CHAPTER XXXII 



ABORTION BACILLUS GROUP 



OXE organism only, the Bacillus abortus of Bang, is placed in 

 this group. It should be noted that other organisms besides the 

 one here discussed are doubtless occasionally responsible for abor- 

 tion in cattle and other animals. 



Bacillus abortus 



Synonyms. Abortion bacillus of Bang; Bacterium abortum. 



Disease Produced. Contagious abortion in the cow. 



Bang, in 1897, described a Bacillus as the probable cause of 

 contagious abortion in the cow. The specific organism was isolated 

 with difficulty. It has been isolated since that time in Europe 

 several times, and, more recently, in the United States. Several 

 investigators in the United States have described members of the 

 colon group and of other groups as present in contagious abortion, 

 but it is doubtful whether in many cases appropriate cultural 

 methods have been utilized for the isolation of this organism. 



Distribution. Contagious abortion has been reported from 

 many localities on the continent of Europe and in Great Britain. 

 It is known to occur in all sections of the United States. 



Morphology and Staining. Bacillus abortus is very small, and, 

 according to Nowak, resembles the bacillus of chicken cholera. 

 Nowak, on the basis of its morphology, groups it with the Pas- 

 teurellas or hemorrhagic septicemia bacilli. It is polymorphic* 

 in culture-media. Involution forms occur as branched and clubbed 

 types. It is non-motile, and neither capsules nor spores have been 

 demonstrated. It stains readily by the aqueous anilin dyes, 

 frequently showing polar granules. It is gram-negative. 



Isolation and Culture. The isolation and cultivation of Bacillus 

 abortus are attended with peculiar difficulties. The organism 

 may be frequently obtained at once in pure culture from the 



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