[Seasonal features of the time course of changes in the aggregated state of the causative agent of plague in the organism of Citellophilus tesquorum altaicus (Siphonaptera)].
The data of experiments made in a Tuva natural plague focus with the main vector of the flea C. lesquorum altaicus during different seasons are analyzed. Ectoparasites were infected with the plague microbial strain typical for the focus and fed on natural nourishment, such as long-tailed sousliks. An analysis indicated that estimation of the parameter "the proportion of infected insects containing the causative agent at the aggregated state" is of greater informative value than is the recording of only sporadic gizzard "blocks". In experiments on fleas of a breeding of the current year, the conglomerates of the causative agent of plague were more frequently observed in males. All things being equal, the greatest efficiency of transmission of the microbe to the carriers of infection and the highest block formation in the fleas were observed in summer. The proportion of specimens with microbial conglomerates drastically increased in autumn during the preparation of the body of imagoes for hibernation. At this state, the microbe survived in the organism of a dormant carrier during winter. In spring, in the imagoes infected during the previous season, bacterial conglomerates were observed during the first feeds ten times more frequently than those in the insects of a breeding and infection of the current year.