The period of infection in epidemic disease / by William Squire.

Date:
1874
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Licence: Public Domain Mark

Credit: The period of infection in epidemic disease / by William Squire. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    tain individuals, the germ of cancer is still more limited ; but some blood diseases, as pytemia, are able to affect others through the medium of the air; its congener, purulent ophthalmia, acts chiefly in this way. They are poisons of animal origin; so are most of the paludal poisons— “ All the infection that the sun sucks up From bogs, fens, flats,” must first have been conveyed and condensed there before they were again called into activity. When, with Sydenham,* we consider the soui’ces of all the air-borne poisons, we find this secret condition of the air is conferred by no chemical vapour whether mineral or vegetable, but by the presence of living oi’- ganisms.t Sydenham, though apparently unaware that small-pox was contagious, justly attributed epidemic diseases “ to a latent and unexplained alteration of the air infecting the bodies of men.” Only so long as the air contains this secret cause can the epidemic rage. Hence this “ state of the air,” which has been translated back to us from the Latin into “ atmospheric consti- tution” means only the presence of the germs of disease. He further saysj that the various epidemic states or constitutions of different years “ owe their origin neither to heat, cold, dry- ness, nor moisture ; but rather depend upon some unknown change from the very bowels of the earth, contaminating the air with such special effluvia as force the human body into this or that disease.” Upon the conveyance of such infecting germs from the sick to the healthy the extension of every epidemic depends; details of the successive infection of each individual would be the full history of the epidemic. The prevention of disease requires us to know the conditions under which the different infections act. It is by careful study of each of the special poisons that a nearer approach is made to the successful investigation of epi- demics. Emanations from scarlatina chiefly cling to everything they touch, and are restricted to small distances; those of hoop- ing-cough and influenza can be widely diffused through the air. Much that is attributed to a remote or indefinite cause, such as season, will be found dependent upon some intermediate condi- * ThoniEB Sydenham, M.D., Opera Omnia, Londini, 1844, Sydenham Society edition, p. 28, cap. 1, § 6. t He noticed how, in obedience to laws regulating all organic growth, “ some vernal epidemics appear early, os in January, and thence gradu- ally increasing, come to this slate about the vernal equinox; after which they gradually decrease, and at length disappear about the summer sol- stice. Others, rising in the spring, and daily increasing, come not to their state till about the autumnal equinox, after which they gradually decrease and vanish at the approach of winter,” The entire works of Dr. Thos. Sydenham, newly made into English, from the originals, by John Swan, M.D., 3rd edit., London, 1703, pp. 6, 7. It Op. cit, p. 30. Observationes Medicee circa Marborum .Acutorum Historiam et Curationem. Authors Tho. Sydenham, Londini, 1865, cap. i, § 6; cap. ii, § 5.
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