Ticks and Tick-borne Diseases

Hyalomma marginatum is a common ectoparasitic tick of ungulates, lagomorphs, insectivores, ground-foraging birds, observed in Corsica for decades, but whose permanent establishment in mainland France is very recent. This species is known to be one of the main vectors of the Crimean-Congo Hemorrhagic Fever virus, but also of various parasitic, bacterial or viral pathogens. In this study, we investigated the molecular infection rates of numerous tick-borne pathogens in H. marginatum ticks mainly sampled on horses, and occasionally on other animal species, from the French Mediterranean rim and Corsica between 2016 and 2020. In total, 1, 195 DNA and RNA purified from individual ticks or pools of ticks were screened for 26 microbial genera or species (viruses, bacteria and parasites), using a high-throughput microfluidic real-time PCR system (BioMark dynamic array system, Standard Biotools). For individual ticks and pooled ones, respectively, the most prevalent tick-borne microorganisms were Francisella-like endosymbionts at 97.0% and 96.8%, followed by Rickettsia aeschlimannii (76.4% and 96.4%), Theileria spp. and Theileria equi (3,5% and 0%; 1,9% and 5,8%), Anaplasma phagocytophilum (3.7% and 6.7%), and West Nile virus (0.1% and 0.4%). Babesia occultans (0.9%), Ehrlichia minasensis (0.3%), and Coxiella-like endosymbionts (0.1%) were only detected in individual ticks. Our study provides an overview of the diversity of microorganisms and tick-borne pathogens detected in the invasive tick H. marginatum in Corsica and the continental departments of the Mediterranean rim. Our study opens up new research perspectives on the epidemiology of tick-borne pathogens carried by H. marginatum and on the associated public and veterinary health risks.

Spatio-temporal scales have a clear influence on microbial community distribution and diversity and are thus essential to consider to identify and study the dynamics of microorganisms. The invasive tick species Hyalomma marginatum has recently become established in southern France. It carries pathogens of medical and veterinary interest including the Crimean-Congo hemorrhagic fever virus, Rickettsia aeschlimannii, Theileria equi and Anaplasma phagocytophilum among others. While the pathogenic communities of H. marginatum were identified and their spatial distribution characterised, their temporal dynamics are still unknown. We performed a monthly H. marginatum tick collection from February to September 2022 in a sentinel site in southern France in order to study their presence and temporal dynamics. On the 281 ticks analysed, we detected pathogens included R. aeschlimannii, A. phagocytophilum and T. equi with infection rates reaching 47.0%, 4.6% and 11.0% respectively. Overall, 14.6% of ticks were infected with at least Theileria or Anaplasma, with monthly fluctuations ranging from 2.9% to 28.6%. Strong temporal patterns were observed for each of the detected pathogens, particularly for R. aeschlimannii whose infection rates drastically increased at the beginning of summer, correlated with the monthly mean temperatures in the sentinel site. Based on these results, we hypothesized that R. aeschlimannii might be a secondary symbiont of H. marginatum that could play a role into stress response to temperature. The analysis of monthly and seasonal fluctuations in H. marginatum-borne pathogens allowed us to conclude that the risk of infection is present throughout H. marginatum activity period, but particularly in summer. HighlightsO_LIStrong monthly fluctuations of pathogen infection rates were observed especially for Rickettsia aeschlimannii, currently identified as a human pathogen whose pathogenic status in humans and its symbiotic status in H. marginatum are both questioned. C_LIO_LIThe increase in temperature is correlated with the increase in Rickettsia aeschlimannii infection rates, providing clues about its potential function as a symbiont in H. marginatum. C_LIO_LITicks are recurrently infected with at least one other pathogen belonging to Theileria or Anaplasma genera with monthly fluctuations ranging from 2.9% to 28.6%. C_LIO_LIThe monthly dynamics of H. marginatum-borne pathogens are important to consider to assess the risk posed by this tick. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=81 SRC="FIGDIR/small/589770v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@b703d5org.highwire.dtl.DTLVardef@15cc273org.highwire.dtl.DTLVardef@e238d4org.highwire.dtl.DTLVardef@ebe1_HPS_FORMAT_FIGEXP M_FIG C_FIG

