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Ticks are blood-sucking ectoparasites that act as vectors for transmission of various pathogens. The purpose of this study was to assess tick-borne bacteria, whether pathogenic or not, in ticks distributed in Korea using 16S rRNA metabarcoding and to confirm the results by PCR. Questing ticks were collected from four provinces in Korea in 2021 using the flagging method. After pooling the DNAs from the 61 tick pools (including 372 ticks), the bacterial 16S rRNA V3-V4 hypervariable region was amplified and sequenced using the MiSeq platform. Rickettsia, Ehrlichia, and the endosymbiont Wolbachia were confirmed by conventional PCR and molecular analysis. In total, 6907 ticks (534 pools) were collected and identified as belonging to five species (Haemaphysalis spp., H. longicornis, H. flava, I. nipponensis, and A. testudinarium). Through 16S rRNA metabarcoding, 240 amplicon sequence variants were identified. The dominant taxa were Rickettsiella and Coxiella. Additionally, pathogenic bacteria such as Rickettsia and Ehrlichia, endosymbiotic bacteria such as Wolbachia and Spiroplasma were identified. Polymerase chain reaction (PCR) was performed to confirm the presence of Rickettsia, Ehrlichia, Bartonella, and Wolbachia in individual ticks. Overall, 352 (65.92%) of 534 pools tested positive for at least one of the screened tick-borne bacteria. Rickettsia was the most prevalent (61.42%), followed by Wolbachia (5.05%). Ehrlichia was detected in 4.86% of tested samples, whereas Bartonella was not detected. In this study, 16S rRNA metabarcoding revealed the presence of Rickettsia, Wolbachia, and Ehrlichia, in that order of abundance, while showing absence of Bartonella. These results were confirmed to exhibit the same trend as that of the conventional PCR. Therefore, large-scale screening studies based on pooling, as applied in this study, will be useful for examining novel or rare pathogens present in various hosts and vectors., (© 2024. The Author(s).)

Ticks are blood-sucking ectoparasites and can transmit various pathogens of medical and veterinary relevance. The life cycle of ticks can be completed under laboratory conditions on experimental animals, but the artificial feeding of ticks has attracted increased interest as an alternative method. This study represents the first report on the successful in vitro feeding of all life stages of two-host tick species, Hyalomma scupense and Hyalomma excavatum, and the three-host tick Hyalomma dromedarii. The attachment and engorgement rates of adults were 84% (21/25) and 76% (19/25) for H. scupense females. For adult H. excavatum and H. dromedarii, 70% (21/30) and 34.4% (11/32) of the females attached and all attached females successfully fed to repletion. The oviposition rates of the artificially fed females were 36.4%, 57.1% and 63.1% for H. dromedarii, H. excavatum and H. scupense, respectively, with a reproductive efficiency index varying between 44.3 and 60.7%. For the larvae, the attachment and engorgement rates were 44.2% (313/708) and 42.8% (303/708) for H. dromedarii, 70.5% (129/183) and 56.8% (104/183) for H. excavatum and 92.6% (113/122) and 55.7% (68/122) for H. scupense. The attachment and engorgement rates for the nymphs were 90.2% (129/143) and 47.6% (68/143) for H. dromedarii, 66.7% (34/51) and 41.2% (21/51) for H. excavatum, and 44.1% (30/68) and 36.8% (25/68) for H. scupense. Molting rates of the immature stages varied between 71.3% (216/303) and 100% (68/68) for the larvae and between 61.9% (13/21) and 96% (24/25) for the nymphs. The successful in vitro feeding of all stages of the three Hyalomma species makes this method a valuable tool for tick research, with potential applications in studies on the pathogens transmitted by these tick species such as Theileria annulata., (© 2024. The Author(s).)

Tick-borne bacteria of the genera Rickettsia and Coxiella cause several emerging veterinary and human infectious diseases. Ticks of the genus Hyalomma are medically important vectors due to their potential role in the transmission of pathogens to vertebrate hosts. There is an inadequate knowledge on tick-borne Rickettsia spp. and Coxiella spp. in ticks infesting transhumant camels in Pakistan. In this study, we conducted a molecular survey for screening of Rickettsia spp. and Coxiella spp. in ticks infesting camels. Seven hard tick species including Hyalomma dromedarii, Hyalomma anatolicum, Hyalomma scupense, Hyalomma isaaci, Hyalomma turanicum, Hyalomma asiaticum, and Rhipicephalus sanguineus s.l were confirmed on camels in three distinct physiographic regions of Khyber Pakhtunkhwa, Pakistan. A subset of morphologically identified ticks were subjected to molecular assays for the genetic characterization of ticks and the detection and genetic characterization of Rickettsia and Coxiella species using standard genetic markers. Ticks screened for pathogens resulted in the detection of Rickettsia aeschlimannii and Candidatus Rickettsia shennongii and Coxiella burnetii. The molecular analysis further reveals the presences of an undetermined Rickettsia aeschlimannii-like species, that is making a distinct phylogenetic clade with R. aeschlimannii. The detection of pathogens in camel ticks poses potential health hazards as these ticks frequently bites humans. Molecular screening of Rickettsia spp. and Coxiella spp. associated with camel ticks is a preliminary step toward the surveillance of evaluating their zoonotic threats in the region., (© 2024. The Author(s).)

