There are certain diseases, the germs of which get into bodies through our mouths. That is, we eat or drink them. Some of these diseases are typhoid fever, cholera, the summer complaints of children, tuberculosis, and diphtheria. At present we shall learn about the germ that causes typhoid fever, how it gets into our food and drink, and how we may prevent the disease by getting rid of this germ.
Typhoid fever, like all other diseases caused by germs, is caused by one kind of germ, and one kind only. You cannot get typhoid fever by eating cholera germs any more than you can get diphtheria from typhoid germs.
Animals free from typhoid
So far as we know, there is no animal except man that has typhoid fever. Since the germs of any disease must come from an animal suffering from that disease, and as man is the only animal that has typhoid fever, it naturally follows that the only way to get typhoid fever is from some person who has the fever or has had it.
How typhoid germs leave the body
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.
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.
Fig. 57. Pollution of a stream with sewage.