Hyalomma marginatum is an invasive tick species recently established in mainland southern France. This tick is known to host a diverse range of human and animal pathogens such as Rickettsia aeschlimannii, Theileria equi, Anaplasma phagocytophilum, Anaplasma marginale, Ehrlichia minasensis, Crimean-Congo hemorrhagic fever and West Nile virus. While information about the dynamics of these pathogens is crucial to assess disease risk and develop effective monitoring strategies, few data on the spatial dynamics of these pathogens are currently available. We thus collected ticks in 27 sites in the Occitanie region to characterize spatial patterns of H. marginatum- borne pathogens. Several pathogens have been detected: Theileria equi (9.2%), Theileria orientalis (0.2%), Anaplasma phagocytophilum (1.6%), Anaplasma marginale (0.8%) and Rickettsia aeschlimannii (87.3%). Interestingly, we found a spatial clustered distribution for the pathogen R. aeschlimannii between two geographically isolated areas with infection rates and bacterial loads significantly lower in Herault/Gard departments (infection rate 78.6% in average) compared to Aude/Pyrenees-Orientales departments (infection rate 92.3% in average). At a smaller scale, R. aeschlimannii infection rates varied from one site to another, ranging from 29% to 100%. Overall, such high infection rates (87.3% in average) and the effective maternal transmission of R. aeschlimannii might suggest a role as a tick symbiont in H. marginatum. Moreover, currently identified as a human pathogen, such results also question about its pathogenic status in humans given the low number of human cases. Further studies are thus needed to understand both the status and the role of R. aeschlimannii in H. marginatum ticks. IMPORTANCETicks are obligatory hematophagous arthropods which transmit pathogens of medical and veterinary importance. Their infections cause serious health issues in humans and considerable economic loss in domestic animals. Information about the presence of pathogens in ticks and their dynamics is crucial to assess disease risk for public and animal health. Analysing tick-borne pathogens in ticks collected in 27 sites in the regions Occitanie, our results highlight clear spatial patterns in the Hyalomma marginatum-borne pathogen distribution and strengthen the postulate that it is essential to develop effective monitoring strategies and consider the spatial scale to better characterize the circulation of tick-borne pathogens.

Tickborne diseases are a significant burden in many parts of the world. In the upper Midwestern United States, Lyme disease is the most common tickborne disease. It is carried by Ixodes scapularis. This vector can also transmit the pathogens causing anaplasmosis, babesiosis, ehrlichiosis, and several more tickborne diseases in this region. There is also concern for other tick species, such as Amblyomma americanum, that are expanding their ranges northward. We launched a citizen science passive tick surveillance program in 2024 to investigate tick species ranges in the upper Midwest, as well as the pathogens carried by I. scapularis. We received over 12,000 ticks in the first two years of this program, primarily from Wisconsin. While we received submissions of adult A. americanum outside of their endemic range, we did not see evidence of establishment in our study area. We measured pathogen prevalence in adult female I. scapularis (n=707) and observed 51% positivity for Borrelia burgdorferi, 9% for Babesia microti, 9% for Anaplasma phagocytophilum, and 3% for Ehrlichia muris eauclairensis. Multiple pathogens were identified in 14% of tested specimens, and significant associations were observed between B. burgdorferi and B. microti, and B. burgdorferi and E. muris eauclairensis. Pathogen prevalences varied across time and geography. Our results can begin to inform risk assessment for tickborne diseases in our region. A non-technical version of this document with interactive maps is available here: https://storymaps.arcgis.com/stories/8008c9d710b5400599f3c6cf88b2c546 Our online data dashboard is available here: redcap.link/TICS

Feline cytauxzoonosis is an emerging tick-borne disease in Europe. While infections have been reported in different European countries, the tick vector remains unknown. This study investigated 665 ticks collected in 2019 (n= 160), 2022 (n= 7) and 2024 (n= 658) in a Cytauxzoon spp. hotspot region in central Switzerland (62 ticks from cats; 603 ticks from vegetation). Ticks were morphologically characterized, pooled by origin and life-stage, screened for Cytauxzoon spp. 18S rRNA by qPCR and conventional PCR and positive samples confirmed by sequencing. All ticks belonged to Ixodes ricinus (50 males, 83 females, 532 nymphs). Four tick pools from 2019 tested Cytauxzoon spp. positive: one pool of 4 non-engorged male ticks from cats and three pools of 5-6 nymphs each from vegetation. All ticks collected in 2022 and 2024 tested negative. Amplification of the almost full-length (1535 bp, 1 pool) or partial (219-140 bp, 3 pools) 18S rRNA gene revealed a sequence identify of 98.6-100% with Cytauxzoon spp. previously detected in cats from this area. The detection of Cytauxzoon spp. in questing Ixodes ricinus nymphs suggests a potential role of this tick species in the parasites transmission cycle in Central Europe and raises the possibility of transovarial transmission. Mitochondrial gene sequencing was unsuccessful, but the detected Cytauxzoon spp. likely represent Cytauxzoon europaeus. Discrepancies between qPCR and conventional PCR results point to possible amplification of tick endosymbionts, highlighting the importance of confirmatory sequencing particularly when testing tick-derived DNA. In conclusion, this is the first report of Cytauxzoon spp. in questing I. ricinus ticks in Europe. Our findings underscore the need for further research to confirm vector competence and clarify transmission dynamics.

