Fig. 59. A full-grown hookworm, magnified; the short line shows the average length of the hookworm.
What the hookworm is
This disease is not caused by a germ, as is typhoid fever, but by a worm from a quarter to half an inch long, and about as thick as a small hairpin. These worms get into a person's intestinal canal, and there lay their eggs, which are later given off in the bowel discharges. When these discharges are thrown on the ground, or are put into an open water-closet, they may be carried about by chickens, flies, and pigs. Then the eggs hatch in the soil and tiny hookworms result. When human excreta are not properly disposed of, in climates where hookworm disease prevails, the soil becomes practically full of these little worms, and from the soil they find their way into the bodies of the people.
How it enters the body
There are two principal ways by which the hookworm may enter the body. One is through the mouth, which these worms reach in practically the same way as do typhoid fever germs. The hookworm may enter the body through the skin also. Some authorities state that the worm bores its way in; but it is probable that it does not actually bore through sound skin, but enters at some point where there is a small break.
Where it lives in the body
After the worm gets through the skin, it is taken into the blood and carried to the lungs, and from there it finds its way to the throat and is swallowed. It makes no difference whether the hookworm is swallowed or enters the body through the skin; it finally reaches the intestinal canal, where it then makes its home. Sometimes thousands of these worms are found in a single person, and each one of them entered the body through the mouth or through the skin. The worms do not multiply in the body, and the eggs they lay never hatch until after they have left the body.
How it affects the patient