We know that typhoid fever germs get into the body with food, but how do they get out? Once in a great while germs are found in the matter that the patient vomits, or spits up, but this is a rare occurrence, so rare that we need hardly consider it. The germs are present in the blood of the sufferer, but other people do not get his blood on their hands or in their food. There are two things that come from the patient that are loaded with these germs, and these are the urine and bowel discharges. In these two excretions of the body are found practically all the typhoid germs that come from the patient, and these are the causes of other infections. In other words, it is from these two excretions that the germs get into food and drink. [Sidenote: How typhoid germs get into water] How do the typhoid germs get into our food? What is done with the excretions after they come from the body? You will probably say that the nurse throws them into the sewer. Very true; but where do they go when they are thrown into the sewer? The sewer must empty somewhere, and in most instances it empties into a stream, the water of which is used for drinking purposes. [Illustration: FIG. 57. Pollution of a stream with sewage.] [Sidenote: The widespread evil due to the sickness of one person] You may think that the germs from one person would not make much difference, but that is where you are mistaken. There is a town in Pennsylvania of about eight thousand inhabitants, which gets its water from a stream that flows down from the mountains. One cold winter, while the stream was frozen, a man living on the bank of the stream was taken sick with typhoid fever. His nurse threw the urine and the discharges from his bowels on the ice on the bank of the creek. When the ice melted, the typhoid germs in the discharges found their way to the stream that furnished drinking water to people farther down, and in a very short time there were over one thousand cases of typhoid fever in that town. Before the ice melted there had not been a single case of typhoid, and every one of the thousand cases came from the water into which had been allowed to flow the discharges from one man with typhoid fever. You see what germs from one person may do. [Sidenote: How long typhoid fever germs live in a stream] Sometimes people say that a stream purifies itself every few miles. It does purify itself of some things, but disease germs live from twenty-five to thirty-five days in water, and a stream flows a long way in thirty days. [Sidenote: The pollution of streams with sewage]