文献中提到,不同蚤种形成菌栓的频率是在蚤与微生物共同进化的长期过程中所形成的。本文叙述了跳蚤同鼠疫菌长期接触影响媒介传染活性的某些指标。实验中采用了在两年半内只在染疫动物体上吸血的第19代Xenopsylla cheopis。以只在健康动物体上吸血的同样的蚤作为对照。未见实验组跳蚤对鼠疫菌传染的抗性有任何增高。 It is mentioned in the literature that the frequency of plug formation by different fleas is formed during the long-term evolution of fleas and microorganisms. This article describes some of the indicators of flea infection with long-term exposure to Yersinia pestis mediated vector activity. In the experiment, the 19th generation Xenopsylla cheopis, which only took blood on infected animals in two and a half years, was used. The same fleas sucking blood only on healthy animals were used as controls. No experimental group fleas infected with Y. pest resistance to any increase.