CHAPTER XLII 



ASIATIC CHOLERA AND THE CHOLERA ORGANISM 



{Spirillum cholera asiaticm, Comma Bacillus) 



The organism of Asiatic cholera was unknown until 1883. In this 

 year, Koch/ at the head of a commission established by the German 

 government to study the disease in Egypt and India, discovered the 

 " comma bacillus " in the defecations of patients, and satisfactorily de- 

 termined its etiological significance. 



Koch's investigations were carried out on a large number of cases 

 and many investigations have since then corroborated his results. 

 The numerous morphologically similar spirilla which were later found 

 in normal individuals and in connection with other conditions, have 

 been shown by accurate bacteriological methods to be closely related, 

 but not identical. 



Apart from the evidence of the constant association of the cholera 

 vibrio with the disease, the etiological relationship has been clearly 

 demonstrated by several accurately recorded accidental infections oc- 

 curring in bacteriological workers, and by the famous experiment of 

 Pettenkofer and Emmerich, who purposely drank water containing 

 cholera bacilli. Both observers became seriously ill with typical clini- 

 cal symptoms of cholera, and one of them narrowly escaped death. 



Morphology and Staining. — The vibrio or spirillum of cholera is a small 

 curved rod, varying from one to two micra in length. The degree of 

 curvature may vary from the slightly bent, comma-like form to a 

 more or less distinct spiral with one or two turns. The spirals do not 

 lie in the same plane, being arranged in corkscrew fashion in three 

 dimensions. The spirillum is actively motile and owes its mptility 

 to a single polar flagellum, best demonstrated by Van Ermengem's 

 flagella stain. Spores are not found. In young cultures the comma 

 shapes predominate, in older growths the longer forms are more nu- 

 merous. Strains which have been cultivated artificially for prolonged 



» Koch, Deut. med. Woch., 1883 and 1884. 



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