Ixodes scapularis density and Borrelia burgdorferi prevalence along a residential-woodland gradient in a region of emerging Lyme disease risk.

The environmental risk of Lyme disease, defined by the density of Ixodes scapularis ticks and their prevalence of Borrelia burgdorferi infection, is increasing across the Ottawa, Ontario region, making this a unique location to explore the factors associated with environmental risk along a residential-woodland gradient. In this study, we collected I. scapularis ticks and trapped Peromyscus spp. mice, tested both for tick-borne pathogens, and monitored the intensity of foraging activity by deer in residential, woodland, and residential-woodland interface zones of four neighbourhoods. We constructed mixed-effect models to test for site-specific characteristics associated with densities of questing nymphal and adult ticks and the infection prevalence of nymphal and adult ticks. Compared to residential zones, we found a strong increasing gradient in tick density from interface to woodland zones, with 4 and 15 times as many nymphal ticks, respectively. Infection prevalence of nymphs and adults together was 15 to 24 times greater in non-residential zone habitats. Ecological site characteristics, including soil moisture, leaf litter depth, and understory density, were associated with variations in nymphal density and their infection prevalence. Our results suggest that high environmental risk bordering residential areas poses a concern for human-tick encounters, highlighting the need for targeted disease prevention.

Passive tick surveillance and detection of Borrelia burgdorferi in ticks from companion animals in British Columbia: 2018 to 2020.

Objective: The present study was designed to identify tick species and determine prevalence of Borrelia burgdorferi infection in ticks obtained from companion animals in British Columbia. Animals and samples: Ticks were submitted by British Columbia veterinarians from client-owned companion animals over a 31-month period. Procedure: Each tick was identified and PCR testing for B. burgdorferi undertaken on all Ixodes species identified by the Zoonotic Diseases and Emerging Pathogens Section of British Columbia Centre for Disease Control Public Health Laboratory (BCCDC PHL). Results: Overall, 85% (n = 300) of ticks submitted were Ixodes spp., with the majority known to transmit B. burgdorferi. Furthermore, 0.8% (95% confidence interval: 0.094 to 2.78%) of these ticks were PCR-positive for B. burgdorferi. Conclusion and clinical relevance: Although the B. burgdorferi positivity rate in this study was low, it remains important for veterinary professionals to inform pet owners that ticks are present and can pose a risk to pets and humans. In eastern North America, B. burgdorferi infection risk has increased rapidly, underscoring the importance of ongoing surveillance in British Columbia to understand current and future distributions of ticks and tick-borne pathogens, especially in the context of climate change.

Surveillance passive des tiques et détection de Borrelia burgdorferi chez des tiques provenant d'animaux de compagnie en Colombie-Britannique: 2018 à 2020. Objectif: Cette étude a été élaboré afin d'identifier les espèces de tiques et de déterminer la prévalence de l'infection à Borrelia burgdorferi chez des tiques obtenues d'animaux de compagnie en Colombie-Britannique. Animaux et échantillons: Les tiques ont été soumises par des médecins vétérinaires de la Colombie-Britannique obtenues d'animaux de compagnie de clients sur une période de 31 mois. Procédure: Chaque tique a été identifiée et un test PCR pour détecter B. burdorferi réalisé sur toutes les espèces Ixodes identifiées par la Section des maladies zoonotiques et des agents pathogènes émergents du Centre for Disease Control Public Health Laboratory de la Colombie-Britannique. Résultats: Au total, 85 % (n = 300) des tiques soumises étaient des Ixodes spp., dont la majorité reconnue pour transmettre B. burgdorferi. De plus, 0,8 % (intervalle de confiance 95 %: 0,094 à 2,78 %) de ces tiques étaient positives pour B. burgdorferi par PCR. Conclusion et signification clinique: Bien que le taux de positivité pour B. burgdorferi dans la présente étude soit faible, il n'en demeure pas moins important pour les professionnels vétérinaires d'informer les propriétaires d'animaux de compagnie que les tiques sont présentes et peuvent représenter un risque pour les animaux de compagnie et les humains. Dans le nord de l'Amérique du Nord, le risque d'infection par B. burgdorferi a augmenté rapidement, soulignant l'importance d'une surveillance continue en Colombie-Britannique pour comprendre la distribution actuelle et future des tiques et agents pathogènes transmis par les tiques, spécialement dans le contexte des changements climatiques.(Traduit par Dr Serge Messier).

