Abstract
Based upon the calendars of seasonal diseases in Japan and some other countries outlined in the preceding papers, efforts are concentrated in this paper upon the historical survey of seasonal disease calendars in Japan, especially in its capital, and an extensive analysis of some selected diseases, particularly on their high mortality in the cold months. (1) A comparison of the 1912-16,1930-34 and 1952-56calendars reveals that more seasonal diseases raged in summer in 1910's and their death rates were much higher than in 1930's, and that senile maladies (heart disease, apoplexy and senility) registered summer mortality peaks, though smaller than the winter ones, in 1910's. (2) As for avitaminosis, tuberculosis and gastritis enteritis groups, the winter and summer mortality graphs clearly indicate that the gap between the summer and winter mortality indices got smaller year by year, until they crossed each other from 1938 through 1954, and then their relations definitely reversed themselves with the winter index exceeding the summer one. In the case of cancer, mortality was highest in autumn, while on the other hand the gap between the summer and winter indices gradually got narrower. As for senile diseases, the winter index has always been bigger than the summer one, and the spread between them has been getting wider since the end of the Second World War. (3) The overall mortality curve shows an interesting variation from 1910's through 1950's. There had been two peaks, a big one in summer and a small one in winter, but the former peak completely disappeared in 1955, whereas the winter peak has since made itself more and more remarkable, indicating the concentration of deaths in the cold season.
Responsible for such high mo r tality in winter the following facts are to be noted:
1) senile dise a ses (which have been winter illnesses) account for an increasing share of overall mortality,
2) some diseases (which form erly prevailed in the hot months have come to rage in the cold season, and 3) the old age group has been markedly increasing in the age structure of the Japanese population since the war's termination (their mortality usually curves up steeply in winter).