Abstract Anaplasma and Ehrlichia are tick-borne bacterial pathogens that cause anaplasmoses and ehrlichioses in humans and animals. In this study, we examined the prevalence of Anaplasma and Ehrlichia species in ticks and domesticated animals in Suizhou County, Hubei Province in the central China. We used PCR amplification and DNA sequencing of the 16S rRNA, groEL, and gltA genes to analyze. We collected 1900 ticks, including 1981 Haemaphysalis longicornis and 9 Rhipicephalus microplus, 159 blood samples of goats (n = 152), cattle (n = 4), and dogs (n = 3) from May to August of 2023. PCR products demonstrated that Anaplasma bovis, Anaplasma capra, and an Ehrlichia species were detected in the H. longicornis with the minimum infection rates (MIR) of 1.11%, 1.32%, and 0.05%, respectively; A. bovis, A. capra, and unnamed Anaplasma sp. were detected in goats with an infection rate of 26.31%, 1.31% and 1.97%, respectively. Anaplasma and Ehrlichia species were not detected from cattle, dogs and R. microplus ticks. The genetic differences in the groEL gene sequences of the Anaplasma in the current study were large, whereas the 16S rRNA and gltA gene sequences were less disparate. This study shows that ticks and goats in Suizhou County, Hubei Province carry multiple Anaplasma species and an Ehrlichia species, with relatively higher infection rate of A. bovis in goats. Our study indicates that multiple Anaplasma and Ehrlichia species exist in ticks and goats in the central China with potential to cause human infection.

Tick bites, associated with the secretion of tick saliva containing the xenoglycan galactose-alpha-1, 3-galactose (alpha-gal or aGal), are recognized as the causal factors of alpha-Gal syndrome (AGS; or red meat allergy) in humans. AGS occurs after the increased production of IgE antibodies against aGal, which is found in most mammalian cells, except for the Old World monkey and humans. The aGal sensitization event has been linked to an initial tick bite, followed by consumption of red meat containing the aGal glycan, which triggers the onset of the allergic response resulting in urticaria, anaphylaxis, or even death. In North America, the lone star tick, Amblyomma americanum, has been identified as the main culprit for AGS. However, only a subset of the human population exposed to lone star tick bites develops AGS. This suggests the presence of unidentified variables associated with the sensitization event. To evaluate the quantitative variations of the aGal in ticks, we evaluated the differences in aGal levels in different strains of A. americanum ticks partially fed on different blood sources using an artificial feeding system and animal hosts. We found significantly higher aGal levels in the female ticks fed on human blood than those fed on the blood of other mammals with large variations among different tick populations and individuals. We propose that host-specific genetic components in the A. americanum ticks are involved in the production of high aGal epitope in the tick saliva, which provides a part of the explanation for the variables associated with the AGS sensitization event of the tick bite., (© 2023. The Author(s).)

Hard ticks are known vectors of various pathogens, including the severe fever with thrombocytopenia syndrome virus, Rickettsia spp., Coxiella burnetii, Borrelia spp., Anaplasma phagocytophilum, and Ehrlichia spp. This study aims to investigate the distribution and prevalence of tick-borne pathogens in southwestern Korea from 2019 to 2022. A total of 13,280 ticks were collected during the study period, with H. longicornis accounting for 86.1% of the collected ticks. H. flava, I. nipponensis and A. testudinarium comprised 9.4%, 3.6%, and 0.8% of the ticks, respectively. Among 983 pools tested, Rickettsia spp. (216 pools, 1.6% MIR) were the most prevalent pathogens across all tick species, with R. japonica and R. monacensis frequently detected in I. nipponensis and Haemaphysalis spp., respectively. Borrelia spp. (28 pools, 0.2% MIR) were predominantly detected in I. nipponensis (27 pools, 13.8% MIR, P < 0.001). Co-infections, mainly involving Rickettsia monacensis and Borrelia afzelii, were detected in I. nipponensis. Notably, this study identified R. monacensis for the first time in A. testudinarium in South Korea. These findings offer valuable insights into the tick population and associated pathogens in the region, underscoring the importance of tick-borne disease surveillance and prevention measures., (© 2024. The Author(s).)

We evaluated the presence of Ehrlichia spp. in unfed capybara ticks, Amblyomma dubitatum, and explored its association with capybaras density, ticks density and environmental variables. We observed that in the Iberá wetlands ecoregion A. dubitatum is infected by "Candidatus Ehrlichia hydrochoerus" and in a lesser extent with an Ehrlichia species closely related to Ehrlichia chaffeensis. The frequency of "Ca. Ehrlichia hydrochoerus" presence in A. dubitatum was not associated with vector abundance, but the probability of finding "Ca. Ehrlichia hydrochoerus"-infected ticks increased when the density of capybaras was low two months before. We hypothesize that when the density of capybaras decreases, A. dubitatum immature stages may seek out alternative hosts one of which could exhibit high realized reservoir competence for "Ca. Ehrlichia hydrochoerus", leading to an increased prevalence of this ehrlichiae in questing A. dubitatum. High minimum temperatures and high cumulative rainfall in the time period previous to tick collection (15 to 60 days) were positively correlated with the prevalence of "Ca. Ehrlichia hydrochoerus" infection in A. dubitatum. Our results suggest that a combination of factors (both biological and abiotic) could raise the risk of human exposure to tick-borne Ehrlichia in the Iberá wetlands ecoregion., (© 2023. The Author(s).)