How do host population dynamics impact Lyme disease risk dynamics in theoretical models?

Lyme disease is the most common wildlife-to-human transmitted disease reported in North America. The study of this disease requires an understanding of the ecology of the complex communities of ticks and host species involved in harboring and transmitting this disease. Much of the ecology of this system is well understood, such as the life cycle of ticks, and how hosts are able to support tick populations and serve as disease reservoirs, but there is much to be explored about how the population dynamics of different host species and communities impact disease risk to humans. In this study, we construct a stage-structured, empirically-informed model with host dynamics to investigate how host population dynamics can affect disease risk to humans. The model describes a tick population and a simplified community of three host species, where primary nymph host populations are made to fluctuate on an annual basis, as commonly observed in host populations. We tested the model under different environmental conditions to examine the effect of environment on the interactions of host dynamics and disease risk. Results show that allowing for host dynamics in the model reduces mean nymphal infection prevalence and increases the maximum annual prevalence of nymphal infection and the density of infected nymphs. Effects of host dynamics on disease measures of nymphal infection prevalence were nonlinear and patterns in the effect of dynamics on amplitude in nymphal infection prevalence varied across environmental conditions. These results highlight the importance of further study of the effect of community dynamics on disease risk. This will involve the construction of further theoretical models and collection of robust field data to inform these models. With a more complete understanding of disease dynamics we can begin to better determine how to predict and manage disease risk using these models.

Multiple factors affecting Ixodes ricinus ticks and associated pathogens in European temperate ecosystems (northeastern France).

In Europe, the main vector of tick-borne zoonoses is Ixodes ricinus, which has three life stages. During their development cycle, ticks take three separate blood meals from a wide variety of vertebrate hosts, during which they can acquire and transmit human pathogens such as Borrelia burgdorferi sensu lato, the causative agent of Lyme borreliosis. In this study conducted in Northeastern France, we studied the importance of soil type, land use, forest stand type, and temporal dynamics on the abundance of ticks and their associated pathogens. Negative binomial regression modeling of the results indicated that limestone-based soils were more favorable to ticks than sandstone-based soils. The highest tick abundance was observed in forests, particularly among coniferous and mixed stands. We identified an effect of habitat time dynamics in forests and in wetlands: recent forests and current wetlands supported more ticks than stable forests and former wetlands, respectively. We observed a close association between tick abundance and the abundance of Cervidae, Leporidae, and birds. The tick-borne pathogens responsible for Lyme borreliosis, anaplasmosis, and hard tick relapsing fever showed specific habitat preferences and associations with specific animal families. Machine learning algorithms identified soil related variables as the best predictors of tick and pathogen abundance.

Antibody-blocking of a tick transporter impairs Anaplasma phagocytophilum colonization in Haemaphysalis longicornis ticks.

The invasive Asian longhorned tick Haemaphysalis longicornis that vectors and transmits several animal pathogens is significantly expanding in the United States. Recent studies report that these ticks also harbor human pathogens including Borrelia burgdorferi sensu lato, Babesia microti, and Anaplasma phagocytophilum. Therefore, studies that address the interactions of these ticks with human pathogens are important. In this study, we report the characterization of H. longicornis organic anion-transporting polypeptides (OATPs) in interactions of these ticks with A. phagocytophilum. Using OATP-signature sequence, we identified six OATPs in the H. longicornis genome. Bioinformatic analysis revealed that H. longicornis OATPs are closer to other tick orthologs rather than to mammalian counterparts. Quantitative real-time PCR analysis revealed that OATPs are highly expressed in immature stages when compared to mature stages of these ticks. In addition, we noted that the presence of A. phagocytophilum upregulates a specific OATP in these ticks. We also noted that exogenous treatment of H. longicornis with xanthurenic acid, a tryptophan metabolite, influenced OATP expression in these ticks. Immunoblotting analysis revealed that antibody generated against Ixodes scapularis OATP cross-reacted with H. longicornis OATP. Furthermore, treatment of H. longicornis with OATP antibody impaired colonization of A. phagocytophilum in these ticks. These results not only provide evidence that the OATP-tryptophan pathway is important for A. phagocytophilum survival in H. longicornis ticks but also indicate OATP as a promising candidate for the development of a universal anti-tick vaccine to target this bacterium and perhaps other rickettsial pathogens of medical importance.

