Observations on the aerial transmission of the enteric fever poison, with a record of an outbreak presumably caused by that means of infection / by John Brownlee.

  • Brownlee, John, 1868-1927.
Date:
1897-98
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the aerial transmission of the enteric fever poison, with a record of an outbreak presumably caused by that means of infection / by John Brownlee. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    to the fact that the detritus was gathered from a locality which was exposed, to a slight extent, to surface water from a manured field. The medium composed of decayed vegetable matter only did not afford anything like so suitable a medium as that con- taminated by even a trace of animal organic matter. I have already referred to the spread of enteric fever by polluted water or milk, but there is in addition another possible means of infection—namely, the aerial dispersion of the organisms. The most natural means, the dispersion of soil, is in the form of dust, when it is easily carried about by the wind. It is well known that the bacillus of enteric fever does not readily survive complete desiccation. The limit of the duration of its life in this state, Fliigge, from his own experiments, in which the bacilli were dried in thin layers, has given at five to fifteen days. By Germane,* in a paper published last August, no certain limit is given, as in his opinion this limit depends on the amount of drying to which the bacilli are subjected. Half dried they lived for some months, wholly dried for but a short time. He found that on garments of wool the infection lingered longer than on those of cotton, a fact which he explains by the greater power the former has of retaining moisture. Now, ordinary soils possess the property of retaining in their inter- stices a certain proportion of moisture, and do not yield this to the ordinary natural means of drying, such as currents of air. In a few experiments made by myself in this connection, ordinary potting soil was placed in a porcelain dish, and thoroughly dried in a hot air steriliser. It was further subjected to continuous dry heat long enough to kill any micro-organisms present. This soil was then moistened with a broth culture of the enteric bacillus. By this means it was practically assured that the minute passages of the soil, filled by the action of capillarity with the broth, would at the same time be mechanically charged with enteric bacilli to the extent that where there was moisture there would also be the micro-organisms. This porcelain dish was then covered with a glass lid, the whole kept at 98° F. for 24 hours, after which the cover was removed and spontaneous evaporation allowed to take place. In the course of a week this soil had become dry enough to be easily scattered by the breath. It had become, in fact, dust such as can be readily blown about Zeitschrift fur Hygiene, XXIV., 3.