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. [ABSTRACT FROM AUTHOR]

Abstract Ticks are blood-sucking ectoparasites that act as vectors for transmission of various pathogens. The purpose of this study was to assess tick-borne bacteria, whether pathogenic or not, in ticks distributed in Korea using 16S rRNA metabarcoding and to confirm the results by PCR. Questing ticks were collected from four provinces in Korea in 2021 using the flagging method. After pooling the DNAs from the 61 tick pools (including 372 ticks), the bacterial 16S rRNA V3–V4 hypervariable region was amplified and sequenced using the MiSeq platform. Rickettsia, Ehrlichia, and the endosymbiont Wolbachia were confirmed by conventional PCR and molecular analysis. In total, 6907 ticks (534 pools) were collected and identified as belonging to five species (Haemaphysalis spp., H. longicornis, H. flava, I. nipponensis, and A. testudinarium). Through 16S rRNA metabarcoding, 240 amplicon sequence variants were identified. The dominant taxa were Rickettsiella and Coxiella. Additionally, pathogenic bacteria such as Rickettsia and Ehrlichia, endosymbiotic bacteria such as Wolbachia and Spiroplasma were identified. Polymerase chain reaction (PCR) was performed to confirm the presence of Rickettsia, Ehrlichia, Bartonella, and Wolbachia in individual ticks. Overall, 352 (65.92%) of 534 pools tested positive for at least one of the screened tick-borne bacteria. Rickettsia was the most prevalent (61.42%), followed by Wolbachia (5.05%). Ehrlichia was detected in 4.86% of tested samples, whereas Bartonella was not detected. In this study, 16S rRNA metabarcoding revealed the presence of Rickettsia, Wolbachia, and Ehrlichia, in that order of abundance, while showing absence of Bartonella. These results were confirmed to exhibit the same trend as that of the conventional PCR. Therefore, large-scale screening studies based on pooling, as applied in this study, will be useful for examining novel or rare pathogens present in various hosts and vectors.

RNA activation (RNAa) is a burgeoning area of research in which double-stranded RNAs (dsRNAs) or small activating RNAs mediate the upregulation of specific genes by targeting the promoter sequence and/or AU-rich elements in the 3'- untranslated region (3'-UTR) of mRNA molecules. So far, studies on the phenomenon have been limited to mammals, plants, bacteria, Caenorhabditis elegans, and recently, Aedes aegypti. However, it is yet to be applied in other arthropods, including ticks, despite the ubiquitous presence of argonaute 2 protein, which is an indispensable requirement for the formation of RNA-induced transcriptional activation complex to enable a dsRNA-mediated gene activation. In this study, we demonstrated for the first time the possible presence of RNAa phenomenon in the tick vector, Haemaphysalis longicornis (Asian longhorned tick). We targeted the 3'-UTR of a novel endochitinase-like gene (HlemCHT) identified previously in H. longicornis eggs for dsRNA-mediated gene activation. Our results showed an increased gene expression in eggs of H. longicornis endochitinase-dsRNA-injected (dsHlemCHT) ticks on day-13 post-oviposition. Furthermore, we observed that eggs of dsHlemCHT ticks exhibited relatively early egg development and hatching, suggesting a dsRNA-mediated activation of the HlemCHT gene in the eggs. This is the first attempt to provide evidence of RNAa in ticks. Although further studies are required to elucidate the detailed mechanism by which RNAa occurs in ticks, the outcome of this study provides new opportunities for the use of RNAa as a gene overexpression tool in future studies on tick biology, to reduce the global burden of ticks and tick-borne diseases., (© 2023. The Author(s).)

Abstract The blacklegged tick, Ixodes scapularis, is an ectoparasitic arachnid and vector for infectious diseases, including Lyme borreliosis. Here, we investigate the diurnal activity and respiration of wild-caught and lab-reared adult ticks with long-term video recording, multi-animal tracking and high-resolution respirometry. We find male and female ticks are in a more active, more arousable state during circadian night. We find respiration is augmented by light, with dark onset triggering more frequent bouts of discontinuous gas exchange and a higher overall volume of CO2 respired. Observed inactivity during the day meets the criteria of sleep: homeostatic in nature, rapidly reversible, a characteristic pose, and reduced arousal threshold. Our findings indicate that blacklegged ticks are in a distinct, heightened state of activity and arousability during night and in dark, suggesting this period may carry higher risk for tick bites and subsequent contraction of tick-borne diseases.

Abstract Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne virus with a mortality rate of up to 30%. First identified in China in 2009, it was later reported in other Asian countries, including Thailand in 2020. SFTSV has been detected in several tick species, including Rhipicephalus sanguineus, known for infesting dogs. We conducted a seroprevalence study of SFTSV in Bangkok and Nong Khai, Thailand, by analyzing 1162 human samples collected between 2019 and 2023. The testing method relied on IgG detection using ELISA and confirmed though a virus seroneutralization test. The results indicated that out of the participants, 12 (1.1%) tested positive for anti-SFTSV IgG antibodies; however, none exhibited positive results in the seroneutralization assay. Additionally, molecular detection of SFTSV, Crimean-Congo hemorrhagic fever (CCHF), Coxiella spp., Bartonella spp., and Rickettsia spp. was performed on 433 Rh. sanguineus ticks collected from 49 dogs in 2023 in Chachoengsao Province, Thailand. No evidence of these pathogens was found in ticks. These findings highlight the importance of exploring viral cross-reactivity. Furthermore, it is important to conduct additional studies to isolate SFTSV from animals and ticks in order to identify the potential transmission routes contributing to human and animal infections in Thailand.