Prevalence of tick-borne pathogens in ticks collected from the wild mountain ungulates mouflon and chamois in 4 regions of France.

Ticks are major vectors of various pathogens of health importance, such as bacteria, viruses and parasites. The problems associated with ticks and vector-borne pathogens are increasing in mountain areas, particularly in connection with global climate change. We collected ticks (n = 2,081) from chamois and mouflon in 4 mountainous areas of France. We identified 6 tick species: Ixodes ricinus, Rhipicephalus bursa, Rh. sanguineus s.l., Haemaphysalis sulcata, H. punctata and Dermacentor marginatus. We observed a strong variation in tick species composition among the study sites, linked in particular to the climate of the sites. We then analysed 791 ticks for DNA of vector-borne pathogens: Babesia/Theileria spp., Borrelia burgdorferi s.l., Anaplasma phagocytophilum, A. marginale, A. ovis, and Rickettsia of the spotted fever group (SFG). Theileria ovis was detected only in Corsica in Rh. bursa. Babesia venatorum (2 sites), Borrelia burgdorferi s.l. (B. afzelii and B. garinii; 2 sites) and Anaplasma phagocytophilum (3 sites) were detected in I. ricinus. Anaplasma ovis was detected at one site in I. ricinus and Rh. sanguineus s.l. SFG Rickettsia were detected at all the study sites: R. monacensis and R. helvetica in I. ricinus at the 3 sites where this tick is present; R. massiliae in Rh. sanguineus s.l. (1 site); and R. hoogstraalii and Candidatus R. barbariae in Rh. bursa in Corsica. These results show that there is a risk of tick-borne diseases for humans and domestic and wild animals frequenting these mountain areas.

Title: Prévalence d'agents pathogènes vectorisés chez des tiques collectées chez des ongulés sauvages (mouflons, chamois) dans 4 zones montagneuses en France. Abstract: Les tiques sont des vecteurs majeurs de différents agents pathogènes d'importance sanitaire, tels que des bactéries, des virus et des parasites. Les problématiques liées aux tiques et aux pathogènes vectorisés augmentent en zones de montagne, en lien notamment avec le réchauffement climatique. Nous avons collecté des tiques (n = 2 081) sur des chamois et des mouflons dans 4 zones montagneuses en France. Six espèces ont été identifiées : Ixodes ricinus, Rhipicephalus bursa, Rh. sanguineus s.l., Haemaphysalis sulcata, H. punctata et Dermacentor marginatus. Nous avons observé une forte variation de la composition en espèces de tiques entre les sites d'étude, en lien notamment avec le climat des sites. Nous avons ensuite recherché les ADN d'agents pathogènes vectorisés sur 791 tiques : Babesia/Theileria spp, Borrelia burgdorferi s.l., Anaplasma phagocytophilum, A. marginale, A. ovis, et de Rickettsia du groupe des fièvres boutonneuses (SFG). Theileria ovis a été détecté uniquement en Corse chez Rh. bursa. Babesia venatorum (2 sites), Borrelia burgdorferi s.l. (B. afzelii and B. garinii; 2 sites) et Anaplasma phagocytophilum (3 sites) ont été détectés chez I. ricinus. Anaplasma ovis a été détecté dans un site chez I. ricinus et Rh. sanguineus s.l.. Les Rickettsia SFG ont été détectées dans tous les sites d'étude : Rickettsia monacensis et R. helvetica chez I. ricinus dans les 3 sites où cette tique est présente; R. massiliae chez Rh. sanguineus s.l. (1 site); et R. hoogstraalii et Candidatus R. barbariae chez Rh. bursa en Corse. Ces résultats montrent un risque de transmission de maladies par les tiques pour les personnes et les animaux domestiques et sauvages fréquentant ces zones de montagne.

Sequences Related to Chimay Rhabdovirus Are Widely Distributed in Ixodes ricinus Ticks across England and Wales.

