Kawasaki disease

Kawasaki disease causes swelling, called inflammation, in the walls of small to medium-sized blood vessels that carry blood throughout the body. Kawasaki disease most often affects the heart arteries in children. Those arteries supply oxygen-rich blood to the heart.

Kawasaki disease is sometimes called mucocutaneous lymph node syndrome. That's because it also causes swelling in glands, called lymph nodes, and mucous membranes inside the mouth, nose, eyes and throat.

Children with Kawasaki disease might have high fever, swollen hands and feet with skin peeling, and red eyes and tongue. But Kawasaki disease is often treatable. With early treatment, most children get better and have no long-lasting problems.

Symptoms of Kawasaki disease include a fever greater than 102.2 degrees Fahrenheit (39 degrees Celsius) for five or more days. And the child has at least four of the following symptoms.

• A rash on the main part of the body or in the genital area.
• An enlarged lymph node in the neck.
• Very red eyes without a thick discharge.
• Red, dry, cracked lips and a red, swollen tongue.
• Swollen, red skin on the palms of the hands and the soles of the feet. Later the skin on fingers and toes peels.

The symptoms might not happen at the same time. Let your child's healthcare professional know about a symptom that has gone away.

Other symptoms might include:

• Belly pain.
• Diarrhea.
• Fussiness.
• Joint pain.
• Vomiting.

Some children get a high fever for five or more days but have fewer than four of the symptoms needed for a diagnosis of Kawasaki disease. They might have what's called incomplete Kawasaki disease. Children with incomplete Kawasaki disease are still at risk of damage to the heart arteries. They still need treatment within 10 days of when symptoms appear.

Kawasaki disease can have symptoms like those of a condition called multisystem inflammatory syndrome in children. The syndrome happens in children with COVID-19.

When to see a doctor

If your child has a fever that lasts more than three days, contact your child's healthcare professional. Treating Kawasaki disease within 10 days of when it began may reduce the chances of lasting damage to the arteries that supply the heart.

No one knows what causes Kawasaki disease. But experts don't believe the disease spreads from person to person. Some think that Kawasaki disease happens after a bacterial or viral infection, or that it's linked to factors in the environment. Certain genes might make children more likely to get Kawasaki disease.

Three things are known to increase a child's risk of developing Kawasaki disease.

• Age. Children under 5 years old are at highest risk of Kawasaki disease.
• Sex. Children who are assigned male at birth are slightly more likely to get Kawasaki disease.
• Ethnicity. Children of Asian or Pacific Islander descent have higher rates of Kawasaki disease.

Kawasaki disease tends to occur seasonally. In North America and countries with like climates, it most often happens in the winter and early spring.

Kawasaki disease is a leading cause of heart disease in children who live in developed countries. But, with treatment, few children have lasting damage.

Heart complications include:

• Swelling of blood vessels, most often the arteries that send blood to the heart.
• Swelling of the heart muscle.
• Heart valve problems.

Any of these complications can damage the heart. Swelling of the heart arteries can weaken them and cause a bulge in the artery wall, called an aneurysm. Aneurysms raise the risk of blood clots. These can lead to a heart attack or cause bleeding inside the body.

Rarely, for children who get heart artery problems, Kawasaki disease can cause death.

There's no single test to diagnose Kawasaki disease. Diagnosis involves ruling out other diseases that cause the same symptoms. These diseases include:

• Scarlet fever.
• Juvenile rheumatoid arthritis.
• Stevens-Johnson syndrome — a disorder of the mucous membranes.
• Toxic shock syndrome.
• Measles.
• Some illnesses caused by ticks, such as Rocky Mountain spotted fever.

A member of your child's healthcare team will do an exam and order blood and urine tests to help in the diagnosis. Tests might include:

• Blood tests. Blood tests help rule out other diseases and check blood cell count. A high white blood cell count, anemia and inflammation are signs of Kawasaki disease.
• Electrocardiogram (ECG or EKG). This quick test checks the heart's electrical activity. It shows how the heart is beating. Sticky patches called electrodes are attached to the chest and sometimes to the arms or legs. Wires connect the patches to a computer. The computer prints or displays results. An ECG can diagnose an irregular heartbeat. Kawasaki disease can cause heart rhythm problems.
• Echocardiogram. This test uses sound waves to make pictures of the heart in motion. It sees how blood flows through the heart and heart valves. An echocardiogram shows how well the heart is working. It also can help see problems with the heart arteries.

