THE COLON-TYPHOID SEEIES 343 



lipovaccine. Vaccination has proved quite successful in 

 preventing a high incidence of typhoid fever in large 

 groups of individuals, such as soldiers exposed to infection. 



Bacterium dysenterue 



A considerable number of closely related species of bac- 

 teria are here grouped together. They produce diseases 

 quite similar clinically, but the bacteria are specific and 

 may be differentiated from each other by their fermentation 

 and serologic reactions. The organisms all closely resemble 

 the typhoid bacillus ; they are, however, nonmotile. Methods 

 of isolation are very similar to those used in typhoid. 



In dysentery in man the intestine, particularly the colon, 

 becomes inflamed and sometimes ulcerated. The stools are 

 usually thin and watery. In most cases the bacteria (unlike 

 typhoid) do not invade the general blood stream, that is, the 

 disease does not develop into a bacteremia. 



Transmission. — Dysentery is spread in quite the same 

 manner as is typhoid and methods of prevention in general 

 are identical. 



' Bacterium abortus 



Synonyms. — Abortion bacillus of Bang, Bacillus abortus, 

 Bacillus abortivus. 



This organism has been repeatedly isolated as the prob- 

 able cause of infectious abortion in the cow. The disease is 

 prevalent in many places in Europe and in the United 

 States in herds of dairy cattle. It should be noted that 

 other organisms besides the one discussed here are found 

 occasioning abortion in cattle and in other animals. 



Morphology. — The organism is a small rod .3-.8/iXl-2Ai. 

 It is somewhat polymorphic in culture media, and involu- 

 tion forms are not 'infrequent. It is nonmotile, does not 

 produce capsules or spores, and stains readily with aniline 

 dyes. Frequently polar granules may be observed. This 