Hematophagous arthropods can acquire and transmit several pathogens of medical importance. In ticks, the innate immune system is crucial in the outcome between vector-pathogen interaction and overall vector competence. However, the specific immune response(s) elicited by the immune cells known as hemocytes remains largely undefined in Ehrlichia chaffeensis and its competent tick vector, Amblyomma americanum. Here, we show that granulocytes, professional phagocytic cells, are integral in eliciting immune responses against commensal and pathogen infection. The chemical depletion of granulocytes led to decreased phagocytic efficiency of tissues-associated hemocytes. We demonstrate E. chaffeensis can infect circulating hemocytes, and both cell-free plasma and hemocytes from E. chaffeensis-infected ticks can establish Ehrlichia infection in recipient ticks. Lastly, we provide evidence to show granulocytes play a dual role in E. chaffeensis infection. Depleting granulocytic hemocytes increased Ehrlichia load in the salivary gland and midgut tissues. In contrast, granulocyte depletion led to a reduced systemic load of Ehrlichia. This study has identified multiple roles for granulocytic hemocytes in the control and systemic dissemination of E. chaffeensis infection.

We assessed the temporal and spatial distribution of Borrelia burgdorferi, Borrelia miyamotoi, Babesia microti, and Anaplasma phagocytophilum among human-biting Ixodes scapularis ticks in Massachusetts using ticks submitted to the TickReport pathogen passive surveillance program. From January 2015 to December 2017, Ixodes scapularis was the most frequently submitted tick species (n=7462). B. burgdorferi prevalence increased in ticks during the study period in adults and nymphs (37.1-39.1% in adults, 19.0%-23.9% in nymphs). The proportion of B. microti infected ticks increased from 5.7% to 8.1% in adult ticks but remained constant in nymphs (5.4-5.6%). Stable or decreasing annual prevalence of B. miyamotoi (2.2 - 2.2% in adults, 1.0-1.9% in nymphs) and A.phagocytophilum (7.6-7.2% in adults, 5.0-4.0% in nymphs) were detected. Coinfections were observed and included all pathogen combinations. Ticks were submitted year-round and had stable infection rates. The temporal pattern of B. burgdorferi- positive nymphs aligned with reported cases of Lyme disease, as did positive B. microti nymphs and babesiosis. A similar situation is seen with B. miyamotoi with an insignificant fall peak in cases. Anaplasmosis demonstrated a significant bimodal distribution with reported cases peaking in the spring and fall. This pattern is similar to that of A. phagocytophilum-infected adult ticks. B. microti infected nymphs were significantly predictive of town-level babesiosis incidence and A. phagocytophilum infected adults were significantly predictive of town-level anaplasmosis incidence in a spatially adjusted negative binomial model. Unlike field collection studies, the high number of ticks submitted provides a high-resolution picture of pathogen prevalence and provides data relevant to human health at the town level. Through temporal and geographic analyses we demonstrate concordance between our passive surveillance tick pathogen data and state reports of tickborne disease.

