Kawasaki Disease

Kawasaki disease is an uncommon condition that mainly affects children aged under five years. It most commonly affects children aged 9-12 months. It causes various symptoms throughout the body (listed below). Kawasaki disease was first described by a Japanese doctor in the 1960s. Since then cases have been reported in many countries. It seems to be getting more common.

A fever (high temperature) which lasts more than five days is usual. In addition, at least four of the following normally develop.

• Redness of the eyes (conjunctivitis).
• Changes in the mouth such as a red throat or tongue, or dry and cracked lips.
• A blotchy red rash. This normally fades within a week.
• Changes in the hands or feet such as mild swelling or redness. The skin often peels on some of the fingers or toes after about 2-3 weeks.
• One or more lymph glands in the neck become swollen.

The diagnosis of Kawasaki disease is based on the above typical group of symptoms. There is no test to confirm the disease. Tests may be done to rule out other diseases that cause similar symptoms such as measles, scarlet fever, etc. Other symptoms may develop in addition to the above. These include diarrhoea, vomiting, abdominal pains, being off food, joint swelling and pains, and jaundice (skin goes yellow). Also, affected children are commonly very irritable.

The cause is not known. The symptoms seem typical of a virus infection. However, it is not contagious. It is rare for contacts of affected children (brothers, sisters, etc) to also become affected. This means that the cause is unlikely to be just a virus infection. It may be an unusual or severe reaction to a common virus that usually causes little or no harm to most people. There are various theories, but no virus or other germ has been proved to cause this disease. However, recent research suggests that a virus called coronavirus may have a part to play.

The symptoms listed above can last up to 10 days. They then usually ease and go. Some children become very unwell, but others have a mild illness similar to many virus infections. However, any child suspected of Kawasaki disease is normally admitted to hospital, even if they appear to have a mild illness. A heart scan is normally done to look for complications (see below). If complications do occur, they usually develop a week or so after the symptoms listed above.

Heart problems.
Without treatment, about 1 in 5 children who have Kawasaki disease develop inflammation of the blood vessels to the heart (coronary arteries). This can cause a swelling of a section of an artery which is called an aneurysm.

A coronary artery aneurysm usually causes no symptoms. Over time it often goes away and the artery returns to normal. However, the wall of an aneurysm is weakened and abnormal. Serious problems may develop in some children with an aneurysm. The most serious is that a thrombosis (clot) may develop in the aneurysm and damage the heart (a heart attack). Without treatment, about 1 in 100 children with Kawasaki disease die of heart problems.

An aneurysm can be detected by a heart scan (an echocardiogram). If an aneurysm does occur, it starts to develop a week or more after the fever and other acute symptoms begin. Treatment within 10 days of symptoms starting often prevents this complication. This is why it is important to diagnose and treat Kawasaki disease in the early stages of the illness.

Other complications
The aneurysm of a coronary artery is caused by inflammation of the artery (a 'vasculitis'). This can occur in other arteries in various parts of the body - but is very rare. Various other rare problems have also been reported in some children with Kawasaki disease.

• Aspirin. This is one of the few times aspirin is given to children. Aspirin helps to reduce the inflammation in the coronary arteries.
• Gammaglobulin. This is an antibody mixture obtained from human blood. It is given by an infusion into the bloodstream. It is not clear how it works. It may modify the response of the immune system in some way to prevent inflammation in the arteries.

A combination of aspirin and gammaglobulin given within 10 days of the onset of Kawasaki disease much reduces the chance of heart complications. Without treatment, about 2 in 10 affected children develop an aneurysm. With treatment, this is reduced to about 2 in 100.

Other treatments aim to make the child comfortable such as giving lots to drink, and nursing them through the acute feverish illness.

Research continues to search for better treatments. For example, recent research suggests that steroid drugs and a drug called abciximab may be of benefit to prevent cmplications. Further research is needed to confirm the role of these drugs in the treatment of Kawasaki disease.

What is the outlook (prognosis)?

Without treatment, most children make a full recovery but complications develop in some cases. With early treatment, complications are much less likely to develop.

Repeat heart scans are usually advised over several weeks. If the heart scan is normal at 6-8 weeks after symptoms began, then long-term heart problems are thought to be very unlikely.

Long-term follow up (such as an annual check up) may be advised if an aneurysm was detected as the long-term effect on the heart is not yet fully known.

Kawasaki Support Group
13 Norwood Grove, Potters Green, Coventry, West Midlands, CV2 2FR   Tel: 024 7661 2178

© EMIS and PIP 2006   Updated: February 2006