385
The supporters of the respiratory-infection theory passing beyond the question of primary plague pneumonia hold the opinion that this mode of infection is the principal one for all forms of plague.
4
Perhaps the most emphatic writing in support of ærial infection is to be found in "A Treatise on Plague" by Major G. Thomson and Dr. J. THOMSON, 1901. Chapter VI of this book gives the authors' reasons for taking this view of plague infection. Briefly and in sum these views may be expressed as follows: that plague is a "want of fresh air" disease and that under the insanitary conditions produced in the overcrowded houses of the poor with their vitiated atmosphere, the human organism is unable to resist the parasitic habit of the plague bacillus which is breathed into the lungs. To quote from this work (page 122) "Infection takes place by remaining in and inhaling the devitalised air in which patients are attacke * * * *** *." And further (page 123) " As in the case of Tuberculosis, it is known the microbes are very generally diffused, and yet general infection of the whole populace does not follow; so in a plague epidemic it is scarcely possible that the germs are entirely absent from all dwellings in which plague cases do not * Free dilution with pure air seems to kill the plague germ
occur.
readily."
* *
***
*
These authors do not proceed to discuss the further progress of the disease but leave us as it were with the bacilli entering the lungs with the inspired air. The opinion of Major and Dr THOMSON was, however, anticipated by Dr. FRANCIS CLARK, Medical Officer of Health. Hongkong, in 1898, for in his Report on the Epidemic of Bubonic Plague in this Colony for that year he writes (page 6 ) “ ***** I am still of the opinion that the atmosphere in the immediate neighbourhood of a patient suffering from the disease, where such patient in confined in a dirty, dark and ill-ventilated dwelling, is infective to very much the same extent as in Typhus Fever, and that when such atmosphere is breathed for any length of time by a healthy individual, the bacilli have every opportunity of gaining access to the lymphatic system of the respiratory tract by inhalation, and of the alimentary tract by swallowing the mucus and saliva of the mouth and pharynx to which any particulate bodies in the atmosphere would naturally adhere'
17
If apart from primary plague · of infection in this disease, the
of the bacillus ? How does the
a we are to consider this a general node st be asked: What is the further path ecome general ?
Here the same question presents itself as in the skin-infection theory, namely, how does the virus having invaded the lymph vessels ultimately pass into the general circulation?
66
Dr. CLARK states his belief in the same report, page 4, that the disease is essentially one of the lymphatic system generally, and that, as can be seen at any post-mortem examination, most of the lymphatic glands of the body are in a more or less inflamed and irritable condition, while the special enlargement of any particular group of superficial glands (which does not by any means always occur) is due to purely accidental circumstances, such as by the carrying of heavy weights upon one's shoulder (as is invariably done by Asiatics) during the initial perio! of the disease, or in fact by any of the ordinary avocations of life which happen to be of a laborious nature.'
27
Dr. CLARK cannot accept the skin-infection theory as sufficient to account for the appearance of general lymphadenitis, and he offers in its stead a theory of primary entrance via the pulmonary, and intestinal lymphatics.
The
The relation of the lymphatic vessels and glands to the disease inust be the same whatever be the seat of the primary invasion of the lymphatic system. course of lymph from the lung tissue to the big veins near the heart is similar in method to its course from any other tissue to the blood-vessels, though in the case of the lungs it may be shorter than in many other cases.
Obviously if the bacilli get into the blood circulation via the normal flow of lymph or by passing into the injured vessels of a primarily infected (bronchial) gland we have only another instance of a plague septicæmia.