Matrix-assisted laser desorption/ionization coupled with time-of-flight mass spectrometry (MALDI-TOF MS) is a fast emerging and robust method for rapid and accurate characterization of arthropod vectors. Correct identification of ticks is key in monitoring medically or veterinary relevant species and associated pathogens. It has been extensively used for tick identification based on leg proteins; however, in North America, MALDI-TOF MS has not been explored for comprehensive identification of ticks, except for a few studies focusing on a limited number of species. Herein, we have generated proteomic spectral profiles of nine North American tick species belonging to five genera obtained from laboratory-maintained colonies. From the 407 high-quality MS spectra generated in this study, 44 were deposited in our newly made database and used as reference. All remaining MS spectra were used to query and validate the database. All specimens were identified correctly to the species level using MALDI-TOF MS, with reliable Log Score Values (LSVs) ranging from 1.72 to 2.86, and median and mean values of 2.41 and 2.40, respectively. A single exception noted: an Amblyomma mixtum was misidentified as Amblyomma tenellum. As a cost-effective, user-friendly, and high-throughput method, MALDI-TOF MS can serve as an alternative for accurately identifying tick species of veterinary and public health importance in North America, thereby supporting tick-borne disease surveillance efforts.

AO_SCPLOWBSTRACTC_SCPLOWOrnithodoros phacochoerus are nidicolous soft ticks of the Ornithodoros moubata complex of species known to be vectors of the African swine fever (ASF) virus. These Ornithodoros ticks depend on endosymbionts to produce essential nutrients necessary for their development. However, endosymbionts are only a part of the complex microbiota hosted by the tick. This microbiota often includes primary or secondary endosymbionts, commensal species from the environment, and, most of the time, some pathogens. The present study was performed to understand the organization and spatial distribution of the microbiota of O. phacochoerus. One of the objectives was to investigate if the pathogen of interest (ASF virus) is involved in the organization of the microbiota through pathogen-induced dysbiosis or other interactions. For this purpose, 704 O. phacochoerus ticks were collected from two conservation areas in Mozambique. Sequencing was performed targeting the V3-V4 region of the 16S rRNA gene, and the resulting dataset was processed using FROGS to characterize the bacterial microbiota hosted by the ticks. The results indicate that the microbiota of Ornithodoros phacochoerus contains very low bacterial diversity, with one primary endosymbiont (Francisella-like endosymbiont), one potential secondary endosymbiont (Rickettsiella), and very few environmental or pathogenic bacterial species. We found a clear spatial structure of the microbiota, with ticks from the same sampling site showing similar patterns. On the contrary, no association with the infectious status for African swine fever virus was detected, suggesting that this pathogen does not shape Ornithodoros microbial communities. Our results on tick - microbiota - pathogen - environment interactions in nidicolous soft ticks, showed patterns that differ from most hard tick studies.

In Europe, Lyme borreliosis is the most common vector-borne human disease, caused mainly by Borrelia afzelii and Borrelia garinii, two species of the Borrelia burgdorferi sensu lato (Bbsl) complex transmitted by the tick Ixodes ricinus. Accurately assessing the spatial risk of human exposure to these pathogens is essential for efficient public health surveillance. However conventional monitoring often struggles to produce geographically explicit, large-scale data that capture the heterogeneity of human exposure and its drivers. Focusing on continental France, we leveraged data from the French CiTIQUE citizen science programme to analyse spatial variation of Bbsl infection in georeferenced human-biting I. ricinus ticks and to model the relationship between Bbsl distribution and environmental, ecological, and anthropogenic factors. From 2017-2019, 1,891 ticks were analysed, of which 15% tested positive for Bbsl. The most prevalent genospecies were B. afzelii (7.2%) and B. garinii (4.2%). Infection rates varied spatially, with distinct distribution patterns across pathogen groups. Tick habitat suitability was the most consistent predictor for overall Bbsl infection probability, genospecies-specific models revealed the importance of their respective reservoir hosts: B. afzelii occurrence was positively associated with rodent species richness, whereas B. garinii was associated with Turdidae species and showed potential traces of a dilution effect due to rodents. Our findings demonstrate the value of citizen science for complementing formal surveillance and provide the first geographically explicit, large-scale insights into Bbsl eco-epidemiology in France. This scalable approach offers an adaptable framework for monitoring vector-borne disease risk and guiding public health strategies. ImportanceLyme borreliosis, caused by Borrelia burgdorferi sensu lato, is the most common human vector-borne disease in Europe. Accurate assessment of spatial exposure risk is essential for effective public health surveillance and interventions. Using data from the French CiTIQUE citizen science program, we reveal pathogen-specific spatial patterns and identify the factors shaping them, at a geographic resolution not previously studied. Our findings demonstrate that citizen science can provide a scalable and adaptive framework for long-term surveillance of vector-borne disease risk, offering valuable insights to guide targeted prevention and control measures.

