Epidemiological and Clinical Characteristics of Kawasaki Disease and Microbiota

Kawasaki disease (KD) is believed to be related to an infectious pathogen, but the causative agent and pathophysiology are still unknown. KD has epidemiological characteristics that are different from common infectious diseases. There is a gap of about 5 to 10 years between when KD first appeared in Japan and when it appeared in neighboring countries such as Korea, Taiwan, and China. KD is spreading slowly and steadily to this day, suggesting that its cause is related to environmental changes such as westernized diet and economic growth. KD incidence varies across population groups, but the same age preference is observed in all ethnic groups. Microbiologically, KD has unique characteristics, including lack of human-to-human transmission, unresponsiveness to antibiotics, and difficulty in detecting pathogens, suggesting that the pathophysiology of KD may be similar to pediatric infection-related immune-mediated diseases such as acute rheumatic fever. Based on the epidemiological and clinical characteristics of KD, this study suggests that the pathogens of KD are certain strains in microbiota, and that acute pyelonephritis and exanthem subitem of which pathogens could be regarded as strains in microbiota showed a similar age distribution and annual and seasonal frequency patterns to KD. Since the immune system and composition of microbiota are changing by ages in childhood, KD may be associated with these factors.