The exact etiology of Kawasaki disease remains unknown ; however, many of the clinical, epidemiologic, and physiologic features of the disease indicate an infectious trigger. Fever and many of the other acute, self-limited manifestations of this disorder are similar to those of viral or bacterial diseases. The activation of immune cells, such as monocytes and T lymphocytes, in Kawasaki disease occurs in other diseases with a known microbial etiology. Cases are often clustered geographically, and outbreaks demonstrate a seasonal pattern, with prevalence highest in winter and spring. Occurrence is more common among siblings than in the general population, and more than 50% of sibling outbreaks develop within 10 days of the first case. Immunity, which develops either asymptomatically or from having the disease, may account for the uncommon onset of the disease in older children and adults and its relative lack of recurrence