(b) Breathing in certain germs which float in the air. In this way one may catch pneumonia, consumption, influenza, diphtheria, whooping cough, tonsilitis, spinal meningitis, measles, and certain other diseases.
(c) Taking certain germs in through the mouth in eating or drinking. Dysentery, cholera, typhoid fever, diarrhea, and intestinal worms may be caught in this manner.
(d) Having certain germs injected into the body by the bites of insects, such as mosquitoes, fleas, and bedbugs. Malaria, yellow fever, dengue fever, and bubonic plague may be caught in this way.
(e) Inheriting the germ from one's parents.
Persons may have these germs sometimes without apparently being sick with any disease. Such persons and persons who are sick with the diseases are a great source of danger to others about them. Germs which multiply in such persons are found in their urine and excretions from the bowels; in discharges from ulcers and abscesses; in the spit or particles coughed or sneezed into the air; in the perspiration or scales from the skin; and in the blood sucked up by biting insects.
Those who have taken care of their health and who have not become weakened by bad habits, exposure, and fatigue are not only less liable to catch disease, but are more apt to recover when taken sick.
Knowing all these things, the soldier can understand the reasons for the following rules and how important it is that they should be carried out by each and every person:
Stay away from persons having "catching" diseases.
If you have any disease, don't try to cure it yourself, but go to the surgeon. Insist that other soldiers do likewise.
Typhoid fever is one of the most dangerous and common camp diseases. Modern medicine has, however, discovered an effective preventative for this disease in the typhoid prophylactic, which renders the person immune from typhoid fever. The treatment consists in injecting into the arm a preventative serum. The injection is given three times at 10-day intervals.