CHAPTER XI.
OF CONTAGION.
Contention on such a subject as contagion is not to be wondered at, when we consider the obscurity attendant on all that relates to subtle agencies (the supposed qualities of contagion); and inasmuch as we observe that different effects arise from the same causes, as also similar effects from different causes in the human body, a vast field is necessarily opened up for contention, as every impartial observer will admit.
That the doctrine of contagion is of comparatively modern origin (subsequently to Hippocrates), historical research fully shows, and it would be really an endless, if not an unprofitable, task to review the innumerable arguments of which contagionists and their opponents have from time to time availed themselves in support of their respective opinions, especially when the controversialists can enlist on the one side such names as Chisholm, Clark, Cleghorn, Pringle, Bianchi, Lind, Meade, Warren, and a host of others, as contagionists, and on the other side, as non-contagionists, such men as Hillary, Huck, Hunter, Jackson, Bouland, Pinckard, Bancroft, Scott, Rush, Miller, Caldwell, Chervin, besides very many others of more modern date.
With reference to our present subject, contagion, it has always been with me a difficulty to understand the precise or real sense in which contagionists generally write; and I must confess my inability to comprehend the meaning they attach to the term contagion, and also to that of infection, so contradictory are their applications of the terms contagion and infection, some using them synonymously, others making distinctions, between contagion and infection, of such arbitrary signification, that they are really neither definite nor intelligible; whilst contagionists themselves often depart from their avowed principles. For example, Papôn, in his work entitled ‘Epoques Mémorables de la Peste,’ considers the undoubted causes of plague to be uncultivated lands, marshy soil, corrupt lakes, filthy cities, concurring with occasional causes, such as intemperature of the seasons and famine, whilst the bent of his researches is evidently to prove that in every modern plague foreign contagion was the cause!
Dr. Meade, notwithstanding his advocacy of contagion, like most other contagionists, is guilty of inconsistency in stating, “that a corrupt state of the air attends all plagues.”
Again, Dr. Patrick Russell, a great contagionist, when giving a most minute account of the origin, spread, and decline of the plague, admits the inutility of quarantine laws for the prevention of contagion, and, curiously enough, he lays much stress on what he terms “a pestilential constitution of the air.”
Dr. Hamilton, another great contagionist, affirmed that the influenza which prevailed in England,—in fact, all over Europe, in the year 1782, was contagious, and that the malady was propagated by contagion only; yet at the same time he informs us that, “in different places, many hundreds were seized with pestilence at one and the same time:” and Dr. (afterwards Sir Gilbert) Blane, also a contagionist, speaks of the influenza as having affected mariners in the very midst of the ocean!
It would appear, however, that to reconcile conflicting opinions, various modern writers of experience and talent have endeavoured to show that epidemic diseases, not contagious at their commencement, may acquire that character from confined air, filth, and other accumulations. That impure air, want of light, crowding together unwashed numbers, &c., will by predisposition contribute to the production and aggravation of disease, as we observe to be the case in jails, hospitals, and in camp, I can fully understand; but that epidemic diseases, such, for instance, as plague, yellow fever, or cholera, are ever propagated by contact—contagion, I, after twenty-five years’ residence in pestilential countries, have no reason to believe; for I have seen epidemics seize on vast numbers at once,—I have sometimes seen them attack a whole people, or a part thereof, whilst at other times they have prevailed amongst the inhabitants of particular provinces and cities only. On what principle of contagion or infection, I would ask, can such universality or partiality of disease be accounted for or explained? Surely not from any cognizable property of contagion. All that I have ever read and seen of the nature of epidemics militates against the doctrine of contagion, whilst all that has been adduced, as far as my researches show, in support of contagion, has been of a negative, or at all events not of a positive, nature.
Epidemic diseases, which have appeared and spread at different seasons,—in fact, at all times of the year,—in the middle of summer, for instance, as well as in the depth of winter,—which have also been found traversing whole continents, continuing their course for many successive months, and often assuming a definite direction or progress, often affecting large masses of people living on the same spot, while others in adjoining localities are exempt,—cannot, I contend, be attributed to contagion, but to the qualities and influences of the surrounding atmosphere, coupled with enervating habits, &c.
Again, contagious diseases are recognizable by the determinate periods of their phenomena, especially as regards specification, as also by their mode of propagation, whilst, if epidemic pestilences were dependent on, or caused by, contagion, they would never cease until whole communities became extinct!