[3]
effect of the rise of temperature not being apparent, of course, until after the lapse of the period of incubation (which varies usually from four to ten days) plus, in most of our cases, the period of duration of the disease, since the cases are seldom discovered or reported until they are either dead or moribund. A fall in the mean weekly temperature to 78,5° F. during the 22nd and 23rd weeks will be seen from the chart to have resulted in a very slight recrudescence of the disease in the 25th week, but after this the temperature ran up rapidly to 83.6° and the number of cases of the disease full with even greater rapidity.
Rats.-The outbreak this year has been specially marked, so far at least as the European cases were concerned, by the finding of dead rats in the dwellings in which such cases occurred. These rats were found generally during the few weeks preceding the occurrence of the case, but, as I have already stated, any dead rats were also found in houses and offices in which the disease did not occur. Of three rats moreover which were caught alive in infected houses, and were kept in cages at the disinfecting station only one died, and this was apparently from an injury incurred at the time it was caught. In the chart showing Bubonic Fever and general rat mortality. I have given the curves for the last quarter of 1900 as well as for the half-year ending June 29th, 1901, as they show that a very rapid rise in the general rat mortality antedated the epidemic outbreak of Bubonic Fever by several weeks, for the disease can hardly be said to have become epidemic until the 17th week (ending April 27th), while by that time the rat mortality had almost reached its maximum, having risen from au average of between four and five hundred per week, to as many as 2,770. It is inter- esting to note also that the maximum rat mortality was reached on the 20th and 21st weeks, when it stood at just over 3,100, while the number of cases of Bubonic Fever reached its maximum in the following week (the 22nd). I have noted on the chart that the price paid per head for rats was increased from 2 cents to 3 cents on January 24th, and it might perhaps be thought that the rapid increase in the number of rats brought in could be accounted for in this way.
This sug- gestion is however discounted by the fact of the equally rapid fall in the rat mortality after the 21st week. corresponding as it does to the full in the number of cases of Bubonic Fever reporte.
There were about thirty men who made a business of collecting these rats, and I find that no less than seven of them died of Bubonic Fever during the period under report, while five others left the Colony because they were sick, and two of these latter are said to have died of this disease on the mainland.
The total number of rats paid for during the half-year, in the city of Victoria alone, was just 48,000; the number obtained during the corresponding half of lust year was 26,880, while during the second half of last year we only obtained 19,700. A small percentage of these rats was examined systematically at the Government Mortuary, and some of them were found to have died of Bubonic Fever.
There has been no evidence of any other animals (than rats and mice) dying of this disease during the year.
House-to-House Visits.—In addition to the visits of the District Inspectors, a gang consisting of seven specially selected Sappers and a European Police Constable was appointed early in March to make systematic house-to-house visits in No. 9 Health District; these men worked in pairs, and each pair was supplied with a native Interpreter. During the two months from March 23rd to May 25th fourteen cases of Bubonic Fever, one case of small-pox, and two dead bodies were discovered by, or reported to them, and during the same period twenty-five dead bodies were found by the Police, mostly at night, in the streets and lanes of the District in which the search-parties were at work. On the 27th of May these men were transferred to Wanchai where they discovered fifteen cases between that date and the end of June, five of these cases being discovered by them on the first day before, that is to say, the natives were aware that they were at work in the District.
The system of house-to-house visiting appears to me to be of the greatest value before the discuse becomes epidemic, and while the few sporadic cases are occurring within a circumscribed area, as the natives resort to every possible device to conceal their sick. I may mention the following as some of the difficulties with which we have to contend in this respect :--
(1.)
a Chinaman of the poorer class, when he is sick or retires to bed, makes no change of costume, hence as soon as it is known that the search party is in the house, the sick man will get up and walk about and make every effort to appear in his ordinary health;
(2.) the other people living in the house will conceal their sick, and an instance occurred this year of a sick woman and a dead body being concealed under the same bed, within a cubicle;
(3.) when it is known that special house-to-house visits are to be paid the sick are con-
veyed from the un-visited to the recently visited houses;
(4.) the sick are also concealed on the flats roofs of the houses;
(5.) if there is no other means of concealing them, they are turned out into the streets to
wander at large.