What Is Kawasaki Disease? Symptoms, Causes, Diagnosis, and Treatment

Kawasaki disease is a condition that causes inflammation of the blood vessels, and mostly affects children under 5 years old. (1,2)

Along with inflammation of the blood vessels and several days of fever, other symptoms include rash; swollen neck glands, hands, and feet; and red eyes, lips, and tongue, according to the American Academy of Pediatrics (AAP). (2)

It is a leading cause of acquired heart disease in the United States, according to the Centers for Disease Control and Prevention (CDC). (1) But with early detection and treatment, long-term heart issues are unlikely to occur. (2)

“The most serious possible consequence is inflammation of the vessels that supply blood to the heart. The main reason we treat Kawasaki disease is to try to prevent these possible cardiac outcomes,” says Vijaya Soma, MD, a clinical assistant professor in the department of pediatrics at New York University's Grossman School of Medicine, who specializes in pediatric infectious disease.

Kawasaki disease has three distinct phases.

What Happens in Phase 1 of Kawasaki Disease?

According to the Kawasaki Disease Foundation, phase 1 symptoms include: (3)

• High fever (commonly above 102.2 degrees F) that lasts for at least five days
• Pink eye (conjunctivitis) that does not cause a thick discharge
• Rashes, particularly on the trunk of the body or the genital region
• Red, dry, cracked lips
• Very reddened, swollen tongue (this is called strawberry tongue)
• Red, swollen palms of the hands and soles of the feet
• Swollen lymph nodes in the neck

What Happens in Phase 2 of Kawasaki Disease?

In phase 2, the following symptoms may develop:

• Peeling of the skin on the hands and feet, particularly on the tips of the fingers and the toes
• Joint pain
• Diarrhea
• Vomiting
• Stomach pain

What Happens in Phase 3 of Kawasaki Disease?

In the third phase, symptoms slowly begin to disappear if there are no complications.

“Most patients do well after treatment,” says Michael Portman, MD, the director of research in the division of cardiology at Seattle Children’s Hospital who studies Kawasaki disease. “The fever usually goes away, but children can take up to a month to totally feel normal again.”

Doctors don’t know what causes Kawasaki disease, but there is evidence suggesting that a virus or infection triggers an abnormal immune system response in children who are genetically predisposed to the condition, according to Merck Manual. (4)

“The general theory is that there is an infection that precedes Kawasaki disease, and this serves as a trigger for an immune response in a genetically susceptible child,” says Dr. Portman.

Genetics appear to play a role in Kawasaki disease, but scientists are still trying to understand these factors, according to the Genetic and Rare Diseases Information Center. (5)

Kawasaki disease is more common in Asian and Asian American populations and among family members of children who have the condition, which suggests that the disease may have a genetic component. Moreover, certain gene variants are associated with an increased risk of developing Kawasaki disease.

Children of parents who have had Kawasaki disease are twice as likely to develop the condition compared with the general population, and children whose siblings have had Kawasaki disease are 10 times more likely to develop the disorder. That said, it’s still rare for more than one child in a family to have the disease.

Risk Factors

Risk factors for Kawasaki disease include:

• Being male
• Being between 6 months and 5 years old
• Having a family history of the disorder

Kawasaki disease is not contagious.

There is no specific test to diagnose Kawasaki disease. (2)

“Kawasaki disease has many characteristics similar to other childhood diseases, which makes it difficult to diagnose for those unaware of it,” says Portman. “Any parent should be suspicious if their child has continuing fever for four days or longer, along with swollen hands, red eyes, red, cracked lips, and a rash, particularly if they are given antibiotics and the fever does not go away.”

Doctors make a diagnosis of Kawasaki disease if a child has had a fever for five days or more and if they have at least four of the following five symptoms: (4)

• Red eyes without discharge
• Reddened, dry, cracked lips and a strawberry tongue
• Swollen, red, and peeling hands and feet
• Red, patchy rash on the trunk of the body
• Swollen, tender lymph nodes in the neck

Blood tests, urine tests, and throat cultures may also be conducted to rule out other conditions that cause similar symptoms. (2,4)

Once Kawasaki disease is diagnosed, your child’s doctor may order electrocardiography (ECG) and ultrasonography of the heart (echocardiography) to look for heart problems such as coronary artery aneurysms. (4)

Your doctor may also refer you to a pediatrician with a specialty in infectious disease, rheumatology, or cardiology. (2)

Prognosis of Kawasaki Disease

With early treatment, almost all children recover from Kawasaki disease. (4) Treatment administered within the first 10 days of symptoms significantly reduces the risk of coronary artery damage and also helps resolve other symptoms.

Without treatment, up to 25 percent of children develop heart problems such as coronary artery aneurysms, which typically begin one to four weeks after the onset of Kawasaki disease. Treatment lowers the risk of heart complications to about 1 in 20. In children who are not treated, the death rate is about 1 percent (death almost always occurs in the first six months of life but can happen up to a decade later). If a child develops aneurysms, they have an increased risk of having heart problems as adults, even if the aneurysms resolve.

