Lyme disease, caused primarily by the bite of a nymphal blacklegged tick (Ixodes scapularis) infected with Borrelia burgdorferi sensu stricto (Bbss), is the most common vector-borne disease in the United States. Counties reporting high Lyme disease incidence (LDI) continue to expand beyond historic foci in the Northeast and Upper Midwest. Identifying areas of expansion aids in targeting efforts to improve Lyme disease awareness in affected communities. Tick surveillance is conducted to track changes in acarological risk for tickborne diseases; the density of host-seeking Bbss-infected I. scapularis nymphs (DIN) is considered the most predictive metric for human LDI. We aimed to identify a threshold in DIN that accurately separated high (≥10 average annual cases/100,000 and ≥3 cases/year; 2022-2023) from low LDI counties in the eastern US. Using previously reported model-derived DIN, we identified 0.98 Bbss-infected nymphs per 1000 m2 as the threshold. Based on this threshold, we classified 18% of eastern counties (487/2695), primarily in the Northeast and Upper Midwest, with both high LDI and elevated acarological risk and 72% (1935/2695) with both low LDI and acarological risk. Another 8% of counties (220/2695), primarily in Michigan, Illinois, Indiana, and Ohio, were predicted to pose elevated acarological risk, but reported low LDI and may reflect areas of emergence that could benefit from expanded tick surveillance and public health outreach. The remaining 2% of counties (53/2695), mainly along the Appalachian Mountains, reported high LDI, but were misclassified as low acarological risk, highlighting the need for additional tick surveillance to improve acarological risk assessments.

Lyme borreliosis (LB) and hard tick-borne relapsing fever caused by Borrelia miyamotoi are emerging tick-borne infections, yet in Kazakhstan routine LB diagnosis relies on single-tier enzyme immunoassay (EIA) without confirmatory testing, and B. miyamotoi is absent from national diagnostic protocols. In 2024-2026, 1300 participants were enrolled in the Ixodes persulcatus-endemic Almaty and Jetisu regions and the non-endemic Zhambyl and Turkistan regions, across diverse clinical and tick-exposure groups. All sera were screened for IgM and IgG to both pathogens by multi-antigen protein arrays, with subsets tested by the LymeBest ELISA and the Anti-Borrelia EUROLINE-WB immunoblot. In addition, 503 ticks removed from participants were tested for borrelial DNA by PCR. Seroreactivity to B. burgdorferi sensu lato (s.l.) was rare (4/1300, 0.3%), whereas B. miyamotoi seroreactivity was more frequent (31/1300, 2.4%) and concentrated in tick-exposed groups. In ticks the pattern was the opposite: B. burgdorferi s.l. DNA was detected in 37/503 ticks (7.4%; 45.3% in I. persulcatus) and B. miyamotoi DNA in 7/64 I. persulcatus (10.9%), with four ticks co-infected, the single B. miyamotoi strain typed by eight-locus MLST matched a sequence type reported from Japan, Mongolia and China. Of the 28 participants bitten by Borrelia DNA-positive ticks who provided follow-up sera, three (10.7%) seroconverted, one to B. burgdorferi s.l. and two to B. miyamotoi. One of the latter, PCR-positive for B. miyamotoi DNA in baseline blood, is, to our knowledge, the first molecularly confirmed case of B. miyamotoi infection in Kazakhstan. The LymeBest ELISA agreed poorly with the other two assays: none of its 27 positive baseline results was confirmed by immunoblot or protein array. In contrast, immunoblot confirmed two of the four baseline samples seroreactive to B. burgdorferi s.l. by protein array, as well as the B. burgdorferi s.l. seroconversion. These findings support two-tier serological testing for LB and dedicated B. miyamotoi diagnostics in Kazakhstan.

