What Is Kawasaki Disease? What Causes Kawasaki Disease?

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Main Category: Pediatrics / Children's Health
Also Included In: Infectious Diseases / Bacteria / Viruses
Article Date: 20 Sep 2009 - 0:00 PST

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Kawasaki disease is a rare syndrome of unknown origin that causes high fever, reddening of the eyes (conjunctivitis), lips and mucous membrane of the mouth, gingivitis (ulcerative gum disease), swollen neck glands and a bright red rash over the skin of the hands and feet, in young children.

Kawasaki disease causes inflammation in the walls of arteries throughout the body, including the coronary arteries, which supply blood to the heart muscle. As it affects the lymph nodes, skin, and mucous membranes inside the nose, mouth and throat it is also called mucocutaneous lymph node syndrome.

Kawasaki disease is more common in boys than girls. It was first diagnosed by Tomiraku Kawasaki, a Japanese doctor in 1967, hence the name. Kawasaki disease has nothing to do with motorbikes or motorbike accidents.

What are the signs and symptoms of Kawasaki disease?

A symptom is something the patient can feel and/or reports, while a sign is something that other people notice. The patient may experience a headache (symptom), while the doctor or family member may detect a rash (sign).

Signs and symptoms develop in three phases.

• Acute phase of Kawasaki disease - Phase 1
  These appear from day 1 to 11. Symptoms appear suddenly and are usually intense:
  
  
  • Elevated body temperature (fever) - the fever continues for at least five days. In some cases the child's temperature may reach 104F (40C). Kawasaki disease induced fevers do not respond to OTC painkillers, such as ibuprofen or Tylenol (paracetamol).
  
  
  • Conjunctivitis - the whites of the child's eyes become reddened. Eyes may also be itchy, watery, and sore.
  
  
  • Sore throat.
  
  
  • Lips may be swollen, chapped and dry.
  
  
  • Red, swollen tongue, often with small lumps at the back (sometimes referred to as strawberry tongue).
  
  
  • Rash - the skin will be red and swollen on the palms of the hands and the soles of the feet. Children may not want to move their legs because of this.
  
  
  • Swollen lymph glands - the glands on the child's neck may be swollen (lumpy on either side).


• Sub-acute phase - second phase
  These symptoms appear from days 12 to 21.
  
  Symptoms will be less severe, but may persist for longer. The body temperature should be back to normal. Complications are more likely to occur during this phase and the child may experience more pain and be moody. Symptoms may include:
  
  
  • Peeling of the skin on toes and fingers
  • Vomiting
  • Diarrhea
  • Tummy ache
  • Joint pain
  • Joint swelling
  • Jaundice
  • Lack of appetite


• Convalescent phase - third phase
  This phase lasts from about day 22 to day 60.
  
  
  During this phase the child gradually recovers and symptoms improve, until eventually all signs of the disease are gone.

What causes Kawasaki disease?

Experts do not really know what causes the disease. We are pretty sure it is a virus because of the characteristics of many of the symptoms. It is not a contagious disease, however - so, it is unlikely to have a virus as its only cause.

Some studies indicate that perhaps Kawasaki disease is caused by an abnormal reaction to some common virus which would not bother most people. Some say it is an autoimmune disorder - the body's immune system attacks its own good tissue as if it were a pathogen (organism that causes disease). Unfortunately, there is no clear evidence of any cause for Kawasaki disease.

What are the risk factors for Kawasaki disease?

A risk factor is something that increases the risk of developing a disease or condition. For example, we know that smoking raises a regular smoker's risk of developing many cancers; therefore, regular smoking is a risk factor for cancer. The following may be considered as risk factors for Kawasaki disease:

• Age - children aged from 2 to 5 years have a higher risk of developing the disease compared to humans of other ages.


• Boys - boys are more likely than girls to develop Kawasaki disease.


• Ethnic background - people of Asian ancestry, specifically Japanese or Chinese, are more likely to develop Kawasaki disease compared to other people.

How is Kawasaki disease diagnosed?

Unfortunately, currently there is no test that can confirm Kawasaki disease. A GP (general practitioner, primary care physician) will examine the patient for symptoms and interview him/her and the parents. Some tests may be ordered to discard the possibility that other conditions or diseases may be causing the symptoms.

The following diseases/conditions with overlapping signs and symptoms will have to be ruled out:

• Measles
• Scarlet fever
• Juvenile arthritis
• Stevens-Johnson syndrome
• Toxic shock syndrome
• Cytomegalovirus or Epstein-Barr virus infection
• Some tick-borne illness (e.g. Rocky Mountain spotted fever)

Urine test - a urine test helps find out whether something else may be the cause of symptoms.

