Epidemics considered with relation to their common nature, and to climate and civilization : in two lectures delivered at the Philosophical Institution, Edinburgh, November 1855 / by Southwood Smith.

  • Smith, Southwood, 1788-1861.
Date:
1856
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Licence: Public Domain Mark

Credit: Epidemics considered with relation to their common nature, and to climate and civilization : in two lectures delivered at the Philosophical Institution, Edinburgh, November 1855 / by Southwood Smith. Source: Wellcome Collection.

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    is dependent on the physical characters of the immediate neighbourhood. Thus intermittents prevail chiefly in marshy and swampy districts ; remittents also chiefly there, though not exclusively ; while in other localities other forms arise approxi- mating to the continued type of temperate climates. For the most part these epidemics are strictly endemic, and are confined to the particular regions in which they are engendered. They never pass the limit of the equatorial or tropical zone. Yellow Fever, one of the most common and destructive of these diseases, is still more restricted in its range, being confined within a definite line determined by temperature. It is incapable of existing where the average range of the thermometer is greater than from 76° to 86° of Fahrenheit, or where the temperature varies more than from 5° to 10° night and day. Extreme heat and moderate cold immediately stop it; nay, even the prevalence of a cold wind for a few hours only. In other instances these epidemics pass beyond the regions in which they are produced, and sometimes extend to all the other quarters of the globe. The Black Death, the range of which we have seen, was engendered in China; the Cholera of our own day, generated in the delta of the Ganges, the great source and centre of Indian epidemics, ravaged that country long be- fore it directed its course to Europe. When these tropical epidemics advance into more temperate climes, they lay aside nothing of their nature; they lose but little of their power. Wherever they go they decimate the populations which they attack. One remarkable peculiarity of some of these epidemics is that natives of the region in which they prevail are for the most part unsusceptible to them. This is true however only of particular forms of pestilence. Some of them acknowledge no acclimatization. Cholera, for example, attacks equally na- tives and new comers. On the other hand, yellow fever rarely attacks the natives who reside permanently within its zone. Its chief victims are strangers who have recently arrived