Climatic Effect on Circulating Eosinophil Count

¹ From the Department of Hygiene, Niigata University School of Medicine, Niigata City, Japan

The level of circulating eosinophils was followed at monthly intervals on 21 normal persons, 12 males and 9 females, over a period of 14 months. Seventeen normal persons, 9 males and 8 females, were studied for a further period of 13 months. In the second observation the number of total leucocytes was simultaneously counted and eosinophilic percentages were calculated. Samples of blood were taken from the cubital vein always at the same time just before the midday meal, except during the menstrual period and ovulation days in females. The circulating eosinophil counts were found to be changed seasonally in a di-cyclic form of variation throughout the year, being decreased both in the cold and in the very hot seasons, and increased during the intermediate ones. Although the total leucocyte counts appeared to vary mono-cyclically throughout the year, showing a maximum in January and a minimum in August, the mean eosinophilic percentage fluctuated in a di-cyclic manner all the year round. On this occasion, however, the level of eosinophilic percentage during summer was higher than that during winter.