Abstract Hard ticks are known vectors of various pathogens, including the severe fever with thrombocytopenia syndrome virus, Rickettsia spp., Coxiella burnetii, Borrelia spp., Anaplasma phagocytophilum, and Ehrlichia spp. This study aims to investigate the distribution and prevalence of tick-borne pathogens in southwestern Korea from 2019 to 2022. A total of 13,280 ticks were collected during the study period, with H. longicornis accounting for 86.1% of the collected ticks. H. flava, I. nipponensis and A. testudinarium comprised 9.4%, 3.6%, and 0.8% of the ticks, respectively. Among 983 pools tested, Rickettsia spp. (216 pools, 1.6% MIR) were the most prevalent pathogens across all tick species, with R. japonica and R. monacensis frequently detected in I. nipponensis and Haemaphysalis spp., respectively. Borrelia spp. (28 pools, 0.2% MIR) were predominantly detected in I. nipponensis (27 pools, 13.8% MIR, P

Abstract 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.

Abstract 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.

Abstract Birds play a crucial role in disseminating ticks that carry pathogens of high veterinary-medical importance. The aim of this study was to analyze data of a long-term tick collection from birds at a single stop-over site in Central Europe, Hungary. Over eight years (2015–2022) 5833 ticks (ten species) were collected from 2395 tick-infested birds. The most abundant species were Ixodes ricinus (n = 3971) and Haemaphysalis concinna (n = 1706). Ixodes ricinus nymphs and larvae were the most frequently occurring on resident and short-distance migratory birds with forest habitat but Ha. concinna was the most abundant species on reed-associated, long-distance migrants. Haemaphysalis concinna occurred mostly on birds feeding above the ground level, while I. ricinus predominated on ground feeding birds. Infestation with I. ricinus nymphs always peaked in the first half of the year, in contrast to larvae which were more abundant on avian hosts in the autumn. At the same time, Ha. concinna larvae and nymphs had their peak numbers in the summer. This is the first long-term study on the tick infestation of birds in Central Europe. The study shows that, migration distance, habitat type, and typical feeding level of birds, as well as characteristics of tick life cycle are all key factors in the role of birds as tick disseminators. It was revealed that Savi’s Warbler (Locustella luscinioides) is the most frequent hosts of Ha. concinna in Central Hungary.

Abstract Ticks are blood-sucking ectoparasites and can transmit various pathogens of medical and veterinary relevance. The life cycle of ticks can be completed under laboratory conditions on experimental animals, but the artificial feeding of ticks has attracted increased interest as an alternative method. This study represents the first report on the successful in vitro feeding of all life stages of two-host tick species, Hyalomma scupense and Hyalomma excavatum, and the three-host tick Hyalomma dromedarii. The attachment and engorgement rates of adults were 84% (21/25) and 76% (19/25) for H. scupense females. For adult H. excavatum and H. dromedarii, 70% (21/30) and 34.4% (11/32) of the females attached and all attached females successfully fed to repletion. The oviposition rates of the artificially fed females were 36.4%, 57.1% and 63.1% for H. dromedarii, H. excavatum and H. scupense, respectively, with a reproductive efficiency index varying between 44.3 and 60.7%. For the larvae, the attachment and engorgement rates were 44.2% (313/708) and 42.8% (303/708) for H. dromedarii, 70.5% (129/183) and 56.8% (104/183) for H. excavatum and 92.6% (113/122) and 55.7% (68/122) for H. scupense. The attachment and engorgement rates for the nymphs were 90.2% (129/143) and 47.6% (68/143) for H. dromedarii, 66.7% (34/51) and 41.2% (21/51) for H. excavatum, and 44.1% (30/68) and 36.8% (25/68) for H. scupense. Molting rates of the immature stages varied between 71.3% (216/303) and 100% (68/68) for the larvae and between 61.9% (13/21) and 96% (24/25) for the nymphs. The successful in vitro feeding of all stages of the three Hyalomma species makes this method a valuable tool for tick research, with potential applications in studies on the pathogens transmitted by these tick species such as Theileria annulata.

Many arthropods harbour bacterial symbionts, which are maintained by vertical and/or horizontal transmission. Spiroplasma is one of the most well-known symbionts of ticks and other arthropods. It is still unclear how Spiroplasma infections have spread in tick populations despite its high prevalence in some tick species. In this study, Ixodes ovatus, which has been reported to harbour Spiroplasma ixodetis at high frequencies, was examined for its vertical transmission potential under experimental conditions. Next, two isolates of tick-derived Spiroplasma, S. ixodetis and Spiroplasma mirum, were experimentally inoculated into Spiroplasma-free Haemaphysalis longicornis colonies and the presence of Spiroplasma in their eggs and larvae was tested. Our experimental data confirmed that S. ixodetis was transmitted to eggs and larvae in a vertical manner in the original host I. ovatus. In the second experiment, there was no significant difference in engorged weight, egg weight, and hatching rate between Spiroplasma-inoculated and control H. longicornis groups. This suggested that Spiroplasma infection does not affect tick reproduction. Spiroplasma DNA was only detected in the eggs and larvae derived from some individuals of S. ixodetis-inoculated groups. This has demonstrated the potential of horizontal transmission between different tick species. These findings may help understand the transmission dynamics of Spiroplasma in nature and its adaptation mechanism to host arthropod species. [ABSTRACT FROM AUTHOR]