It's best to start treatment for Kawasaki disease as early as possible, when your child still has a fever. Treatment for Kawasaki disease often happens in a hospital. The goals of treatment are to lower fever, reduce swelling and prevent heart damage.

Medication

Treatment for Kawasaki disease can include:

• Gamma globulin. A protein called gamma globulin is given through a vein. This treatment lowers inflammation in the blood vessels. It can lower the risk of problems with the heart artery.

  With treatment, a child might start to improve soon after one gamma globulin treatment. Without treatment, Kawasaki disease lasts about 12 days. However, heart complications might last longer.

  After getting gamma globulin, wait at least 11 months to get a live vaccine, such as the chickenpox or measles vaccine. Gamma globulin can affect how well these vaccines work.

• Aspirin. High doses of aspirin might help treat inflammation. Aspirin also can decrease pain, joint swelling and fever. The aspirin dose will likely be lowered once the fever has been gone for 48 hours.

  For most other conditions, aspirin shouldn't be given to children. Aspirin has been linked to Reye's syndrome, a rare life-threatening condition, in children or teenagers who have the flu or chickenpox.

  A healthcare professional needs to oversee giving aspirin to children with Kawasaki disease. Children who get flu or chickenpox during treatment might need to stop taking aspirin.

After the first treatment

Once the fever goes down, a child might need to take low-dose aspirin for at least six weeks. This can be longer if a there are problems with the heart artery. Aspirin helps prevent blood clotting.

With treatment, a child might start to improve soon after one gamma globulin treatment. Without treatment, Kawasaki disease lasts about 12 days. However, heart problems might last longer.

Watching heart problems

If your child has any signs of heart problems, the healthcare professional might suggest follow-up tests to check your child's heart health. Tests are often done 6 to 8 weeks after the illness began, and then again after six months.

If heart problems keep on, your child might be sent to a specialist who treats heart disease in children, called a pediatric cardiologist. Treatment for heart issues linked to Kawasaki disease depends on the type of heart condition.

Find out all you can about Kawasaki disease so that you can make good choices with your child's healthcare team about treatment.

Most often, children who have been treated for Kawasaki get well fast and return to their usual activities. If your child's heart has been affected, talk to the pediatric cardiologist about whether you need to restrict your child's activities.

You'll likely first see your family healthcare professional or pediatrician. Sometimes children with Kawasaki disease see doctors with special training in heart conditions, bone and joint disorders, or infectious diseases. A doctor who treats children with heart conditions is called a pediatric cardiologist. A rheumatologist treats children with bone and joint disorders.

Here's some information to help you get ready for your appointment.

What you can do

Bring someone with you to the appointment if you can. A family member or friend can take notes and help you remember all the information you're given.

Make a list of:

• Your child's symptoms, and when they began. Include any that don't seem linked to Kawasaki disease. Try to keep track of how high your child's fever has been and how long it has lasted.
• All medicines, vitamins or supplements your child takes, including doses.
• Write down questions to ask your child's healthcare professional.

For Kawasaki disease, some questions to ask include:

• What's the most likely cause of my child's symptoms?
• Are there any other possible causes for the symptoms?
• Does my child need tests?
• How long will the symptoms last?
• What treatments are there? Which do you suggest?
• How can I make my child more comfortable?
• Can you give me brochures or other printed information? What websites do you suggest?

Be sure to ask all the questions you have.

What to expect from your doctor

Your child's healthcare professional is likely to ask you questions, such as:

• How bad are the symptoms? How high has your child's fever been? How long did it last?
• What, if anything, seems to improve the symptoms?
• What, if anything, seems to worsen the symptoms?
• Has your child been around people with infectious diseases?
• Does your child have allergies?