Ticks are the main arthropod vector of pathogens to humans and livestock in the British Isles. Despite their role as a vector of disease, many aspects of tick biology, ecology, and microbial association are poorly understood. To address this, we investigated the composition of the microbiome of adult and nymphal Ixodes ricinus ticks. The ticks were collected on a dairy farm in Southwest England and RNA extracted for whole genome sequencing. Sequences were detected from a range of microorganisms, particularly tick-associated viruses, bacteria, and nematodes. A majority of the viruses were attributed to phlebo-like and nairo-like virus groups, demonstrating a high degree of homology with the sequences present in I. ricinus from mainland Europe. A virus sharing a high sequence identity with Chimay rhabdovirus, previously identified in ticks from Belgium, was detected. Further investigations of I. ricinus ticks collected from additional sites in England and Wales also identified Chimay rhabdovirus viral RNA with varying prevalence in all tick populations. This suggests that Chimay rhabdovirus has a wide distribution and highlights the need for an extended exploration of the tick microbiome in the United Kingdom (UK).

The risk of contact between visitors and Borrelia burgdorferi-infected ticks is associated with fine-scale landscape features in a southeastern Canadian nature park.

BACKGROUND: Infectious diseases are emerging across temperate regions of the world, and, for some, links have been made between landscapes and emergence dynamics. For tick-borne diseases, public parks may be important exposure sites for people living in urbanized areas of North America and Europe. In most cases, we know more about the ecological processes that determine the hazard posed by ticks as disease vectors than we do about how human population exposure varies in urban natural parks. METHODS: In this study, infrared counters were used to monitor visitor use of a public natural park in southern Quebec, Canada. A risk index representing the probability of encounters between humans and infected vectors was constructed. This was done by combining the intensity of visitor trail use and the density of infected nymphs obtained from field surveillance. Patterns of risk were examined using spatial cluster analysis. Digital forest data and park infrastructure data were then integrated using spatially explicit models to test whether encounter risk levels and its components vary with forest fragmentation indicators and proximity to park infrastructure. RESULTS: Results suggest that, even at a very fine scales, certain landscape features and infrastructure can be predictors of risk levels. Both visitors and Borrelia burgdorferi-infected ticks concentrated in areas where forest cover was dominant, so there was a positive association between forest cover and the risk index. However, there were no associations between indicators of forest fragmentation and risk levels. Some high-risk clusters contributed disproportionately to the risk distribution in the park relative to their size. There were also two high-risk periods, one in early summer coinciding with peak nymphal activity, and one in early fall when park visitation was highest. CONCLUSIONS: Here, we demonstrate the importance of integrating indicators of human behaviour visitation with tick distribution data to characterize risk patterns for tick-borne diseases in public natural areas. Indeed, understanding the environmental determinants of human-tick interactions will allow organisations to deploy more effective risk reduction interventions targeted at key locations and times, and improve the management of public health risks associated with tick-borne diseases in public spaces.

Italian peninsula as a hybridization zone of Ixodes inopinatus and I. ricinus and the prevalence of tick-borne pathogens in I. inopinatus, I. ricinus, and their hybrids.

BACKGROUND: Ixodes inopinatus was described from Spain on the basis of morphology and partial sequencing of 16S ribosomal DNA. However, several studies suggested that morphological differences between I. inopinatus and Ixodes ricinus are minimal and that 16S rDNA lacks the power to distinguish the two species. Furthermore, nuclear and mitochondrial markers indicated evidence of hybridization between I. inopinatus and I. ricinus. In this study, we tested our hypothesis on tick dispersal from North Africa to Southern Europe and determined the prevalence of selected tick-borne pathogens (TBPs) in I. inopinatus, I. ricinus, and their hybrids. METHODS: Ticks were collected in Italy and Algeria by flagging, identified by sequencing of partial TROSPA and COI genes, and screened for Borrelia burgdorferi s.l., B. miyamotoi, Rickettsia spp., and Anaplasma phagocytophilum by polymerase chain reaction and sequencing of specific markers. RESULTS: Out of the 380 ticks, in Italy, 92 were I. ricinus, 3 were I. inopinatus, and 136 were hybrids of the two species. All 149 ticks from Algeria were I. inopinatus. Overall, 60% of ticks were positive for at least one TBP. Borrelia burgdorferi s.l. was detected in 19.5% of ticks, and it was significantly more prevalent in Ixodes ticks from Algeria than in ticks from Italy. Prevalence of Rickettsia spotted fever group (SFG) was 51.1%, with significantly greater prevalence in ticks from Algeria than in ticks from Italy. Borrelia miyamotoi and A. phagocytophilum were detected in low prevalence (0.9% and 5.2%, respectively) and only in ticks from Italy. CONCLUSIONS: This study indicates that I. inopinatus is a dominant species in Algeria, while I. ricinus and hybrids were common in Italy. The higher prevalence of B. burgdorferi s.l. and Rickettsia SFG in I. inopinatus compared with that in I. ricinus might be due to geographical and ecological differences between these two tick species. The role of I. inopinatus in the epidemiology of TBPs needs further investigation in the Mediterranean Basin.

