Sessional_Paper_1903 — Page 470

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curve of the epidemic is almost constant. This opinion was strengthened by the fact that in August, 1899, the body of a Chinese lift-man at Queen's Buildings who was accidentally killed when attempting to enter the lift while in motion was found to contain plague bacilli. A similar result followed the examination of a man who on the 4th March, 1901, was killed at Tai Koo sugar works by a bag of sugar falling on his head from a height of 20 feet; while on the 2nd April, 1903, in the body of the chief steward of a ship lying in dock, found floating with a large wound on the head, were also found plague bacilli. Early in June several men from H. M. S. Ocean were sent to the Naval Hospital, suffering from pneumonia ; on examination of their blood seven were found to be suffering from mild cases of plague. In like manner two Officers of the Sherwood Foresters who developed feverish symptoms were, on having their blood examined, found to be similarly affected. In the "Boletim Official" of Macao containing the report on the plague epidemic, 1895, Dr. GOMES DA SILVA, the Medical Officer who published the re- port in 1895, stated that during the height of the epidemic he had discovered plague bacilli in his own excreta.

21. In June I directed Inspector GIDLEY to obtain as many specimens of blood as possible, on slides procured from the Government Bacteriologist. He obtained 110 specimens from men, women and children taken at random. These slides were sent to Dr. HUNTER for examination, who reported that in five slides he found plague bacilli, and in seven slides "bacilli were present in considerable numbers, some of which showed bipolar staining. They were not sufficiently distinctive, however, to be regarded as B. pestis.' These slides were obtained between the 23rd June and 10th July. Since they were obtained there were but three cases of plague in the district, from none of which was a specimen of blood taken.

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22. I am not unmindful of the fact that these reports were the result of microscopic examination only. But the examination was the same as that on which a great many of the cases treated in Kennedy Town Hospital were sent to that institution where their cases ran the usual course of plague invasion.

23. Now, putting aside the five doubtful slides, it will be seen that of those people examined at random 4.54% were found to be infected with plague though to all appearance perfectly healthy. If we exclude all the well-to-do, and take the working coolie population alone, they probably number 180,000 and, assuming the same average amount of infection, there are among that class alone 8,172 persons at present infected in Hongkong. If even a quarter of that average be accepted for the 105,000 inhabitants of superior class the number of infected will be increased to 9,364. In Appendix G. will be found the number of rats examined in each month of the present year with the proportion of infected rats. I am afraid that the incidents mentioned in para. 5 weakens deduction as regards Hong- kong. But from whatever source the rats were procured the proportion of infection in June was 9% or 4.46 % more than the percentage of the slides examined, or, if the doubtful cases mentioned by Dr. HUNTER be included, 1% less, while in January the proportion falls to .8%. This being so, with the complete circle of vermin, insects, food, rats, domestic animals and man all infected in possibly simi- lar, possibly different proportion, it appears to me unsound to concentrate attention upon the rat as the principal means of bridging over the dormant season.

24. I do not know whether the conduct of a culture of the bacillus pestis has ever been observed for an annual cycle. I am informed that the usual culture in a culture tube dies in a short period, either by having exhausted the nutriment from the culture medium or by having poisoned it by its own toxin. If the blood of those in whom plague bacilli now exist without producing the usual effects of plague could be periodically examined all through the coming year much light might be thrown upon the dormant period, and the highly important question of the infectivity of these people might he solved. But failing this I have suggested the possibility of preparing a culture in so large a quantity of culture medium as will permit of the spread of the bacillus to the utmost extent during the period shown to be that of annual activity and still leave the medium in sufficient quantity to support any renewal of propagation. In this way I suppose that the annual movement of the bacillus might be observed.