Platelet count - platelets are cells in the blood that clump together when there is a lesion to stop bleeding; they form part of our blood's clotting (coagulation) system. The platelet count of a child with Kawasaki disease is usually abnormally high.

An Erythrocyte Sedimentation Rate (ESR) test - a sample of red blood cells is placed into a test tube of liquid. The amount of time the red blood cells take to fall to the bottom is measured at a rate of millimeters per hour. If they fall faster than normal it could mean the child has an inflammatory condition (Kawasaki is an inflammatory condition). The ESR test can only determine whether there is an infection, it cannot tell us what is causing it.

A C Reactive Protein (CRP) test - this test measures how much C reactive protein there is in the blood. CRP is produced by the liver. A higher-than-usual blood level of CRP means there is an inflammation in the body. However, this test, like the ESR one, does not tell us what is causing the inflammation.

Checking the heart - Kawasaki disease can occasionally affect the heart. The doctor may want to verify whether the heart is working properly. The following tests may be ordered:

• Electrocardiogram (ECG) - this device records the electrical activity and rhythms of the patient's heart. Electrodes are attached to the patient's skin and impulses are recorded as waves and displayed on a screen (or printed on paper).


• Echocardiogram - this is an ultrasound scan that checks the pumping action of the patient's heart. Sound waves are used to create a video image of the patient's heart, which helps the doctor see how well the heart is pumping.

What is the treatment for Kawasaki disease?

Because of the risk of complications, Kawasaki disease is usually treated in hospital. Treatment should be done promptly for faster recovery and to reduce the risk of complications.

Two main medicines for Kawasaki disease treatment:

• Aspirin - children under 16 should not be given aspirin. However, it is prescribed if a child has Kawasaki disease. Children with Kawasaki disease have a very high blood platelet count, making them very susceptible to blood clots forming in their bloodstream. Aspirin helps prevent blood clots, as well as reducing the fever, rash and joint inflammation.
  
  For aspirin-therapy to be effective the child will normally require a high dose. It is important that the child is checked and monitored closely to make sure no undesirable side effects occur. Aspirin therapy may continue for several weeks after the child has recovered from symptoms.


• Gammaglobulin - these are cells in the blood which help fight infection (antibodies). Gammaglobulin is administered intravenously (through a vein in the child's arm). Symptoms tend to improve rapidly; within 24 hours of administering gammaglobulin.

When the child is back home it is important to make sure he/she receives plenty of fluids and does not become dehydrated.

After initial treatment

If the child develops a coronary artery aneurysm aspirin treatment will continue for longer.

If the child becomes infected with flu or chickenpox during treatment he/she will have to stop taking aspirin.

Monitoring the heart (heart problems are rare)

If there are any indications of heart problems the doctor may order follow-up tests, usually 6 to 8 weeks after symptoms started. If the child develops continuing heart problems the doctor may refer the child to a pediatric cardiologist - a doctor specialized in diagnosing and treating childhood heart problems. The following may be prescribed or ordered:

• Anticoagulant medications - examples may include warfarin, heparin or aspirin. These drugs prevent the undesirable formation of blood clots.


• Coronary artery angioplasty - this procedure opens up an artery that has narrowed by inflating a small balloon inside the artery which squashes a clot against the wall of the blood vessel.


• Stent - a stent may be placed in the clogged artery to help prop it open, reducing the risk of it becoming blocked again. A stent placement is often done along with an angioplasty.


• Coronary artery bypass graft - blood flow is rerouted round a diseased coronary artery by grafting a section of blood vessel from the chest, arm or leg to use as the alternate route. The bypass effectively goes around the blocked area of the artery, allowing blood to pass through into the heart muscle.

What are the complications of Kawasaki disease?

If children receive treatment promptly the risk of complications is very small. Complications tend to happen when either there is no treatment or it started late. Even when there are heart complications, most children recover from them completely within a few weeks.

Even though complications are very rare, when they do occur they can be serious, and on some occasions fatal.

• Aneurysm - the blood vessels leading to the heart can become inflamed, causing a section of the artery wall to weaken and bulge outwards. If the aneurysm does not heal itself a blood clot can form, which raises the risk of a heart attack or internal bleeding if the aneurysm bursts.

The following complications from Kawasaki disease are also possible:

• Myocarditis - inflammation of the myocardium (heart muscle).
• Pericarditis - inflammation of the pericardium (lining around the heart).
• Arrhythmia - irregular heart beat.
• Cardiomegaly - the heart becomes larger than normal as a result of heart disease.
• Mitral regurgitation - blood flows back from the left ventricle to the left atrium of the heart due to a valve problem (blood flows back when it shouldn't).

Written by Christian Nordqvist


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