Kawasaki’s Disease

Kawasaki’s disease is a rare condition that causes inflammation in blood vessels throughout the body, mainly affecting young children. While it can seem frightening with its high fever and visible symptoms, early treatment can prevent serious complications and most children recover fully.

Table of contents

• What is Kawasaki’s Disease?
• Who is Most Affected
• Signs and Symptoms
• What Causes This Disease
• How Doctors Diagnose Kawasaki’s Disease
• Possible Complications
• Treatment Options
• Recovery and Follow-up Care

What is Kawasaki’s Disease?

Kawasaki syndrome, mucocutaneous lymph node syndrome

Kawasaki’s disease is a condition that causes swelling and inflammation in the walls of small to medium-sized blood vessels that carry blood throughout the body. Vasculitis (inflammation of blood vessels) is the main problem in this disease^[1]. The inflamed blood vessels can become weak and stretched out, and when this happens, they are at risk of tearing. They can also develop scarring and become too narrow, which limits how much blood can get through to nourish tissues and organs^[2].

The disease most often affects the heart arteries in children, particularly the coronary arteries that supply oxygen-rich blood to the heart muscle^[1]. This is why early treatment is so important. Without proper medical care, serious complications can develop that may not be initially recognized^[8].

Kawasaki disease was first discovered in 1967 by a Japanese pediatrician, Dr. Tomisaku Kawasaki^[4]. It is now recognized as the most common cause of acquired heart disease in children in the United States, Japan, and other developed countries^[3]. The term “acquired” means the heart condition develops after birth, rather than being present from birth.

Who is Most Affected

Kawasaki’s disease primarily affects young children. About 75 to 80 percent of cases occur in children younger than five years old, with the typical age at diagnosis being around 1.5 years^[14]. The disease can affect children of any age, but it is rare in babies younger than four months, possibly because they are protected by antibodies from their mothers^[4]. While less common, older children and even adults can sometimes develop the condition^[6].

Boys are more likely to develop Kawasaki’s disease than girls, with a ratio of about 1.5 boys for every girl affected^[3]. Boys are also more likely to suffer from complications and have a higher risk of serious outcomes^[4].

The disease shows clear differences across ethnic groups. Children of Asian or Pacific Islander descent are much more likely to get Kawasaki’s disease than children of other backgrounds^[2]. In the United States, it is estimated that 10 to 20 out of every 100,000 children under five years old develop the disease each year. In contrast, in Japan, Korea, and Taiwan, the rates are much higher, affecting 50 to 250 out of every 100,000 children in this age group^[2].

There appears to be a seasonal pattern to the disease, with more cases happening in late winter and early spring^[2]. Researchers have also found that siblings of children who have had Kawasaki’s disease are 10 to 20 times more likely to develop it than the general population, suggesting that genetics may play a role^[4].

Signs and Symptoms

The main sign of Kawasaki’s disease is a high fever, typically above 102.2 degrees Fahrenheit (39 degrees Celsius), that lasts for five days or more^[1]. Along with the fever, children need to have at least four of the following five symptoms to be diagnosed with the typical form of the disease^[1]:

• A rash on the main part of the body or in the genital area. The rash is often red and can appear in different forms, most commonly as raised bumps or looking similar to scarlet fever^[1]
• Red eyes (called conjunctivitis) without a thick discharge. The redness usually affects both eyes, is painless, and often has a clear zone around the colored part of the eye^[8]
• Changes in the mouth, lips, and tongue. The lips become very red, dry, cracked, and may bleed. The tongue may appear bright red and bumpy, often called a “strawberry tongue.” The inside of the mouth and throat become red^[1]
• Swelling and redness of the hands and feet. Later, the skin on fingers and toes begins to peel, usually starting around the nails. This peeling typically happens in the second week of illness^[1]
• An enlarged lymph node in the neck. Usually only one side is affected, and at least one node is larger than 1.5 centimeters^[3]

It is important to know that these symptoms might not all appear at the same time. They can show up one after another over several days^[8]. Other symptoms that may occur include belly pain, diarrhea, vomiting, fussiness or irritability, joint pain, and painful urination^[1]. In some children, enlargement of the gall bladder can cause belly pain and vomiting^[8].

