Ixodid Tick-borne Borrelioses Research Articles

Epidemiological situation of natural focal infections in the Volgograd region in 2023

Objective: analysis of epizootiological and epidemiological aspects of natural focal infections, namely plague, tularemia, HFRS, West Nile fever, Crimean hemorrhagic fever, Ixodic tick-borne borreliosis, Cu fever, leptospirosis and rabies, in the Volgograd region over 10 months in 2023.Materials and methods: the article analyzes the epidemiological manifestations of natural focal infections (NFI) in the Volgograd region for 10 months of 2023. The work uses official statistical data from institutions of Rospotrebnadzor of the Volgograd region on NFI for 2023. The main research method is epidemiological analysis.Results: the numbers of small mammals, potential carriers of NFI, on the territory of the Volgograd region in the 2023 season were within the same indicators of the previous year (SIPY), while the number of ticks in the spring-summer period was higher than the SIPY, but in the fall the number of arthropods in stationary points was lower than in previous seasons. The number of mosquitoes carrying arbovirus infections exceeded the long-term average. When studying environmental objects for the presence of markers of NFI pathogens, a slight decrease in the proportion of positive samples was noted compared to SIPY for all nosological forms. Over the 10 months of this year, there has been a deterioration in the epidemiological situation in the Volgograd region for several infections compared to the same period in 2022. There were 18 cases of West Nile fever (WNF), 10 cases of ixodid tick-borne borreliosis (ITB), and 6 cases of hemorrhagic fever with renal syndrome (HFRS). No patients with plague, tularemia, rabies, leptospirosis, Crimean hemorrhagic fever (CHF) and Q fever were identified.Conclusion: the presence of natural foci of dangerous infectious diseases of varying degrees of activity on the territory of the Volgograd region requires constant monitoring and an adequate response to changes in the foci in order to prevent complications of the epidemiological situation due to NFI.

Multilocus sequence-typing scheme for <i>Borrelia miyamotoi</i> — the erythema-free ixodid tick-borne borreliosis pathogens

Introduction. Borrelia miyamotoi is a pathogen of erythema-free ixodid tick-borne borreliosis (ITBB), a disease widespread in Russia. To date, there are no generally accepted methods for B. miyamotoi genotyping. The multilocus sequencing typing (MLST) scheme of Borrelia was originally developed for B. burgdorferi, and does not have the required discrimination power for monitoring the ITBB pathogens.
 The objective of this study is to develop the MLST scheme for B. miyamotoi.
 Materials and Methods. The whole genome sequences of 10 reference strains (GenBank) were analyzed for the selection of the house-keeping loci. The MLST scheme development was based on principles published by the authors of the method. For this experiment, 81 B. miyamotoi strains and positive clinical samples were used to test the MLST scheme.
 Results. After analyzing the genomic data, 8 house-keeping loci were chosen for MLST, for which the PCR and sequencing primers were designed. Each MLST loci was represented by several alleles (from 4 to 7) which form 15 sequence types. The genetic diversity of pathogens isolated from ITBB patients and ticks were characterized.
 Discussion. Based on pairwise distances between allelic profiles, the sequence types can be classified into four groups. The first two groups are clonal complexes; the other two groups are formed by once identified sequence types. The first clonal complex unites 11 sequence types (80 or 88% of the characterized B. miyamotoi), the second consists of 2 sequence types (9 or 9.8%). The genetic differences between B. miyamotoi are associated with the sources of strains and biological isolates. The MLST based classification confirms the previously described genetic heterogeneity of B. miyamotoi populations associated with ecologically unrelated vectors of ITBB pathogens.
 Conclusion. The proposed MLST scheme is an appropriate tool for ITBB pathogen classification and evolutionary change characterization within clonal complexes.

