Popular Science Monthly/Volume 25/October 1884/The Cholera-Germ
AT the present moment, when the Continent has again become the battle-field between cholera and the human race, all questions concerning the cause, diffusion, and prevention of the cholera-virus must take a prominent place in the deliberation on the best sanitary measures to be adopted in combating this insidious foe. Almost all practical preventive measures in this country and on the Continent as regards cholera and other infectious maladies are based on the assumption—supported by a good deal of evidence both theoretical and practical—that the virus is particulate, and, as indicated by its self-multiplication within the affected person, is a living organism. But the nature of this supposed organism of cholera has, until quite recently, been altogether mysterious. As is well known, Professor Koch and colleagues, sent out last year by the German Government to investigate the cholera in Egypt and India, have ascertained that in the rice-water stools voided by patients suffering from the disease there are present, besides micrococci and bacilli, common to the evacuations of other than cholera patients, peculiar curved bacteria, so-called "comma-shaped" bacilli, which Koch has not been able to discover in any cases of diarrhœa. These "comma-shaped" bacilli Koch has succeeded in isolating by artificial culture. Unfortunately, cholera has hitherto not been found transmissible to the lower animals, and therefore the function of these "comma-shaped" bacilli must at present remain unknown. All we can therefore say is that Koch has shown that in cholera evacuations there exist, besides micrococci and straight bacilli, other organisms also characterized by this—that they are curved or comma-shaped. Whatever else has been said by Koch, his followers, and critics, scientific and daily papers, as to these "comma-shaped" bacilli being the cause of cholera, is simply and purely a supposition, which, as we shall presently show, is wanting in the most essential elements.
First and foremost, Koch has been unable to find anything of this "comma-shaped" bacillus in the blood or tissues in any stage of cholera. Now, all experience on cholera teaches that, whatever its cause may be, the alimentary canal is not the only passage through which the cholera-poison enters the system, but that its entrance through the respiratory organs is also an established fact. For this reason it is necessary to assume that, as in other infectious diseases, it passes through the blood and system in the stage of incubation of the disease. The symptoms of cholera, the whole nature of the disease, shows that it is not a local distemper of the alimentary canal, but that the latter is merely a symptom of the malady, as much as in typhoid fever the distemper of the ileum and spleen, or in scarlatina that of the skin, throat, and kidney. Had Koch found the "comma-shaped" bacillus in the blood or the tissues, e. g., the bloodvessels of the alimentary canal, mesenteric glands and spleen, the nature of this "comma-shaped" bacillus would have been as obscure as ever, but still there would have been some sure element in the chain of surmises. Of course it might be argued, and as a matter of fact it is argued by Koch in the reports to his Government, that the bacillus, having found entrance into the cavity of the intestines, there multiplies, and produces some ferment, which, absorbed into the system, sets up the whole chain of appearances constituting the symptoms of cholera. This is quite possible, and, to a certain limited extent, is borne out by experience, notably in the case of putrid or pyæmic poisoning, where, owing to the presence of putrefaction in a wound, the products of putrefaction—the sepsin—absorbed in sufficient quantities into the system, create the above disease, often terminating fatally. In this case no specific organisms are detected in the blood or tissues; their presence is limited to the wound only, and their effect is merely this, that some ferment—ptomaine or some other substance—produced by them is absorbed into the system.
That this should also be the case in cholera is, as we just said, possible, but it is not probable, for the simple reason that the cholera-virus in a large percentage of cases enters the system by the respiratory organs, and therefore it must be assumed in these instances to pass into the general circulation, and consequently, if it is to be identified, must be identified in the blood or tissues.
The practical consequences of an assumption that the cholera-virus passes into the system exclusively by the alimentary canal, and that it has its breeding-ground in the latter only, are so great, that before acting on such an assumption the basis for it ought to be established, which it certainly is not.
Secondly, is it a well-established fact that this "comma-shaped" bacillus is present only in cholera evacuations? If it should be found that this bacillus is absent from the alimentary canal in all other diseases, then we could at best recognize it as pathognomonic, but it by no means follows that it is also pathogenetic.
I have lately had the opportunity of inspecting this "comma-shaped" bacillus in specimens prepared by Koch, from the rice-water evacuations, and also in artificial cultures, and I have fully convinced myself of its reality. But I possess prepared specimens of evacuations of patients suffering from severe diarrhœa (in an epidemic outbreak of diarrhœa in adults in Cornwall in the autumn of 1883, and investigated by Dr. Ballard, Inspector to the Local Government Board), in which specimens, besides micrococci and straight bacilli, there are undoubtedly present bacteria which, in shape and size and mode of staining, so closely resemble the "comma-shaped" bacilli of cholera that I am unable to discover a difference between them. I have, however, not made any artificial cultivation of them, and therefore can not say whether there exist any differences between the two, notably as regards their mode of growth.
Here is one other point to which we wish to draw attention: as Cohn ("Beitrage zur Biologic der Pflanzen," Heft ii) has shown, and as is now generally accepted, a rod bacterium which is characterized by being curved is regarded not as a bacillus but as a vibrio; and it is not quite clear why, unless for the sake of novelty, Koch, generally accepting Cohn's terminology, should in the case of the cholera bacterium have deviated from it, and should not rather have spoken of it as a vibrio, because a vibrio, and particularly a Vibrio rugula (sp. Cohn), is the organism which he describes as a "comma-shaped" bacillus.—Nature.