
• Symptoms involving the mouth or throat, including redness and inflammation of the lips or throat, cracked lips, bleeding lips or a strawberry-colored tongue
• Symptoms affecting the hands or feet, including swelling, redness of the skin on the palms and soles or peeling skin on the fingertips, toes, palms or soles
• A rash, primarily on the torso
• Swollen glands in the neck

People with Kawasaki syndrome can have other symptoms that are not part of the definition of the disease. These can include:

• Pain and swelling of the joints
• Diarrhea
• Vomiting
• Abdominal pain
• Cough
• Earache
• Runny nose
• Irritability
• Seizures
• Weakness in the arms or legs
• Weakness of facial muscles
• Heart rhythm abnormalities
• Signs of heart failure

Diagnosis

Because Kawasaki syndrome is rare in the United States, doctors will want to check for other illnesses that are more common and cause similar symptoms.

If your doctor suspects that your child has Kawasaki syndrome, he or she may begin by asking you about:

• Your child's medications, to rule out a drug reaction
• Any recent exposure to someone with strep throat, to rule out scarlet fever, which is caused by a streptococcal infection
• Any recent exposure to someone with measles, to rule out measles if your child has not been immunized against this illness
• Any recent tick bite, to rule out Rocky Mountain spotted fever

As part of the diagnostic workup for Kawasaki syndrome, your doctor may need to order blood tests and diagnostic procedures to check for other infectious or noninfectious causes of your child's symptoms. Once it becomes clear that Kawasaki syndrome is a possibility, your doctor may schedule an echocardiogram, a painless test that uses sound waves to outline the heart's structure. This allows the doctor to check for any dilation or aneurysms in the coronary arteries. In some cases, your doctor may recommend coronary angiography, a procedure in which dye is injected into the arteries that supply the heart to look for evidence of aneurysm or narrowing typical of Kawasaki syndrome.

Your doctor will diagnose Kawasaki syndrome if your child has symptoms that fit the definition of the illness and if there is no other explanation for these symptoms. Researchers continue to look for a reliable diagnostic test for this illness, but, so far, none is available.

Expected Duration

Kawasaki syndrome lasts for several weeks, progressing through three different stages:

• Acute phase This is the most intense part of the illness, when symptoms are most severe. It usually lasts one to two weeks.
• Subacute phase This stage begins when the child's fever, rash and swollen lymph nodes go away. However, the child still feels irritable, has a poor appetite and slight eye redness and may develop peeling skin on the fingers and toes. This stage usually ends three to four weeks after the fever began.
• Convalescent stage This stage begins when all clinical symptoms are gone, but the results of a blood test called the erythrocyte sedimentation rate (ESR), an indicator that there is still inflammation in the body, remain abnormal. When the ESR results finally return to normal, usually six to eight weeks after the fever began, the convalescent stage ends.

Prevention

Because the cause of Kawasaki syndrome is unknown, there is no way to prevent it.

Treatment

Kawasaki syndrome is treated with a single dose of gamma globulin, given intravenously (directly into a vein), together with aspirin taken by mouth. Gamma globulin is a purified collection of proteins and antibodies from donated blood. It is not known why it is effective against this disease. The gamma globulin injections may be repeated over several days if fever continues.

Parents generally are warned against giving aspirin to children because it can trigger Reye's syndrome, a serious disorder that can damage the brain and liver. However, aspirin is the best treatment for Kawasaki syndrome, so the benefits outweigh the risk of Reye's syndrome, which is rare. The child usually continues to take aspirin for six to eight weeks after the acute symptoms of Kawasaki syndrome subside.

Other treatments, including corticosteroids or immunosuppressive medications are not always helpful, but sometimes are recommended if gamma globulin injections are not effective. A procedure called plasmapheresis is sometimes recommended for Kawasaki syndrome that does not respond to other treatments. In plasmapheresis, blood is removed, filtered to remove proteins (including antibodies) and then returned to the body.

When To Call A Professional

Call your doctor immediately if your child develops a high fever, with or without other symptoms of Kawasaki syndrome.

Prognosis

Without proper treatment, 20% to 25% of children with Kawasaki syndrome develop abnormalities in their coronary arteries. With treatment, this percentage drops to 2% to 4%. In general, the risk of death from cardiac complications is about 1% to 2%, most commonly during the first two to 12 weeks of illness.

Up to 25% of people with Kawasaki syndrome have coronary aneurysms during the first one to three months of illness. The aneurysms often go away on their own within the next year or two. Children who continue to have coronary abnormalities usually need regular testing, including stress tests, echocardiography and sometimes coronary angiography. If cardiac health deteriorates because of damage to the coronary arteries, surgery may be needed to correct the problem.

Recent Japanese studies have shown that the death rate for people with Kawasaki syndrome is about the same after the acute phase has passed as for people without Kawasaki syndrome.

Additional Info

Office of Rare Diseases

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Phone: (301) 402-4336

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National Heart, Lung, and Blood Institute (NHLBI)

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Phone: (301) 592-8573

TTY: (240) 629-3255

Fax: (301) 592-8563

E-Mail: nhlbiinfo@rover.nhlbi.nih.gov

http://www.nhlbi.nih.gov/