ЗАБОЛЕВАЕМОСТЬ ИКСОДОВЫМ КЛЕЩЕВЫМ БОРРЕЛИОЗОМ У ЖИТЕЛЕЙ КРАСНОЯРСКОГО КРАЯ, ПЕРЕНЕСШИХ COVID-19

A retrospective epidemiological analysis of the incidence of natural focal zoonotic infections among the human population in the Krasnoyarsk Kray showed that the increase in the incidence of ixodid tick-borne borreliosis in 2022 could be caused by an increase in the number of people with post-acute COVID-19 syndrome, who probably have dysregulation of the immune response and increased sensitivity to various pathogens. There were no significant gender differences in infectious sensitivity to Borrelia in people who underwent COVID-19. At the same time, among people diagnosed with borreliosis, the proportion of women who have previously had COVID-19 is increased. The same happens with tick-borne encephalitis: a higher infectious sensitivity of women to the encephalitis virus is a statistically justified fact in people who have undergone COVID-19. Key words: COVID-19, ixodid tick-borne borreliosis, Krasnoyarsk Kray

Features of the immune response in early period of ixodid tick-borne borreliosis

Lyme borreliosis is a group of transmissible infectious diseases that are similar in etiology, but diverse in clinical manifestations. The development of Lyme disease symptoms is due not only to the activity of the pathogen itself, but also to the result of its interaction with immune system of macroorganism. The first line of defense, represented by a variety of cellular and humoral components of innate immunity, is most rapidly involved in immune response, and it is it that seeks to limit dissemination of the causative agent from the initial site of infection. However, a wide range of protective surface proteins of Borrelia and a number of other structures aimed at avoiding immune mechanisms prevent the destruction of the pathogen. Not the last place in this dynamic process is occupied by ixodid ticks themselves, since the secret of their salivary glands has an inhibitory effect on a number of cells and complement system. In parallel with innate immunity, adaptive immune response factors are activated, serving as a second line of defense. The synthesis of specific antibodies in the early period of Lyme disease has its own ambiguous features, but this does not exclude their importance in fight against borreliosis infection. To date, the issues of interaction with dendritic cells and cytotoxic T-lymphocytes remain less studied. Research of all aspects, including little-studied ones, is extremely important for both practical healthcare and fundamental medicine.

Immunoassay based on peroxidase silver conjugate for the determination of human immunoglobulins against tick‐borne borreliosis (lyme disease) by voltammetry and spectrophotometry

AbstractIn this work two strategies for the synthesis of peroxidase silver conjugates for the qualitative and quantitative determination of immunoglobulins (IgG) to ixodid tick‐borne borreliosis (ITBB) (Lyme disease) in human serum were proposed. The first approach for Ab‐HRP@AgNP conjugate synthesis involved silver nanoparticles (Ag NPs) capped with a commercial peroxidase conjugate (Ab‐HRP) by passive adsorption. The second strategy was based on the initial coupling of Ag NPs with human anti‐species antibodies (Ab) by passive adsorption followed by the introduction of horseradish peroxidase (HRP) enzyme into the reaction mixture as a blocking reagent for Ab@AgNP@HRP conjugate synthesis. The formation of peroxidase silver conjugates was proved by UV/Vis spectroscopy and Transmission Electron Microscopy (TEM). The catalytic activity of Ab‐HRP@AgNP and Ab@AgNP@HRP conjugates was evaluated by Michaelis‐Menten kinetics. A commercially available 96‐well microtiter plate with recombinant antigens to ITBB was used as a platform for immobilization of analyzed IgG. The HRP in Ab‐HRP@AgNP conjugate was found to retain a sufficient level of activity for interaction with the H2O2 substrate to form an intensely colored reaction product. Therefore Ab‐HRP@AgNP conjugate can be used in enzyme‐linked immunosorbent assay (ELISA) with spectrophotometric detection of 3,3’,5,5’‐Tetramethylbenzidine (TMB Ox) for quantitative determination of IgG to ITBB in human serum in the concentration range 12.5–800 ng ml−1 with LOD 2 ng ml−1. Ab@AgNP@HRP conjugate is recommended for the electrochemical determination of IgG to ITBB in human serum at LOD 3 ng ml−1 with registration of silver oxidation by linear sweep anodic stripping voltammetry (LSASV). Ag NPs in Ab‐HRP@AgNP and Ab@AgNP@HRP conjugates do not change electrochemical activity during storage and can be used as an electrochemical label in LSASV method in case of HRP inactivation. The immunoassay based on peroxidase silver conjugates expands the analytical potential for the determination of IgG to ITBB especially during the period of increasing incidence.