Companion animals, such as dogs and cats, and wildlife are recognized as sentinel species in One Health surveillance due to periodic exposure to ticks and infection by tick-borne pathogens (TBPs). Surveillance of this type is a strategy that captures a broad range of genetic, immunological, and behavioral factors that affect tick and disease dynamics. In contrast, non-human animals (hereafter referred to as 'animals') that are traditionally farmed for their meat and other products have been largely overlooked as sentinel species. Community-dwelling farm sanctuary residents, such as cattle, pigs, horses, and other traditionally 'farmed' animals have close daily contact with human caregivers, making them excellent candidates for One Health surveillance. These animals, often free-range in pastures and/or woodlands, bridging the territory inhabited by wildlife and that occupied by humans. This study collected 67 ticks, from bovines (n = 22), equines (n = 35) and canines (n = 6) residing in a farm animal sanctuary and screened them for microbes associated with tick borne illnesses using 16S rRNA V4 amplicon targeted sequencing (515F/906R) with custom Rickettsia buchneri blocking primers to boost sensitivity. Only 60 ticks were viable for analysis, 59 were of Ixodes species and one was Dermacentor variabilis. Of these, 31.6% (n = 19) tested positive for potential pathogens, including 21.6% (n = 13) for the causative agent of Lyme disease (Borrelia burgdorferi) and 15% (n = 9) for Anaplasma phagocytophilum, with a co-infection rate of five percent (n = 3). Utilizing community dwelling sanctuary residents allowed us to detect potential threats to both animal and human health and was instrumental in the rapid diagnosis of anaplasmosis in two study participants (a horse and a pony) who showed symptoms of lethargy and inappetence after being bitten by ticks.

The changing distributions and activity patterns of tick populations underscore the urgent need for enhanced surveillance and risk assessment strategies for ticks and tick-borne diseases (TBDs) affecting humans and animals. Biomarkers of exposure to tick salivary peptides can be used to identify tick bite history and to monitor tick species distributions. Here, we derived peptides from previously identified immunogenic proteins, namely IrCalreticulin, IrLip1, and IrSPI. Bioinformatic predictive analysis of 3D structure and computed docking strength were used to identify candidate peptides based on predicted immunogenicity and arthropod homology. Using ELISA, several peptides distinguished sera from experimentally Ixodes ricinus -exposed and unexposed sheep for both IgM and IgG antibodies, as was true for clinical patient samples IgG positive for tick-borne Borrelia bacteria. These findings offer the potential for developing new effective strategies for the surveillance of ticks and TBDs, disease diagnostic guidance as well as assessing tick population control strategies.

Equine tick-borne diseases pose increasing challenges due to climate change and expanding tick geographical ranges. With no vaccines available for Lyme disease or equine anaplasmosis in horses, tick bite prevention remains the primary control method. This two-year study evaluated tick species composition on horses in Pennsylvania and assessed the effectiveness of physical barriers for tick prevention through community-based participatory research. The study engaged horse owners as research partners. Year 1 (2022) established baseline tick surveillance across 45 participants with 60 horses, conducting weekly tick checks from April to June. Year 2 (2023) evaluated physical barrier interventions using 50 horses assigned to three treatments: No Treatment (control), Physical Barrier (Untreated), and Physical Barrier (Treated with permethrin), with twice-weekly surveillance. A total of 413 ticks were collected, with species composition shifts between years. Species recovered included American dog ticks (Dermacentor variabilis), blacklegged ticks (Ixodes scapularis), and longhorned ticks (Haemaphysalis longicornis), which were detected for the first time in one of the counties in the study region. Tick attachment occurred across eight body locations and differed significantly between years. Physical barriers, particularly untreated fly boots and masks, were associated with reduced tick attachment. Comprehensive whole-body surveillance remains essential given consistent tick distribution across anatomical regions.