Vector-borne pathogens manipulate their vertebrate hosts to enhance their transmission to arthropod vectors. The ability of vertebrate hosts to develop acquired immunity against arthropod vectors represents an existential threat for both the vector and the pathogen. The purpose of the study was to test whether the tick-borne spirochete bacterium Borrelia afzelii could suppress the development of acquired immunity to its tick vector Ixodes ricinus in the bank vole Myodes glareolus, which is an important host for both the tick and the pathogen. We created a group of B. afzelii-infected bank voles and an uninfected control group by exposing lab-reared animals to infected or uninfected ticks. At 1, 2, and 3 months post-infection, all bank voles were infested with larval I. ricinus ticks. The bank voles developed a strong antibody response against tick salivary gland extract proteins. This anti-tick immunity had negative effects on tick fitness traits including engorged larval weight, unfed nymphal weight, larva-to-nymph molting time and larva-to-nymph molting success. Infection with B. afzelii did not suppress the development of acquired immunity against I. ricinus ticks. The development of anti-tick immunity was strongly correlated with a dramatic temporal decline in both the bacterial abundance in the host ear tissues and the host-tick transmission success of B. afzelii. Our study suggests that the development of anti-tick immunity in bank voles has important consequences for the density of infected ticks and the risk of Lyme borreliosis. ImportanceMany pathogens enhance their persistence and transmission by suppressing the immune system of their host. We used an experimental infection approach to test whether the Lyme disease pathogen, Borrelia afzelii, could suppress the development of acquired immunity against its tick vector (Ixodes ricinus) in the bank vole (Myodes glareolus), but found no evidence for this phenomenon. Uninfected and B. afzelii-infected bank voles both developed a strong IgG antibody response against tick salivary gland extract following repeated infestations with I. ricinus ticks. The development of anti-tick immunity was negatively correlated with the abundance of B. afzelii in ear tissue biopsies and with host-to-tick transmission to I. ricinus ticks. Our study suggests that anti-tick immunity in the bank vole reduces the prevalence of this important tick-borne pathogen.

Australias spotted fever group (SFG) rickettsiae cause significant illness, yet microbial diversity in wildlife ticks remains incompletely understood. Metagenomic sequencing of nine tick pools representing three Ixodidae species, Ixodes tasmani, I. holocyclus, and Haemaphysalis bancrofti, from Australian wildlife revealed a genome of a novel SFG Rickettsia species from I. tasmani ticks collected from koalas in New South Wales. Phylogenomic analysis confirmed this as a distinct species closely related to Rickettsia tasmaniensis fragments previously reported from Tasmanian devils. Additionally, we discovered four novel DNA Anellovirus species forming a new genus Sintorquevirus and one Circovirus from likely vertebrate blood meals, revealing wildlife viral diversity. Species distribution modelling of I. tasmani for assessing Rickettsia risk revealed suitable habitat along Australias eastern coastlines, with overlap between vector distribution, marsupial hosts, and population centres. This identified potential Candidatus R. tasmanensis exposure zones in coastal regions where positive samples originated, highlighting areas for surveillance.

We analysed the geographic risk of Lyme borreliosis taking into account the biogeography of tick vectors and carrier hosts, together with environmental and anthropogenic factors. Four pathogeographical scenarios were set in order to represent the contribution of vectors and hosts in the spatial zoonotic risk. For that propose, we built distribution models based on the occurrence of Lyme borreliosis cases in humans and ixodid vectors. Besides Ixodes species, we considered other ixodid ticks with potential to be vectors. These models were combined through fuzzy logic operators, according to the criteria stablished in each scenario. Finally, the transmission risk model for Lyme borreliosis which best fitted its global distribution was selected. The risk model selected considered ixodid vectors and mammal carriers as explanatory variables together with environment and anthropogenic factors. Ixodes species contributed to explain the geographical risk of Lyme borreliosis to larger extent than other ixodid ticks. The risk model described regions with Lyme borreliosis transmission risk where its presence is still uncertain, such as northern Africa and inland areas of western USA. Likewise, our model indicated favourable conditions for the presence of human cases in northern latitudes beyond its endemic distribution. Applying this multi-scenario methodology approach have led us to a risk model, in which the diversity of ixodid vectors and carrier hosts might modify the spatial risk without a geographical limitation.

