FEATURES OF YERSINIA PESTIS BIOFILM FORMATION IN CITELLOPHILUS TESOUORUM ALTAICUS FLEA

Data of the experimental investigation, using typical for the focus virulent Yersinia pestis subsp. pestis strains were analyzed to detect special features of a plague microbe biofilm formation (conglomerates, «blocks») in the main plague carrier, Citellophilus tesquorum altaicus fleas, in Tuva natural focus. It was established that biofilm (bacterial «blocks») played the important role both in plague transmission, by fleas and also in the agent preservation, by these insects. Results of the analysis indicated the prevailing significance of C. tesquorum. altaicus females in plague agent preservation and. explained some mechanisms of its survival in fleas during a cold season in Tuva natural plague focus. Under adverse conditions during the autumn period Y. pestis biofilms («blocks») accumulate mainly in a digestive tract of the main carrier females and. so can survive in fleas for a long time

Plague Microbe Aggregation in the Organism of Fleas (Siphonaptera) with Different Vector Ability

The following factors have been used to characterize 12 species and subspecies of fleas (Siphonaptera) and plague microbe (Yersinia pestis subs. pestis): the proportion of fleas with “blocks”, “blockules” and their ratio, called the index of microbe aggregation. The block formation is registered in 10, whereas formation of blockules are registered in all of the studied species and subspecies of Siphonaptera , the difference between active and passive transmitters according to the last characteristics being unreliable. The fleas, among of which “blocked” ones are not revealed in the experiments, are capable to transmit the causative agent of plague, sometimes with generalization of infectious process in animals, that can provide for continuous transmission of microbe without formation of “blocks” in the proventriculus. Thus, the high value of “rate of block formation” does not reflect the existence of coevolution in the interactions between microbe and its transmitter

Species Determined Peculiarities of the Tick-Man Contacts in the South of the Primorsky Territory

Ticks’ ability to attack man (aggressiveness) is an important characteristic impacting the ticks’ epidemiological role. Objective of the study is to assess the aggressiveness of the ticks inhabiting the south of the Primorsky Territory. It is based on the materials collected in the territory of Partizansky Region in 2012-2013. Ticks’ aggressiveness toward man has been defined by comparing the species’ community structure when collecting imago specimens on a cloth from plants (3,944 specimens are examined) and when removing ticks from people (437). In total, five species are identified: Ixodes persulcatus , Haemaphysalis concinna , H. japonica douglasi, Dermacentor silvarum (being dominant species), and I. pavlovskyi (which is rarely found in Partizansky Region) . Cases of tick attacks have been registered during April through October and November: this period being the peak of activity in I. persulcatus , and activity decay in H. concinna. The percentage of I. persulcatus against the total number of ticks, removed from people, has amounted to 86.3 %; the percentage of the same species collected from plants has amounted to 44.9 %. This is maximum index of aggressiveness. I. pavlovskyi also shows high level of aggressiveness, but as it is of rare occurrence it does not have any epidemiological weight in Partizansky Region. H. japonica attacks more often than H. concinna. In order to assess the difference in the epidemiological significance of these two species individual infection rate should be studied. As for D. silvarum, the percentage of this species removed from people is lower than that collected from plants, thus currently the epidemiological significance of this species in the south of Primorsky Territory is relatively low

Різання пластин з твердих та надтвердих матеріалів струминними методами

Проілюстрована можливість використання багатопрохідної обробки для отримання складнопрофільних високоякісних крайок у заготовках із твердих сплавів та надтвердих матеріалів із використанням багато прохідного різання, яка веде до значного зниження відхилень від правильної геометричної форми. Встановлено, що зменшення швидкості обходу контуру має бути пропорційним товщині оброблюваного матеріалу та його фізико-механічним властивостями.The paper deals with cutting workpieces of Carbide and Superhard Materials Chip by the abrasive water jet of small diameter, give are some aspects of the stress state of the material under the action of the jet. It is shown that cutting superhard materials multi pass processing leads to an increase in the width of the cut and the emergence of some spatial errors. To improve the accuracy of performance slots, edges, holes in the slab is proposed to use a functional approach, based on the partition of the process into separate stages and to find appropriate methods of their execution. Thus, the change in the angle and speed of leakage bypass circuit can significantly improve the accuracy of processing. Found that the decrease in speed around the contour should be proportional to the thickness of the processed material and its physical and mechanical characteristics.Показана возможность использования многопроходной обработки для получения сложнопрофильных высококачественных кромок в заготовках из твердых сплавов и сверхтвердых материалов с использованием многопроходного резания, что приводит к значительному снижению отклонений от правильной геометрической формы. Установлено, что уменьшение скорости обхода контура должно быть пропорционально толщине обрабатываемого материала и его физико-механическим характеристикам

Display of variability of bilateral features in taiga ticks in contrast conditions of habitation

The current research is aimed at studying the changes in a ratio of symmetrical to asymmetrical forms based on the counting bilateral characters in Ixodes persulcatus samples in various living conditions. Phenotypic variation was described with the following indices: (of) for a dispersion of the number of bristles at the left and right side; (Sa) for actual and (St) for theoretical number of symmetrical specimens with the supposition of an independent manifestation of such characters at the both sides of a body; and the difference between Sa and St. 4 bilateral characters were studied on the coxae of the fourth leg of the ticks collected by dragging off the plants outside Irkutsk (299 specimens) and Bratsk (156 specimens). The both territories are characterized by an excess of Sa and St. The σd2 value was proved to be higher among the ticks outside Bratsk where they live in a difficult environment. Given that no differences were revealed in the average values of «Sa-St» index, being characteristic of a subdivision of samples, the observed difference in of values may be considered as a prove of an increased instability during ontogeny under adverse circumstances

