Kawasaki disease

Page last reviewed: 13/07/2011

Kawasaki disease, also known as mucocutaneous lymph node syndrome, is a rare condition that mainly affects children under five years of age. It causes a severe high temperature (fever) that does not respond to medication, and a variety of virus-like symptoms such as:

  • a rash
  • swollen glands
  • dry, cracked lips

Kawasaki disease was first diagnosed in 1967 by a Japanese doctor called Dr Tomisaku Kawasaki. The cause of Kawasaki disease is still unknown, and there is no single test or procedure that can confirm the diagnosis.

How common is Kawasaki disease?

Data collected in Ireland from 2008 to 2009 showed that 74% of people with Kawasaki disease were under five years of age.The study estimated the incidence of the disease to be about 2 per 100,000 in this age group.

Kawasaki disease is more common among children of North Asian ethnicity, particularly Korean or Japanese children and possibly Chinese children. In Japan, every year there are 184 cases of Kawasaki disease in children under five for every 100,000 people. 

Outlook

The symptoms of Kawasaki disease are sometimes confused with other conditions, so a diagnosis can often be difficult to make. It is important to seek medical attention straight away. Although Kawasaki disease cannot be prevented, with prompt and effective treatment, most children with the condition will make a full recovery in six to eight weeks.

Kawasaki disease causes inflammation (swelling) of the blood vessels, which can cause complications in the coronary arteries (the blood vessels that supply blood to the heart). Up to 5% of children may experience complications associated with their heart and, in around 1% of cases, the complications may be fatal.

The complications that are associated with Kawasaki disease mean that, in the UK, the condition has become the leading cause of acquired heart disease (when the heart's blood supply is blocked or interrupted).

Glossary

Disease
A disease is an illness or condition that interferes with normal body functions.

Fever
A fever is when you have a high body temperature of 38C (100.4F) or over.

Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

Blood vessel
Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries.

Heart
The heart is a muscular organ that pumps blood around the body.

Page last reviewed: 13/07/2011

The symptoms of Kawasaki disease usually develop in three phases. The phases are outlined below.

Phase one: acute (weeks 1-2)

During the acute phase, your child's symptoms will appear very suddenly and can often be severe. The symptoms of the acute phase are described below.

High temperature (fever)

A high temperature (fever) of 38C (100.4F) or above is usually the first and most common symptom. This can come on rapidly and will not respond to antibiotics or antipyretics (medicines that are used to reduce a fever, such as ibuprofen or paracetamol). If your child has a fever, they may be very irritable.

The fever will usually last for at least five days. However, without appropriate treatment, it can last for around 11 days. In some cases, it may last as long as three to four weeks. The fever will be remittent (come and go) and it may reach a high of up to 40C (104F). 

Changes in hands and feet

The skin on your child's palms or the soles of their feet may become red or hard, and their hands and feet may swell up. Your child's hands and feet may also be tender (painful) to touch or to put weight on, so they may be reluctant to walk or crawl.

Rash

A blotchy, red rash may appear. This usually starts in the genital area, before spreading to the trunk (torso), arms and legs, and the face. There may be flat or raised red spots, but there will not be any blisters (fluid-filled pockets of skin).

Conjunctival injection

Conjunctival injection is when the whites of the eyes become red and swollen. It usually affects both eyes and does not cause any pain. Unlike conjunctivitis (when part of the eye is infected), the conjunctival injection that is associated with Kawasaki disease does not cause fluid to leak from the eyes. 

Lips, mouth and tongue

Your child's lips may be:

  • red
  • dry
  • cracked
  • peeling
  • swollen
  • bleeding

The inside of your child's mouth and throat may also be red, and they may have 'strawberry tongue'. This is when your child's tongue appears red and inflamed (swollen) and is covered in small lumps.

Swollen lymph glands

If you gently feel your child's neck, you may be able to feel swollen lumps on one or both sides. The lumps could be swollen lymph glands.

The lymph glands are part of the immune system (the body's defence system that helps fight infection). They may swell to over 1.5cm in diameter and feel firm and slightly painful.

Second phase: sub-acute (weeks 3-4)

During the sub-acute phase, your child's symptoms will become less severe, but they may last for longer. Your child's fever should subside, but they may still be persistently irritable and in considerable pain.