The Effect of COVID‑19 on the Incidence of Human Vector-Borne Infections Transmitted by Ixodid Ticks (Illustrated by the Example of Krasnoyarsk Territory)

In 2022, there was an increase in the incidence of tick-borne encephalitis (TBE) and ixodid tick-borne borreliosis (ITBB) in the subjects of the Russian Federation, federal districts and the country as a whole. At the same time, among people affected by ixodid ticks, the proportion of clinical forms of the diseases has increased. The aim of this study is to analyze the possible causes of the simultaneous increase in the incidence of vector-borne infections and the proportion of clinical forms among the people bitten by the ticks, using the materials on Krasnoyarsk Territory as an example. Materials and methods. We analyzed the incidence of TBE and ITBB among the people who have or haven’t had COVID‑19, the number of people affected by tick bites in 2021–2022 in Krasnoyarsk Territory. Statistical analysis is performed by standard methods of variational statistics using Excel. Results and discussion. It is shown that in the Krasnoyarsk Territory, with a decrease in the number of individuals affected by tick bites in 2022 as compared to 2021 (12216 and 13214, respectively), there was an increase in the number of cases of TBE (from 124 to 250) and ITBB (from 115 to 224), as well as the proportion of people who had clinical forms of the infections after tick bites. Among three possible explanations of the observed pattern, a decrease in the immune status of Krasnoyarsk residents who had had COVID‑19 before the contact with ticks is considered as the most likely one. Using statistical methods it was substantiated that among people with TBE and ITBB, the proportion of individuals who have had COVID‑19 is significantly higher than expected, based on the actual incidence of the Krasnoyarsk Territory population with a new coronavirus infection. Thus, COVID‑19 affects the incidence of vector-borne infections indirectly, through a change in the number of people contacts with natural stations, and directly, by changing the immune status.

Asthenic syndrome in the convalescents of ixodid tick-borne borrelioses

Aim to study the catamnesis of patients with ixodid tick-borne borreliosis in the period of convalescence who presented the signs of asthenic syndrome.
 Material and methods. The study was based on the data of prospective dispensary observation of 37 in-patients diagnosed with "ixodid tick-borne borreliosis, erythemic form, moderate severity, acute course" who received treatment at the Clinic of Infectious Diseases of the SamSMU in 2016-2019. The subjects were divided into 3 groups according to their age: the first age-group from 18 to 35 years included 12 people, the second group ranged from 36 to 55 years and included 15 people, the third age-group from 56 to 75 years consisted of 10 people. The examination of patients was carried out after discharge from the hospital on the 14th day, after 3, 12 and 36 months. The MFI-20 asthenia scale (the Multidimensional Fatigue Inventory) was used to analyze the asthenic syndrome in the participants.
 Results. The duration of asthenia after ixodid tick-borne borreliosis may be up to 3 years. Patients require the closest observation in the first 2 weeks of the convalescence period. Indicators of physical and psychological health in convalescents return to the norm depending on their age and place of residence. Mental asthenia prevails in people living in rural areas and persists much longer than in urban residents. Older people (from 56 to 75 years) are more susceptible to general and physical asthenia.

Lymphocyte enzymes as an indicator of immune response activity in ixodid tick-borne borreliosis

