[Changes in the numbers of the causative agent of intestinal yersiniasis (Yersinia enterocolitica) in Xenopsylla cheopis (Aphaniptera) fleas in the process of blood digestion].

In infected fleas the agent of intestinal yersiniosis underwents a complex cycle of quantitative changes after each feeding. A species belonging of blood consumed greatly affected the dynamics of the agent abundance. The general peculiarity of the development of microbes in insects, which fed on various animals (white mice, Sirian hamsters, white rats and guinea pigs), is characterized by the decrease in the abundance of the agent during the first hours after feeding. This was followed by an active multiplication of microbes replaced by a new fall after which the abundance maintained on the level close to the initial one. A comparison of obtained results with the data on the digestion in fleas has shown that the phases of the primary dying off and depression of the agent falls within the intensive-decay of the food clot. The active multiplication proceeds at the end of digestion that may be promoted by the decrease in the fermentative activity and abundance of products of blood decay easily assimilated by microbes. The next fall in the agent's abundance and the absence of multiplication are associated with the exhaustion of the nutrient medium in the process of absorbtion and vital activity of microbes.