YELLOW FEVER 289 



YELLOW FEVER. 



Organism discovered by Sanarelli probably the specific organism — 

 Morphological characters of Bacillus icieroides — Growth on media 

 — Diagnostic growth on agar— Pathogenicity for animals — Difficulty 

 of isolation— Secondary infections. 



This disease is endemic in the West Indies, Mexico and 

 the West African coast. Various organisms have been 

 described by different observers as the specific cause of this 

 disease. The method of conveyance of the disease is also 

 unknown. It was formerly regarded as akin to malaria, 

 but it has far more points of resemblance to cholera in its 

 etiology. In the year 1892 Sternberg suggested the em- 

 ployment of the blood serum of convalescent patients as a 

 means of conferring immunity on persons about to proceed 

 to districts where the disease is prevalent. 



Sanarelli has recently announced to the University of 

 Monte Video the discovery of an organism which he has 

 called the Bacillus icteroides, which he believes to be the 

 specific organism of yellow fever. The organism is small, 

 with rounded ends, and is often seen united in pairs. It 

 develops on most of the ordinary media, the growth on 

 agar being characteristic, according to the temperature of 

 growth. It does not liquefy gelatine. In beef bouillon 

 the bacillus grows quickly, without forming either pellicles 

 or deposits. On solidified blood serum it grows in an 

 almost imperceptible manner. Cultures on agar-agar 

 represent for the Bacillus icteroides a means of diagnosis 

 of the first order, but the demonstration by this means 

 of diagnosis is eflScacious only under certain determined 

 conditions. 



When the colonies on agar grow in the incubator, they 

 present an appearance that does not differ from that of the 



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