Search Results (46)

Background: Borrelia miyamotoi is an emerging tick-borne pathogen causing relapsing fever in humans. Although Saint Petersburg and the surrounding Leningrad Oblast harbor a high abundance of ixodid ticks (I. ricinus, I. persulcatus), no integrated assessment has yet simultaneously addressed pathogen circulation in vectors, reservoir hosts, and human populations in this specific northwestern region of Russia. Methods: During 2022–2024, we collected 1518 questing adult ticks and trapped 516 small mammals in Saint Petersburg and Leningrad Oblast. B. miyamotoi DNA was detected by real-time PCR. Sera from 3743 randomly selected volunteers (1553 from Saint Petersburg, 2190 from Leningrad Oblast) were tested for anti-B. miyamotoi IgG/IgM using a protein microarray (antigens: GlpQ, Vmps, flagellin). Infection rates and seroprevalence with 95% Wilson confidence intervals were compared using chi-square tests. Results: The overall tick infection rate was 3.78% (57/1506). I. ricinus had a significantly higher prevalence (4.94%; 95% CI: 3.67–6.60%) than I. persulcatus (2.29%; 95% CI: 1.39–3.74%; p = 0.011). Ticks from Leningrad Oblast also showed markedly elevated infection rates (4.98%; 95% CI: 3.75–6.58%) compared to those from Saint Petersburg (1.89%; 95% CI: 1.06–3.35%; p = 0.004). Small mammals exhibited substantially higher infection rates in Leningrad Oblast (39.44%; 95% CI: 31.78–47.65%) than in Saint Petersburg (13.90%; 95% CI: 10.76–17.78%; p < 0.001). Bank voles (Myodes glareolus) and yellow-necked mice (Apodemus flavicollis) were the main reservoirs; synanthropic rodents trapped within the city were found to be infected for the first time. No significant organotropism was detected, but positive correlations between infection in the heart, liver, and kidney suggested hematogenous dissemination. The overall human seroprevalence of B. miyamotoi was 1.71% (95% CI: 1.34–2.18%) and was significantly higher in Leningrad Oblast (2.19%; 95% CI: 1.66–2.89%) than in Saint Petersburg (1.03%; 95% CI: 0.64–1.67%; p = 0.010). In contrast, the seroprevalence of B. burgdorferi s. l. did not differ between the two regions (approximately 5.1%). Conclusions: This first comprehensive, multi-level investigation in Saint Petersburg and Leningrad Oblast reveals a stable epidemiological gradient: natural foci in Leningrad Oblast sustain higher B. miyamotoi circulation in ticks and rodents, which translates into a two-fold higher exposure of the rural population. The findings highlight the need to include B. miyamotoi in regional tick-borne infection surveillance programs and to adopt differentiated risk assessment strategies for urban and rural settings. Full article

Tick-borne encephalitis virus (TBEV) is primarily transmitted by Ixodes spp. and poses significant health risks, leading to morbidity and mortality in humans. Two of the five subtypes, Siberian and Far Eastern are known to circulate in Mongolia. In 2021, Ixodes persulcatus ticks were collected from Bulgan aimag (province) using flagging and dragging methods and subsequently screened for TBEV using PCR. Positive samples underwent sequencing using an Oxford Nanopore Technologies-based hybrid capture approach, resulting in two coding-complete TBEV genomes from separate tick pools. Phylogenetic analysis classified both genomes within the Siberian subtype, grouping them with other Mongolian sequences from I. persulcatus collected in 2014, 2020, 2021, and 2023. The study sequences, PX654173 and PX654174, showed high genetic similarity (99.9% and 99.8%, respectively) to the sequence PQ479142, obtained from I. persulcatus ticks in Selenge, Mongolia, in 2021. The estimated time to most recent common ancestor (TMRCA) of the Siberian genotype was approximately 981 CE (95% HPD: 646–1347) with the emergence of a distinct Mongolian clade of TBEV around 1888 CE (95% HPD: 1834–1934). These findings highlight the value of expanded whole-genome sequencing to improve our understanding of TBEV’s genetic diversity and evolutionary history in Central Asia. Full article

