CHAPTER XXIX 



BACILLI OF THE COLON-TYPHOID-DYSENTERY GROUP 



(Continued) 



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 ' described a bacillus which he isolated 

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

 tablished with scientific accuracy its etiological significance. Since the 

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

 scribed 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 in- 

 structive example of the successful application of modern bacteriological 

 methods to 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 agglutinate 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 

 dejections 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. 



Morphology. Shiga's bacillus is a short rod, rounded at the ends, 



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

 xliv, and xlv, 1901. 



435 



