290 HUMAN PHYSIOLOGY CHAP. 



the poisons produced are absorbed into the blood and 

 finally paralyze the nerve centers controlling circula- 

 tion and heat production. 



198. Typhoid Fever. This disease is due to a rod- 

 shaped bacillus. The germ enters the body through 



water, milk, or other foods. The 

 germ is contained in the excretions 

 of patients, which are its only source 

 so far as is known at present. The 

 water polluted with typhoid germs 

 used in the dairy or in washing 

 vegetables is a frequent cause of 

 FIG. 158. Bacteria of this disease. Flies and other insects 



typhoid fever. . 



spread typhoid germs. 



The typhoid germs get into the intestines and mul- 

 tiply rapidly. They injure the walls of the intestines, 

 causing ulcers, and *in severe cases, hemorrhages and 

 perforations. For that reason the patient should not 

 be given any solid foods at all. There is no danger 

 of infection except from the excretions, which should 

 be properly cared for, and from soiled sheets or cloth- 

 ing, which should be carefully disinfected as soon as 

 removed. 



199. Dysentery. This is an infectious disease, 

 especially common among children. It is due to an 

 organism that does not belong to the bacteria. The 

 disease-producing organism probably lives in the soil 

 and water and gets into the body through the mouth 

 with water and foods. The organisms develop very 

 rapidly in the intestines and are numerous in the excre- 



