Objective: Clustering of cases of Kawasaki disease throughout Japan was noted three times during the period before 1986. During the ensuing 10 years, however, no nationwide epidemic has been recognized. The purpose of this study is to test the hypothesis that local outbreaks have persisted after 1987.
Method: The data on 56 980 patients reported from 1987 through 1996 were classified according to the area of residence. The time trend of the incidence rate was compared by year and by quarter of the year (January to March, April to June, July to September and October to December) in 10 geographical areas in Japan.
Results: No nationwide outbreaks have been noted since 1987 in Japan, but the existence of local outbreaks of various magnitudes was recognized as occurring in different periods in certain areas. The incidence rates were continuously high in Area 1 between 1987 and 1988 and in Area 4 between 1995 and 1996. In Area 9 local outbreaks were noted on three separate occasions (from 1987 to the first half of 1988, between 1990 and 1991 and from the second half of 1992 to 1993). No clusterings were witnessed in other areas during the 10-year period.
Conclusion: The current annual number of patients ranges from 5000 to 6000, and local epidemics occur in various areas. The current epidemiologic patterns support the infection theory for the etiology of this disease.