619
A study of the chart is most instructive. The epizootic started on the 8th of April. The epidemic began on the 15th of April. A regular rise in the epizootio is followed by a similar rise in the epidemic about a week or ten days later.
The epizootic reaches its maximum a fortnight before the highest point in the -curve of the epidemic. The fall in rat plague occurs previous to the fall in human
plague.
During the month of July another recrudescence of rat and human plague took place. The relations existing between the two are the same as those already mentioned.
During the month of August a close inter-relationship existed between rat and human plague.
Conclusions drawn from District No. 9.-
1. The epizootic preceded the epidemic by one week. 2. The epidemic increased in proportion to the epizootic.. 3. Both diminished in proportion.
4. A relapse occurred in both cases with similar results.
5. From this chart, it would appear that the epidemic stands in direct relation to the epizootic. With an increased epizootic, one obtains an increased epidemic and vice versa.
The History of Health District No. 10 in 1902. —A general survey of the two curves in this district is, in my opinion, of a very convincing nature in regard to the relationship existing between the epizootic and the epidemic.
The epizootic is first in the field. It is followed by the epidemic, the march of which is at first sight slower.
Notwithstanding, the epidemic reaches its maximum about a fortnight after the climax of the epizootic. Both fall gradually, the epizootic first in order. From the month of July onwards, recrudescences of both outbreaks take place from time to time. This is in harmony with the results obtained in other districts. possible explanation of this will be brought forward later.
Conclusions drawn from this District.-—
A
1. The epidemic follows the epizootic with an interval varying fróm 7
to 14 days.
2. The detail in the epidemic is apparently moulded by that of the
epizootic.
3. Characteristic is the fall of the epidemic in accordance with the
decline in rat plague.
The History of Kowloon in 1902.—The district is an extremely large ones and the results which I have obtained on comparing the epidemic with the epizootic, give one practically the same picture as obtained on preparing a general -chart for Hongkong.
The general chart of Hongkong for 1902 is almost identical with this one. My intention was to deal with Kowloon in a similar manner to Hongkong, but, being single handed, and pressed for time, I found the labour too great.
Such
Doubtless if the details of Kowloon were given, the results would compare favourably with those obtained for each individual district in Hongkong. curves as these, when placed alongside many of those prepared for single districts, show us how carefully the question of inter-relationship of epizootic and epidemic must be approached. General curves give us a fair survery of what is at work. but it is only on thoroughly going into each district in detail, that the closer relations between the two outbreaks become evident,
A glance at these curves of Kowloon show us the great preponderance of the epizootic. Yet notwithstanding, the epidemic follows, in its rise and fall, the course of the rat plague, showing the usual interval between the occurrence of the one and the appearance of the other. Of great interest is the severity of the epizootic during the last quarter of the year.