Warming, but not infection with Borrelia burgdorferi, increases off-host winter activity in the ectoparasite, Ixodes scapularis.

Warming winters will change patterns of behaviour in temperate and polar arthropods, but we know little about the drivers of winter activity in animals such as ticks. Any changes in behaviour are likely to arise from a combination of both abiotic (e.g. temperature) and biotic (e.g. infection) drivers, and will have important consequences for survival and species interactions. Blacklegged ticks, Ixodes scapularis, have invaded Atlantic Canada and high proportions (30-50%) are infected with the bacteria causing Lyme disease, Borrelia burgdorferi. Infection is correlated with increased overwintering survival of adult females, and ticks are increasingly active in the winter, but it is unclear if infection is associated with activity. Further, we know little about how temperature drives the frequency of winter activity. Here, we exposed wild-caught, adult, female Ixodes scapularis ticks to three different winter temperature regimes (constant low temperatures, increased warming, and increased warming + variability) to determine the thermal and infection conditions that promote or suppress activity. We used automated behaviour monitors to track daily activity in individual ticks and repeated the study with fresh ticks over three years. Following exposure to winter conditions we determined whether ticks were infected with the bacteria B. burgdorferi and if infection was responsible for any patterns in winter activity. Warming conditions promoted increased activity throughout the overwintering period but infection with B. burgdorferi had no impact on the frequency or overall number of ticks active throughout the winter. Individual ticks varied in their levels of activity throughout the winter, such that some were largely dormant for several weeks, while others were active almost daily; however, we do not yet know the drivers behind this individual variation in behaviour. Overall, warming winters will heighten the risk of tick-host encounters.

A next generation sequencing assay combining Ixodes species identification with pathogen detection to support tick surveillance efforts in the United States.

The burden of tick-borne diseases continues to increase in the United States. Tick surveillance has been implemented to monitor changes in the distribution and prevalence of human disease-causing pathogens in ticks that frequently bite humans. Such efforts require accurate identification of ticks to species and highly sensitive and specific assays that can detect and differentiate pathogens from genetically similar microbes in ticks that have not been demonstrated to be pathogenic in humans. We describe a modification to a next generation sequencing pathogen detection assay that includes a target that accurately identifies Ixodes ticks to species. We show that the replacement of internal control primers used to ensure assay performance with primers that also act as an internal control and can additionally differentiate tick species, retains high sensitivity and specificity, improves efficiency, and reduces costs by eliminating the need to run separate assays to screen for pathogens and for tick identification.

SCGB1D2 inhibits growth of Borrelia burgdorferi and affects susceptibility to Lyme disease.

Lyme disease is a tick-borne disease caused by bacteria of the genus Borrelia. The host factors that modulate susceptibility for Lyme disease have remained mostly unknown. Using epidemiological and genetic data from FinnGen and Estonian Biobank, we identify two previously known variants and an unknown common missense variant at the gene encoding for Secretoglobin family 1D member 2 (SCGB1D2) protein that increases the susceptibility for Lyme disease. Using live Borrelia burgdorferi (Bb) we find that recombinant reference SCGB1D2 protein inhibits the growth of Bb in vitro more efficiently than the recombinant protein with SCGB1D2 P53L deleterious missense variant. Finally, using an in vivo murine infection model we show that recombinant SCGB1D2 prevents infection by Borrelia in vivo. Together, these data suggest that SCGB1D2 is a host defense factor present in the skin, sweat, and other secretions which protects against Bb infection and opens an exciting therapeutic avenue for Lyme disease.

Tick hemocytes have a pleiotropic role in microbial infection and arthropod fitness.

