First identified in Japan in 1967, Kawasaki disease (also called mucocutaneous lymph node syndrome) affects young children, usually under the age of 5. It is believed to be caused by a noncontagious infection, although scientists are unsure of the exact cause.

Kawasaki disease is a self-limiting disease, meaning that symptoms appear for a short while and will go away on their own. Symptoms of Kawasaki include fever, rash and swelling in the hands, feet and lymph nodes. The condition may also affect the linings of blood vessels and the heart muscle, and it can lead to aneurysms and heart attack.

Prompt treatment can dramatically reduce the likelihood of cardiovascular damage from the disease, and the overall mortality rate is low. Less than 1 percent of children with Kawasaki disease die from it. Surgery or a catheter-based procedure is also available to treat some long-term effects of the disease.

Kawasaki disease is a condition that primarily affects young children. It is believed to be caused by a non-contagious infection, although scientists are unsure of the exact cause. About 80 percent of cases occur in children under the age of 5, and boys are more likely to get it than girls.

Although a pathogen is suspected, scientists have been so far unable to identify the virus or bacterium that causes Kawasaki disease. Some recent research suggests that Kawasaki disease may be caused, in some children, by the New Haven coronavirus, a newly discovered virus related to the severe acute respiratory syndrome (SARS) virus. While clinical data appears to suggest a link between these illnesses, further testing is required to substantiate a relationship between the two.

Other studies have suggested a genetic component because siblings of affected children are more likely to develop Kawasaki disease than children in the same neighborhood. Also, people of Japanese descent are more likely to develop Kawasaki disease no matter where they live in the world. It does, however, affect children of all races, and between 1,500 and over 4,000 cases are diagnosed in the United States every year, according to the National Institutes of Health.

Some recent research suggests that Kawasaki disease may be caused, in some children, by the New Haven coronavirus, a newly discovered virus related to the severe acute respiratory syndrome (SARS) virus. While clinical data appears to suggest a link between these two illnesses, further testing is required to substantiate a relationship between the two.

During Kawasaki disease, the blood vessels may become inflamed. Kawasaki disease is a self-limiting disease, meaning that symptoms appear for a short while and disappear on their own. The disease has three specific phases, each associated with certain signs and symptoms. The most dangerous phase is the acute phase, which typically lasts from 10 to 14 days, depending on whether or how it is treated. Overall, Kawasaki disease usually lasts between six and eight weeks, although it may take a year or more for complete healing.

Kawasaki disease is rarely fatal. Less than 1 percent of treated children will die because of the disease. Among untreated children, up to 25 percent of children will experience coronary artery aneurysms in connection with the disease. This rate drops to 10 to 15 percent among children who are treated. A coronary artery aneurysm is a condition where part of the wall of the coronary artery bulges out, sometimes resulting in a heart attack. However, modern treatment techniques have reduced the rate of coronary aneurysm to about 5 percent. Throughout the disease course, however, various cardiac abnormalities may occur, including arrhythmias, damage to the heart valves, pericarditis, and other cardiovascular problems.

Kawasaki disease was first identified in Japan, where it is most common, in 1967 by a Japanese pediatrician named Dr. Tomisaku Kawasaki. The medical term for the condition is mucocutaneous lymph node syndrome. Prior to Dr. Kawasaki’s description, some infants and children with this condition were said to have a condition called infantile periarteritis nodosa.

There is no known prevention for Kawasaki disease, although physicians have developed ways to treat the disease. Successful treatment depends on rapid diagnosis and action. If treated within the first 10 days, the potential cardiovascular damage from Kawasaki disease can be dramatically limited.

There are three stages of Kawasaki disease, and each stage has its own associated signs and symptoms. The classic symptom of Kawasaki disease is a persistent high fever (sometimes up to 104˚F) that lasts for at least five days and does not respond to fever-reducing medications such as acetaminophen. In some cases, the fever may last for up to two weeks.

Because there is no lab test for Kawasaki disease, the U.S. Centers for Disease Control and Prevention (CDC) has developed guidelines to help physicians. A diagnosis can be made if a child has a persistent high fever, combined with four of the five remaining signs and symptoms associated the acute phase. These include: 

Stage 1: Week 1, the Acute Phase 

Stage 2: Weeks 2 to 12, the Subacute Phase 

Stage 3: When symptoms disappear, convalescence

Major aneurysms in the later stages of Kawasaki disease could lead to a more immediate threat of complications. However, death as a direct result of this condition is relatively infrequent.