BACKGROUND: Acute ixodid tick-borne borreliosis tends to turn into a protracted and chronic course. This suggests studying the causes of the violation of the immune status of a sick person. The central structural unit of immunity is the lymphocyte. It is known that the formation of specific T-lymphocyte subpopulations is based on the central role of IL-2, leading to the restructuring of cellular metabolic pathways. The regulation of signaling pathways and lymphocyte metabolism primarily determines disease outcomes.
 AIM: This study determines the pathogenetic mechanisms of the infectious and inflammatory processes in the erythemal form of acute ixodid tick-borne borreliosis based on the study of the lymphocytic lysosomal enzyme activity, the level of IL-2, and the clinical disease manifestations.
 MATERIALS AND METHODS: The main group is represented by 609 patients hospitalized at the Krasnodar City Clinical Hospital from 2010 to 2019. The study group comprised 45 patients with an erythemal form of acute ixodid tick-borne borreliosis. In the dynamics of the disease, the level of IL-2 and the cytochemical activity of acid phosphatase and non-specific alpha naphthyl esterase of lymphocytes were determined.
 RESULTS: During the height of ixodid tick-borne borreliosis, a decrease in the cytochemical activity of hydrolytic enzymes of lymphocytes was noted compared with the control group. IL-2 levels had a high dispersion and were associated with clinical disease manifestations. A low level of IL-2 correlated with a decrease in the activity of alpha-naphthyl esterase lymphocytes. During the period of convalescence, there was a restoration of lymphocytic enzymatic activity and an increase in the number of cells with a pronounced activity of alpha-naphthyl esterase, typical of T-lymphocytes with killer activity.
 CONCLUSION: The hydrolytic enzymes of the lysosomes of acid phosphatase and alpha-naphthyl esterase lymphocytes enable judging the intensity of intracellular metabolic processes and, combined with clinical disease symptoms and IL-2 activity, are indicators of the state of the immune process, supplementing the results of traditional immunological studies in patients with the erythema form of acute ixodid tick-borne borreliosis. The predominance of enzymatically inactive forms of T-lymphocytes in the acute period of the disease reflects a specific deficiency of T-cell immunity.

Incidence and trends of ixodid tick-borne borreliosis and Siberian tick typhus in the Eastern Transbaikalia

Aim. To study the trends and to assess longterm incidence of ixodid tick-borne borreliosis (ITB) and Siberian tick typhus (STT) in Eastern Transbaikalia for the improvement of preventive measures.Materials and Methods. We carried out a retrospective analysis of ITB and STT incidence in different districts of the Eastern Transbaikalia during 2003–2021. Epidemic trends were characterised using linear regression equations.Results. Average annual incidence of ITB in 2003–2021 was 4 cases per 100,000 population. Analysis of two periods (2003–2012 and 2013– 2021) showed an increase in ITB incidence in 2013–2021 (5.1 ± 0.79 per 100,000 population) as compared to 2003–2012 (2.6 ± 0.73 per 100,000 population, p < 0.05). Within 2013–2021 period, there has been a statistically insignificant trend towards decreasing ITB incidence. The incidence of STT was lower than that of ITB and there was no statistically significant trend towards change of this scenario (average annual incidence in 2003– 2021 was 2.1 ± 0.37 per 100,000 population). Between 2012 and 2021, in particular before 2017, the incidence of STT reduced (average annual incidence in 2012–2021 was 1.5 ± 0.43 per 100,000 population). The epidemiological risk of ITB and STT varied across the distinct territories of Eastern Transbaikalia.Conclusion. In order to prevent the incidence of tick-borne diseases, acaricide treatments should be regularly carried out. Amounts of such interventions should be determined depending on the risk of human infection.

Allelic Variants of P66 Gene in Borrelia bavariensis Isolates from Patients with Ixodid Tick-Borne Borreliosis.

Protein P66 is one of the crucial virulence factors of Borrelia, inducing the production of specific antibodies in patients with ixodid tick-borne borreliosis (ITBB). Various species of Borrelia are characterized by genetic variability of the surface-exposed loop of P66. However, little is known about this variability in Borrelia bavariensis. Here we describe the variability of the nucleotide sequences of P66 gene locus in isolates of B. bavariensis. Analysis of nucleotide sequences of P66 in 27 isolates of B. bavariensis from ITBB patients revealed three allelic variants of this gene. The alignment score of amino acid sequences in the isolates showed amino acid replacements in various positions confirming the presence of three allelic variants. Two of them are characteristic only for some isolates of B. bavariensis of the Eurasian gene pool from various parts of the geographic ranges of B. bavariensis from various samples. At least three allelic variants of P66 B. bavariensis have been identified, which have different amino acid expression, occur with different frequency in ITBB patients and, presumably, can have different effects on the course of the infection.