The symptoms during the sub-acute stage may include:

  • peeling skin on your child's fingers and toes, and sometimes on their palms or the soles of their feet
  • abdominal pain 
  • vomiting
  • diarrhoea
  • urine that contains pus
  • lethargy (feeling drowsy)
  • headache
  • joint pain and swollen joints
  • jaundice (yellowing of the skin and whites of the eyes)

It is during the second phase that complications, such as coronary artery aneurisms (a bulge in one of the blood vessels that supply blood to the heart) are more likely to develop. For more information, see Complications of Kawasaki disease.

Third phase: convalescent (weeks 4-6)

During the convalescent phase, your child will begin to recover. Your child's symptoms should improve and all signs of the illness should eventually disappear. However, your child may still be listless (lacking energy) and easily worn out during this time. Complications can occasionally develop during the third phase.

Glossary

Disease
A disease is an illness or condition that interferes with normal body functions.

Fever
A fever is when you have a high body temperature of 38C (100.4F) or over.

Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

Lymph glands
Lymph nodes are small oval tissues that remove unwanted bacteria and particles from the body. They are part of the immune system.

Diarrhoea
Diarrhoea is the passing of frequent watery stools when you go to the toilet.

Vomiting
Vomiting is when you bring up the contents of your stomach through your mouth.

Jaundice
Jaundice is a condition that causes yellowing of the skin and the whites of the eyes, brought on by liver problems.

Blood vessel
Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries.

Heart
The heart is a muscular organ that pumps blood around the body.

Aneurysms
An aneurysm is a blood-filled sac that forms in a weakened part of a blood vessel.

Page last reviewed: 13/07/2011

The cause of Kawasaki disease is not fully understood, but it is thought to be caused by an infectious agent (something that causes an infection).

Infection

Kawasaki disease acts as if it is caused by an infection, which would mean that a bacteria or virus could be responsible. However, so far no viral or bacterial cause has been identified. Also, Kawasaki disease is not contagious (passed from person to person), which means it is unlikely to be caused by a virus alone.

Kawasaki disease does not usually affect babies under six months of age. This suggests that newborn babies are protected from Kawasaki disease by antibodies (proteins that destroy disease-carrying organisms and toxins) that are passed to them by their mother, either before they were born or during breastfeeding.

Most older children and adults must also have become immune to whatever causes Kawasaki disease because they are rarely affected. This suggests that many people are exposed to whatever causes Kawasaki disease, but only a few develop the symptoms.

Genetics

As only some children are affected by Kawasaki disease, it is possible that they are genetically predisposed to the condition. This means that the genes (units of genetic material) that they inherit from their parents somehow make them more likely to get Kawasaki disease.

One theory suggests that, rather than there being a single gene that causes Kawasaki disease, it may be the result of many genes that each slightly increase the chances of a child developing the condition. Research is currently underway to identify which genes may be responsible. 

Other theories

Other ideas about Kawasaki disease suggest that it may be an autoimmune disorder, when the immune system (the body's defence system) attacks its own tissues and organs.

Other theories suggest that it is a reaction to certain medications or pollutants in the environment, such as chemicals or toxins.

Glossary

Disease
A disease is an illness or condition that interferes with normal body functions.

Bacteria
Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and some are good for you.

Antibodies
Antibodies are your body's natural defence against any foreign antigens that enter your blood. An antibody is a protein that is produced by the body to neutralise or destroy disease-carrying organisms and toxins.

Genetic
Genetic is a term that refers to genes. Genes are the characteristics inherited from a family member.

Gene
A gene is a unit of genetic material that determines your body's characteristics.

Immune system
The immune system is the body's defence system, which helps protect it from disease, bacteria and viruses.

Page last reviewed: 13/07/2011

There is no single test that can be used to confirm Kawasaki disease. Instead, your GP will diagnose your child's condition by looking at their symptoms and by carrying out a physical examination.

Fever and key symptoms

The UK's National Institute for Health and Clinical Excellence (NICE) states that your child may have Kawasaki disease if they have a high temperature (fever) of 38C (100.4F) or above for longer than five days, and they have at least four of the following key symptoms:

  • conjunctival injection in both eyes, where the whites of your child's eyes are red and swollen  
  • changes to the mouth or throat, such as dry, cracked lips or a red, swollen tongue
  • changes to the skin on the arms or legs, such as swelling, redness or peeling skin 
  • a rash
  • swollen lymph nodes in the neck

For a more detailed description of these symptoms, see Symptoms of Kawasaki disease.

