Current Status of the Natural Foci of Tick-Borne Diseases in the Stavropol Region

Background: Tick-borne diseases are a serious threat to the epidemiological safety of the population of the Stavropol Region, making up more than 70 per cent of all natural focal infectious diseases registered in this territory annually. A wide range of hosts contributes to high tick abundance, diversity of tick-borne pathogens, and maintenance of the natural foci. Objective: To assess the activity of natural foci of tick-borne infections in the Stavropol Region in 2016–2020. Materials and methods: We used notifications submitted by the Center for Hygiene and Epidemiology in the Stavropol Region to the Scientific and Methodological Center for Monitoring the Pathogens of Infectious and Parasitic Diseases of Pathogenicity Groups II–IV for the subjects of the North Caucasian and Southern Federal Districts and the results of an epizootological survey of the Stavropol territory by specialists of the Stavropol Plague Control Research Institute. Markers of the causative agents of tick-borne diseases were detected by ELISA and PCR methods. Data processing was carried out using Microsoft Excel 2010. Results: Active natural foci of Crimean-Congo hemorrhagic fever, Q fever, a group of tick-borne spotted fevers, Lyme disease, human granulocytic anaplasmosis, and human monocytic ehrlichiosis were established in the region in 2016–2020. Human cases of the Crimean-Congo hemorrhagic fever, Lyme borreliosis and Q fever were also registered annually. The abundance of infected ticks in resort towns of the Caucasian Mineral Waters is of particular concern. Conclusion: We established up-to-date epizootic and epidemic manifestations of tick-borne infections in the Stavropol Region in the modern period, which are an important link in epidemiological surveillance and the basis for improving preventive measures

Results of epizootic monitoring of natural foci of particularly dangerous infections common to humans and animals in Rostov Oblast

Objective: To analyze the results of epizootic monitoring of natural foci of particularly dangerous infections common to humans and animals in Rostov Oblast to establish their activity.Materials and Methods: The data of epizootic monitoring conducted by zoologists; the results of laboratory research of field material obtained in natural foci of infectious diseases. Descriptive, zoological, genetic, serological methods, and retrospective epidemiological analysis were used.Results: The results of the conducted epizootic monitoring showed the presence in Rostov Oblast of natural foci of particularly dangerous infectious diseases common to humans and animals. While the natural focus of the plague is in a depressed state and does not show activity, in the foci of tularemia, West Nile fever (WNF), Crimean hemorrhagic fever (CHF), ixodic tick-borne borreliosis (ITB), hemorrhagic fever with renal syndrome (HFRS), Q fever, Batai fever, California serogroups, Syndbis revealed the antigens of these pathogens in biological material obtained from small mammals and blood-sucking insects, which indicates the epizootic activity of these foci. In the natural foci of WNF, CHF, ITB, HFRS, cases of these disease among the population were recorded, which confirms the epidemic activity of these foci.Conclusion: The obtained results of epizootic monitoring over the period from 2008 to 2020 emphasize the relevance and necessity of continuing these studies in natural foci in Rostov Oblast.

Current epidemiological situation on leptospirosis in the territories adjacent to Lake Baikal

Background. In presence the epizootiological situation on leptospirosis in the territories adjacent to Lake Baikal is not studied well. The showing up of natural focus, discovering of host animal’s species composition and etiological structure of leptospirosis causative agents are essential to plan any epidemiological response and to organize the specific prophylaxis.Aim: to analyze contemporary characteristics of leptospirosis natural foci at the territories adjacent to Lake Baikal.Materials and methods. From 2011 till 2020 the territory of nine Irkutsk Region's administrative districts was investigated. Trapping has been done at four kind of sites (wetland, meadow, forest-shrub, steppificated meadow) and boroughs. 1152 small mammals which belonged to 35 species were collected. Collected samples were studied by complex of methods. Serogroup belonging was detected by micro agglutination and decomposition test, and genomic species – by Microflex LT mass analyzer.Results. A leptospirosis natural foci in the Irkutsk city boundary was newly founded and there were isolated (from small mammals) four pathogenic cultures of leptospiras belonging to Javanica serogroup. Main hosts of causative agents at the territories adjacent to Lake Baikal were defined (insect-eating mammals: tundra shrew, largetoothed Siberian shrew, even-toothed shrew, shrew-mouse, and rodents: root vole, ground vole, narrow-skulled vole, sewer rat). By micro agglutination were defined pathogenic leptospirosis serogroups (Icterohaemorrhagiae, Grippotyphosa, Javanica, Pomona, Sejroe, Autumnalis, Australis), all over 2.4 ± 0.45 % seropositive. Antibody dilution at survey animals ranged from 1 : 20 to 1 : 640. On the grounds of PCR results the mean value of infected animals in studied sample was 16.4 ± 1.14 %. Positive PCR findings were at 19 from 35 animal species.Conclusion. At the territories adjacent to Lake Baikal In the Baikal region, the proportion of animals that have had contact with pathogenic leptospira is quite high. Natural focus of this infection are highly pervasive in this region, they are evolved mainly in dewy sites.