Optimized multilocus sequence analysis for laboratory identification of pathogens of ixodid tick-borne borreliosis

Introduction. The most common etiological agents of ixodid tick-borne borreliosis (ITBB) in Russia are Borrelia garinii, B. afzelii, B. bavariensis. Multilocus sequence typing and multilocus sequence analysis (MLSA) have been used in recent studies for Borrelia species identification. The results of using the MLSA scheme for identification of pathogens causing erythemic forms of ITBB have been presented earlier.
 The purpose of the study was to explore the possibility of MLSA optimization for laboratory identification of ITBB pathogens. Objectives: comparative analysis of nucleotide sequences of 6 conserved genes (rrs, hbb, fla, groEL, recA, ospA) and the rrfA-rrlB intergenic spacer, which are recommended by the MLSA protocol; identification of the minimum set of genes, the concatenated sequences of which are essential for species identification of Borrelia isolates.
 Materials and methods. The sequences of the above loci of 23 reference isolates collected from patients with ITBB and assigned, using MLSA, to B. bavariensis were compared with the sequences of similar genes of other Borrelia species available in international databases. The UPGMA method was used to build and analyze dendrograms based on the obtained data.
 Results. The sequences of ospA gene loci of reference species demonstrated the greatest difference (not less than 8.5%) from the sequences of the above gene in other analyzed species of Borrelia; approximately similar species-related differences (not less than 6.7%) were demonstrated by the comparison of recA gene sequences. The sequences of the identified variants of these two genes in B. bavariensis differed from the sequences of the similar genes in the most closely related species B. garinii. The dendrogram of the concatenated nucleotide sequences of recA and ospA genes demonstrated that it was totally consistent with the results of identification of the isolates based on the MLSA protocol.
 Conclusion. The optimized approach to MLSA of the B. burgdorferi sensu lato group suggests that species identification should be based on the concatenated analysis of loci of only two genes (recA and ospA) out of 7 loci recommended by the MLSA protocol.

Study of natural foci of infections transmitted by ticks in the Republic of Tatarstan

The paper presents the history of tick-borne infections study, which was carried out at the Kazan Research Institute of Epidemiology and Microbiology, and an analysis of the current epidemiological situation of tick-borne infections in the Republic of Tatarstan. Tick-borne encephalitis was previously quite fully studied in the natural foci of the taiga zone of the USSR, but there was practically no information regarding the features of its distribution in the forest-steppe zone. The occurrence of a number of outbreaks of this disease in the territory of the Tatar ASSR and neighboring republics made research in this direction particularly relevant. Since 1955, the Kazan Research Institute of Epidemiology and Microbiology has begun work to identify and study natural foci of tick-borne encephalitis in the Middle Volga region. These studies have acquired the character of constant monitoring and are being systematically continued up to the present time. It was found that the main carriers of ixodid tick-borne borreliosis pathogens in Tatarstan are two types of ixodid ticks, the same as in viral tick-borne encephalitis. The similarity of the areas and basic patterns of the epidemiology of viral tick-borne encephalitis and borreliosis, as well as the possibility of the simultaneous circulation of the causative agents of these diseases (virus and borrelia) in the same ecosystem, has been revealed. Studies of the Kazan Research Institute of Epidemiology and Microbiology on the etiology, epidemiology and prevention of infections transmitted by ticks were carried out as part of long-term observations of the state of populations of various types of ixodid ticks in the physical and geographical regions of the Republic of Tatarstan, starting from the 50s of the XX century. This made it possible to trace changes in their spatial structure and assess their current epizootological significance. Landscape and epidemiological zoning of the republic's territories according to tick-borne infections has been carried out. Starting from 2012, new infections have been studied: monocytic ehrlichiosis and human granulocytic anaplasmosis.

Clinical variants of the non-erythema form of ixodid tick-borne borreliosis

The patients with the nonerythematous form of borreliosis (83 persons) were observed in the epidemic seasons of 19971999. The organ pathology often develops on the background of the general infections syndrome. The clinical variants of the early period are described: arthromyalgic, similar to influenza, regional lymphadenitis, neurologic, cardiovascular, hepatitis, mixed.

