[Effect of the digestive process on the survival of the plague agent in Xenopsylla gerbilli Minax fleas].

Hystological investigations of experimentally infected X. gerbilli minax have shown that at the early stages of the digestion, while in the intestine compact clots of non-digested blood, are preserved, proceeds the reproduction of the plague agent. With the decay of the alimentary clot it changes into the dying off of the microbe population and after the ceasing of digestion the accumulation of bacteria renews again. Simultaneously with the changes in the number of microbes their morphology varies. At the initial stage of blood digestion bacilli typical for the agent are dominant. With the decay of the alimentary clot they are replaced by ovoid and spheroid forms. After the ceasing of the digestion cycle the microbe mass is represented by small coccobacteria. During the decrease in the plague agent abundance bacteria are absent mostly often from the midgut and posterior parts of the alimentary canal. Most favourable conditions for their preservation exist in this period in the proventriculus and in adjoining to it oesophagus part.