Ticks are important vectors of bacterial pathogens with veterinary and public health significance. However, information on the diversity of tick-associated bacteria in forest ecosystems of northeastern China remains limited. In this study, 821 questing ticks were collected from Huoshankou National Forest Park in Mudanjiang City, Heilongjiang Province, and identified as Haemaphysalis japonica, Hae. concinna, and Ixodes persulcatus. Molecular screening based on rrs gene amplification detected Anaplasma, Ehrlichia, and Coxiella-like endosymbionts (CLE), which were further characterized using multilocus phylogenetic analyses. Anaplasma bovis was detected in Hae. concinna and exhibited two distinct genotypes. In addition, a potentially novel Anaplasma lineage was identified in I. persulcatus. Phylogenetic analyses based on the rrs, gltA, and groEL genes consistently placed this lineage in a separate clade from currently recognized Anaplasma species. Furthermore, two genetically distinct Ehrlichia lineages were detected in Hae. japonica and Hae. concinna. Two lineages of tick-associated CLE were also characterized using five genetic genes. Overall, these findings demonstrate considerable genetic diversity of tick-associated bacteria in forest ecosystems of northeastern China and expand current understanding of their molecular diversity. Further studies incorporating broader sampling and genome-based analyses will be necessary to clarify their taxonomic status and epidemiological relevance. Full article

Tick-borne encephalitis virus (TBEV) causes tick-borne encephalitis (TBE), a severe disease of the human central nervous system. Currently, the data on the genetic variants of TBEV in Kyrgyzstan are practically absent. Therefore, the aim of this study was to analyze and describe the genetic diversity of TBEV in this region. The complete genome sequences of seven TBEV strains from the collection of the Scientific Centre for Family Health and Human Reproduction Problems (Irkutsk, Russia) were determined. These strains, isolated from Ixodes persulcatus ticks from Kyrgyzstan, were sequenced using the next generation sequencing approach on a MiSeq high-performance sequencer (Illumina, San Diego, CA, USA). A molecular genetic analysis of the obtained sequences, along with sequences of two previously isolated TBEV strains from Kyrgyzstan available in the GenBank database, demonstrated that the Siberian subtype of three genetic lineages (Zausaev, Vasilchenko and Bosnia) is predominantly distributed in Kyrgyzstan. The Far Eastern subtype of TBEV is also present. To date, this location probably represents the southernmost boundary of these TBEV subtypes’ ranges. Full article

Ticks and tick-borne diseases pose a significant threat to public health. The Tumen River Basin is located at the junction of China, North Korea and Russia, whose warm climate and favorable ecological environment are suitable for the growth and reproduction of ticks. At the same time, the cattle industry in this region is highly developed, with cattle serving as the primary economic source for the area. This study performed an epidemiological investigation and analysis of pathogens carried by ticks and cattle in the Tumen River basin. A total of 913 ticks and 247 bovine blood samples were collected from seven cities primarily focused on cattle farming in the Tumen River basin. Morphological and molecular biological identification of ticks was carried out to determine the distribution of ticks and their pathogens in the region. Through the detection of pathogens carried by cattle blood samples in the surrounding area, the correlation with tick distribution was confirmed. The species and distribution of ticks of different genders and in different collection environments, and the infection of pathogens in bovine blood samples were statistically analyzed. The results showed that the 913 ticks had 5 species, including Haemaphysalis longicornis, Haemaphysalis concinna, Haemaphysalis japonica, Dermacentor silvarum and Ixodes persulcatus. Three pathogens, Babesia ovata, Theileria orientalis and Theileria sinensis, were detected in the blood samples of vector ticks and cattle. These results provide a theoretical basis for the prevention and control of ticks and tick-borne diseases in the Tumen River basin. Full article

Ticks transmit diverse pathogens, posing significant public health threats in northeastern China; clarifying human-biting tick species and their carried pathogens is crucial for risk assessment and prevention. This study was designed as a pathogen detection and molecular epidemiological investigation. During the May-August period of each of 2023 and 2024, 232 ticks that had bitten humans were collected from a local sentinel hospital. Ticks were morphologically identified, followed by DNA extraction, semi-nested/nested PCR targeting specific genetic markers, and Sanger sequencing to detect bacterial pathogens. Four tick species were found, with Ixodes persulcatus dominant (87.9%), followed by Dermacentor silvarum (6.9%), Haemaphysalis concinna (3.5%), and Haemaphysalis japonica (1.7%). Seven bacterial pathogens were detected, including Candidatus Rickettsia tarasevichiae (35.3%) and Borreliella garinii (17.2%); 49.6% of ticks were pathogen-positive. The coinfection rate was 13.8%, most commonly Candidatus R. tarasevichiae plus B. garinii, and I. persulcatus carried all pathogens. These findings provide basic data on human-biting tick species and their bacterial pathogen spectrum in the region, serving as a reference for subsequent tick-borne disease research and targeted prevention. Full article

