Major epidemics of monthly KD incidence in Japan.
The three main historical KD epidemics are highlighted in red in panel a (cases). Time averaged sea level pressure (hPa) and surface winds (m/s) prior to the March/May 1979, May 1982 and March 1986 epidemics are shown in panels b, c and d, respectively. Monthly atmospheric variables were averaged for the preceding summer (JJA 1978 in b1, JJA 1981 in c1 and JJA 1985 in d1), when winds from the south typically blow across Japan and for the rising phase of the epidemics, from September to the last month before the peak (Sep 1978 to Mar 1979 in b2, Sep 1981 to Apr 1982 in c2 and Sep 1985 to Feb 1986 in d2) , when winds shifted and blew from the northwest. Colored dots depict the increase in KD incidence (per million inhabitants) by prefecture between the preceding September and the peak (Apr 1979 minus Sep 1978 in b2, May 1982 minus Sep 1981 in c2 and Mar 1986 minus Sep 1985 in d2).