Epidemiological observations of Kawasaki disease in Japan, 2013-2014

Background: The etiology of Kawasaki disease (KD) is unknown. In Japan, the number of patients and incidence rate of KD has increased continuously since its discovery. The aim of this report was to analyze the latest nationwide epidemiological survey of KD in Japan. Methods: The 23rd nationwide survey of KD was conducted in 2015. To report on all patients diagnosed with KD in 2013 and 2014, a questionnaire was sent to hospitals with >= 100 beds containing pediatric departments, as well as specialized pediatric hospitals. Results: The number of KD patients reported was 15 696 in 2013 and 15 979 in 2014, resulting in an annual incidence rate of 302.5 and 308.0 per 100 000 population aged 0-4 years, respectively. The number of patients and incidence rate of KD in 2014 were the highest ever recorded in Japan. The number of patients diagnosed per month peaked in January, and a gradual increase in summer was also observed. Eight patients died of KD in 2013 and 2014. Conclusions: The number of patients and incidence rate of KD in Japan continue to increase. Continued surveillance of epidemiological trends of KD is therefore required.