Biological Properties and Genetic Characteristics of Francisella tularensis Strains Isolated in the Territory of the Rostov Region in 2020

Objective of the study was to investigate biological properties and genetic characteristics of tularemia agent strains isolated from natural foci of the Rostov Region in 2020.Materials and methods. Field material from natural foci of the Rostov Region was examined by serological, bacteriological, biological, and molecular-genetic methods. Cultural-morphological, biochemical, antigenic and pathogenic properties of isolated cultures were studied. Protein profles were obtained through MALDI-TOF MS using mass spectrometer Autoflex speed III Bruker Daltonics and Flex Control of Biotyper software. The genetic characteristics of the strains were determined by VNTR and INDEL typing and SNP analysis.Results and discussion. Six strains of tularemia pathogen were isolated from mouse-like rodents using biological method. The investigation of their biological features and data of PCR analysis and INDEL typing with canonical markers showed that all strains are typical representatives of the Francisella tularensis subsp. holarctica biovar EryR. VNTR typing by six genetic loci revealed that all strains belong to four individual genotypes. The strain isolated in 2020 in the Salsky district was identical to the strain which was isolated in the same area in 1989. Based on the whole genome sequencing of two strains, we established that they are closest to the cultures isolated in Turkey (2009, 2012) and Khanty-Mansiysk (2013) by the studied set of SNP markers. Thus, we found that both identical (or closely related) clones of the tularemia agent and new strains with unique genotypes which previously were not described for the Rostov Region can circulate in natural foci of this region for a long period of time.

Qualitative assessment of the impact of some anthropogenic factors on natural foci of tularemia in the Rostov agglomeration

AIM: To qualitatively assess the impact of some anthropogenic factors (construction of industrial facilities, transport networks, intensification of agriculture) on natural foci of tularemia in the Rostov agglomeration. MATERIALS AND METHODS: The official data and reports of the Federal State Budgetary Institution Rosselkhoznadzor, the data of the Department of Rospotrebnadzor for the Rostov region, the Federal State Budgetary Institution Center of Hygiene and Epidemiology in the Rostov Region of Rospotrebnadzor were analyzed. Zoological and parasitological studies were carried out in accordance with modern regulatory documents in force. The detection of F. tularensis markers in field samples was carried out using serological and molecular genetic methods. RESULTS: It was found that the existing territories under natural protection of the Russian agglomeration restrict degradation processes, while maintaining the simultaneous coexistence of native species and synanthropic animals that make up the parasitic circulation system of the tularemia pathogen. CONCLUSION: The qualitative assessment of anthropogenic pressure/action can probably be interpreted as conditionally neutral. This could lead to potential risks of infection of the unvaccinated population of the Rostov agglomeration in natural foci of tularemia. The dynamism of the processes of anthropogenic action requires constant monitoring of the changes in the species diversity of carriers and vectors, their abundance, and infection in the natural foci of tularemia in the Rostov agglomeration.