The usual duration of an episode of Kawasaki disease is six to eight weeks. During the healing period, which begins 45 days after onset and may take a year to complete, the body is able to heal most of the cardiovascular damage it may have sustained. However, damage to the coronary arteries may remain and could increase the risk of heart attack in adulthood. In general, patients with confirmed coronary artery aneurysms will require long-term follow-up. Even without signs of damage by standard imaging techniques, there may be microscopic changes in the walls of these arteries or in the tissues surrounding the arteries.

There is no single test that can identify Kawasaki disease. Instead, the U.S. Centers for Disease Control & Prevention (CDC) has developed criteria to help physicians. If a child has a persistent, unexplained fever for five days, and at least four of the following symptoms, a diagnosis can be made. These symptoms include:

• Red tongue
• Oral-mucosal changes, including cracked, dry lips
• Pink eye (conjunctivitis)
• Enlarged lymph nodes
• Red, patchy rash over the whole body

Not all children will meet these criteria exactly. Children who have fewer than four of these symptoms may still be diagnosed with atypical Kawasaki disease. The treatment course for this form of the disease is the same as for complete Kawasaki disease.

The symptoms will be identified during a physical examination. Both children and parents will also be asked questions about the patient’s medical history and family history. If the condition is suspected, tests such as the following may be ordered:

If these noninvasive tests cannot confirm or rule out a diagnosis, then a more invasive test called a coronary angiogram may be ordered. This catheter-based test is an x-ray of the arteries located on the surface of the heart (the coronary arteries). It may be more helpful than less invasive tests when making a diagnosis of Kawasaki disease.

Children who have been diagnosed with Kawasaki disease are usually admitted to hospital, where gamma globulin is typically administered through an intravenous (I.V.) line for 10 hours. This dramatically reduces the risk of damage to the coronary arteries and diminishes the inflammatory process in general. The patient is also given relatively high doses of aspirin for the first two weeks to reduce fever, swelling and inflammation. Some other medications may also be employed depending on the response of the child to the initial treatment. These may include steroids and medications that inhibit clot formation.

This combination of medications tends to show good results within 24 hours. Because gamma globulin may make the child less responsive to viral vaccines, common childhood vaccines are generally delayed for a number of months after treatment. For example, the measles-mumps-rubella vaccine is delayed for 11 months, and the chicken pox vaccine is delayed for at least five months.

After the initial course of high-dose aspirin, low-dose aspirin (or another antiplatelet) will likely be prescribed for another four to six weeks to prevent the formation of blood clots. Physical activity is also restricted during this time.

According to the American Heart Association, any further treatment is determined by which of the following five risk levels best characterizes the young patient:

The long-term aspirin therapy recommended for children in risk levels III to V should not cause problems in an otherwise healthy child, but there is a small risk of developing Reye syndrome if the child comes down with the flu or chicken pox while taking aspirin. Children on long–term aspirin therapy may be given the flu vaccine to help reduce this risk. Parents of children on aspirin therapy are urged to contact their children’s pediatrician as soon as possible if their children show any signs or symptoms of the flu or chicken pox.

Some research has indicated that adding steroids to the treatment regimen may reduce the risk of long-term complications. However, more research is needed on this subject.

Data has shown that there may be microscopic changes in the walls of the coronary arteries or in the tissues around the coronary arteries even years after Kawasaki disease. Some pediatric cardiologists recommend that all patients with this condition be rechecked every two to three years indefinitely.

Patients and parents are advised to discuss any questions they may have about Kawasaki disease with their pediatrician or cardiologist.

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to Kawasaki disease:

1. What tests will you use to confirm whether my child has Kawasaki disease?
   
   
2. Do you know how my child developed the disease?
   
   
3. Could my child have Kawasaki disease if they don't have any of the symptoms?
   
   
4. Has my child suffered any heart damage as a result of the disease?
   
   
5. What sorts of treatment would you suggest for my child?
   
   
6. How effective do you think treatment will be for my child?
   
   
7. How long do you expect my child will need to recover from treatment?
   
   
8. Should my child avoid/discontinue any medications if they have Kawasaki disease?
   
   
9. Are there any lifestyle changes my child will need to make?
   
   
10. Will my child need to regularly visit a doctor as a result of this illness? For how long?