The disease first occurred in China in the year 1919. The earliest date was given to me by a Chinese student who gave a reliable account of his own disease. For its "historical" interest the history may be briefly mentioned here:

Student, aged 25; March 1919 whilst in Shanghai, fever of ten days' duration, dizziness and double vision, later sleepiness continuing for several weeks. Since 1922 increased difficulty of speech, increased salivation and appearance of involuntary movements of head and hands.

Findings: Typical Parkinsonian posture and gait, myoclonus of left sternocleidomastoideus, tremor of both hands, pupils dilated, absence of light reaction, paresis of rectus internus, tendon reflexes active, W-R negative.

In the same year four other patients contracted the disease, one in July in Foochow, the rest in autumn in Peking, Paoting and Taiyuan (Shansi). Recently the number of cases which I have observed has gradually increased, probably partly due to the growing interest of the medical men, who had sent these patients to us for further study. On the other hand during the last few years several small epidemics have occurred in Peking and its neighbourhood, to which I have to refer later.

With regard to the season Table No. 3 shows that the disease occurred throughout the year, but as it is known from other countries a marked rise sets in, especially in 1923 and 24 in Peking, during the winter months, December to March. At this time, the climatic condition of Peking and Northern China is dry and cold with dusty winds, the season of catarrhs of the respiratory tract.

Table 3.

There is a second but only slight elevation of the curve in August, the end of the rainy and beginning of the dry season. It might be mentioned here that the outbreak of the great epidemic of a special form of encephalitis epidemica in Japan in 1924 also set in during a remarkably dry summer and abated with the onset of the wet season.

Table 4.

With regard to age (see table 4) the majority of the patients were between the years of puberty and middle age, (more than half between 14 and 27 years), the youngest was 5 months, the oldest 61 years old, 80 of the total number of 100 patients were males, 20 females; 82 Chinese, the rest foreigners.