Ultrastructural, immunofluorescence, and RNA evidence support the hypothesis of a "new" virus associated with Kawasaki disease.

The authors concluded that a very common infectious agent, one that usually results in an asymptomatic infection, causes Kawasaki disease in a subset of genetically predisposed children. They argued that the available data supported the theory of a new RNA virus, without substantial homology to known viruses, will eventually be shown to be the infectious agent of Kawasaki disease. Digital facsimile from PubMedCentral at this link.

(Thanks to Juan Weiss for this reference and its interpretation.)