Kawasaki disease is an inflammatory illness in children that involves the body's blood vessels. The disease is characterized by high fever, swollen glands, and a rash, and it may lead to complications affecting the heart.
For children in the United States, Kawasaki disease is the leading cause of acquired heart disease, that is, heart disease that is not present at birth but develops later in life. In 1967 the Japanese pediatrician Tomisaku Kawasaki (b. 1925) first described the illness. He called it mucocutaneous (myoo-ko-kyoo-TAY-nee-us) lymph node syndrome, but later it became better known as Kawasaki disease. Even after many years of research, as of 2015 the cause of this disease remained unknown, but doctors suspected that an infectious microorganism * may trigger the onset of inflammation in the body. Kawasaki disease sometimes occurs in outbreaks, often in late winter or spring, and can resemble diseases such as measles or scarlet fever * , which suggests a possible link to an infectious organism.
Kawasaki disease can cause inflammation of blood vessels, mucous membranes (moist linings of the mouth, nose, eyes, and throat), lymph nodes * , and the heart. Although it eventually clears up on its own, if left untreated, it can damage the blood vessels that supply the heart muscle. Kawasaki disease is associated with a one-in-five risk of coronary aneurysms * . This blood vessel damage can lead to a heart attack, especially in very young children.
As many as 3,500 children are hospitalized with Kawasaki disease each year in the United States. Four out of five children who get the disease are younger than five years of age. The disease is extremely rare in children older than 15. Kawasaki disease develops in boys about twice as often as in girls. It is more common in children of Asian descent, although it occurs in all races.
The disease itself has not been proved to be contagious. Doctors suspect, however, that an infectious microorganism may trigger it and that the organism might be contagious. Nonetheless, it is rare for more than one child in a family to have Kawasaki disease.
Kawasaki disease has distinctive features. A high fever, often more than 104° F (40° C), usually appears first and lasts for at least five days. Afterward, signs of Kawasaki disease show up in stages and may include a red rash over the entire body; cracked lips; inflamed lining of the mouth; and a red, swollen tongue. Infected children may also have reddened and swollen hands, feet, fingers, and toes, with peeling skin; pink eye (conjunctivitis) * in both eyes; sore, stiff joints; and swollen lymph nodes in the neck. Some children experience abdominal pain and diarrhea as well. The earliest phase of the disease, including fever and rash, usually lasts 10 to 14 days. The later phase, with peeling skin and slowly easing joint pain, can persist for up to two months. Heart problems, if they occur, are more likely to show up during this time.
No single laboratory test can identify Kawasaki disease, so doctors make the diagnosis based on the child's symptoms and a physical examination: five days of high fever, accompanied by most of the associated signs. Blood tests help support the diagnosis and include tests to determine the numbers of white blood cells (cells that respond to infection) and platelets * , and tests that detect inflammation in the body. An echocardiogram * and a chest x-ray are performed to look for evidence of damage to the heart and coronary arteries * .
Kawasaki disease is treated in the hospital. Children typically receive high doses of aspirin to decrease inflammation, prevent blood clots * in the blood vessels of the heart, and reduce fever and joint pain. A one-time dose of intravenous gamma globulin * is also given to lower the risk of heart problems, particularly coronary aneurysms. (Even though aspirin is an important part of the treatment for Kawasaki disease, children normally are not given aspirin for minor fever or pain, because Reye's syndrome * , a dangerous condition, has been linked to aspirin use in children.)
Much of the treatment for Kawasaki disease focuses on keeping the patient comfortable while the illness runs its course. After the disease clears up, children still need follow-up testing to make sure it has not caused heart disease. They may have additional echocardiograms or angiograms * to examine the heart for damage and, sometimes, a stress test * to check the heart's function.
Up to 25 percent of children with untreated Kawasaki disease may experience complications that involve the heart and coronary arteries. With treatment, that risk goes down to less than 5 percent. Babies younger than one year and children older than nine years have the greatest risk of heart problems. By far, the most serious complication of Kawasaki disease is coronary aneurysm. If an aneurysm clots or, more rarely, bursts in a blood vessel supplying the heart muscle, it can cause a heart attack or even death. Kawasaki disease can affect the heart in other ways as well, leading to myocarditis * or an irregular heartbeat.
Because little was known about its cause as of 2015, there were no proven ways to prevent Kawasaki disease.
See also Heart Disease: Overview • Myocarditis and Pericarditis
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Hsu, Jeremy. “The Mystery of Kawasaki Disease.” Ars Technica, June 30, 2015. Available at: http://arstechnica.com/science/2015/06/the-mystery-of-kawasaki-disease (accessed October 20, 2015).
MedlinePlus. “Kawasaki Disease.” U.S. National Library of Medicine. http://www.nlm.nih.gov/medlineplus/ency/article/000989.htm (accessed October 20, 2015).
American Heart Association. 7272 Greenville Ave., Dallas, TX 75231-4596. Toll-free: 800-AHA-USA1. Website: http://www.heart.org (accessed October 20, 2015).
Kawasaki Disease Foundation. 9 Cape Ann Cir., Ipswich, MA 01938. Website: http://www.kdfoundation.org (accessed October 20, 2015).
U.S. National Library of Medicine. 8600 Rockville Pike, Bethesda, MD, 20894. Toll-free: 888-346-3656. Website: http://www.nlm.nih.gov (accessed October 20, 2015).
* microorganism is a tiny organism that can be seen only by using a microscope. Types of microorganisms include fungi, bacteria, and viruses.
* scarlet fever is an infection that causes a sore throat and a rash.
* lymph nodes (LIMF nohds) are small, bean-shaped masses of tissue containing immune system cells that fight harmful microorganisms. Lymph nodes may swell during infections.
* coronary aneurysm (KORuh-nair-e AN-yuh-rih-zum) is an abnormal stretching and weakening of a blood vessel that supplies blood to the heart. If it breaks open, it may cause serious damage to the heart, sometimes leading to death.
* pink eye (conjunctivitis) (konjung-tih-WY-tis) is an inflammation of the thin membrane that lines the inside of the eyelids and covers the surface of the eyeball.
* platelets (PLATE-lets) are tiny disk-shaped particles within the blood that play an important role in clotting.
* echocardiogram (eh-ko-KARdee-uh-gram) is a diagnostic test that uses sound waves to produce images of the heart's chambers, valves, and blood flow through the heart.
* coronary arteries (KOR-uh-nair-e AR-tuh-reez) are the blood vessels that supply blood directly to the heart.
* blood clots occur when the blood thickens into a jellylike substance that helps stop bleeding. Clotting of the blood within a blood vessel can lead to blockage of blood flow.
* gamma globulin (GAH-muh GLAH-byoo-lin) is a type of protein in the blood that contains the antibodies produced by the cells of the body's immune system. Gamma globulin can help defend the body against infection-causing germs, such as bacteria and viruses.
* Reye's syndrome (RYES SIN-drome) is a rare condition that involves inflammation of the liver and brain, and sometimes appears after illnesses such as chickenpox or influenza.
* angiograms (AN-jee-o-grams) are tests in which x-rays are taken as dye is injected into the body, showing the flow of blood through the heart and blood vessels.
* stress test measures the health of a person's heart while the heart is intentionally stressed by exercise or medication.
* myocarditis (my-oh-kar-DYE-tis) is an inflammation of the muscular walls of the heart.