Bovine Tuberculosis 685 



BOVINE TUBERCULOSIS 



Bacillus Tuberculosis Bovis 



The tuberculous diseases of the lower animals and especially cattle 

 have lesions closely resembling those of human tuberculosis, and 

 containing bacilli similar both in morphology and in staining reac- 

 tion to those found in human tuberculosis. The conclusion that 

 they are identical seems inevitable, but in his monograph upon 

 tuberculosis Koch called attention to certain morphologic and cul- 

 tural differences that exist between bacilli obtained from human and 

 from animal tuberculosis. Unfortunately, very little attention was 

 paid to the subject until Theobald Smith* carefully compared 

 a series of bacilli obtained from human sputum with another 

 series obtained from cattle, horses, hogs, cats, dogs, and other 

 animals. 



His observations form the foundation of the following description 

 of the bovine tubercle bacillus : 



Morphology. — 'The size of the bovine bacillus is quite constant, 

 the individuals being quite short (1-2 m). They are straight, not 

 very regular in outline, and sometimes of a spindle, sometimes a 

 barrel, and sometimes an oval shape. The human bacilli, on the 

 other hand, are prone to take an elongate form under artificial 

 cultivation. . 



Staining. — The bovine baciUus usually stains homogeneously; the 

 human bacillus commonly shows the so-called "beaded appearance." 



Vegetation. — The human bacillus grows upon dogs' serum much 

 more luxuriantly and rapidly than the bovine bacillus. 



Metabolic Products. — Smithf observed that cultures of the two 

 organisms in glycerin bouillon differ in the induced reaction of the 

 media. The cultures of the bovine bacillus tend toward neutrality, 

 those of the human bacillus toward acidity. 



Pathogenesis. — (a) Guinea-pigs. — The bovine bacilli are more 

 virulent than those of human tuberculosis, intraperitoneal inocula- 

 tion of the former producing death in adult animals in from seven 

 to sixteen days; of the latter, in from ten to thirty-eight days. Sub- 

 cutaneous inoculation of the bovine bacillus causes death in less 

 than fifty days; of the human bacillus, in from fifty to one hundred 

 days. 



(b) Rabbits. — ^Rabbits inoculated into the ear vein with the bovine 

 bacillus die in from seventeen to twenty-one days. Those receiving 

 human bacilli sometimes live several months. 



(c) Cattle. — 'Cows and heifers receiving intrapleural and intra- 

 abdominal injections of the human bacilli usually gain in weight and 

 show no symptoms. When examined postmortem, circumscribed 



* "Trans. Assoc. Amer. Phys.," 1896, xi, p. 75, and 189 

 of Experimental Medicine," 1898, in, 495. 



t "Trans. Assoc. Amer. Phys.," 1903, vol. xviii, p. 109. 