Uncovering the complexity of systems in non-model organisms is critical for understanding arthropod immunology. Prior efforts have mostly focused on Dipteran insects, which only account for a subset of existing arthropod species in nature. Here we use and develop advanced techniques to describe immune cells (hemocytes) from the clinically relevant tick Ixodes scapularis at a single-cell resolution. We observe molecular alterations in hemocytes upon feeding and infection with either the Lyme disease spirochete Borrelia burgdorferi or the rickettsial agent Anaplasma phagocytophilum. We reveal hemocyte clusters exhibiting defined signatures related to immunity, metabolism, and proliferation. Depletion of phagocytic hemocytes affects hemocytin and astakine levels, two I. scapularis hemocyte markers, impacting blood-feeding, molting behavior, and bacterial acquisition. Mechanistically, astakine alters hemocyte proliferation, whereas hemocytin affects the c-Jun N-terminal kinase (JNK) signaling pathway in I. scapularis. Altogether, we discover a role for tick hemocytes in immunophysiology and provide a valuable resource for comparative biology in arthropods.

Blood meal analysis reveals sources of tick-borne pathogens and differences in host utilization of juvenile Ixodes ricinus across urban and sylvatic habitats.

AIMS: Urban green spaces are locations of maximal human activity, forming areas of enhanced risk for tick-borne disease (TBD) transmission. Being also limited in spatial scale, green spaces form prime targets for control schemes aiming to reduce TBD risk. However, for effective control, the key species maintaining local tick and tick-borne pathogen (TBP) populations must be identified. To determine how patterns of host utilization vary spatially, we utilized blood meal analysis to study the contributions of voles, shrews, squirrels, leporids and cervids towards blood meals and the acquisition of TBPs of juvenile Ixodes ricinus in urban and sylvatic areas in Finland. METHODS AND RESULTS: A total of 1084 nymphs were collected from the capital city of Finland, Helsinki and from a sylvatic island in southwestern Finland, and subjected to qPCR analysis to identify DNA remnants of the previous host. We found significant differences in host contributions between urban and sylvatic environments. Specifically, squirrels and leporids were more common hosts in urban habitats, whereas cervids and voles were more common in sylvatic habitats. In addition to providing 18.4% of larval blood meals in urban habitats, red squirrels were identified as the source of 28.6% (n = 48) of Borrelia afzelii detections and 58.1% (n = 18) of Borrelia burgdorferi sensu stricto detections, indicating an important role for local enzootic cycles. CONCLUSIONS: Our study highlights that the key hosts maintaining tick and TBP populations may be different in urban and sylvatic habitats. Likewise, hosts generally perceived as important for upkeep may have limited importance in urban environments. Consequently, targeting control schemes based on off-site data of host importance may lead to suboptimal results.

Surveillance of tick-borne bacteria infection in ticks and forestry populations in Inner Mongolia, China.

Ticks are one of the most important vectors that can transmit pathogens to animals and human beings. This study investigated the dominant tick-borne bacteria carried by ticks and tick-borne infections in forestry populations in Arxan, Inner Mongolia, China. Ticks were collected by flagging from May 2020 to May 2021, and blood samples were collected from individuals at high risk of acquiring tick-borne diseases from March 2022 to August 2023. The pooled DNA samples of ticks were analyzed to reveal the presence of tick-borne bacteria using high-throughput sequencing of the 16S rDNA V3-V4 region, and species-specific polymerase chain reaction (PCR) related to sequencing was performed to confirm the presence of pathogenic bacteria in individual ticks and human blood samples. All sera samples were examined for anti-SFGR using ELISA and anti-B. burgdorferi using IFA and WB. A total of 295 ticks (282 Ixodes persulcatus and 13 Dermacentor silvarum) and 245 human blood samples were collected. Rickettsia, Anaplasma, Borrelia miyamotoi, and Coxiella endosymbiont were identified in I. persulcatus by high-throughput sequencing, while Candidatus R. tarasevichiae (89.00%, 89/100), B. garinii (17.00%, 17/100), B. afzelii (7.00%, 7/100), and B. miyamotoi (7.00%, 7/100) were detected in I. persulcatus, as well the dual co-infection with Candidatus R. tarasevichiae and B. garinii were detected in 13.00% (13/100) of I. persulcatus. Of the 245 individuals, B. garinii (4.90%, 12/245), R. slovaca (0.82%, 2/245), and C. burnetii (0.41%, 1/245) were detected by PCR, and the sequences of the target genes of B. garinii detected in humans were identical to those detected in I. persulcatus. The seroprevalence of anti-SFGR and anti-B. burgdorferi was 5.71% and 13.47%, respectively. This study demonstrated that Candidatus R. tarasevichiae and B. garinii were the dominant tick-borne bacteria in I. persulcatus from Arxan, and that dual co-infection with Candidatus R. tarasevichiae and B. garinii was frequent. This is the first time that B. miyamotoi has been identified in ticks from Arxan and R. solvaca has been detected in humans from Inner Mongolia. More importantly, this study demonstrated the transmission of B. garinii from ticks to humans in Arxan, suggesting that long-term monitoring of tick-borne pathogens in ticks and humans is important for the prevention and control of tick-borne diseases.

