168 INFECTIONS OF THE DIGESTIVE TRACT 



cause of animal diseases. There is little doubt that they 

 have their normal habitat in the intestinal tract of 

 domestic animals, and this accounts for their very wide 

 distribution and for the occurrence of some of them in 

 the human intestine. It is especially those members of 

 the group that are pathogenic for man that interest us 

 here, and of these we may select for brief consideration 

 the bacteria grouped under the term "paratyphoid." 



Only five years ago Schotmiiller first maintained that 

 there are cases of fever which run a clinical course 

 indistinguishable from typhoid fever but differing from 

 it in being incited by the paratyphoid bacilli. This 

 position is now firmly established by numerous observa- 

 tions ; for although some of the characteristic lesions of 

 typhoid fever, such as ulcerated Peyer's patches, are 

 relatively seldom found in paratyphoid infections, it 

 is not clear that there are any essential differences in 

 the lesions observed. 1 That the poisons made by one 

 variety of paratyphoid bacilli are probably closely re- 

 lated to the poisons made by the typhoid bacteria is 

 suggested by the very close agglutination relationships 

 that have been discovered between these bacteria. 



It became necessary to make a separation of the para- 

 typhoid bacilli into two groups owing to agglutinative 

 and cultural differences paratyphoid A and B. The 

 bacillus of paratyphoid B is probably widely distributed. 

 It is the cause of many instances of disease running a 



1 "Weitere Mittheilungen iiber mehrere das Bild des Typhus 

 bietende Krankheitsfalle, hervorgerufen durch typhusahnliche 

 Bacillen (Paratyphus)," Zeitschr. /. Hyg., xxxvi, p. 368, 1901. 



