Objective: Kawasaki disease (KD), an acute febrile disease that induces systemic vasculitis in infants, has been
proposed by Awaya and Sahashi in 2003 to be epidemiologically linked with pollen exposure. In this report, seasonal
variation patterns of the monthly development of KD in 5,917 patients (Pt.) in Kanagawa, Japan were compared with the
monthly pollen release numbers (Nos.) from 1991 to 2002. Methodology: A correlation coefficient (c.c.) matrix was generated
using regression analyses of the correlation of KD onset and pollen exposure in each month. The percent of Japanese
cedar pollen Nos. was calculated from the pollen numbers (Po.Nos.) of all the species surveyed in March and April
throughout the years. Results: Significant c.c. associations were revealed between Po.Nos. from all species in March and
KD Pt.Nos. in August (0.88), November (0.72), May (0.68), and April (0.66). Significant c.c. associations were also found
between Po.Nos. from all species in April and KD Pt.Nos. in August (0.70), and between Po.Nos from all species in February
and KD Pt.Nos. in July (0.62). Mean c.c. values of 0.60 in March, 0.47 in October, 0.45 in July, 0.35 in April, and
0.31 in February between Po.Nos. and KD Pt.Nos. were shown. February, March and April contributed 4.7%, 40.6% and
38.8% of the annual Po.Nos., respectively, of which 93.8%, 84.3% and 10.9% were from cedar pollen, respectively.
Conclusions: A positive association was demonstrated between the Po.Nos. from all species, particularly cedar Po.Nos. in
March, and the KD Pt.Nos. in the following several months.