' CHAPTER XXXIV 



BACILLI OF THE COLON-TYPHOID-DYSENTERY GROUP (Continued} 

 BACILLARY DYSENTERY AND THE DYSENTERY BACILLI 



ALTHOUGH acute dysentery has been an extremely prevalent disease, 

 occurring almost annually in epidemic form in some of the Eastern coun- 

 tries and appearing sporadically all over the world, its etiology was 

 obscure until 1898 when Shiga 1 described a bacillus which he isolated 

 from the stools of patients suffering from this disease in Japan, and 

 established with scientific accuracy its etiological significance. Since the 

 discovery of Shiga's bacillus a number of other bacilli have been 

 described by various workers, all of which, while showing slight biological 

 differences from Shiga's microorganism, are sufficiently similar to it 

 culturally and pathogenically -to warrant their being classified together 

 with it in a definite group under the heading of the " dysentery bacilli." 



The manner in which Shiga made his discovery furnishes an instruct- 

 ive example of the successful application of modern bacteriological 

 methods of etiological investigation. Many workers preceding Shiga 

 had attempted to throw light upon this subject by isolations of bacilli 

 from dysenteric stools, and by extensive animal inoculation. Shiga, 

 following a suggestion made by Kitasato, approached the problem by 

 searching for a microorganism in the stools of dysentery patients which 

 would specifically agg r utinate with the serum of these patients. His 

 labors were crowned with success in that he found, in thirty-six cases, 

 one and the same microorganism which showed uniform serum agglu- 

 tinations. Further, he found that this bacillus was not present in the 

 dejecta of patients suffering from other diseases nor in those of normal 

 men, and that when tested against the blood serum of such people it 

 was not agglutinated. 



Description of Shiga's Bacillus. Shiga's bacillus is a short rod, rounded 

 at the ends, morphologically very similar to the typhoid bacillus, and, like it, 

 inclined to involution forms. The organism generally occurs singly, more sel- 

 dom in pairs. It is decolorized by Gram's method of staining. With the 



1 Shiga, Cent. f. Bakt., xxiii, 1898; ibid., xxiv, 1898; Deut. med. Woch., xliii, 

 xliv, and xlv, 1901. 



700 