Borrelia burgdorferi sensu lato (s.l.) persistence in reservoir hosts is essential for the maintenance of the spirochaetes in the enzootic cycle. In this study, we investigated the persistence of Siberian B. burgdorferi s.l. strains in naturally infected voles and their transmission to Ixodes ticks. A long-term study conducted in 2013–2024 demonstrated the presence of Borrelia afzelii, Borrelia bavariensis, and, rarely, “Candidatus Borrelia sibirica” DNA in blood samples of small mammals. Among these, B. bavariensis exhibited the highest genetic diversity. All identified Borrelia species persisted in naturally infected Clethrionomys spp. voles throughout their lifespan (up to 50 weeks), providing the first evidence of long-term persistence of B. bavariensis and “Candidatus B. sibirica” in these hosts. Notably, the persistence of two Borrelia genospecies or several genovariants of a single genospecies within the same vole was common. Xenodiagnosis with laboratory-reared Ixodes spp. confirmed efficient transmission of all identified Borrelia genospecies to Ixodes persulcatus after 35–42 weeks of B. burgdorferi s.l. persistence. Moreover, B. bavariensis was transmitted to Ixodes pavlovskyi and I. persulcatus/I. pavlovskyi interspecies hybrids after at least 23 weeks of pathogen persistence. These findings demonstrate the reservoir competence of Clethrionomys spp. for B. afzelii, B. bavariensis, and “Candidatus B. sibirica”. Full article

A novel flavi-like virus with a segmented genome—Alongshan virus (ALSV)—has been isolated from Ixodes ticks in Russia. In this study, 4458 ixodid ticks collected in 22 regions of Russia were tested for genetic markers of ALSV by RT PCR. The highest rates of ALSV infection in ticks were detected in the Republic of Khakassia (3.3%) and in Kemerovo Oblast (2.4%), while low infection rates were more typical in the European part of Russia (0.4–0.7%). Complete four-segment genomes of 20 ALSV isolates derived from 22 PCR-positive Ixodes persulcatus ticks were sequenced using a high-throughput approach. The nucleotide sequences for Asian ALSV isolates have a 94.5–96.5% identity to ALSV isolates previously found in China, with this range for the European isolates being 89–93%. This data, together with phylogenetic analysis, indicates the existence of Asian and European subtypes of ALSV, and these may be associated with I. persulcatus and I ricinus ticks. The obtained results express the spread of ALSV in Russia and also may be useful for the diagnosis, prophylactics, and treatment of this infection. Full article

Ixodid ticks are blood-sucking ectoparasites of vertebrates. They constitute an integral part of natural foci and are responsible for the worldwide transmission of infections to humans, which can result in severe symptoms. For instance, the Tomsk region, where three abundant tick species (Dermacentor reticulatus, Ixodes pavlovskyi, I. persulcatus) occur, is an endemic area for tick-borne encephalitis virus (TBEV). An increasing number of novel infectious agents carried by ticks have been identified using metagenomic sequencing. A notable example is the Yezo virus (Orthonairovirus yezoense, YEZV), which was discovered in patients with fever after tick bites in Japan and China between 2014 and 2025. For the first time, we have performed metagenomic sequencing of the virome of ticks collected in the Tomsk region. In a sample obtained from a pool of I. pavlovskyi ticks, all three segments of the YEZV genome were detected. The phylogenetic analysis showed that the newly identified isolate formed a sister group to previously described virus isolates, indicating the presence of a new genetic variant. This study presents the first report of YEZV detection in I. pavlovskyi ticks in the Tomsk region, thereby expanding the geographical range and number of vector species for YEZV and highlighting the importance of monitoring viral agents circulating among ticks in Western Siberia. Full article

