1. By strengthening the body through hygienic living so that it offers greater resistance to the invasions of germs.
2. By living as far as possible under conditions that are unfavorable to germ life.
3. By understanding the agencies through which disease germs are spread from person to person.
Conditions Favorable and Unfavorable for Germs.—Conditions favorable for germ life are supplied by animal and vegetable matter, moisture, and a moderate degree of warmth. Hence disease germs may be kept alive in damp cellars and places of filth. Even living rooms that are poorly lighted or ventilated may harbor them. Water may, if it contain a small per cent of organic matter, support such dangerous germs as those of typhoid fever. Fresh air, sunlight, dryness, cleanliness, and a high temperature, on the other hand, are destructive of germs. The germs in impure water, as already noted (page 165), are destroyed by boiling.
How Germs are Spread.—Some of the more common methods by which the germs of disease are spread, and by so doing find new victims, are as follows:
1. By Means of Foods.—Foods, on account of the locality in which they are produced or the method of gathering or of handling-them, may become contaminated with germs, which are then transported with the foods to the consumer.
2. By Means of Dust.—Material containing germs, e.g., discharges from the throat and lungs, will on drying[pg 396] form dust. This is lifted with other fine particles by the air and may be carried quite a distance. The dust from public halls and other places where people congregate is the kind most likely to contain disease germs. Dust should be breathed as little as possible and only through the nostrils. Where one is compelled, as in sweeping, to breathe dust-laden air for some time, he should inhale through a moistened sponge, or cloth, tied in front of the nostrils.
3. By Means of Domestic Pets and Different Kinds of Household Vermin.—Germs sticking to the bodies of small animals are carried about and may be easily communicated to people. By this means, rats, mice, bedbugs, etc., where such exist, are frequently the means of spreading disease; and particularly dangerous, on this account, is the common house fly. Feeding as it does on filth of all kinds, it is easy for it to transfer the bacteria that may stick to its body to the food which is supplied to the table. The proper screening of houses and the destruction of material in which flies may develop, such as the refuse from stables, are necessary precautions.
Germs are spread also by the clothing of people, by railroad and steamship lines, by the mails, and by the natural elements. In fact, any kind of carrier, in or upon which germs can live, may serve as a means of spreading those of certain kinds.
Public Sanitation.—The general conditions under which germs may thrive and some of the means by which they are scattered, emphasize the practical value of measures which have for their purpose the making of one's surroundings more wholesome and hygienic. Such measures may be directed both toward one's immediate surroundings—the home—and toward the neighborhood, town, or city in[pg 397] which one lives. The hygienic conditions of primary importance in every city or town are as follows: