TYPHOID FEVER 



101 



of Peyer's patches and the mesenteric glands and the spleen, with subsequent necro- 

 ses, but focal necroses of the same character are found in the liver. 



A striking feature of the pathology of typhoid fever is the long-con- 

 tinued persistence of the organisms in the gall-bladder and elsewhere. 

 It is beginning to be believed that a previous typhoid infection, pos- 

 sibly so mild as to have passed unnoticed, is at the basis of gall-bladder 

 infections and resulting gall-stones. Various bone infections, especially 

 osteomyelitis, have shown the typhoid bacilli in pure culture. For- 

 merly it was supposed that the typhoid bacillus brought about its lesions 

 by a local infection centered in the ileum. The present view is that 

 typhoid bacilli effect an entrance into the blood stream through some 

 lymphoid channel, as by tonsil or other alimentary lymphoid structure. 

 Of animals, only the chimpanzee seems to be susceptible. 



FIG. 33. Seventy-two-hour-old culture of typhoid bacillus on gelatin. (Kolle and 



Wassermann.) 



They develop in the general lymphatic system, the spleen in partic- 

 ular, where they are protected from the bactericidal power of the blood. 

 After a time, however, approximately the period of incubation, they 

 become so abundant in these lymphatic organs that they are carried 

 over into the general circulation. Then as a result of bacteriolysis the 

 intracellular toxins are liberated and symptoms develop. If bac- 

 teriolysis takes place other than in the blood we have various suppurative 

 processes. As a result of the formation of antibodies, the development 

 in spleen, etc., is checked but should these immunity reactions become 

 less potent relapses may occur or various local infections manifest 

 themselves. 