By-degree Health and Economic Impacts of Lyme Disease, Eastern and Midwestern United States.

Lyme disease (LD) is the most common vector-borne disease in the United States (U.S.). This paper assesses how climate change may influence LD incidence in the eastern and upper Midwestern U.S. and the associated economic burden. We estimated future Ixodes scapularis habitat suitability and LD incidence with a by-degree approach using variables from an ensemble of multiple climate models. We then applied estimates for present-day and projected habitat suitability for I. scapularis, present-day presence of Borrelia burgdorferi, and projected climatological variables to model reported LD incidence at the county level among adults, children, and the total population. Finally, we applied an estimate of healthcare expenses to project economic impacts. We show an overall increase in LD cases with regional variation. We estimate an increase in incidence in New England and the upper Midwestern U.S. and a concurrent decrease in incidence in Virginia and North Carolina. At 3°C of national warming from the 1986-2015 baseline climate, we project approximately 55,000 LD cases, a 38-percent increase from present-day estimates. At 6°C of warming, our most extreme scenario, we project approximately 92,000 LD cases in the region, an increase of 145 percent relative to current levels. Annual LD-related healthcare expenses at 3°C of warming are estimated to be $236 million (2021 dollars), approximately 38 percent greater than present-day. These results may inform decision-makers tasked with addressing climate risks, the public, and healthcare professionals preparing for treatment and prevention of LD.

The role of Rab27 in tick extracellular vesicle biogenesis and pathogen infection.

BACKGROUND: The blacklegged tick, Ixodes scapularis, transmits most vector-borne diseases in the US. It vectors seven pathogens of public health relevance, including the emerging human pathogen Anaplasma phagocytophilum. Nevertheless, it remains critically understudied compared to other arthropod vectors. Ixodes scapularis releases a variety of molecules that assist in the modulation of host responses. Recently, it was found that extracellular vesicles (EVs) carry several of these molecules and may impact microbial transmission to the mammalian host. EV biogenesis has been studied in mammalian systems and is relatively well understood, but the molecular players important for the formation and secretion of EVs in arthropods of public health relevance remain elusive. RabGTPases are among the major molecular players in mammalian EV biogenesis. They influence membrane identity and vesicle budding, uncoating, and motility. METHODS: Using BLAST, an in silico pathway for EV biogenesis in ticks was re-constructed. We identified Rab27 for further study. EVs were collected from ISE6 tick cells after knocking down rab27 to examine its role in tick EV biogenesis. Ixodes scapularis nymphs were injected with small interfering RNAs to knock down rab27 and then fed on naïve and A. phagocytophilum-infected mice to explore the importance of rab27 in tick feeding and bacterial acquisition. RESULTS: Our BLAST analysis identified several of the proteins involved in EV biogenesis in ticks, including Rab27. We show that silencing rab27 in I. scapularis impacts tick fitness. Additionally, ticks acquire less A. phagocytophilum after rab27 silencing. Experiments in the tick ISE6 cell line show that silencing of rab27 causes a distinct range profile of tick EVs, indicating that Rab27 is needed to regulate EV biogenesis. CONCLUSIONS: Rab27 is needed for successful tick feeding and may be important for acquiring A. phagocytophilum during a blood meal. Additionally, silencing rab27 in tick cells results in a shift of extracellular vesicle size. Overall, we have observed that Rab27 plays a key role in tick EV biogenesis and the tripartite interactions among the vector, the mammalian host, and a microbe it encounters.

First detection of Candidatus Rickettsia tarasevichiae in Hyalomma marginatum ticks.