The habitats of shrews substantially overlap with those of rodents, which are well known as reservoirs for many tick-borne diseases. However, the ecological role of shrews (Mammalia: Eulipotyphla: Soricidae) remains poorly understood. We examined 103 Sorex spp. (S. unguiculatus, S. gracillimus, S. caecutiens) from Kushiro, Hokkaido, Japan, to investigate their relationships with ticks and tick-borne microorganisms, including Piroplasmida and Anaplasmataceae. Pathogen screening revealed Babesia microti Hobetsu lineage (9.7%), Neoehrlichia mikurensis (26.2%), Ehrlichia japonica (13.6%), and E. muris (0.97%). These intracellular protozoa and bacteria, typically associated with rodents, are recognized zoonotic agents or have zoonotic potential. Detection rates were highest in S. caecutiens (62.5%, 10/16), followed by S. unguiculatus (45.3%, 24/53) and S. gracillimus (23.5%, 8/34). Co-infections were observed between N. mikurensis and B. microti (n = 3) and between N. mikurensis and E. japonica (n = 4). Immature stages of Ixodes ovatus and I. persulcatus were collected from the body surface of shrews, and transstadial transmission of N. mikurensis was suggested by its detection in a molted I. ovatus nymph. These results indicate that shrews act as feeding hosts for immature ticks and reservoirs for multiple tick-borne pathogens. Shrews should be considered important reservoirs for tick-borne diseases. Full article

Ticks are important parasites of economic and public health because of their ability to transmit zoonotic diseases. Tick-borne encephalitis virus (TBEV), now officially Orthoflavivirus encephalitidis, is a Flavivirus with five main subtypes of which three, the European (TBEV-EU), the Siberian (TBEV-Sib), and the Far-Eastern subtypes (TBEV-FE), are supposedly circulate in Latvia. Several hard tick species are involved in TBEV circulation and transmission in nature. This study set out to describe the genetic landscape of TBEV subtypes in Latvian tick populations. In 2019 and 2021 to 2023, a total of 3026 ticks were collected in three Latvian regions, with Ixodes ricinus as the dominant species (2822 specimens), followed by Ixodes persulcatus (200 specimens) and Dermacentor reticulatus (4 specimens). Ticks were morphologically identified, pooled, and screened for TBEV RNA by RT-qPCR. TBEV of positive tick pools were isolated and genetically characterized by genome sequencing. Our study demonstrates the prevalence of two TBEV subtypes in Latvia with specific spatial patterning. In the sympatric Vidzeme region, these subtypes display a preferential species association of TBEV-EU with Ixodes ricinus and TBEV-Sib with Ixodes persulcatus. Phylogeographic analysis suggests independent introductions of multiple genotypes from both subtypes. Further investigations are necessary to better understand the natural transmission and the medical importance of these TBEVs. Full article

The recent discovery of the Yezo virus (YEZV) in Japan and China has raised particular concern due to its potential to cause human diseases ranging from mild febrile illnesses to severe neurological disorders. We report, for the first time, the detection of five YEZV isolates in I. persulcatus ticks from three regions of Russia. The analysis was performed using 5318 ticks of two Ixodes genus collected in 2024 from 23 regions of Russia. The minimum infection rate of YEZV in Russia among I. persulcatus ticks was 0.12% (95% CI: 0.05–0.28). The westernmost and northernmost YEZV detection points have been recorded. YEZV isolates circulating in Russia are genetically diverse. Protein domains of Russian YEZV isolates’ genomes were characterized using HMMER, AlphaFold 3, and InterProScan. The YEZV nucleoprotein (N) of Russian isolates has a racket-shaped structure with “head” and “stalk” domains similar to those of Orthonairovirus haemorrhagiae. The Lys261–Arg261 substitution in the YEZV N Chita 2024-1 isolate occurs in the α11 structure in the region of interaction with viral RNA. Our results show that the distribution area of YEZV is much wider than previously known, provide new data on complete YEZV genomes, extend our structural insight into YEZV N, and suggest a potential target for antiviral drug development to treat YEZV infection. Full article