But if your child doesn’t develop a coronary aneurysm, they are likely to have an excellent long-term outcome, according to the AAP, which says that after treatment, children will benefit from a heart-healthy diet and lifestyle, and monitoring of cholesterol levels. (2)

Kawasaki disease may last from 2 to 12 weeks or longer. (4)

Medication Options

The standard treatment for Kawasaki disease consists of high doses of both aspirin and immunoglobulin, which is a purified form of proteins and antibodies from donated blood. (1,4) These treatments can substantially reduce the risk of serious heart complications, and should be started as soon as possible. (4)

For one to four days, immunoglobulin is administered intravenously, and aspirin is given orally. When the child has no fever for four to five days, the dose of aspirin is lowered. But children with Kawasaki disease must continue to take aspirin for at least eight weeks from the onset of the illness.

If there are no coronary artery aneurysms and no further signs of inflammation, aspirin may be discontinued. But children with coronary artery abnormalities need long-term treatment with aspirin. It’s important to note that aspirin can cause a serious liver condition called Reye's syndrome, so it should be given to young children only under a doctor's supervision. (2)

Additional treatments may be required if a patient does not respond well to the initial dose of immunoglobulin, their fever comes back, or there are abnormal findings on the first echocardiogram. In these cases, doctors may recommend another dose of immunoglobulin or other medications that fight inflammation, such as steroids, infliximab, or etanercept.

Children with large coronary aneurysms may be given anticoagulants, which are drugs that prevent the blood from clotting. (4)

The most serious potential complication of Kawasaki disease is the development of a coronary artery aneurysm, which is a bulge in the wall of the arteries that supply blood to the heart. Coronary artery aneurysms can rupture or cause a blood clot, leading to a heart attack and sudden death.

“The risk of developing coronary disease in children treated with immunoglobulin therapy is low,” says Daphne T. Hsu, MD, the division chief of pediatric cardiology and the codirector of the pediatric heart center at Children's Hospital at Montefiore in New York City. “Even though the risk is low, it is important that the child be followed closely in the first six weeks after the diagnosis [of Kawasaki disease] is made to see if the coronary arteries show signs of being affected.”

Portman adds that some children may have problems with their heart for the rest of their lives. Some may need special procedures or surgery to keep the coronary arteries open. In these cases, they will be monitored by a pediatric cardiologist as they grow up.

Other possible complications include painful inflammation of the tissues lining the brain (meningitis), ears, eyes, liver, joints, urethra, and gallbladder. (4)

Also, the AAP recommends that live viral vaccines be postponed for 11 months after a child is treated for Kawasaki disease, because the treatment may reduce the effectiveness of vaccines for illnesses including MMR (measles, mumps, rubella) and varicella (chicken pox). Children older than 6 months of age should also get the inactivated influenza (flu) vaccine.

According to the CDC, Kawasaki disease affects about 9 to 20 per 100,000 children younger than 5 in the United States. (1) It is estimated that more than 4,200 children are diagnosed with Kawasaki disease in the United States each year. (3)

According to the AAP, 80 to 90 percent of cases of Kawasaki disease happen in children older than 6 months and younger than 5 years. (2) It is less common for older children and adolescents to get the disease, but it does happen.

The average age of children who develop Kawasaki disease is 2 years old, and boys are 1.5 times more likely than girls to develop the condition, according to the American Heart Association. (6)

Kawasaki disease predominantly affects children of Japanese and Korean descent, according to KidsHealth. (7) While it is more prevalent among children of Asian and Pacific Islander descent, the condition affects children of all racial and ethnic groups. (3)

Multisystem inflammatory syndrome in children (MIS-C) — a rare but serious complication associated with COVID-19 that causes inflammation in various body parts — reportedly features some Kawasaki disease-like features, like fever, rash, and bloodshot eyes. (1)

More than half of children with MIS-C are Black, according to a small study published in May 2020 in the BMJ. (8)

It’s important to note that Kawasaki-like multisystem inflammatory syndrome associated with COVID-19 has characteristics that differ from those of classic Kawasaki disease, according to the study. In addition to it being more common among children of African ancestry, it also features predominant acute gastrointestinal symptoms, hemodynamic instability (abnormal or unstable blood pressure), and myocarditis (inflammation of the heart muscle).

Kawasaki disease may be mistaken for the following other conditions that can cause similar symptoms: (4)

• Measles
• Scarlet fever
• Juvenile idiopathic arthritis

American Academy of Pediatrics

The AAP’s HealthyChildren.org website is supported by 67,000 pediatricians committed to the physical, mental, and social health and well-being of all children. HealthyChildren.org features information about signs and symptoms, complications, and treatment of Kawasaki disease.

Kawasaki Disease Foundation

KDF is the only nonprofit organization dedicated exclusively to addressing issues related to Kawasaki disease. Its website features frequently asked questions about Kawasaki disease, education, and support resources, and patient stories.

Genetic and Rare Diseases Information Center

GARD is a program of the National Center for Advancing Translational Sciences (NCATS) and is funded by parts of the National Institutes of Health. Its website features information about the symptoms, causes, and treatment of Kawasaki disease.