We report the multi-year collection of the Gulf Coast tick, Amblyomma maculatum Koch (Acaridae: Ixodida: Ixodidae) in Staten Island, New York City (NYC) as well as their detection in Brooklyn, NYC, and in Atlantic and Cumberland counties in southern NJ, USA. The first detections on all sites were of adults but in Freshkills Park on Staten Island larvae were collected in a following year. Based on known observations on birds of this tick species, it is likely A. maculatum are expanding north on migratory birds, which are now often seen in Freshkills Park. The presence of larvae indicates that adults are being successful at finding hosts in Staten Island. We describe the landscape features of the area in Staten Island where populations were highest and larvae were detected, which could have facilitated the establishment of A. maculatum. Notably, we also report the presence of human pathogens Rickettsia parkeri in 5/10 (50%) of adults tested and R. felis in 1/24 (4.17%) of larvae tested. In addition to established populations in Staten Island we found evidence of A. maculatum in NJ and other NYC boroughs, suggesting current or future establishment is possible. The failure thus far to detect established populations in these areas may be due to inherent difficulties in detecting low density, spatially heterogeneous incipient populations, which could require targeted surveillance efforts for this species. We discuss the consequences to public health of the establishment of A. maculatum and detection of two additional rickettsial pathogens in the densely populated Northeastern US.

Ticks are vectors of many debilitating pathogens that are transmitted during blood meal acquisition. As both vector and pathogen species continue to emerge, there is a critical need for improved pathogen diagnostic and host remnant identification methods to develop interventions. Current pathogen detection methods are limited in their ability to subtype and detect emerging variants and non-vector borne "look-alike" diseases. Determination of tick blood meal sources is also an elusive step for understanding tick interactions with the biotic community in a given environment, with consequences for environmental management and disease prevention strategies. We have created an accessible hybridization capture next-generation sequencing panel called "TICKHUNTER" to improve molecular detection and subtyping of bacterial and parasitic pathogens in both clinical and tick samples. For disease ecology studies, the panel also detects host blood meal sources of interest. An alternative method for unbiased blood meal remnant analysis is also presented. We find that TICKHUNTER is a promising tool for effective and accurate detection of a variety of tick-borne pathogens, based on comparable linearity, limit of detection, sensitivity, and specificity to real-time PCR. Additionally, it can detect and characterize unexpected pathogens due to the large capacity for multiplexing and flexibility in variant detection.

A Central Texas resident found an engorging Ornithodoros turicata tick attached to their leg while at home. The tick was submitted for testing, which confirmed that it was infected with a Borrelia species. Spirochetes were successfully cultured and whole genome sequencing confirmed that the species was Borrelia turicatae. The tick submitter reported being hospitalized and was recovering from Bells Palsy. Searching the Texas National Electronic Disease Surveillance System indicated that the individual had an undiagnosed febrile illness that spanned three weeks prior to finding the tick attached on them. These findings indicated possible recurrent tick exposure in a domestic environment.

Borrelia burgdorferi, a tick-vectored spirochete bacteria best known for causing Lyme disease, has been found to induce physiological and behavioural changes in its tick vector that can increase tick fitness and its ability to transmit the bacteria. The mechanism by which this bacterium modulates these changes remains unknown. Epigenetics plays a central role in transducing external and internal microbiome environmental influences to the organism, so we investigated DNA methylation and the expression of a key histone modification enzyme in Borrelia-infected and uninfected Ixodes scapularis ticks. DNA methylation of the pericentromeric tandem repeats family, Ixodes scapularis Repeats (ISR) were assessed by methylated-DNA immunoprecipitation (MeDIP) followed by qPCR of the ISR regions. DNA methylation of the ISR sequences was found. The different repeats had different levels of DNA methylation, however, these levels were not significantly affected by the presence or absence of B. burgdorferi. The epigenetic regulator euchromatic histone lysine methyltransferase 2 (EHMT2) is recognized as having a key role in modulating the organismal stress response to infections. To assess EHMT2 transcription in Borrelia-infected and uninfected ticks, real-time reverse transcriptase PCR was performed. Uninfected ticks had over 800X lower EHMT2 expression than infected ticks. This study is among the first to identify a gene that may be involved in producing epigenetic differences in ticks depending on infection status and lays the groundwork for future epigenetic studies of I. scapularis in response to B. burgdorferi as well as other pathogens that these ticks transmit.

