Kawasaki disease (originally named mucocutaneous lymph node syndrome, but now named after Tomisaku Kawasaki, the Japanese doctor who first described the disease in 1967) is a vasculitis, or inflammation of blood vessels, seen fairly frequently in children.
We aren't sure exactly what causes Kawasaki disease. We suspect that it may be caused by an infection: this is because the symptoms and signs resemble known infections such as streptococcal sore throat or adenovirus infections. (Kawasaki disease can occur at the same time as other infections, too: I once had a patient with both lab-proven strep throat and Kawasaki disease.) The disease may also be an immune-system response gone haywire. There may also be genetic associations: Kawasaki disease can be seen in children of any ethnicity, but it's seen more often in children of East Asian descent, and relatives of a patient with Kawasaki disease seem to have the disease more frequently than average. There have been recent reports of a possible association between the new rotavirus vaccine and Kawasaki disease, but the statistics so far don't support a connection.
Typically, a patient with Kawasaki disease has:
Some patients (up to 1 out of 4) with Kawasaki disease have arthritis (inflammation of the joints) as well. Less often, patients have swollen glands in the front part of the neck on either side.
Except for fever. these signs are not always seen in Kawasaki disease. The textbook criteria for diagnosing Kawasaki disease are fever for 5 days or more, accompanied by at least four of these signs:
and with no other explanation for the signs.
These criteria aren't perfect. A child with fever and three or fewer of the other signs may still have Kawasaki disease (we call this atypical Kawasaki disease), and another child who has all of the signs may not have the disease. Also -- and more important -- as many as 1 out of 10 children who have the most common complication of Kawasaki disease don't meet these criteria.
The most important complication of Kawasaki disease is the formation of aneurysms, or bulging sacs, in the walls of arteries: sometimes peripheral arteries such as the brachial arteries (which supply blood to the arms) but also in the coronary arteries. These aneurysms very rarely burst -- a good thing, since a ruptured coronary artery aneurysm almost always results in death. More often blood clots form in the aneurysm, then break off and float "downstream" to block something important; it is possible for a child with Kawasaki disease to have a myocardial infarction (permanent damage to the heart muscle) just like an adult can. It's also possible for clots from the aneurysm to cause narrowing of the coronary artery with effects similar to narrowing from cholesterol deposits in an adult.
Intravenous immune globulin (IVIG) harvested from donated blood (and processed to eliminate infectious agents such as HIV) has proven to be effective treatment for Kawasaki disease. Aspirin is also used in treatment, partly because it reduces inflammation and partly because it reduces the clotting ability of platelets; there is some argument over whether aspirin is truly beneficial, and I have not seen hard evidence one way or the other. Aspirin may also lead to Reye's syndrome (a serious liver problem, usually seen when someone takes aspirin during or after certain viral infections including influenza, chickenpox, or mononucleosis. Because of this, we encourage any child who is being treated for Kawasaki disease to be vaccinated agaist flu and chickenpox.