Multilocus Sequence Analysis of Isolates from Patients with the Erythemic Form of Ixodid Tick-Borne Borrelioses

Multilocus Sequence Analysis of Isolates from Patients with the Erythemic Form of Ixodid Tick-Borne Borrelioses

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.

Development and application of the technique for identification of Borrelia miyamotoi surface antigens

Introduction. Borrelia miyamotoi is a pathogen causing erythema-free ixodid tick-borne borreliosis (ITBB), a disease widespread in Russia. The genome of B. miyamotoi contains genes of multiple variable major proteins (Vmps). Vmps fall into two families — Vsps and Vlps (with subfamilies δ, γ, α and β). At a particular time, a single B. miyamotoi expresses only one variant of Vmp gene.The purpose of the work is to develop a technique for identification of the Vmp present at the expression site.Materials and methods. The technique is designed in the format of a real-time multiplex PCR. It was tested by using B. miyamotoi DNA samples extracted from blood collected from 172 ITBB patients and 109 ticks. The samples were collected in 14 regions of Russia.Results. The new technique made it possible to identify the expressed Vmp in 82% of the examined samples, thus having demonstrated its efficiency. Negative results were much less often observed with samples from patients than with samples from ticks. At the same time, the percentage of samples with one type of Vmp is identical for clinical samples and ticks, while the percentage of samples containing concurrently two types of Vmps is significantly higher among samples from patients with the most frequent occurrence of the Vlp-δ and Vsp combination.Discussion. The frequent occurrence of the combination of two Vmp types in the blood samples can indicate the concurrent presence of several subpopulations of B. miyamotoi in ITBB patients. A new antigenic Vmp variant is synthesized after protective antibodies have been produced for the major protein of the strain transmitted by a tick. This phenomenon known as immune evasion allows the pathogen to persist within a host.Conclusion. The developed technique of real-time multiplex PCR allows to simultaneous detect of several antigenic variants of the variable basic surface proteins of B. miyamotoi. The study of the antigenic spectrum of B. miyamotoi strains in comparison with the characteristics of conserved regions of the genome by the method of multilocus sequencing will clarify the stages of evolution and distribution of B. miyamotoi sensu lato.

Multilocus sequence analysis of isolates from patients with erythemic form of ixodid tick-borne borrelioses

Multilocus sequence analysis of isolates from patients with erythemic form of ixodid tick-borne borrelioses

Еpidemiological aspects of ixodid tick-borne borrelioses in Kemerovo region

Aim. To study the epidemiological patterns of Lyme disease in the Kemerovo Region. Materials and Methods. We performed a descriptive and retrospective epidemiological study of 3,133 cases to investigate the spread of Lyme disease in the Kemerovo Region during the recent 15 years (2005-2019). 1,000 ticks of the Ixodes genus were investigated for the presence of Borrelia burgdorferi senso lato s. l. and Borrelia miyamotoi DNA, while 98 patients with tick-borne fevers of unknown aetiology were examined to identify the DNA of the causative agents of ixodid tick-borne borrelioses and tick-borne recurrent fevers by PCR. Antibodies to Borrelia in the patient serum were detected by enzyme-linked immunosorbent assay. Results. In the structure of tick-borne infections over the study period, the proportion of ixodid tickborne borrelioses was 29.88% [95% CI = 27,25- 32,61]. The incidence demonstrated a 2,8-fold increase from 3.2200 / 0000 [95% CI = 3,20-4,57] in 2005 up to 9,2000 / 0000 [95% CI = 12,47-15,31] in 2019. Annually, around 30,000 people suffered from the tick attack. Bite rates ranged from 813.510 / 0000 [95% CI = 804,05-825,50] to 1506.100 / 0000 [95% CI = 1491,57-1520,02]. Two-thirds of the victims were attacked by ticks during the unorganized recreation in the forest, gathering wild plants and working in the garden plots. Lyme disease was characterised by a spring-summer seasonality with a maximum incidence in June. Rural population showed a higher level of ixodid tick-borne borrelioses incidence as compared to the urban population. In age groups, the maximum rates were recorded in the individuals over 40 years of age. Northern territories of the region showed the highest prevalence of ixodid tickborne borrelioses. In a study of 1000 ticks, DNA of Burgdorferi s. l. and B. miyamotoi was detected in 32.5% and 5.2%, respectively. In contrast, B. miyamotoi prevailed in patients with tick-borne fevers (13.26% of positive cases in comparison with 4.08% for B. Burgdorferi s. l. Tick-borne aetiology of the diseases was confirmed by the enzyme-linked immunosorbent assay measurements. Conclusions. Ixodid tick-borne borrelioses is prevalent in Kemerovo Region, demonstrating an upward and seasonal trend. Risk groups include rural population and those > 40 years of age. A high level of Ixodes persulcatus-mediated transmission of B. burgdorferi s. l. and B. miyamotoi infections was revealed; the latter agent often caused tick-borne fevers of unknown etiology