Ticks are important vectors of zoonotic diseases and play a major role in the circulation and transmission of many rickettsial species. The aim of this study was to investigate the carriage of Candidatus Rickettsia tarasevichiae (CRT) in a total of 1168 ticks collected in Inner Mongolia to elucidate the potential public health risk of this pathogen, provide a basis for infectious disease prevention, control and prediction and contribute diagnostic ideas for clinical diseases that present with fever in populations exposed to ticks. A total of four tick species, Haemaphysalis concinna (n = 21), Dermacentor nuttalli (n = 122), Hyalomma marginatum (n = 148), and Ixodes persulcatus (n = 877), were collected at nine sampling sites in Inner Mongolia, China, and identified by morphological and molecular biological methods. Reverse transcription PCR targeting the 16S ribosomal RNA (rrs), gltA, groEL, ompB and Sca4 genes was used to detect CRT DNA. Sequencing was used for pathogen species confirmation. The molecular epidemiological analysis showed that three species of ticks were infected with CRT, and the overall positive rate was as high as 42%. The positive rate of I. persulcatus collected in Hinggan League city was up to 96%, and that of I. persulcatus collected in Hulun Buir city was 50%. The pool positive rates of D. nuttalli and H. marginatum collected in Bayan Nur city and H. concinna collected in Hulun Buir city were 0%, 28% and 40%, respectively. This study revealed the high prevalence of CRT infection in ticks from Inner Mongolia and the first confirmation of CRT detected in H. marginatum in China. The wide host range and high infection rate in Inner Mongolia may dramatically increase the exposure of CRT to humans and other vertebrates. The role of H. marginatum in the transmission of rickettsiosis and its potential risk to public health should be further considered.

Seasonal pattern of questing ticks and prevalence of pathogenic Rickettsia and Anaplasmataceae in Khao Yai national park, Thailand.

BACKGROUND: Tick-borne diseases (TBD) are considered neglected diseases in Thailand with disease burden likely underestimated. To assess risk for emerging TBD in Thailand, the seasonality of questing tick and pathogen prevalence were studied in Khao Yai National Park, a top tourist destination. METHODS: During 2019, questing ticks around tourist attractions were systematically collected bimonthly and analyzed for Rickettsia and Anaplasmataceae bacterial species by polymerase chain reaction and DNA sequencing. RESULTS: Larvae and nymphs of questing ticks peaked in Khao Yai National Park during the late rainy-winter season, though no specific trends were observed in adult ticks. Winter (November to February) was the highest risk for human tick-bites due to higher numbers of both ticks and visitors. Of the total 5916 ticks analyzed (651 pools), Anaplasma phagocytophilum, Neoehrlichia mikurensis, Ehrlichia ewingii, and Ehrlichia chaffeensis were detected at low rates (≤0.05%). There was a higher prevalence of human rickettsioses (0.2-7%) in ticks surveyed with Rickettsia tamurae, Rickettsia raoultii, and Rickettsia montana the major species. Amblyomma ticks had the highest prevalence of Rickettsia (85%, 35/44 Amblyomma adults), in which only R. tamurae and R. raoultii were found in Amblyomma with mixed species infections common. We report the first detection of R. africae-like and N. mikurensis in Ixodes granulatus adults in Thailand, suggesting I. granulatus as a potential vector for these pathogens. CONCLUSION: This study demonstrated the risk of emerging TBD in Thailand and underscores the need for tick-bite prevention among tourists in Thailand.

Ixodid ticks and zoonotic tick-borne pathogens of the Western Balkans.

Ixodid ticks are distributed across all countries of the Western Balkans, with a high diversity of species. Many of these species serve as vectors of pathogens of veterinary and medical importance. Given the scattered data from Western Balkan countries, we have conducted a comprehensive review of available literature, including some historical data, with the aim to compile information about all recorded tick species and associated zoonotic pathogens in this region. Based on the collected data, the tick fauna of the Western Balkans encompasses 32 tick species belonging to five genera: Ixodes, Haemaphysalis, Dermacentor, Rhipicephalus and Hyalomma. A range of pathogens responsible for human diseases has also been documented, including viruses, bacteria and parasites. In this review, we emphasize the necessity for integrated surveillance and reporting, urging authorities to foster research by providing financial support. Additionally, international and interdisciplinary collaborations should be encouraged that include the exchange of expertise, experiences and resources. The present collaborative effort can effectively address gaps in our knowledge of ticks and tick-borne diseases.