Kawasaki disease

About Kawasaki disease

Kawasaki disease is the most common cause of acquired heart disease in children in the developed world and occurs mostly in children of Asian and Pacific Island descent. It usually affects children under five and is more common in boys than girls.

Most children make a full recovery from Kawasaki disease after several weeks. However, associated heart complications mean that some children are left with long-term health problems or, very rarely, die because of damage to their heart. A very small number of children may get the disease again.

The disease is named after the Japanese doctor, Dr Tomisaku Kawasaki, who first identified it in 1961.

The exact cause of Kawasaki disease is unknown despite much research.

Symptoms of Kawasaki disease

Kawasaki disease doesn’t have a unique symptom, which is why it’s difficult to diagnose. However, the main symptom of Kawasaki disease is a sudden fever which is higher than 39°C (102.2°F) and lasts longer than five days. Your child may also be much more irritable than at other times when he or she previously had a fever. The other main symptoms your child may have are:

  • red, bloodshot eyes caused by conjunctivitis, but with no pus
  • a blotchy, red rash mainly on the trunk of your child's body or on the genitals
  • reddened, dry or cracked lips
  • a red, inflamed tongue with circular white patches that look like a strawberry, often with a red sore throat
  • large swollen lumps (lymph glands) on either side of your child's neck
  • swollen hands and feet which become red and hard, often resulting in peeling skin on the fingertips and toes two to three weeks after the disease has started

Not all the symptoms of Kawasaki disease may show, or they may not show all at the same time; it’s therefore very important that if your child has any of these symptoms, see your GP immediately.

You may also notice that your child has other symptoms, including:

  • sore throat
  • cough
  • sore abdomen (tummy)
  • vomiting
  • diarrhoea
  • painful or swollen joints

Complications of Kawasaki disease

Kawasaki disease can cause severe damage to your child's heart and blood vessels. Without treatment about one in four children go on to develop heart disease.

The arteries in your child's heart can become inflamed causing a coronary artery aneurysm. This is when a main blood vessel supplying blood to the heart muscle becomes damaged and swells because the artery wall is weakened by inflammation. This creates a balloon-like bulge in the artery which can burst and be fatal. Damage to the vessel can also increase the risk of a clot forming. A severe clot can stop blood flow to the heart muscle and cause a heart attack.

Further damage to the heart can occasionally develop in the later stages of the disease as your child's body tries to heal itself. Complications can include thrombosis (a blood clot within a blood vessel), stenosis (when a blood vessel narrows) or problems with your child’s heart beat. These reduce or stop blood flow to the heart altogether, which can cause reduced ability of the heart to contract properly, or a heart attack.

All these can lead to long-term health problems for your child, and in rare cases, can be fatal. Kawasaki disease can potentially cause problems in adult life too, including heart attack, heart disease, or a ruptured aneurysm. However, the risk of long-term complications isn't yet fully known.

Causes of Kawasaki disease

Doctors still don't know what causes Kawasaki disease. However, it may be linked to how the body responds to a virus or infection. It may also be genetic – some children may be genetically more susceptible to the disease than others. The exact role of these factors, however, is unknown. Kawasaki disease itself isn’t contagious and can’t be passed from one child to another.

Diagnosis of Kawasaki disease

Kawasaki disease can be difficult to diagnose as many of the symptoms overlap with those of other common childhood diseases, such as scarlet fever and measles. There are currently no tests available that can confirm the condition.

Your GP may suspect your child has Kawasaki disease if he or she:

  • has a fever lasting longer than five days
  • doesn't have any signs of other diseases that could be causing the symptoms
  • has four or more of the main symptoms

However, because it’s so important to diagnose Kawasaki disease early, your GP may diagnose what is known as incomplete Kawasaki disease. For example, if your child has had a fever for more than five days but only has two or three main symptoms or no other diagnoses seems likely. This is because the symptoms may not appear at the same time, or the disease hasn't yet fully developed. This diagnosis is more often made if your child is under the age of one.

If your GP suspects that your child has Kawasaki disease, he or she will urgently refer your child to a paediatrician, a doctor specialising in children's health.

The paediatrician will review your child and the diagnosis. He or she may arrange for your child to have an echocardiogram. This uses an ultrasound probe, which is run over your child's chest to get a moving picture of the heart. The echocardiogram will show whether your child has developed a coronary artery aneurysm and how well the heart muscle is working.

Your child may have other tests including blood tests, X-ray and electrocardiogram (ECG) to see if the disease has affected your child’s heart.

Treatment of Kawasaki disease

Your child will be given treatment as quickly as possible after diagnosis because of the potentially damaging complications to your child’s heart.

Treatment aims to reduce the inflammation in your child's body to relieve symptoms and to prevent a coronary artery aneurysm from forming. This is done using two medicines – immunoglobulin and aspirin.

Immunoglobulin

Immunoglobulin (also known as gamma globulin) is a concentrate of antibodies from a number of blood donors. It has been shown to be extremely effective in treating Kawasaki disease, and to greatly reduce the likelihood of a coronary artery aneurysm if it's given within 10 days of the symptoms starting.

Immunoglobulin is given as a single dose over a few hours. A smaller dose over five successive days may occasionally be given if heart complications are suspected. The doctor will inject the immunoglobulin into your child's vein using a cannula (a small plastic tube) and an infusion pump.

You will often see some improvement in your child within 24 hours. If your child's fever doesn't go down after 36 hours, your child’s doctor may give another dose of immunoglobulin.

Corticosteroids

If your child's fever continues after two courses of immunoglobulin treatment, your child may be given steroids. However, more research is needed to confirm their effectiveness.