Gene-specific features of tick-borne borreliosis in Russia

Aim. To study the gene-specific composition of Borrelia spp. in ixodid ticks inhabiting the foci of ixodid tick-borne borreliosis (ITBB) in the south of Western Siberia.Materials and Methods. The gene-specific composition of Borrelia spp. in ixodid ticks was determined by inoculation on a BSK-H nutrient medium, real-time polymerase chain reaction, and sequencing (1148 specimens of ixodid ticks collected from vegetation and 2183 specimens withdrawn from humans).Results. Infection of ticks with borrelia ranged from 22.4% in the Altai Republic to 56.9% in the Novosibirsk Region. There were no significant differences in the levels of Borrelia infection between two major ixodides, I. persulcatus and I. pavlovskiy (average infection levels 40.0% and 38.8%, respectively). At least five gene species of pathogenic Borrelia (B. garinii, B. afzelii, B. bavariensis, B. miyamotoi, and B. spielmanii) have been identified. The GenBank database contains 45 nucleotide sequences of the intergenic spacer rrf (5S)-rrl (23S). Prevalence of gene species B. garinii and B. afzelii in different ticks (I. persulcatus and I. pavlovskiy) did not differ significantly, yet B. garinii was found to be more frequent than B. afzelii. The frequency of infection of I. persulcatus ticks with B. miyamotoi was significantly (3.5-fold) as compared to those of B. garinii and B. afzelii. In D. reticulatus ticks, the DNA of B. spielmanii and B. miyamotoi was detected.Conclusion. It is necessary to continue studies to assess the role of the meadow ticks D. reticulatus in the circulation of different Borrelia spp. in various natural foci within the Russian Federation.

Biological properties and phylogenetic relationships of tick-borne encephalitis virus (Flaviviridae, Flavivirus) isolates of siberian subtype isolated in the south of East siberia in modern period

Introduction. Tick-borne encephalitis virus (TBEV) is medically most important representative of the same-name serogroup of genus Flavivirus (Flaviviridae). In the view of various researchers there are 3 to 5 TBEV subtypes, of them siberian being the most prevalent. The aim of the work is to compare the biological properties and to reveal phylogenetic relationships of large group of modern (2006–2019) TBEV isolates of siberian subtype from natural foci in southern East Siberia.Material and methods. Ixodid ticks (Ixodidae) and small mammals (Mammalia) from tick-borne encephalitis (TBE) natural foci in Irkutsk Region, Republic of Buryatia and Republic of Tuva, as well as specimens from TBE patients, were examined for TBEV markers using enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR). Virus was isolated from suspensions with positive result, and its pathogenicity for white mice (Mus) (WM) was studied by different inoculation ways. Analysis of the nucleotide sequences of E gene was performed for isolates at 1st passage. Phylogenetic tree was constructed using MEGA X program.Results. The phylogenetic analysis has shown that TBEV of siberian subtype that circulates in natural foci of the studied territory belong to two genetic lines. These lines are «Vasilchenko» and «Zausaev» with a strong predominance of the first. The differences in biological properties between the two groups of strains have been demonstrated. Most of the strains from both groups showed high virulence for WM both after intracerebral and subcutaneous inoculation. Only four strains demonstrated the reduced ability to overcome the blood-brain barrier. However, the analysis of the E protein coding sequences revealed evident correlation between phylogenetic clustering and geographical origin of isolates, but not with TBE host or pathogenicity for WM.Conclusion. Further search for TBE genome regions associated with pathogenicity require the analysis of complete genome sequences of representative group of strains with different biological properties.

О находках Rhipicephalus (Boophilus) annulatus (Say, 1821) (Acari, Ixodidae) на западе Атырауской области

Blood-sucking ticks are vectors of protozoal, bacterial, viral and rickettsial diseases. The study of ixodes ticks: fauna, ecology, biology is of great importance not only for epidemiology but is also of scientific interest. Changes in natural and climatic conditions, hydrological regime, rapid development of human economic activities lead to the changes in the fauna of invertebrates including ixodid ticks. As they invade new territories ticks may expand their habitats for these dangerous for animals and humans infections. That is why the study of tick fauna, changes in species diversity of ticks and monitoring of their abundance is so important for monitoring of natural foci. The emergence of a new species of ixodid tick Rhipicephalus annulatus, in western Kazakhstan, which began to be registered from 2019 in Kurmangazy district of Atyrau region, bordering the Astrakhan region of the Russian Federation and its re-finding in 2020 is a very important fact to assess the epidemiological danger for humans and animals in this territory.

