The cause of Kawasaki disease isn't fully understood, but the condition is thought to be caused by an infection. Genetics may also increase the chance of developing the condition.
The symptoms of Kawasaki disease are similar to those of an infection, so bacteria or a virus may be responsible. However, so far a bacterial or viral cause hasn't been identified.
As Kawasaki disease isn't contagious, it can't be passed from one person to another. This makes it unlikely that it's caused by a virus alone.
Kawasaki disease doesn't usually affect babies under six months old, although sometimes very young children can develop the condition.
This suggests that newborn babies are protected by antibodies passed on to them by their mother, either before birth or during breastfeeding. Antibodies are proteins that destroy disease-carrying organisms.
As few older children and adults are affected by Kawasaki disease, they may be immune to whatever causes it. While many people are exposed to Kawasaki disease, only a few go on to develop the symptoms.
The children who develop Kawasaki disease may be genetically predisposed to it. This means the genes they inherit from their parents may make them more likely to get the condition.
One theory is that rather than there being a single gene responsible for Kawasaki disease, it may be the result of many genes that each slightly increase the chances of a child developing the condition.
Kawasaki disease is more common in children from northeast Asia, especially Japan and Korea. This also suggests there may be a genetic cause.
One theory is that Kawasaki disease may be an autoimmune condition, where the immune system attacks healthy tissues and organs.
Other theories suggest Kawasaki disease may be a reaction to certain medications or environmental pollutants, such as chemicals or toxins (poisons).