Report of the Board of Health on a second outbreak of plague at Sydney, 1902 / by J. Ashburton Thompson.

  • Thompson, J. Ashburton (John Ashburton), 1848-1915.
Date:
1903
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Licence: Public Domain Mark

Credit: Report of the Board of Health on a second outbreak of plague at Sydney, 1902 / by J. Ashburton Thompson. Source: Wellcome Collection.

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    exclude diffusion of the infection by man, and to trace association between cases of plague and plague- rats as clearly as could be reasonably expected. Both, however, committed themselves to statements concerning the connecting link between rat and man which, it is most important to note, bad not been at that date sufficiently supported by direct evidence, as I have myself elsewhere pointed out.* 229. These results constituted a step of which the importance has hardly been appreciated (TV. Kolle alone, as far as I know, has perceived their bearing and weight: see Bericht uber die Thatigkeit in der zu Studien fiber Pest eingerichteten Station des Instituts fur Infectionskranklieiten, 1899-1900, Zeit. f. Hyg., 1901, p. 397). If under conditions which admitted of accurate observation the generally accepted causes of epidemic plague were seen not to have been in operation, some other cause was to be sought. Por what had been thus pointed out was not merely the result of interference with the natural course of the disease by good management—such, for instance, as is implied in prompt removal of patients to hospital, and in prompt disinfection of their dwellings; nor could it be ascribed to generally favourable conditions of housing, feeding, work, and climate. Although it might fairly be argued that the comparative smallness of the total number of cases was due to those factors, yet the cause of the absolutely large number (303) which did occur still remained to be discovered. It was certain that the infection had not been diffused and maintained by man ; how then had it been spread ? Place-infection having been excluded by the facts, but one other means presented itself, and, in my opinion, but one other could be reasonably surmised. This was the rat, in whose body, and in whose body alone out of all places external to man’s body, the infection had been shown to be commonly present. 230. If man commonly received the infection from the rat—if epizootic plague were indeed the cause of epidemic plague at Sydney; then coincidence between plague-rats and plague in man on the same premises' should be demonstrable, and (it seemed, a priori), easily demonstrable. But in the course of the review referred to we found that we had not demonstrated it. Dr. Tidswell had, indeed, been enabled to identify but 23 plague-rats throughout the epidemic, and none of them were obtained from premises which had yielded cases of plague in man. Or, if findings of putrid carcases in which the nature of the disease, which, evidently, had been the cause of death, could not be rigidly identified, be accepted as evidence of epizootic plague (as under all the circumstances it reasonably may), then dead rats in number were only observed on about 70 premises, although 221 premises were the adjudged places of infection for 255 cases. But the reader who has perused the foregoing pages need not be told that, so far, at all events, there is no evidence that this discrepancy was a matter of fact; clearly it may have been apparent only, and may have resulted from the method of observation, which was certainly imperfect. 231. On recurrence of the disease in 1902, then, we were prepared by former experience to examine this relationship more closely, as well as to check the correctness of our earlier observations on the share taken by man, fomites, and place-infection in diffusing and maintaining the disease. It has already been shown that former conclusions regarding these factors have been completely confirmed. Besides this, further continuous observation and reflection have completely failed to suggest any other source of the infection than that furnished by diseased rats. 232. The ground, therefore, seems to be thoroughly cleared. All that remains is to inquire whether during the second epidemic improved methods of observation did or did not reveal such frequent and close association between plague-rats and plague in man as suffices to furnish a strong presumption that diffusion of plague- rats was the sole cause of the epidemic. 233. Prom the method of description selected, the reader is now in a position to judge in how far the connection referred to has been discovered, and in how far it deserves to be recognised as the essential condition which we are convinced it wras. Here it is necessary only to mention a few numerical statements, to refer briefly to the more cogent facts already related, to trace the course of the epizootic, and to advert to the conditions of observation in the field which—and which alone, I think ■ have caused the results, although improved upon those attained in 1900, still to remain defective. Lime * Public Health, Vol. XIV, pp. 340-1,