Analysis of laboratory methods for monitoring of tick-borne encephalitis natural foci

Introduction. Ixodid ticks simultaneously are hosts and vectors of tick-borne encephalitis virus (TBEV), presenting a high risk to humans. Monitoring of the vectors part of TBEV population is usually held by means of express analysis methods (ELISA and PCR), but only isolation and identification of infectious virus is reliable evidence of TBEV circulation in the natural foci. Objectives — to demonstrate the TBEV infection rates of Ixodid ticks from natural TBE foci of Baikal Region, based on comprehensive study, including ELISA, PCR and isolation of virus on laboratory mice (LM) model. Methods. Questing adult Ixodid ticks (n = 20 111, mainly — Ixodes persulcatus Schulze, 1930), were collected in TBE natural foci of Baikal Region during 2013–2020. The suspension on saline solution was prepared from the each tick and analyzed by ELISA first. The samples with positive ELISA results were verified in PCR-RT. Furthermore, randomly selected samples with negative ELISA results were analyzed by PCR. Suspensions with positive ELISA and PCR results have been inoculated to suckling LM intracerebrally. Results. The samples with positive PCR results have been divided into two groups: group 1 — all suspensions with positive ELISA results, group 2 — randomly selected samples with negative ELISA results. The positive PCR results in group 1 made up 70.5 % with average Ct rate 24.9. The positive PCR results in group 2 have been obtained in 2.2 % of cases with average Ct rate 30.7. The isolation on LM model was more successful in group 1 (25.8 vs 13.0 %; р < 0.01; df = 69). Conclusion. ELISA is more useful for study of large amounts of ticks during monitoring of natural TBE foci, offering insight into the epidemically important vectors rate. To get the more full assessment of the ticks’ infection rate one must use ELISA and PCR simultaneously, and sum the results into general rate. For high strains isolation results the LM should be inoculated with the suspensions, which had shown positive both ELISA and PCR results.

Transmissible tick-borne infections in the south of the Far East

Natural foci of tick-borne infections associated with tick-borne encephalitis virus (TBEV), borrelia (Borrelia burgdorferi sensu lato), including Borrelia miyamotoi, anaplasma, ehrlichia and rickettsia are widespread in the Primorsky Krai. The carriers of these pathogens are ixodid ticks. The population of Primorsky Krai meets with ticks in natural biotopes, as well as in anthropurgic foci. The aim of the study is to give a comparative assessment of the epizootic activity in the natural foci of transmissible tick-borne infections in the south of Primorsky Krai in the epidemic seasons of 2017–2020. In this periodixodid ticks (3778 samples), taken from humans in natural foci in the Primorsky Territory, were studied. The TBEV antigen was determined by enzyme-linked immunosorbent assay (ELISA), genetic markers of pathogens were detected by real-time polymerase chain reaction (RT-PCR). The incidence of tick-borne infections has been analyzed. Based on the results of monitoring the infection of ixodid ticks, we found that 26.9 % of the studied samples were infected with various pathogens of tick-borne infections. Low infection rate of TBEV in ixodid ticks and high infection with pathogens of a bacterial nature were established. TBEV antigen was detected in 30 cases (1.4 %), TBEV RNA was detected in 20 cases (0.7 %), Borrelia burgdorferis. l. DNA — in 820 cases (30.7 %), ehrlichia — in 64 (2.4 %), anaplasma — in 55 (2.1 %).Genetic marker of Rickettsia spp. was detected in 3 cases (0.9 %) out of 322 examined ixodid ticks, B. miyamotoi — in 26 cases (6.9 %) out of 373 examined samples. A positive correlation was noted between the incidence rates and the cases of detection of TBEV and Lyme borreliosis in ticks. The results obtained indicate the need for annual epidemiological monitoring of infections transmitted by ixodid ticks, to determine the real epidemic situation and the activity of the functioning natural foci transmissible tick-borne infections on the territory of Primorsky Krai.