The spectrum of ixodid ticks that bite humans in Western Siberia has significantly changed over the past two decades. In this study, we determined tick species attacking people in the vicinity of Novosibirsk and the range of bacterial agents they were infected with. This study included 301 ticks taken from people and 46% were Ixodes pavlovskyi, followed by Ixodes persulcatus (19.6%), I. persulcatus/I. pavlovskyi interspecies hybrids (19.6%), Dermacentor reticulatus (12.8%), and single Dermacentor marginatus and Dermacentor nuttalli/Dermacentor silvarum. Human DNA was determined in ticks, first demonstrating that all Ixodes spp., including hybrids, can effectively feed on humans. The DNA of Borrelia spp., Rickettsia spp., and Anaplasmataceae bacteria was detected in different tick species. Borrelia garinii prevailed in Ixodes species, being found in 8.8% of ticks, whereas B. afzelii and B. bavariensis were found in single ticks. Borrelia miyamotoi was revealed in 3.7% of ticks. “Candidatus Rickettsia tarasevichiae” and R. raoultii were identified mainly in I. persulcatus and D. reticulatus (44.8% and 26.3%, respectively), while Rickettsia helvetica was found only in 2.2% I. pavlovskyi. The prevalence of Anaplasma phagocytophilum, Ehrlichia muris, and Neoehrlichia mikurensis did not exceed 2%. The obtained results indicate a high risk for humans to be infected with agents of Lyme borreliosis, primarily B. garinii. Full article

Ticks are the second most significant vector of pathogens worldwide. Ixodes persulcatus is one of the dominant tick species in Inner Mongolia that can carry and transmit various pathogenic microorganisms. However, only one specific pathogen has been detected in a particular developmental stage of I. persulcatus, moreover metagenomic analysis has been conducted only in the adult tick stage. In this study, we used I. persulcatus at different developmental stages (first-generation female adult ticks, eggs, larval ticks, engorged larval ticks, nymphal ticks, engorged nymphal ticks, and second-generation adult ticks) from Inner Mongolia as materials for nucleic acid extraction. Subsequently, we constructed Illumina PE250 and Illumina PE150 libraries and sequenced them on the Illumina NovaSeq 6000 platform. Finally, we used molecular biology software and sequence analysis platform to analyze microbial community structures. Illumina PE250 sequencing revealed that the seven developmental stages of I. persulcatus were annotated to 21 phyla, 43 classes, 104 orders, 188 families, 391 genera, and 556 species of bacteria. Among them, 4 phyla and 14 genera were present at all developmental stages, with Proteobacteria being the dominant phylum and Rickettsia spp. being the dominant genus. In addition, Rickettsia had the highest relative abundance in the seven developmental stages. All developmental stages were annotated to a certain abundance of Brucella spp. Illumina PE150 sequencing revealed that the three samples (X-I-YDCP: first-generation adult ticks; X-I-MIX: mixed samples of eggs, larval ticks, and nymphal ticks; X-I-EDCP: second-generation adult ticks) of I. persulcatus were annotated to six orders, 28 families, 72 genera, and 158 species of viruses, of which 46 genera and 80 species were found in all three sample species. To the best of our knowledge, this is the first study that comprehensively analyzed the microbial community composition of I. persulcatus at different developmental stages. Based on the study outcomes, certain abundance of Rickettsia japonica, bovine viral diarrhea virus, and African swine fever virus were annotated to I. persulcatus. Full article

Tick-borne encephalitis virus (TBEV) causes neurological disease in humans, with varied clinical severity influenced by the viral subtype. TBEV is endemic to Mongolia, where both Siberian and Far-Eastern subtypes are present. Ixodes persulcatus is considered the main vector of TBEV in Mongolia; although, the virus has also been detected in Dermacentor species. To further characterize the disease ecology of TBEV within the endemic Selenge province of Mongolia, 1300 Ixodes persulcatus ticks were collected in May 2020 from regions outside Ulaanbaatar. Pooled tick samples (n = 20–50) were homogenized and the supernatant was inoculated into Vero cells. Two RT-PCR assays were conducted on the cell supernatant following an observed cytopathic effect: one for TBEV detection and the second for viral subtyping. Lysed cell cultures were processed for next-generation sequencing (NGS) using Illumina technology. TBEV was detected in 10.7% of tick pools (3/28), and isolates were identified as the Siberian subtype. Phylogenetic analysis showed PQ479142 clustering within the Siberian subtype and sharing high similarity with published isolates collected in Selenge in 2012 from Ixodes persulcatus. Subtype analysis of circulating TBEV isolates and sequencing analytics to track viral evolution in ticks are vital to continued understanding of the risk to local populations. Full article