BUREAU OF ANIMAL INDUSTRY. 137 



tion. A living-organism vaccine has been exclusively employed, 

 inasmuch as the results from inoculations of bacterins and serums 

 during previous years have proved to be disappointing. Such a 

 vaccine when used under purely experimental conditions in already 

 infected herds has continued to give promising results. The single 

 treatment of nonpregnant animals with this vaccine permits the con- 

 venient employment of the immunizing procedure, which is a highly 

 desirable feature. Serological and bacteriological work has indicated 

 that the subcutaneous injection of a living-organism vaccine usually 

 produces but a temporary infection of the nonpregnant animal. This 

 is seemingly explanatory of the immunity conferred as well as of the 

 failures to obtain beneficial results when animals harboring abortion 

 infection have been vaccinated. Abortion-free animals treated with 

 a living-organism abortion vaccine during the nonpregnant stage 

 have given evidence of possessing subsequently a resistance to abor- 

 tion disease suggestive of that exhibited by animals which under herd 

 conditions have acquired and fully recovered f roni abortion infection. 

 Much routine work has been performed, consisting of the applica- 

 tion of the laboratory tests to several hundred samples of blood serum 

 from suspected cases. Correspondence has furnished a means of dis- 

 seminating information regarding control measures to herd owners. 



BOTULISM. 



Further opportunities were afforded for the study of botulism. 

 In cooperation with the Bureau of Chemistry considerable work was 

 done in determining the toxicity and identifying the type of cultures 

 of Bacillus hotiilinus recovered from olives, the consumption of which 

 had caused fatal botulism in man. It was found that in every case 

 the olives were infected with what is known as the type A organism. 

 Experimental work showed that suspensions of B. hotulhms spores 

 heated to 80° C. to destroy the soluble toxin were capable of inducing 

 typical botulism in guinea pigs when given in sufficiently large doses 

 either by the mouth or subcutaneously. ■ 



A small flock of hens kept under back-yard conditions in the Dis- 

 trict of Columbia developed severe illness about 18 to 24 hours after 

 eating the contents of a jar of spoiled home-canned corn. The whole 

 flock .succumbed within 48 hours. Bacteriologic examination of the 

 crop contents of one of the dead birds reA^ealed the presence of B. 

 hofuUnus of the same type as the Nevin strain (type B). It pro- 

 duced a toxin having a minimum lethal dose for guinea pigs of 

 0.0001 cubic centimeter. Subcutaneous injection of 5 c. c. of the 

 toxin produced fatal results in an adult fowl, and 10 c. c. given by 

 the mouth to a large hen caused severe symptoms of botulism from 

 which the bird recovered after about two months. 



Sheep haA'e been immunized against both type A and type B strains 

 of B. hotiilinus toxin. The serum from these sheep in 1 c. c. doses 

 has shown an ability to protect guinea pigs against about 10.000 

 minimum lethal dose's of toxin. Some of the type A serum has been 

 sent out for human cases of botulism and promising results have been 

 re])orted following its use. 



Some of the type A serum has been tried in cases of forage poison- 

 ing in mules, but sufficient data have not been gathered on wliich to 



24435— AGR 1920 10 