Dynamics of the Epidemic Process of Tick-Borne Encephalitis in Irkutsk Region in 2001–2021

The aim of this work was to analyze the spatial and temporal features of the epidemic process dynamics of tick-borne encephalitis (TBE) in Irkutsk Region in 2001–2021.Materials and methods. The data of the Rospotrebnadzor Administration for the Irkutsk Region, the Reference Center of the Irkutsk Research Anti-Plague Institute, the materials of the state statistical reporting form No. 2 “Information on infectious and parasitic diseases”, and scientific publications were analyzed. The chronological and chorological features of the change in the incidence of TVE have been traced. In the latter case, the administrative-territorial formations (ATF) of the subject were differentiated by epidemiological risk groups over two ten-year periods: 2001–2010 and 2011–2020. At each time interval, the grouping of areas according to the level of TBE incidence was carried out using the calculation of 95% confidence interval. Time sequences of observations were analyzed using the construction of regression equations. Standard methods of variation statistics in the Microsoft Excel were deployed.Results and discussion. Over the course of the 21st century, the incidence of TBE in Irkutsk Region has been declining. Based on 2001–2010 data, there were no cases of TBE in six ATF, and endemic areas were divided into three groups: with low (15 districts), medium (6) and high (8) incidence of TBE. A separate assessment of morbidity rates was conducted in the administrative center of the entity, the city of Irkutsk. In 2011–2020, the structure of ATF with varying epidemiological risk of TBE underwent a change. Six non-endemic areas, groups of low (12 ATFs), medium (9), high (6) and very high (2) epidemiological risk were identified. The spatial arrangement of high epidemiological risk zones changed, and their area increased. Each ATF cluster with different TBE incidence in 2011–2020 is characterized by the number of TBE cases and the volume of measures to prevent the infection. It is concluded that preventive measures were insufficient in ATF groups of high and very high epidemiological risk

Genetic heterogeneity of <i>Rickettsia helvetica</i> population

Background. To date, the genetic variability of Rickettsia helvetica has not been sufficiently studied.The aim. To study the prevalence and genetic variability of R. helvetica in Ixodes spp. collected in Western Siberia and the Russian Far East.Materials and methods. Ixodes  spp. collected from rodents in the Omsk province, Western Siberia (n = 280) and collected by flagging on Putyatin and Russky Islands in Primorsky Krai, Russian Far East (n = 482) were analyzed for the presence of Rickettsia spp. All positive samples were genotyped for the gltA gene fragment. For a number of R. helvetica samples, fragments of the 16S rRNA, ompA, ompB, sca4, htrA, and groEL genes and 23S–5S intergenic spacer were additionally sequenced.Results. Four Rickettsia species (R. helvetica, “Candidatus Rickettsia tarasevichiae”, “Candidatus Rickettsia uralica”, and “Candidatus Rickettsia mendelii”) were found. Of them, R. helvetica was identified in 72.2 % of Ixodes apronophorus and 18.8 % of  Ixodes trianguliceps from the Omsk province and in single Ixodes persulcatus from the Omsk province and Putyatin Island. This is the first finding of Rickettsia spp. in I. apronophorus. All known R. helvetica sequences from this study and the GenBank database belonged to four well supported monopheletic groups forming genetic lineages I–IV. Lineage I included European isolates from Ixodes ricinus, Western Siberian isolates from I. persulcatus, and some sequences from I. apronophorus. All R. helvetica sequences from I. trianguliceps from the Omsk province and I. persulcatus from  the  Komi Republic and one sequence from I.  apronophorus were assigned to  lineage  II. Most sequences from I.  apronophorus formed lineage  III; all known R. helvetica sequences from I. persulcatus from the Far East formed genetic lineage IV.Conclusion. The genetic heterogeneity of R. helvetica population was first demonstrated. Known isolates of R. helvetica are reliably assigned to four genetic lineages, but not in all cases the association of different lineages with a specific tick species or specific territory was observed

Differentiation of Transbaikal Territory by Tick-Borne Viral Encephalitis Incidence

Objective of the study was to differentiate the Administrative Districts of theTransbaikalTerritory at the time of Tick-borne viral encephalitis (TBVE) incidence recession by epidemiological risk groups and to characterize them by volume of specific and nonspecific preventive measures.Materials and methods. Retrospective analysis of TBVE epidemiological situation is based on the statistical reporting data “Information on infectious and parasitic diseases” in 2009–2019 and other materials of the Rospotrebnadzor Administration in the Transbaikal Territory. The clustering of areas with various levels of epidemiological risk was conducted by calculation of 95 % confidential interval for long-term annual average of TBVE cases in municipal units of the Territory over a decade and assessment of appurtenance of the deviating values to the aggregate under study.Results and discussion. Twenty four out of 32 districts of the Transbaikal Territory are endemic for TBVE. These areas are divided into five groups: with very high epidemiological risk (2 districts), high (5), medium (8), and low (8) risk respectively, as well as the administrative center of the constituent entity which by the whole complex of indicators (disease manifestation, population density, factors of targeted TBVE decrease, social-and-living and economical conditions) cannot be considered together with the rest of municipalities. Each group of the districts was characterized by the number of cases and TBVE incidence rates, medical aid seeking by persons who suffered from tick bites, vaccination volumes, seroprevention, areas of acaricide treatments. Recommendations are presented for the essential complex and scope of measures to prevent TBVE in the groups of administrative districts that differ by the level of epidemiological risk