When the worm has once attached itself in the intestine, it may live for from five to fifteen years.

All this time it is constantly laying eggs; and these eggs, which are so tiny that they have to be put under a microscope to be seen, pass out in the feces; and if they are not deposited in a proper water closet, or deep vault, but scattered about upon the surface of the soil, the eggs quickly hatch into tiny, little wriggling worms called _larvae_, which are still scarcely large enough to be seen with the naked eye.
These larvae live in the soil; and, when it is wet and muddy, they get up between the toes of boys and girls who are going barefoot, burrow their way in through the skin, and produce a severe itching inflammation of the skin of the feet, known as "ground-itch," "toe-itch" or "dew-itch." When they have worked their way through the skin, they bore on into a blood vessel, are carried to the heart, pumped by the heart into the lungs, and there again work their way out of the blood vessels into the bronchial, or air tubes, crawl up these through the windpipe and voice organ into the throat, are swallowed into the stomach, and from there pass on into the upper intestine to attach themselves for their blood-sucking life.

If they are sufficiently numerous, their victim becomes thin, weak, and bloodless, with pale, puffy skin, and shortness of breath; he is easily tired on the least exertion, and ready to fall a victim to any disease, like tuberculosis, pneumonia, or typhoid, that may happen to attack him.
Their spread can be absolutely prevented either by the strict use of toilets or deep vaults, thus preventing the deposit of feces anywhere upon the surface of the ground; or by the constant wearing of shoes or sandals, thus preventing the larvae from attacking the feet and working their way through the skin and body into the intestine.
Fortunately, the disease is as curable as it is common, and two doses of a proper germicide, with a day in bed, and a laxative, will promptly cure it except in the worst cases.
The Rashes of Measles, Scarlet Fever, etc.

Many of the infectious fevers, such as measles, scarlet fever, chicken-pox, and smallpox, are attended by rashes, or _eruptions_, upon the surface of the skin, due to a special gathering or accumulation of the particular germs causing each disease, just under the skin.

When the skin sheds, or flakes off, after the illness, the germs are shed in the scales and float, or are carried about, and thus spread the disease to others.
These rashes or eruptions are not dangerous in themselves, though often very uncomfortable, but help us to recognize the disease; they probably show us the sort of thing that is going on in the deeper parts of the body.