Migratory birds disperse ticks and associated tick-borne pathogens along their migratory routes. Four selected pathogens of medical importance (Coxiella burnetii, Rickettsia spp., Francisella tularensis, and Toxoplasma gondii) were targeted for detection in 804 ticks (365 pools) collected from migratory birds at Hong and Heuksan Islands in the Republic of Korea (ROK) from 2010 to 2011 and 2016. Toxoplasma gondii and Rickettsia spp., were detected in 1/365 (0.27%) and 34/365 (9.32%) pools of ticks, respectively. T. gondii and five rickettsial species were recorded in ticks collected from migratory birds for the first time in ROK. The five rickettsial species (R. monacensis, Candidatus Rickettsia longicornii, R. japonica, R. raoultii, and R. tamurae) were identified using sequence and phylogenetic analysis using ompA and gltA gene fragments. Rickettsia spp. are important pathogens that cause rickettsiosis in humans, with cases recorded in the ROK. These results provide important evidence for the potential role of migratory birds in the introduction and dispersal of T. gondii and Rickettsia spp. along their migratory routes and raise awareness of potential transmission of zoonotic tick-borne pathogens associated with migratory birds in the ROK., (© 2022. The Author(s).)

The public health problem of tick-borne diseases has attracted much attention in recent years due to an increasing incidence in humans and animals. The aim of this study was to compare the risk of exposure to ticks and tick-borne infections in dogs and cats in recreational and urbanized areas in the Lesser Poland and Silesian Provinces. For molecular testing for the presence of the selected pathogens, 207 I. ricinus females collected from 119 dogs and 50 cats, and 2 I. hexagonus females collected from 2 domestic dogs, were examined. Overall, A. phagocytophilum was found in 3.7% of the I. ricinus specimens, B. microti in 27.1%, and B. burgdorferi s.l. in 0.9%. In urban areas of both provinces, A. phagocytophilum was found in 4.8% of the I. ricinus specimens, B. microti in 41.6% and B. burgdorferi s.l. in 3.9%. Pathogens were detected B. microti in both studied I. hexagonus specimens. These findings may indicate the important role that these animals play in the circulation of these pathogens in nature., (© 2022. The Author(s).)

Abstract Tick bites, associated with the secretion of tick saliva containing the xenoglycan galactose-alpha-1, 3-galactose (alpha-gal or aGal), are recognized as the causal factors of alpha-Gal syndrome (AGS; or red meat allergy) in humans. AGS occurs after the increased production of IgE antibodies against aGal, which is found in most mammalian cells, except for the Old World monkey and humans. The aGal sensitization event has been linked to an initial tick bite, followed by consumption of red meat containing the aGal glycan, which triggers the onset of the allergic response resulting in urticaria, anaphylaxis, or even death. In North America, the lone star tick, Amblyomma americanum, has been identified as the main culprit for AGS. However, only a subset of the human population exposed to lone star tick bites develops AGS. This suggests the presence of unidentified variables associated with the sensitization event. To evaluate the quantitative variations of the aGal in ticks, we evaluated the differences in aGal levels in different strains of A. americanum ticks partially fed on different blood sources using an artificial feeding system and animal hosts. We found significantly higher aGal levels in the female ticks fed on human blood than those fed on the blood of other mammals with large variations among different tick populations and individuals. We propose that host-specific genetic components in the A. americanum ticks are involved in the production of high aGal epitope in the tick saliva, which provides a part of the explanation for the variables associated with the AGS sensitization event of the tick bite.

Abstract Lyme disease, one of the most common tickborne diseases, has been rapidly spreading in parallel with the expansion of the range of its tick vector. Better tick surveillance efforts are needed to accurately estimate disease risk and to guide public health and clinical management. We have developed two multiplex loop-mediated isothermal amplification (LAMP) reactions coupled with oligonucleotide strand displacement (OSD) probes to identify the tick host, Ixodes scapularis, and the Lyme disease pathogen, Borrelia burgdorferi, they carry. In each multiplex LAMP-OSD assay the co-presence of two target sequences is computed at the DNA level by linking the two corresponding amplicons and detecting the co-product on colorimetric lateral flow dipsticks. In tests with synthetic DNA, the co-presence of as few as four copies of input DNA could be detected, without producing spurious signals. Most importantly, though, the LAMP-OSD assay is amenable to being carried out directly with macerated tick samples, without any sample preparation. In such field conditions, assays performed robustly and demonstrated 97–100% sensitivity and 100% specificity with both field-collected and lab-raised artificially infected ticks. Such easy-to-use, arthropod and pathogen-specific assays would be well suited to field and near patient use without relying on complex instrumentation or infrastructure.

Abstract We evaluated the presence of Ehrlichia spp. in unfed capybara ticks, Amblyomma dubitatum, and explored its association with capybaras density, ticks density and environmental variables. We observed that in the Iberá wetlands ecoregion A. dubitatum is infected by "Candidatus Ehrlichia hydrochoerus” and in a lesser extent with an Ehrlichia species closely related to Ehrlichia chaffeensis. The frequency of "Ca. Ehrlichia hydrochoerus" presence in A. dubitatum was not associated with vector abundance, but the probability of finding "Ca. Ehrlichia hydrochoerus"-infected ticks increased when the density of capybaras was low two months before. We hypothesize that when the density of capybaras decreases, A. dubitatum immature stages may seek out alternative hosts one of which could exhibit high realized reservoir competence for "Ca. Ehrlichia hydrochoerus", leading to an increased prevalence of this ehrlichiae in questing A. dubitatum. High minimum temperatures and high cumulative rainfall in the time period previous to tick collection (15 to 60 days) were positively correlated with the prevalence of "Ca. Ehrlichia hydrochoerus" infection in A. dubitatum. Our results suggest that a combination of factors (both biological and abiotic) could raise the risk of human exposure to tick-borne Ehrlichia in the Iberá wetlands ecoregion.