It is also possible for your child to be diagnosed with Kawasaki disease if they do not have four of these key symptoms. They may have an atypical (irregular) or incomplete case of Kawasaki disease.

If your child has only had a fever for four days but has four or more of the key symptoms above, they may still be diagnosed with Kawasaki disease. 

Further tests

Your child may need to have some further tests to rule out any other conditions that could be causing their symptoms (see box, right).

There are also a number of tests that can be carried out during the first 7-10 days of the condition to help support the diagnosis. Individually, these tests may not be conclusive, but when combined with some of the key symptoms above, they can help confirm that your child has Kawasaki disease. 

White blood cells

A sample of your child's blood will be tested to see how many infection-fighting white blood cells it contains. In over 50% of cases of Kawasaki disease, the blood contains a higher number of white blood cells than normal. 

Platelet count

The number of platelets (clotting cells) in the blood may also be tested. The platelet count is usually at its highest during the second or third week of having Kawasaki disease. A platelet count may not help diagnose Kawasaki disease in the first two weeks, but it can be used to confirm the diagnosis later on.

Urine analysis

A urine sample may be tested to see whether it contains white blood cells, which could also indicate Kawasaki disease. If your child has Kawasaki disease, their urine should not contain any bacteria. 

C reactive protein (CRP)

C reactive protein (CRP) is produced by the liver at the start of an infection or inflammation (swelling) in the body. The amount of CRP in the blood can be measured. An increased amount indicates inflammation or an infection.

The CRP test cannot diagnose the condition that is causing the inflammation, but it can confirm that there is a problem.

Erythrocyte sedimentation rate (ESR)

The erythrocyte sedimentation rate (ESR) is a measure of how much inflammation (swelling) there is in the body. To calculate your child's ESR, a blood sample is placed in a test tube. The amount of time that it takes the red blood cells (the cells that transport oxygen around the body) to sink to the bottom of the tube is measured.

If the red blood cells sink faster than usual, it may mean that your child has an inflammatory condition, such as Kawasaki disease. Like a CRP test, ESR only shows whether or not there is inflammation in the body, but not what condition is causing it.

Cerebrospinal fluid (CSF)

Cerebrospinal fluid (CSF) is the fluid that surrounds the brain and spinal cord. A procedure called a lumbar puncture involves taking a sample of CSF by inserting a needle between the vertebrae (back bones) in the lower spine. The CSF can be tested for white blood cells, which could be a sign of Kawasaki disease.

Other blood tests

A sample of your child's blood may also be tested to see what else it contains, such as:

  • sodium (salt)
  • proteins
  • enzymes (proteins that speed up and control chemical reactions)
  • lipid (fats)

If the blood contains abnormal amounts of any of these, it may be a sign of Kawasaki disease.

Heart problems

When Kawasaki disease causes complications, they usually affect the heart (see Complications of Kawasaki disease). Therefore, your child may need to have some tests to check that their heart is functioning normally, such as:

  • Electrocardiogram (ECG): this measures the electrical activity of the heart using electrodes (flat metal discs) that are attached to your child's arms, legs and chest. The ECG can detect damage to the heart or problems with the rhythm of the heart.
  • Echocardiogram: this uses ultrasound (high-frequency sound waves) to produce images of the heart. This will reveal whether there are any problems with the heart's structure or function.

During the acute phase of Kawasaki disease (weeks 1-2), several heart abnormalities may be identified. These could include:

  • tachycardia (a rapid heart rate)
  • pericardial effusion (a collection of fluid in the heart)
  • myocarditis (inflammation of the heart muscle)

In about 30-50% of cases of Kawasaki disease, the blood vessels around the heart are widened slightly, which can cause the above heart abnormalities. In most cases, these abnormalities resolve six to eight weeks after the start of the condition, although in some people further complications can develop. 

Glossary

Disease
A disease is an illness or condition that interferes with normal body functions.

Fever
A fever is when you have a high body temperature of 38C (100.4F) or over.

Lymph nodes
Lymph nodes are small oval tissues that remove unwanted bacteria and particles from the body. They are part of the immune system.

Bacteria
Bacteria are tiny, single-celled organisms that live in the body. Some can cause illness and disease and some are good for you.

Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

Blood
Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.

Platelet
Platelets are cells in the blood that control bleeding by plugging the broken blood vessel and helping the blood to clot.

White blood cells
White blood cells are the part of blood that fights infection and disease.

Red blood cells
Red blood cells are cells in the blood that transport oxygen around the body.