Some children develop what doctors call “incomplete” or “atypical” Kawasaki’s disease. This means they have a high fever for five or more days but show fewer than four of the main symptoms^[1]. Infants and adolescents often present with incomplete Kawasaki’s disease, and these age groups are at particularly high risk of developing serious heart complications^[16].

What Causes This Disease

The exact cause of Kawasaki’s disease remains unknown, which makes it one of the mysteries in medicine^[3]. Many scientists believe that the disease may be triggered by an infection, possibly a virus or a toxin from bacteria, in children who have a genetic predisposition^[8]. The thinking is that an infectious agent enters through the breathing passages and starts a chain reaction in the body^[4].

When this happens, the body’s immune system responds by activating certain cells and chemicals that fight infection. However, in Kawasaki’s disease, this response becomes exaggerated and causes damage to blood vessels throughout the body^[4]. The immune system mistakenly injures the blood vessels, causing them to become inflamed and potentially narrow or close off^[6].

Research has shown that certain genetic markers make some children more likely to develop the disease. Studies have found specific gene variations that are more common in children with Kawasaki’s disease^[4]. This genetic link helps explain why the disease is more common in certain ethnic groups and why siblings of affected children have a higher risk.

It is important to know that Kawasaki’s disease is not contagious. It does not spread from one person to another through contact^[2]. There is no evidence that the disease passes from child to child, even though researchers suspect an infectious trigger^[4].

How Doctors Diagnose Kawasaki’s Disease

There is no single specific test that can confirm Kawasaki’s disease. Instead, doctors make the diagnosis based on recognizing the pattern of symptoms and ruling out other conditions that can cause similar problems^[8]. The doctor will perform a physical examination and carefully look for the characteristic signs of the disease.

To help with diagnosis, doctors typically order several tests^[9]:

• Blood tests to check for signs of inflammation, anemia, and high white blood cell counts, which are typical in Kawasaki’s disease. These tests also help rule out other diseases^[9]
• Urine tests to look for signs of inflammation and rule out other conditions^[8]
• An electrocardiogram (also called ECG or EKG), which is a quick test that checks the heart’s electrical activity and can detect irregular heartbeats^[9]
• An echocardiogram, which uses sound waves to create moving pictures of the heart. This test is very important because it can show how well the heart is working and whether there are any problems with the coronary arteries^[9]

An echocardiogram should be performed as soon as Kawasaki’s disease is suspected, even before all symptoms have appeared^[14]. This imaging test is the primary way doctors screen for coronary artery aneurysms (bulging or ballooning of the heart arteries)^[8].

Before making a diagnosis of Kawasaki’s disease, doctors need to rule out other conditions that cause similar symptoms. These include scarlet fever, juvenile rheumatoid arthritis (a type of arthritis in children), toxic shock syndrome, measles, and some tick-borne illnesses^[9].

Possible Complications

The most serious complication of Kawasaki’s disease involves the heart and blood vessels. Without proper treatment, about one in four children will develop problems with their coronary arteries^[5]. With appropriate treatment, this risk can be significantly reduced.

The main heart-related complications include^[2]:

• Aneurysms (weakness or bulging) in the coronary arteries. These are areas where the artery wall becomes weak and stretches out, creating a balloon-like bulge^[8]
• Blood clots forming in the coronary arteries, which can block blood flow to the heart muscle^[2]
• Narrowing of the coronary arteries, which reduces blood flow to the heart^[2]
• Problems with heart valves, which help blood move through the heart properly^[2]
• Inflammation in the heart muscle itself, called myocarditis^[2]
• Build-up of fluid around the heart^[8]
• In severe cases, heart failure or even heart attack^[2]

When aneurysms develop, they can rupture (burst), which is extremely dangerous. In severe cases, some children may require coronary artery bypass surgery^[2].

