Plague, a contagious disease / [Anon].

  • Gooch, Robert, 1784-1830
Date:
[1825]
Catalogue details

Licence: Public Domain Mark

Credit: Plague, a contagious disease / [Anon]. Source: Wellcome Collection.

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    ignorance of those who are attempting to mislead the public, and the indiscretion of those who are inclined to believe them. Some diseases become prevalent because their causes are so diffused as to affect many persons in the same place at the same time; other diseases become prevalent because the bodies of the sick give out a noxious material, which excites them in the bodies of the healthy. The former are called epidemic, the latter contagious diseases. The causes of epidemic diseases may be either deficient food, as in a general scarcity ; or heat, or cold, or great vicissitudes from one to the other; or noxious states of the atmosphere, which are not perceptible by our senses, ther¬ mometers, or barometers. Some of these are understood, as marsh exhalations; others are involved in great obscurity. The human constitution is a delicate instrument, and can perceive qualities which our philosophical instruments and chemical tests do not enable us to detect. The noxious matters produced by the bodies of the sick, which propagate contagious diseases from person to person, may be either something visible and substantial, as that formed in the pustules of small-pox, or the vesicles of the cow-pock; or something invisible, the existence of which is known only by its effects, as in the measles, the scarlet-fever, the hooping-cough. The only way in which we can distinguish those diseases which are prevalent from an extensive cause acting at the same time on a number of people, from those diseases which are prevalent be¬ cause they are communicated from person to person, is by certain circumstances in the mode of their diffusion. Now the circum¬ stances by which we know that a disease is propagated by conta¬ gion, are these; 1st, that those persons are most liable to the disease who approach those affected with it, and that in pro¬ portion to the nearness of the approach; 2dly, that those who avoid intercourse with persons affected with the disease, gene¬ rally or always escape it, and that in proportion to the care with which they avoid them; 3dly, that the disease is communicable from one to another by inoculation. If all these circumstances can be ascertained in the diffusion of a disease, and each with clearness and distinctness, we have all the evidence, which we can have, for believing that the disease is propagated by conta¬ gion. The proof is as complete as the nature of the subject admits. But the evidence for the belief that a disease is propa¬ gated by contagion, varies very much in degree in different cases; it may amount only to that which creates a strong sus¬ picion—or it may amount to that which creates an absolute cer¬ tainty. The most decisive single proof that a disease is con¬ tagious, is inoculation. Yet there are several diseases the con¬ tagiousness