Positive Correlation Between Japanese Cedar Pollen Numbers and the Development of Kawasaki Disease

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.