Understanding the genes and molecular pathways that shape host responses to infection is essential for advancing our knowledge of host-parasite interactions and their ecological and evolutionary implications. Such insights are especially valuable for conserving endangered species that may be vulnerable to emerging or novel pathogens. Here, we investigated the impact of the recently introduced gastrointestinal nematode Ashworthius sidemi on gene expression in its novel host, the European bison (Bison bonasus). We analyzed abomasal transcriptomes (n = 45) from individuals characterized by a wide range of infection intensities (0-8,620 parasites per host). Despite substantial variation in parasite burden, differential expression analyses detected no individual genes significantly associated with infection intensity. However, gene set enrichment analyses based on p-value distributions revealed multiple immune-related gene ontology categories, including B and T cell activation, neutrophil chemotaxis, inflammatory responses, and regulation of IL-6 production. These findings indicate that European bison mount a clear yet subtle transcriptional response to A. sidemi infection and highlight molecular pathways potentially involved in mediating host defense against this emerging parasite.

BackgroundBagaza virus (BAGV) emerged in Portugal in 2021. BAGV and other flaviviruses such as West Nile virus (WNV) and Usutu virus (USUV) represent emerging threats in Europe, yet uncertainties persist regarding their epidemiological status in Portugal. AimThis study aimed to elucidate the epidemiological dynamics of BAGV, WNV, and USUV in Portugal using the red-legged partridge (Alectoris rufa) as a susceptible bird model species. MethodsSerum samples collected from a partridge population in Southern Portugal, between 2018 and 2022, were analysed to characterize exposure to flaviviruses through enzyme-linked immunosorbent assay (ELISA; n=468) and virus neutralization test (VNT; n=433). ResultsELISA test revealed an average seroprevalence of 58.1% for WNV and WNV-cross-reacting antibodies between 2018 and 2022, while 66.3% of individuals tested positive using VNT: 28.8% specific for WNV, 8.1% for BAGV, 2.1% for USUV and 27.2% for "undetermined flaviviruses". BAGV seroprevalence was first detected in October 2021 (8.7%), alongside an outbreak detection, peaking in November 2021 (26.3%) and persisting until October 2022 (2.3%). WNV antibodies were detected throughout all sampling periods, with the highest seroprevalence in October 2020 (44.8%). USUV seroprevalence was detected until the BAGV outbreak in 2021, peaking in October 2020 (6.9%). ConclusionLong-term serological surveillance of partridges revealed endemic circulation of WNV and sporadic circulation of BAGV and USUV in Portugal. Notably, the highest WNV seroprevalence coincided with the human WNV outbreak in southern Spain in the summer of 2020, highlighting the role of red-legged partridges in the transmission/maintenance cycle and as sentinels of flaviviruses circulation.

Piroplasms, which include the agents of cattle fever and human and dog babesiosis, are a diverse group of blood parasites of significant veterinary and medical importance. The invasive Asian longhorned tick, Haemaphysalis longicornis, is a known vector of piroplasms in its native range in east Asia and invasive range in Australasia. In the US state of Virginia, H. longicornis has been associated with Theileria orientalis Ikeda outbreaks that caused cattle mortality. We examined 667 H. longicornis collected in 2021 from three sites in New Brunswick, New Jersey, the US state where established populations of this species were first detected in 2017. We used primers targeting the 18S small subunit rRNA and the cytochrome b oxidase loci and unveiled the presence of DNA from an unidentified Theileria species (in 1 nymph) and Theileria cervi type F (1 adult, 5 nymphs). In addition, we sequenced a 130 bp fragment of the cytochrome oxidase b locus from Odocoileus virginianus, the white-tailed deer, in a partially engorged questing H. longicornis, supporting the association of this tick species with deer. We also detected DNA from an undescribed Babesia sensu stricto ( true Babesia, 2 adults, 2 nymphs) as well as Babesia sp. Coco (1 adult, 1 nymph). Finally, we detected DNA from Babesia microti S837 (1 adult, 4 nymphs). Babesia microti S837 has been sequenced from striped skunks, Mephitis mephitis, and is closely related to the human pathogen B. microti US-type. The five parasites we are associating with H. longicornis represent a diverse assemblage spanning three clades in the piroplasm phylogeny, two undescribed, raising concerns of transmission amplification of veterinary pathogens as well as spillover of pathogens from wildlife to humans.