Abstract Many arthropods harbour bacterial symbionts, which are maintained by vertical and/or horizontal transmission. Spiroplasma is one of the most well-known symbionts of ticks and other arthropods. It is still unclear how Spiroplasma infections have spread in tick populations despite its high prevalence in some tick species. In this study, Ixodes ovatus, which has been reported to harbour Spiroplasma ixodetis at high frequencies, was examined for its vertical transmission potential under experimental conditions. Next, two isolates of tick-derived Spiroplasma, S. ixodetis and Spiroplasma mirum, were experimentally inoculated into Spiroplasma-free Haemaphysalis longicornis colonies and the presence of Spiroplasma in their eggs and larvae was tested. Our experimental data confirmed that S. ixodetis was transmitted to eggs and larvae in a vertical manner in the original host I. ovatus. In the second experiment, there was no significant difference in engorged weight, egg weight, and hatching rate between Spiroplasma-inoculated and control H. longicornis groups. This suggested that Spiroplasma infection does not affect tick reproduction. Spiroplasma DNA was only detected in the eggs and larvae derived from some individuals of S. ixodetis-inoculated groups. This has demonstrated the potential of horizontal transmission between different tick species. These findings may help understand the transmission dynamics of Spiroplasma in nature and its adaptation mechanism to host arthropod species.

Abstract Dermacentor reticulatus ticks are sporadically removed from human skin and therefore the medical consequences of their feeding are neglected compared to Ixodes ricinus. We investigated the prevalence of pathogens in D. reticulatus removed from human skin and possible clinical manifestations suggestive of tick-borne diseases after a tick bite. A total of 2153 ticks were studied and of these only 34 were D. reticulatus. The mean prevalence of Rickettsia in D. reticulatus was 50.0% and R. raoultii was identified in 82.4% of infected D. reticulatus ticks. We confirmed the first case of R. aeschlimannii infection in D. reticulatus ticks. Among participants bitten by D. reticulatus, 13.3% reported reddening around the tick bite site and flu-like symptoms, including lymphadenopathy and 3.3% reported eschar on the tick site bite. All of the participants with flu-like symptoms after tick removal were bitten by ticks infected with R. raoultii. The results of this study indicate that even though D. reticulatus ticks bite humans sporadically, pathogenic Rickettsia have a remarkably high prevalence in this tick species. We can expect that the incidence of tick-borne lymphadenopathy might increase with the reported expansion of the D. reticulatus into new areas and its growing abundance in Central Europe.

Abstract Ixodes ricinus and Dermacentor reticulatus ticks are important reservoirs and vectors of pathogens. The aim of the present study was to investigate the dynamic of the prevalence and genetic diversity of microorganisms detected in these tick species collected from two ecologically diverse biotopes undergoing disparate long-term climate condition. High-throughput real time PCR confirmed high prevalence of microorganisms detected in sympatrically occurring ticks species. D. reticulatus specimens were the most often infected with Francisella-like endosymbiont (FLE) (up to 100.0%) and Rickettsia spp. (up to 91.7%), while in case of I. ricinus the prevalence of Borreliaceae spirochetes reached up to 25.0%. Moreover, pathogens belonging to genera of Bartonella, Anaplasma, Ehrlichia and Babesia were detected in both tick species regardless the biotope. On the other hand, Neoehrlichia mikurensis was conformed only in I. ricinus in the forest biotope, while genetic material of Theileria spp. was found only in D. reticulatus collected from the meadow. Our study confirmed significant impact of biotope type on prevalence of representatives of Borreliaceae and Rickettsiaceae families. The most common co-infection detected in D. reticulatus was Rickettsia spp. + FLE, while Borreliaceae + R. helvetica was the most common in I. ricinus. Additionally, we found significant genetic diversity of R. raoultii gltA gene across studied years, however such relationship was not observed in ticks from studied biotopes. Our results suggest that ecological type of biotope undergoing disparate long-term climate conditions have an impact on prevalence of tick-borne pathogens in adult D. reticulatus and I. ricinus.

Abstract RNA activation (RNAa) is a burgeoning area of research in which double-stranded RNAs (dsRNAs) or small activating RNAs mediate the upregulation of specific genes by targeting the promoter sequence and/or AU-rich elements in the 3′- untranslated region (3’-UTR) of mRNA molecules. So far, studies on the phenomenon have been limited to mammals, plants, bacteria, Caenorhabditis elegans, and recently, Aedes aegypti. However, it is yet to be applied in other arthropods, including ticks, despite the ubiquitous presence of argonaute 2 protein, which is an indispensable requirement for the formation of RNA-induced transcriptional activation complex to enable a dsRNA-mediated gene activation. In this study, we demonstrated for the first time the possible presence of RNAa phenomenon in the tick vector, Haemaphysalis longicornis (Asian longhorned tick). We targeted the 3ʹ-UTR of a novel endochitinase-like gene (HlemCHT) identified previously in H. longicornis eggs for dsRNA-mediated gene activation. Our results showed an increased gene expression in eggs of H. longicornis endochitinase-dsRNA-injected (dsHlemCHT) ticks on day-13 post-oviposition. Furthermore, we observed that eggs of dsHlemCHT ticks exhibited relatively early egg development and hatching, suggesting a dsRNA-mediated activation of the HlemCHT gene in the eggs. This is the first attempt to provide evidence of RNAa in ticks. Although further studies are required to elucidate the detailed mechanism by which RNAa occurs in ticks, the outcome of this study provides new opportunities for the use of RNAa as a gene overexpression tool in future studies on tick biology, to reduce the global burden of ticks and tick-borne diseases.

Abstract Chronic wasting disease (CWD) is a fatal neurodegenerative disease caused by infectious prions (PrPCWD) affecting cervids. Circulating PrPCWD in blood may pose a risk for indirect transmission by way of hematophagous ectoparasites acting as mechanical vectors. Cervids can carry high tick infestations and exhibit allogrooming, a common tick defense strategy between conspecifics. Ingestion of ticks during allogrooming may expose naïve animals to CWD, if ticks harbor PrPCWD. This study investigates whether ticks can harbor transmission-relevant quantities of PrPCWD by combining experimental tick feeding trials and evaluation of ticks from free-ranging white-tailed deer (Odocoileus virginianus). Using the real-time quaking-induced conversion (RT-QuIC) assay, we show that black-legged ticks (Ixodes scapularis) fed PrPCWD-spiked blood using artificial membranes ingest and excrete PrPCWD. Combining results of RT-QuIC and protein misfolding cyclic amplification, we detected seeding activity from 6 of 15 (40%) pooled tick samples collected from wild CWD-infected white-tailed deer. Seeding activities in ticks were analogous to 10–1000 ng of CWD-positive retropharyngeal lymph node collected from deer upon which they were feeding. Estimates revealed a median infectious dose range of 0.3–42.4 per tick, suggesting that ticks can take up transmission-relevant amounts of PrPCWD and may pose a CWD risk to cervids.

Theileria annulata is a protozoan parasite with a complex life cycle involving a bovine host and a tick vector. It is transmitted by Hyalomma ticks and is the causative agent of tropical theileriosis, a debilitating and often fatal disease in southern Europe, northern Africa and large parts of Asia. Understanding the biology of different life cycle stages is critical for the control of tropical theileriosis and requires the use of experimental animals which poses an ethical concern. We present for the first time the in vitro infection of red blood cells (RBCs) with T. annulata differentiated schizonts. The Ankara cell line of T. annulata was cultured at 41 °C for nine days to induce merogony and subsequently incubated with purified RBCs for one to three days. Percentage of parasitized erythrocyte (PPE) over the short culture period was estimated by Giemsa staining (0.007-0.01%), Flow cytometry activated sorting (FACS) (0.02-1.1%) and observation of FACS sorted cells by confocal microscopy (0.05-0.4%). There was a significant difference in the PPE between FACS and the two other techniques (one-way ANOVA followed by Tukey test, P = 0.004) but no significant difference was observed between the confocal imaging and Giemsa staining methods (ANOVA one-way followed by Tukey test, P = 0.06). Importantly, all three complementary methods confirmed the invasion of RBCs by T. annulata merozoites in vitro. Although the experimental conditions will require further optimization to increase the PPE, the in vitro infection of RBCs by T. annulata merozoites is pivotal in paving the way for the eventual completion of the T. annulata life cycle in vitro when combined with artificial tick feeding., (© 2024. The Author(s).)

A. phagocytophilum is a zoonotic and tick-borne bacterium, threatening human and animal health. Many questions persist concerning the variability of strains and the mechanisms governing the interactions with its different hosts. These gaps can be explained by the difficulty to cultivate and study A. phagocytophilum because of its strict intracellular location and the lack of specific tools, in particular monoclonal antibodies, currently unavailable. The objective of our study was to develop DNA aptamers against A. phagocytophilum, or molecules expressed during the infection, as new study and/or capture tools. Selecting aptamers was a major challenge due to the strict intracellular location of the bacterium. To meet this challenge, we set up a customized selection protocol against an enriched suspension of A. phagocytophilum NY18 strain, cultivated in HL-60 cells. The implementation of SELEX allowed the selection of three aptamers, characterized by a high affinity for HL-60 cells infected with A. phagocytophilum NY18 strain. Interestingly, the targets of these three aptamers are most likely proteins expressed at different times of infection. The selected aptamers could contribute to increase our understanding of the interactions between A. phagocytophilum and its hosts, as well as permit the development of new diagnostic, therapeutic or drug delivery appliances., (© 2024. The Author(s).)

