[SPECIFIC FEATURES OF RELATIONSHIPS BETWEEN THE FRONTOPSYLLA LUCULENTA LUCULENTA (JORDAN ET ROTHSCHILD, 1923) FLEA AND THE PLAGUE PATHOGEN WITH DIFFERENT PLASMID COMPOSITION].

It was experimentally established that plague pathogen strains with different plasmid composition variously suppressed the viability of Frontopsylla luculenta luculenta fleas. Dead insects were most frequently observed among those infected with a virulent strain having the cryptic plasmid pTP33. The presence of the avirulent and apesticinogenic plasmid I-3480 in the fleas less deteriorated their state.

[The sensitivity of plague agent from Siberian natural focuses of disease to antibacterial preparations in vitro].

The comparative analysis was applied concerning antimicrobic action of different groups of antibacterial preparations on the plague agent strains isolated from Siberian natural focuses of disease. The analysis was applied to results obtained using such different methods as disco-diffusive technique, serial dilution and HiCOMB MIC test. It is established that freshly isolated cultures of Yersinia pestis have high sensitivity to antibacterial preparations of different groups.

[Host influence on the frequency of block formation in males and females of Citellophilus tesquorum altaicus Ioff, 1936 (Siphonaptera: Ceratophyllidae) and transmission the plague pathogen by these fleas].

Data obtained during feeding of Citellophilus tesquorum aitaicus Ioff, 1936 infested females and males (Siphonaptera: Ceratophyllidae), the main vectors of plague in Tuva natural plague locus, on the natural host and laboratory animal was analyzed. It was found that sexual differences in fleas depended on the type of the host. Females fed more actively on the longtailed ground Citellus undulatus than on white mouse.

[Interaction of plague microbe strains varying in plasmid composition with the fleas Xenopsylla cheopis (Roths. 1903)].

The interaction of two Yersinia pestis strains varying in plasmid composition with the fleas Xenopsylla cheopis was studied. The reference virulent strain I-2638 having four plasmids (pCad, pPst, pFra, and pTP 33) and its selected avirulent strain I-3480 that had lost the plasmids pCad and pPst formed a proventricular block in the fleas with equal frequency. There were no differences in the block-forming capacity of these strains among the infected females; however, the stock strain was more active in blocking the proventriculus in females in spring than was the mutant one.

[Gender differences in the transmission of plague pathogen by fleas (Siphonaptera)].

The data of a long-term study of the relationships of the plague pathogen with male and female fleas, the vectors of this infection in Siberian natural foci, were analyzed. Gender differences were established in the rate of block formation and vector activity of fleas. In female and male fleas, these indices depend on both the species-specific features of ectoparasites and the pro-feeders used in the experiments, the season of their performance, and keeping conditions.

[The formation of proventriculus block, alimentary activity and mortality of flea Amphipsylla primaris primaris infected with Yersinia pestis].

The results of experiments held in 1982-1983 in Tuva plague natural focus with flea Amphipsylla primaris primaris (Jordan et Rothschild, 1915) from natural populations, whish were inflected and fed on specific host--flat-headed vole (Alticola strelzovi), are analyzed. The initial infectivity of the insects in autumn was higher than in spring: 90 and 50 % respectively. Accumulation of the agent in aggregated form in the organism of A.

[Relationship of the flea Citellophilus tesquorum altaicus (Siphonaptera: Ceratophyllidae) with the plague agent].

Some aspects of relationships of the flea Citellophilus tesquorum altaicus and bacterium Yersinia pestis of two strains isolated from different parts of the Tuva natural plague focus were studied. Peculiarities of elimination and blood meal activity of fleas infected with two strains of the plague agent were not revealed. Differences in mortality and alimentary activity are considerably determined by the sex of insects.

[Differences between two populations of Citellophilus tesquorum altaicus from the Tuva natural focus of plague].

Citellophilus tesquorum altaicus fleas from two natural (Karginsky and Barlyksky) populations have been studied. There are differences between the fleas of these populations in susceptibility to plague microbe. The adaptability and abundance of the causative organism in the body are higher in the fleas of the Barlyksky population.

[Differences in the blocking of the proventriculus in male and female Xenopsylla cheopis (Siphonaptera: Pulicidae)].

Frequency of block formation was studied in Xenopsylla cheopis infected with the triptophan-dependent and the typical strains of Yersinia pestis from the Mountain-Altai natural plague focus. It was shown that the rate of blocked males in comparison with that of females was statistically higher. In experiments with the triptophan-dependent strain the frequency of blocking in males was 40.

[Methods of reducing the level of parasitic oscillations in the construction elements of ultrasonic therapy applicators].

The methods of reducing parasitic oscillations in hand-pieces for ultrasonic therapeutic probes are proposed. The set and the method for measuring these oscillations are described as well as some experimental results.