Military hygiene : a manual of sanitation for soldiers / by R.H. Firth.

  • Firth, R. H. (Robert Hammill), Sir, 1858-1931.
Date:
1908
Catalogue details

Licence: In copyright

Credit: Military hygiene : a manual of sanitation for soldiers / by R.H. Firth. Source: Wellcome Collection.

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    convey infection of some disease from which the cow at the time is suffering, as, for instance, tuberculosis. AVater may be contaminated with sewage or the excreta of a single infectious patient, AA^hen the air acts as a con- veyor of infection, the infectious matter must generally be in the condition of dust. In this manner the con- tagion of small-pox can be carried considerable distances, that of tubercle possibly only a short space, and that of tjqffius but a few feet. Of diseases spread by inoculation or damage to the skin notable examples are tetanus or lock-jaw following the fouling of wounds with earth, malaria and yellow fever resulting from bites of mos- (piitoes, plague from bites of fleas from rats, and sleep- ing-sickness from the bites of a special fly found in various ])arts of Africa. Susceptibility to Infection.—It may be asked, naturall}’-, if, then, these disease-causing germs are so widely scattered and can reach man in such a variety of ways, why is it that man is not infected oftener than he is ? The answer is that persons vary in susceptibility to attack by different infective diseases; moreover, the possibility and intensity of an attack de]>end on the condition of the person, and on the number and the virulence of the particular microbes infecting the person. The main protection against infection by germs exists in man’s own body, more particularly in the blood, whose white corpuscles swallow up and destroy a certain number of bacteria after they have been damaged bj' means of a chemical substance dissolved in the watery part of the blood. This protective action varies in different persons, and in the same person at different times, the most important disturbing factors being age,
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