Enzymes
Enzymes are proteins that speed up and control chemical reactions in the body, such as digestion.

Heart
The heart is a muscular organ that pumps blood around the body.

Similar conditions

Diagnosing Kawasaki disease can be difficult because the symptoms can be similar to a number of other conditions. Therefore, your GP or another healthcare professional may need to test for other conditions to rule them out before they can diagnose Kawasaki disease.

For example, Kawasaki disease can be confused with:

  • scarlet fever: a bacterial infection that causes a distinctive pink-red rash
  • toxic shock syndrome: a rare, life-threatening bacterial infection
  • measles: a highly infectious viral illness that causes a fever and distinctive red-brown spots
  • glandular fever: a viral infection that can cause a fever and swollen lymph glands
  • Stevens-Johnson syndrome: a very severe allergic reaction to medication
  • viral meningitis: an infection of the meninges (the protective membranes that surround the brain and spinal cord) 

Page last reviewed: 13/07/2011

Kawasaki disease usually has to be treated in hospital as it can cause serious complications. It is best for your child to receive treatment as soon as possible, ideally within 10 days of their symptoms first starting.

If your child's condition is not treated promptly, it may take longer for them to recover and they are at greater risk of developing complications.

There are two main medicines used to treat Kawasaki disease:

  • aspirin
  • intravenous immunoglobulin

These are described in more detail below.

Aspirin

If your child has Kawasaki disease, they may be prescribed aspirin. This is one of the few occasions when a child who is under 16 years of age will be given aspirin. Unless it is prescribed by a healthcare professional treating your child, never give your child aspirin.

Aspirin is a non-steroidal anti-inflammatory drug (NSAID). It is used to treat Kawasaki disease because:

  • aspirin can ease pain and discomfort
  • aspirin can reduce a high temperature (fever)
  • at high doses, aspirin is an anti-inflammatory (it reduces swelling)
  • at low doses, aspirin is an antiplatelet (it prevents blood clots from forming)

Initially, your child may be given a high dose of aspirin, which will then be changed to a low dose. The dose that your child is prescribed and how long they need to take it for will depend on your child's symptoms.

In general, your child may be prescribed a high dose of aspirin until they no longer have a fever. After this, they may be prescribed a low dose of aspirin until six to eight weeks after the start of their symptoms. This is to prevent coronary artery abnormalities (problems developing in the blood vessels that supply blood to the heart).

A review into using aspirin to treat Kawasaki disease did not find any evidence either for or against its use. In theory, aspirin should prevent heart complications because it works as an anti-inflammatory and an antiplatelet. Aspirin is likely to continue to be used to treat Kawasaki disease, although further research is needed. 

Intravenous immunoglobulin

Intravenous immunoglobulin is also called IVIG. Immunoglobulin is a solution of antibodies (proteins produced by the immune system to fight disease-carrying organisms) that is obtained from healthy donors. Intravenous means that is injected into a vein.

The immunoglobulin used to treat Kawasaki disease is also called a gamma globulin.
 
After you child receives IVIG, their symptoms will usually improve within 36 hours. Research has shown that IVIG can reduce your child's fever and reduce the risk of heart problems. If their fever does not disappear after 36 hours, your child may be given a second dose of IVIG.

Possible treatment

Corticosteroids (steroids) are a type of medication that contains hormones (powerful chemicals that have a wide range of effects on the body). They are currently being researched to see if they are beneficial in treating Kawasaki disease.

One review of research into corticosteroids found that they can reduce the need to be treated again with IVIG, but do not reduce the risk of heart problems. While further research is underway, corticosteroids may be used if a second dose of IVIG does not work.

After treatment

When your child is discharged from hospital, you should be given instructions for how to care for them at home. This could include making sure that your child is as comfortable as possible and that they get plenty of fluids. 

Make sure that your child continues to take any medication they have been prescribed as instructed and watch out for any side effects.

You will be given a follow-up appointment and your child's heart will continue to be monitored. Once an echocardiogram (an ultrasound scan of the heart) has confirmed that your child does not have any heart abnormalities, they can usually stop taking aspirin.

Some symptoms, such as peeling skin, may not occur until three to four weeks after the start of the condition and a full recovery could take around six weeks (see Symptoms of Kawasaki disease). 

Glossary

Disease
A disease is an illness or condition that interferes with normal body functions.

Fever
A fever is when you have a high body temperature of 38C (100.4F) or over.

Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

Blood
Blood supplies oxygen to the body and removes carbon dioxide. It is pumped around the body by the heart.

Platelet
Platelets are cells in the blood that control bleeding by plugging the broken blood vessel and helping the blood to clot.

Heart
The heart is a muscular organ that pumps blood around the body.

Blood vessel
Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries.

Antibodies
Antibodies are your body's natural defence against any foreign antigens that enter your blood. An antibody is a protein that is produced by the body to neutralise or destroy disease-carrying organisms and toxins.

Immune system
The immune system is the body's defence system, which helps protect it from disease, bacteria and viruses.

Hormones
Hormones are groups of powerful chemicals that are produced by the body and have a wide range of effects.

Side effects of aspirin

Aspirin is not usually given to children under 16 years of age because it can cause side effects, including Reye’s syndrome. Reye’s syndrome is very rare, but it can cause serious liver and brain damage, and it can be fatal if it is not treated quickly.

The symptoms of Reye’s syndrome include persistent vomiting and a lack of energy. Seek medical attention immediately if your child experiences either of these symptoms.

Other side effects of aspirin include:

  • irritation of the digestive system
  • indigestion
  • nausea
  • bruising

Page last reviewed: 13/07/2011

With prompt treatment, most children make a full recovery from Kawasaki disease. However, complications can develop. These are mainly related to the heart. Complications occur because of the inflammatory (swelling) effect that Kawasaki disease has on blood vessels.

Aneurysm

Inflammation in the coronary arteries (the blood vessels that supply blood to the heart) can cause a section of the artery wall to weaken. As the blood passes through the weakened part of the artery wall, the blood pressure causes it to bulge outwards like a balloon. This is known as an aneurysm.

Some aneurysms heal by themselves over time. However, sometimes a blood clot (thrombosis) can form in a weakened section of the artery. This can cause a heart attack (when part of the heart muscle dies because it is starved of oxygen) or heart disease (when the heart's blood supply is blocked or interrupted).

In rare cases, the aneurysm may rupture (burst), which could cause severe internal bleeding.

It is also possible for other major arteries to be involved, such as the brachial artery (the main blood vessel in the upper arm) or the femoral artery (the main blood vessel in the upper thigh).

The risks

Approximately 15-25% of children with Kawasaki disease who do not receive treatment (because their condition is not diagnosed correctly, for example) may experience complications associated with their heart.

For children who receive intravenous immunoglobulin (IVIG) to treat their Kawasaki disease (see Treatment of Kawasaki disease), the risk of complications is reduced to 5%. These complications are serious and, in 1% of cases, may be fatal.   

Treating complications

If your child develops a serious heart abnormality, they may require medication or, in some cases, surgery. Possible treatments include:

  • Anticoagulant medicines and antiplatelet medicines: medicines that stop the blood from clotting, which may prevent your child from having a heart attack if their arteries are particularly inflamed.
  • Coronary artery bypass graft: a surgical procedure that diverts blood around narrow or clogged arteries, improving the blood flow and oxygen supply to the heart.
  • Coronary angioplasty: a surgical procedure to widen blocked or narrowed coronary arteries to improve the blood flow to the heart. In some cases, a stent (a short, hollow metal tube) is placed in the blocked artery to keep it open.

Some children with severe complications may experience permanent damage to their heart muscles or valves (the flaps that control the flow of blood). Their condition will be closely monitored and they will usually have regular follow-up appointments with a heart specialist (cardiologist).

Complications in later life

If your child has experienced any heart complications as a result of Kawasaki disease, they may be at higher risk of developing cardiovascular complications in later life. Cardiovascular means related to the heart and blood circulation and includes conditions such as heart attacks and heart disease.

As Kawasaki disease was only discovered in 1967, its long-term effects are still unclear. The long-term risk for children who do not experience any complications is also unknown.

Glossary

Disease
A disease is an illness or condition that interferes with normal body functions.

Heart
The heart is a muscular organ that pumps blood around the body.

Inflammation
Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.

Blood vessel
Blood vessels are the tubes in which blood travels to and from parts of the body. The three main types of blood vessels are veins, arteries and capillaries.

Arteries
Arteries are blood vessels that carry blood from the heart to the rest of the body.

Aneurysms
An aneurysm is a blood-filled sac that forms in a weakened part of a blood vessel.

Content provided by NHS Choices www.nhs.uk and adapted for Ireland by the Health A-Z.

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