356 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



reaches into the millions, while the potential loss is enormous and 

 practically inestimable. Furthermore, the disease may be brought 

 into a herd by an unsuspected animal and spread rapidly to other indi- 

 viduals without attracting attention, inasmuch as there are no readily 

 noted symptoms present in the diseased animals. 



"Wliile the bureau has for several years concerned itself with the 

 general problem of infectious abortion in cattle, a few important 

 phases have been more extensively studied during the past year, and 

 even though many of the problems remain unsolved and some experi- 

 ments are as yet not finished, still some valuable data have been 

 obtained. Probably the most important and comprehensive facts 

 which have been demonstrated in connection with this disease are 

 (1) the discovery that the abortion bacillus is eliminated with the 

 milk of the infected cow, and (2) that this bacillus is found in the 

 tonsils of children, presumably as a result of drinking such infected 

 milk. 



At the meeting of the American Veterinary Medical Association in 

 Toronto in the summer of 1911, Schroeder and Cotton, of the Experi- 

 ment Station of this bureau, presented a paper on a bacillus which they 

 obtained from milk and which was capable of producing tubercular- 

 like lesions in guinea pigs. The name of " Bacillus 637 " was given 

 t(5 the organism, as the first cow found secreting such contaminated 

 milk was No. 637. A comparison of this organism with BaciUits 

 ahortus demonstrated conclusively that the}' were identical. Not 

 only was this proof obtained by a study of morphology, biological 

 characteristics, and pathogenicity, but the identity of the organisms 

 was further established by the complement-fixation test on serum 

 from animals affected naturally and artificially with infectious 

 abortion in which both the 637 and abortion bacilli were used sepa- 

 rately as antigens. 



The frequency of the presence of Bacillus abortus in a food product 

 like milk, and the ability of the organisms to produce lesions in 

 guinea pigs, pregnant cows, and other animals led at once to the 

 thought that Bacillus abortus might prove pathogenic for human 

 beings. As a result our endeavors were directed along three lines; 

 one was to obtain sera promiscuously from human beings and in 

 case of positive reaction to learn more about the history of the indi- 

 vidual whose serum showed the reaction; the second was to obtain 

 samples of milk from women in order to examine it for the abortion 

 bacillus, and third to obtain tonsils from milk-consuming children 

 at the various children's hospitals and inoculate such material into 

 guinea pigs. Material for these lines of work was not forthcoming 

 as fast as desired. Out of 25 sera from human beings no positive 

 results were obtained by either the complement-fixation or agglutina- 

 tion tests, although in similar tests made by Larson 3 out of 100 speci- 

 mens of sera gave positive results. No samples of human milk have 

 thus far been obtained. Out of 28 tonsils and adenoids inoculated 

 into guinea pigs, tonsil No. 3 produced necrotic areas in the liver, 

 but cultures from this organ remained sterile. Tonsils from case 

 No. 8 inoculated into two guinea pigs showed in one of them after 

 three months distinct lesions of infection in the liver, spleen, and tes ■ 

 tides, and Bacillus ahortus was obtained from the lesions. 



The pathogenicity of this organism for white mice, Avhite rats, 

 chickens., kittens, and dogs was sought for with varying results. 



