Kawasaki disease is a rare illness that typically strikes children younger than age 5. It is also known as mucocutaneous lymph node disease. Kawasaki disease is a mysterious illness of unknown cause, although some scientists suspect that the cause may be an infection (such as a virus or a toxin from a bacterium. Kawasaki disease was first identified among Japanese children in 1967, and within nine years, the illness had been reported in American children living in Hawaii. Although researchers assume that the Kawasaki disease could have been caused by an infection that was carried between Japan and Hawaii, this has never been confirmed. Recent evidence suggests that inherited (genetic) factors may also be important, but the cause of Kawasaki disease remains a mystery.
Kawasaki disease makes children ill by triggering inflammation in many different parts of the body. In the heart, this inflammation can take the form of myocarditis (inflammation of heart muscle), pericarditis (inflammation of membranes covering the heart) or valvulitis (inflammation of the heart valves). Kawasaki disease can cause a type of meningitis (inflammation of membranes covering the brain and spinal cord), and it can cause inflammation in the skin, eyes, lungs, lymph nodes, joints and mouth. However, the most dangerous problem related to Kawasaki disease is the threat of vasculitis (blood vessel inflammation), especially in the body's medium-sized arteries. This vasculitis can be especially dangerous when it damages the heart's coronary arteries, causing an abnormal widening (dilation) or bulge (aneurysm) in these vessels. In rare cases, artery damage related to Kawasaki disease can significantly interfere with the heart's blood supply, even to the point of causing a heart attack in a very young child.
In the United States and other industrialized nations, Kawasaki disease is now the most common cause of heart disease that is not present at birth in children. . The disease is rather rare, affecting fewer than 1 in 5000 children under the age of 5 in the U.S. Seventy-five percent to 80% of the cases are children under the age of 5 years old. Boys are affected more often than girls.