Ticks transmit several arthropod-borne pathogens in New York State. The primary human-biting ticks in this region are Ixodes scapularis, Amblyomma americanum, and Dermacentor variabilis. Body regions where tick bites human vary depending on the tick species and life stage, and clothing worn by the host. A community tick submission system was used to acquire information about bite-site location prior to pathogen testing to understand species and life stage-specific body-segment preferences. These data resulted in the identification of species-specific preferences for location, with D. variabilis preferentially biting the head and neck and A. americanum preferring the thighs, groin, and abdomen. Ixodes scapularis was found across the body, although it showed a significant life stage difference with adults preferring the head, midsection, and groin, while nymphs/larvae preferred the extremities. Infection with Borrelia burgdorferi resulted in a significant change in attachment site. This provides an assessment of which body region ticks of the most common species in New York are likely to be found. [ABSTRACT FROM AUTHOR]

Rickettsia are obligate intracellular bacteria often associated with ticks and best known for causing human diseases (rickettsiosis), including typhus fever and sporadic cases of serious infection. In this study, we conducted a large survey of ticks in French Guiana to understand the overall diversity of Rickettsia in this remote area largely covered by dense rainforests. Out of 819 individuals (22 tick species in six genera), 252 (30.8%) samples were positive for Rickettsia infection. Multilocus typing and phylogenetic analysis identified 19 Rickettsia genotypes, but none was 100% identical to already known Rickettsia species or strains. Among these 19 genotypes, we identified two validated Rickettsia species, Rickettsia amblyommatis (spotted fever group) and Rickettsia bellii (bellii group), and characterized a novel and divergent Rickettsia phylogenetic group, the guiana group. While some tick hosts of these Rickettsia genotypes are among the most common ticks to bite humans in French Guiana, their potential pathogenicity remains entirely unknown. However, we found a strong association between Rickettsia genotypes and their host tick species, suggesting that most of these Rickettsia genotypes may be nonpathogenic forms maintained through transovarial transmission.

Abstract Ticks transmit several arthropod-borne pathogens in New York State. The primary human-biting ticks in this region are Ixodes scapularis, Amblyomma americanum, and Dermacentor variabilis. Body regions where tick bites human vary depending on the tick species and life stage, and clothing worn by the host. A community tick submission system was used to acquire information about bite-site location prior to pathogen testing to understand species and life stage-specific body-segment preferences. These data resulted in the identification of species-specific preferences for location, with D. variabilis preferentially biting the head and neck and A. americanum preferring the thighs, groin, and abdomen. Ixodes scapularis was found across the body, although it showed a significant life stage difference with adults preferring the head, midsection, and groin, while nymphs/larvae preferred the extremities. Infection with Borrelia burgdorferi resulted in a significant change in attachment site. This provides an assessment of which body region ticks of the most common species in New York are likely to be found.

Abstract Cases of mosquito- and tick-borne diseases are rising worldwide. Repellent products can protect individual users from being infected by such diseases. In a previous study, we identified five essential oils that display long-distance mosquito repellency using a Y-tube olfactometer assay. In the current study, the contact repellent efficacy of 20 active ingredients from the Environmental Protection Agency’s (EPA) Minimum Risk Pesticides list were tested using Aedes aegypti and Ixodes scapularis. We utilized an arm-in-cage assay to measure complete protection time from mosquito bites for these active ingredients. To measure tick repellency, we used an EPA-recommended procedure to measure the complete protection time from tick crossings. We found that of the 20 ingredients tested, 10% v/v lotion emulsions with clove oil or cinnamon oil provided the longest protection from both mosquito bites and tick crossings. We conclude that in a 10% v/v emulsion, specific active ingredients from the EPA Minimum Risk Pesticides list can provide complete protection from mosquito bites and tick crossings for longer than one hour.

Abstract The parasitoid wasp, Ixodiphagus hookeri (Hymenoptera: Encyrtidae), is the natural enemy of a wide range of hard and soft tick species. While these encyrtid wasps are supposed to be distributed worldwide, only a few studies report on their actual distribution around the globe. Within a shotgun sequencing-based metagenome analysis, the occurrence of I. hookeri was screened at multiple Ixodes ricinus (Acari: Ixodidae) tick sampling points in Hungary to contribute to the assessment of the distribution patterns of the parasitoid wasps in Central Europe. To our knowledge, the first report of the species in Hungary and the description of the southernmost I. hookeri associated geoposition in Central Europe took place within our study. I. hookeri infested I. ricinus nymphs were detected at five sampling points in Hungary. The results show that the exact distribution range of I. hookeri is still barely studied. At the same time, unprecedented public health issues being brought about by climate change might require steps toward the exploitation of the tick biocontrol potential and as an ecological bioindicator role of the parasitoid wasp in the future.

Blood-feeding behavior has independently evolved in arthropods multiple times. Unlike hard ticks, soft ticks employ a rapid-feeding strategy for hematophagy, and there are comparatively limited studies on the transcriptomes of these organisms. This study investigates the soft tick Ornithodoros hermsi, conducting histopathological examinations at bitten skin sites and tick whole-body transcriptomic analyses across various developmental and feeding stages, including larvae, 1st-nymphal, and 2nd-nymphal stages. The results revealed the ability of O. hermsi to induce skin hemorrhage at the bite sites. Transcriptomic analyses identified three consistent transcriptional profiles: unfed, early-fed (6 h, 12 h, 24 h), and late-fed (5 days). The unfed profile exhibited high transcriptional activity across most of the functional classes annotated. In contrast, early-fed stages exhibited decreased expression of most functional classes, except for the unknown, which is highly expressed. Finally, transcriptional expression of most functional classes increased in the late-fed groups, resembling the baseline expression observed in the unfed groups. These findings highlight intense pre-feeding transcriptional activity in O. hermsi ticks, aligning with their rapid-feeding strategy. Moreover, besides shedding light on the temporal dynamics of key pathways during blood meal processing and tick development, this study contributes significantly to the transcriptome repertoire of a medically relevant soft tick species with relatively limited prior knowledge. [ABSTRACT FROM AUTHOR]