LAUSR

Data concerning the seasonality and geographical location of tsutsugamushi disease (TD) in Japan from 1955 to 2014 were compiled. After disappearance of "classical" TD in the mid-1960s, there was a long near-vacuum. Then, in 1975, a TD epidemic with October-December seasonality emerged in southern prefectures, and in 1979, that with May-June seasonality in northern prefectures. The current TD epidemic could be classified according to seasonality and geography into three types: a large October-December epidemic with a negligibly small May-June epidemic in the southern part of Japan, a large May-June epidemic with a mid-sized October-December epidemic on the Pacific coast of northern Japan, and a large epidemic in May-June with a negligibly small October-December epidemic on the Japan Sea coast of northern Japan. In addition, there were a few patients that were scattered throughout the year in various places in Japan. How these different epidemic patterns emerged is discussed.