SCHIZOPHYTA— SCHIZOMYCETRS 



173 



disease. The organism itself may or may not gain entrance into the circula- 

 tion or organs. 



Immunity. As before stated, anti-toxins are not developed. Agglutinins, 

 however, are developed. 



Bacillus typhosus, Zopf 



Disease produced. Typhoid fever. 



Animals infected. Man. Inoculation of experimental animals usually 

 negative, except when injected in considerable quantities. 





ri u.'i' l-mm ifm'\ immii' ■mil 



iiiip 



i'v''Jx' 



Fig. 29. Typhoid fever bacillus. (Bacillus typhosus). 

 Section from spleen showing bacteria clustered in center. 

 After Fliigge. 



Pathogenesis. The organism invades the solitary lymph nodes and Peyer's 

 patches in the intestine and produces more or less necrosis and sloughing of 

 tissue. By means of the lymphatic channels, the internal organs are all infected, 

 particularly the spleen which becomes very much enlarged. The bacilli invade 

 the blood, and hence the disease is a true bacteremia. When they lodge in bony 

 tissues, osteitis, periosteitis, and osteomyelitis may be produced. 



Poisonous properties. No soluble toxin has been discovered, an endotoxin, 

 however, is present and may be secured through self digestion in cultures, or by 

 grinding and extracting the bodies of the bacteria. 



Immunity. No true anti-toxin serum has been produced, inasmuch as no 

 toxin has been discovered. The blood serum of typhoid patients agglutinates 

 the bacteria. Vaccination with killed cultures produces an immunity which lasts 

 probably in most cases several years. The blood serum of animals immunizes 

 against typhoid bacilli, but is not used because it is quickly thrown out of the 

 system when injected, and because it possesses very little curative quality. 



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