HEMORRHAGIC SEPTICEMIA GROUP 305 



Pathogenesis. Experimental Evidence. The organism readily 

 infects mice, rats, guinea-pigs, rabbits, dogs, cats, and monkeys, 

 when they are experimentally inoculated. The symptoms and 

 lesions produced are entirely typical of bubonic plague in man. 

 Accidental infection of man resulting in four cases of plague 

 occurred in a Vienna laboratory at a time when bubonic plague did 

 not exist elsewhere in Europe. The causal relationship of the 

 organism to the disease may be held to be fully established. 



Character of Disease and Lesions Produced. The disease in 

 experimental animals may be a rapidly fatal septicemia, or in 

 those animals which are somewhat resistant, as the rat, typical 

 buboes (enlarged and suppurating lymph-nodes) or abscesses 



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Fig. 124. Bacillus pestis, bacilli from a bubo (Giinther). 



in the spleen or liver are produced. The disease in man may be 

 of one of three types septicemic, usually rapidly fatal with the 

 organisms generally distributed through the blood and various 

 tissues of the body; the pneumonic, also rapidly fatal; and the 

 bubonic, the most common, in which the lymph-nodes are infected, 

 become enlarged, and ulcerate. The bubonic type is less fatal, 

 recovery taking place in a small percentage of cases. The sep- 

 ticemic type of the disease is often accompanied by extensive sub- 

 cutaneous hemorrhages, which gave the name " black death " 

 to the epidemics of mediaeval Europe. 



Immunity. No true toxin has been demonstrated for B. pestis, 

 although endotoxins have been shown to be present. Agglutinins 

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