The cause of Kawasaki disease is unknown. It may be related to an infection, since the disease is almost always seen only in children, suggesting adults have developed an immunity to something that may cause the disease. The disease is also similar to other infectious diseases such as scarlet fever and some viruses. Kawasaki disease is not contagious. No bacteria or virus has been proven to cause Kawasaki disease. Genes may play a role, since individuals of Japanese origin, no matter where they live, are more likely to be affected, and siblings of children who have Kawasaki disease have a higher risk of getting the disease.