[The effect of the vole subspecies of the plague microbe on the viability of Callopsylla caspia fleas].

When infected with cultures of plague microbe reared at 28 C the experimental fleas showed no reliable differences in the mortality as compared to control ones. By contrast, the infection with agent cultures reared at 37 C as well as the infection on agonizing white mice caused a statistically reliable increase in the mortality in insects of both sexes. In the groups of fleas infected on white mice the most intensive mortality was observed during the first 24 hours after the infectious feeding that, apparently, is connected with the effect of toxins present in the blood of agonizing animals.