1 64 PATHOLOGY 



blindness, deafness, etc. Recovery after the use of 

 Flexner's serum is not accompanied by these defects. 



TYPHOID FEVER 



Definition. An infectious disease caused by the 

 Bacillus typhosus and characterized by hyperplasia and 

 ulceration of the intestinal lymph-follicles, and swelling 

 of the mesenteric glands and spleen. 



Etiology. The specific cause is the typhoid germ, 

 which gains entrance to the body through the alimentary 

 canal, locating in the intestinal glands. Predisposing 

 causes are lowered vitality from any cause. The great- 

 est susceptibility exists between the ages of fifteen and 

 twenty-five. Infants are rarely attacked. The most 

 frequent sources of infection are milk and water, though 

 any food-product which is eaten raw may convey the 

 infection. 



Flies are probably the greatest disseminators of in- 

 fection. One attack usually confers immunity for life, 

 but a second and even a third attack may occur. The 

 germs may persist in the bile-passages and intestines 

 of persons fully recovered from the disease. Such 

 carriers become a serious menace to all with whom they 

 may come in contact. 



Morbid Anatomy. A catarrhal condition exists 

 throughout the large and small intestines. There is 

 hyperplasia of Peyer's patches, which become infil- 

 trated, hardened, and elevated above the mucous mem- 

 brane. The solitary glands may project into the in- 