Human Infecting with Tick-Borne Diseases on the Territory of Irkutsk City: 25 Years of Survey

Background. The existence of antropogenic foci of Ixodid tick-borne infections (TBI) have been registered on the territory of many cities during several last decades. The infected ticks’ biting occurs directly in urban conditions. There is a lot of publications devoted to ticks and their hosts studying in the urbanized landscapes, but much less data concerning human infecting after tick bite in these conditions.Аim – the comparative analysis of the cases of human infecting with TBI within the city limits and beyond, and determination the sites of infection risk on the territory of Irkutsk.Material and methods. The epidemiological investigation cases records from Irkutsk Regional Center for Hygiene and Epidemiological Surveillance have been analyzed: tick-borne encephalitis (TBE, n = 1607), ixodid tick-borne borrelioses (ITBB, n = 938) dated 1995–2019 and tick-borne rickettsiosis (TBR. n = 270) dated 2001–2019. Statistical analysis was computed in Microsoft Excel Software. The map of infecting sites is made in ArcGis Soft (ESRI, USA).Results. According to the patients reports, 281 of all registered TBI cases during period under the review, occurred within the city limits. There were 115 TBE cases (7.2% of all TBE cases registered among Irkutsk citizens), 139 ITBB (14.8%) and 27 TBR (10.0%). 86.5% of the patients associate their disease with tick bite. There are no valid linear trends in the dynamics of TBE and ITBB from 2001 (with available information on all three infections) up to the end of period under the review, but significant growth trend in TBR incidence. The groups of patients, infected within and beyond the city limits, differ in some ecological and demographical parameters and also in structure of TBI morbidity. Tree area groups with different risk level for TBI contracting have been determined in the city.Conclusion. Judging by the fact that TBI occurs annually on the territory of the city, it is likely that there are perennial anthropogenic foci within its boundaries, which must be identified and studied all of their components.

Emerging Natural Focal Infectious Diseases in Russia: A Medical-Geographical Study.

In Russia, as in other countries, the problem of emerging natural focal infectious diseases (EIDs) became more acute toward the end of the 20th century. However, the situation in Russia is unknown to foreign readers, while the prevention and control of these diseases require international collaboration. The aim of the study is to provide a medical–geographical assessment of the distribution of the main natural focal EIDs in Russia, as well as to present the approaches used in the country to create aggregate maps of risk assessment. To consider its current status, we determined the most important natural focal EIDs for Russia (tick-borne encephalitis, ixodid tick-borne borrelioses, hemorrhagic fever with renal syndrome, Crimean–Congo hemorrhagic fever, West Nile fever, Astrakhan spotted fever, leptospiroses, and tularemia) and analyzed the patterns of their epidemic manifestation. As a result, a working classification of such infections and a series of maps showing the current situation of EID morbidity in Russia were created. To design an aggregated risk map, we developed an original mapping methodology and recalculated the model disease incidence by taking data from administrative units and adjusting them for natural geographical boundaries (biomes) for European Russia, and then evaluated the risk of infection for separate model diseases and for a set of them. The highest risk rates are confined to the northwest regions of European Russia, the Cis-Urals and the Volga region, which are naturally related to forest biomes, as well as to the southern steppe regions of the interfluves between the Volga and the Don, and the foothills of the North Caucasus.