Aspirin

Aspirin shouldn’t be given to children under the age of 16 except under very specific circumstances. For the treatment of Kawasaki disease, doctors believe the benefits of aspirin outweigh the harms.

Your child will be given four doses of aspirin to take at regular intervals through the day. It's important that you follow your doctor's instructions precisely when giving your child medicines.

Once your child's fever has settled, the dose of aspirin can be reduced. However, he or she will need to continue taking regular doses for a minimum of a further six weeks. The length of time your child will need to continue taking aspirin depends on whether or not his or her coronary arteries have been damaged. If there is damage, your child may need to take aspirin for much longer.

After your child's treatment

Most children recover from Kawasaki disease if they receive early treatment and some children have heart problems that are only temporary. However, if your child does have lasting heart damage, he or she will need further long-term monitoring and treatment such as:

  • echocardiograms – to check his or her heart after diagnosis
  • anticoagulants – these are medicines that prevent blood clots forming in damaged arteries – your child may have to take them for up to 18 months to allow the arteries to heal, but may need to take them for longer

The duration of monitoring and ongoing treatment will depend on how severely your child’s heart has been affected. Very rarely, your child may need surgery such as:

  • coronary artery bypass graft – where blood is carried away from damaged arteries
  • angioplasty – where blocked arteries are widened, sometimes using a stent to hold the artery open

What should I do if I think my child has Kawasaki disease?

Answer

Kawasaki disease can cause long-term health problems for your child or may even be fatal, so it's vital that you seek medical advice quickly. Mention the name Kawasaki disease to the doctor that you see.

Explanation

If your child has had a high temperature for longer than five days and has two or more of the main symptoms of the disease, see your GP as soon as possible, or go to your local accident and emergency department.

It's important that your child receives treatment within 10 days of symptoms to reduce the risk of damage to his or her coronary arteries caused by the inflammation, which can cause an aneurysm and damage to the heart muscle. Most children with Kawasaki disease who have received prompt treatment go on to make a full recovery. However, because of the complications associated with the disease, some children suffer long-term health conditions, possibly into adulthood, and some may even die.

Kawasaki disease is most common in Japan with around 6000 children reported as having the disease each year. Eight out of 10 children who have Kawasaki disease are under five years old. Although the disease can’t be prevented, early treatment with immunoglobulin reduces the risk of potentially fatal heart complications.

Will Kawasaki disease have any long-term health effects on my child?

Answer

Most children make a full recovery from Kawasaki disease. However, those who have damage to their coronary arteries or heart muscle may need regular monitoring indefinitely to treat conditions that develop as a complication of the disease.

Explanation

Kawasaki disease is the most common cause of acquired heart disease in children in the developed world. If your child has developed heart disease, he or she may need regular long-term monitoring, treatment and lifestyle changes to prevent their coronary arteries from becoming blocked or having a heart attack. How much will depend on how serious the damage to their heart is.

Some long-term health effects are listed below.

  • Your child may not be able to do much exercise. An echocardiogram which measures the heart rate during stress and rest can tell doctors how much activity your child can do as well as keep an eye on any damage.
  • Your child may be more prone to developing coronary atherosclerosis as an adult. This is when fat and cholesterol in the blood build up on an artery wall, forming a plaque, which narrows the coronary arteries. The plaque can prevent the heart muscle from getting the blood supply it needs. This can cause chest pain (angina) when doing physical exertion or when he or she is under emotional stress.
  • More rarely, the disease may come back.

If you have any concerns about your child's long-term health after Kawasaki disease or any persistent symptoms, you should talk to your GP or your paediatrician.

How can I prevent my child from getting Kawasaki disease?

Answer

Doctors don't know the exact cause of Kawasaki disease, so unfortunately you can't protect your child from getting it. However, being vigilant and picking up on symptoms of the disease early could help prevent long-term damage to your child's health as early treatment helps prevent potential heart complications.

Explanation

Preventing your child from getting Kawasaki disease isn't possible at the moment. This is because the cause of the disease isn't understood. Doctors think that it may be due to an infection to which some children are more genetically susceptible.

The best way to help your child is to be alert to any changes in their health and to know the symptoms to look out for. The most characteristic symptom of Kawasaki disease is a fever that lasts longer than five days along with four or more other symptoms.

Many of the symptoms are similar to symptoms of other childhood disease such as measles, so it can be difficult to differentiate, particularly early in the illness. However, if you think your child has the disease, make an urgent appointment with your GP or go to your nearest accident and emergency department. Long-term heart damage is a complication of Kawasaki disease, so early treatment is crucial to prevent this from happening.

Isn't it dangerous to give children under the age of 16 aspirin? Why is it given to children to treat Kawasaki disease?

Answer

Children under the age of 16 who take aspirin have an increased risk of a condition called Reye's syndrome. However, for those with Kawasaki disease, the benefits of taking aspirin to treat potentially fatal complications of the disease outweigh the risks.

Explanation

Reye's syndrome is a rare disease that mainly affects children and teenagers. It affects all the organs in the body, but can be especially harmful to the brain and liver. The condition can be life-threatening so it must be treated immediately. Its exact causes are unclear, but it has been linked to giving aspirin to children who have a fever from viral infections, such as the flu or chicken pox. This has led to government-backed advice that aspirin shouldn’t be given to children under the age of 16.

However, aspirin is an important treatment for Kawasaki disease because it's very good at reducing inflammation in the body quickly. It also helps prevent blood clots forming that could cause long-term damage to the heart.

Doctors believe that the benefits of taking aspirin for a relatively short period of time to prevent this type of damage outweigh the risks of Reye's syndrome. There are only very few situations in which aspirin should be given to children under 16 years, and these should always be under medical supervision.

Always ask your doctor for advice and read the patient information leaflet that comes with your child's medicine.