Kawasaki’s disease can also affect other parts of the body beyond the heart. Other possible complications include inflammation in the liver (hepatitis), inflammation in the lungs, inflammation in the pancreas (pancreatitis), and aseptic meningitis (inflammation of the membranes covering the brain, but not caused by infection)^[2].

Without treatment, serious complications can develop in about 2 to 3 percent of cases, which can be fatal^[5]. This is why prompt recognition and treatment are so critical.

Treatment Options

Kawasaki’s disease is always treated in the hospital^[3]. The earlier treatment begins, the better the outcome and the lower the risk of complications^[9]. Treatment should ideally start as soon as possible, while the child still has a fever.

The main treatments are^[3]:

Intravenous immunoglobulin (IVIG) is a solution of antibodies collected from healthy blood donors. It is given through a vein (intravenously) in a single large dose of 2 grams per kilogram of the child’s body weight^[14]. This treatment has been shown to reduce fever, decrease inflammation, and significantly lower the risk of developing coronary artery problems. Research shows that higher doses given in a single infusion work better than smaller divided doses^[14]. After receiving IVIG, symptoms should improve within 36 hours^[10].

Aspirin is used for several purposes in Kawasaki’s disease. High doses help reduce fever and inflammation, while low doses help prevent blood clots from forming^[10]. This is one of the few situations where doctors prescribe aspirin to children. Initially, children receive high-dose aspirin (80 to 100 milligrams per kilogram per day divided into four doses) until the fever has been gone for 48 to 72 hours. Then they switch to low-dose aspirin, which they may continue taking for 6 to 8 weeks after symptoms began^[14].

If a child’s symptoms do not improve after the first dose of IVIG, they may need a second dose. In some cases, additional medications may be necessary^[3]:

• Corticosteroids, which are powerful anti-inflammatory medications containing hormones. These may be recommended if IVIG hasn’t worked well or if the child has a high risk of heart problems^[10]. Research suggests that corticosteroids may help prevent coronary abnormalities when used along with IVIG^[14]
• Other medications, such as infliximab, cyclosporin, or other immunomodulatory drugs, may be used in cases that don’t respond to standard treatment^[15]

The goal of treatment is to control symptoms quickly, prevent complications, and reduce the risk of long-term heart problems.

Recovery and Follow-up Care

With prompt treatment, most children recover from Kawasaki’s disease in about two months and have no long-lasting problems^[2]. Full recovery could take around 6 weeks, though it may take longer in some children^[10].

When a child is discharged from the hospital, parents will receive instructions on how to care for them at home. This includes making sure the child is comfortable, drinks plenty of fluids, and continues taking any prescribed medicines^[10]. It is important to watch for any side effects from medications and to look out for any returning or worsening symptoms.

Follow-up care is essential. Children who have had Kawasaki’s disease need regular check-ups to monitor their heart health. A cardiologist (heart doctor) will see the child for follow-up appointments and may repeat echocardiograms to check the heart and coronary arteries^[8]. The frequency and intensity of monitoring depend on whether the child developed any coronary artery problems and how severe they were.

For children who had coronary artery problems, more intensive long-term monitoring may be needed. This can include regular echocardiograms, electrocardiograms, and sometimes other heart tests^[14]. Even children who did not have visible coronary artery changes may benefit from periodic cardiovascular risk assessment as they grow, since some research suggests they might be at slightly higher risk for heart disease later in life^[14].

Once an ultrasound scan confirms that there are no heart abnormalities, children can usually stop taking aspirin^[10]. For most children, Kawasaki’s disease is a one-time occurrence with an excellent outlook. The vast majority recover without any long-term problems, especially when treatment is started early.

Parents should educate their child about the condition as they grow older, so they can recognize any new symptoms and understand the importance of regular heart check-ups^[20]. It is also important to inform other healthcare providers about the child’s history of Kawasaki’s disease during future medical visits.