Ixodes scapularis ticks transmit a number of pathogens important to human health, including Borrelia burgdorferi sensu stricto, the causative agent of Lyme disease. While I. scapularis is found across the Eastern United States, Lyme disease transmission is largely limited to the Northeast and Upper Midwest and is nearly absent in the South. This indicates that differences in northern versus southern clades of I. scapularis are associated with differences in Lyme disease transmission risk. Ixodes scapularis is undergoing range expansion, including into the Great Plains region of the United States. Determining where I. scapularis populations in the Great Plains originated can inform future risk of Lyme disease transmission in this region. In this study, we use a population genomics framework to characterize diversity, structure and B. burgdorferi infection rates of I. scapularis populations in the Great Plains region. We generated whole genome sequence data and single nucleotide polymorphism (SNP) datasets from I. scapularis ticks collected in Iowa, Kansas, Nebraska and South Dakota to compare to publicly available data from across the species' range. Our analysis of 200 I. scapularis SNP datasets indicated geographically well-defined populations that correspond to historical northern and southern ancestral clades of I. scapularis. Ticks from South Dakota, Iowa and northeastern Nebraska are genetically similar populations from the Upper Midwest, while ticks from Kansas are more genetically similar to ticks from the Southeast. Ticks collected in the east central region of Nebraska, however, represent an evenly admixed population of both northern and southern genomic backgrounds. Analysis of B. burgdorferi reads from genomic datasets shows ~50% infection rate in ticks from Iowa and northeastern Nebraska, whereas ticks from Kansas show no evidence of B. burgdorferi infection. Of note, evenly admixed ticks from the east central region of Nebraska also show no evidence of B. burgdorferi infection. These results provide further evidence that tick genomics may influence traits associated with B. burgdorferi infection status, and thus the potential for Lyme disease transmission. As the range of I. scapularis continues to expand, bringing historically isolated populations into contact, there is a clear need to understand the consequence of genomic admixture for B. burgdorferi transmission potential to inform future risk of Lyme disease in the United States.

Ticks are agents causing tick-borne diseases (TBDs) in the United States, with the blacklegged tick (Ixodes scapularis Say) posing particular concern. Synthetic acaricides remain an important approach for tick control and TBDs prevention. However, increasing public concern and emerging acaricide resistance highlight the need for alternative products. In this study, we evaluated the efficacy of an undiluted oil-in-water emulsion of Flavocide™ (FLC-EW; 50% AI), a nature-identical active with a novel mode of action, in comparison with two commercial standards: Talstar-P, a pyrethroid product, and Outdoor Pest Control (OPC), a natural product, against I. scapularis nymphs under laboratory conditions. To assess both product efficacy and tick behavior, we developed a portable test arena ("Phenocosm") capable of incorporating substrates (leaf litter, mulch, and turfgrass) simulating natural tick habitats. In contact assays, preliminary assessment of FLC-EW indicated significantly higher mortality than Talstar-P at 24 and 48 hrs post-exposure (PE), despite lower knockdown (KD) at 1 hr PE. FLC-EW exhibited residual activity through four weeks. OPC exhibited only repellency against I. scapularis nymphs. Tick viability assays without acaricide indicated tick survival above 80% at week four in Phenocosms with leaf litter and mulch, and 78% in turfgrass at week three. Overall, >55% of ticks were consistently found sheltering on or beneath substrates with implications for acaricide applications. These findings suggest the acaricidal potential of FLC-EW and support further studies to assess its efficacy at lower AI concentrations. Additionally, they highlight the Phenocosm as a versatile test arena for assessing acaricide efficacy and tick behavior.

Severe fever with thrombocytopenia syndrome (SFTS), caused by the SFTS virus (SFTSV), is a highly fatal tick-borne zoonosis that poses a substantial public health threat. Although livestock husbandry environments represent important ecological settings for viral maintenance and circulation, molecular surveillance within these settings remains insufficient.

Lyme disease poses an escalating global health challenge partly driven by climate change and land-use transformation, while mechanistic understanding of transmission remains limited. We analyzed prevalence records from 43 Eurasian countries to map pathogen biogeography and applied theory-driven structural equation modeling (SEM) to evaluate hypothesized direct, indirect, and cascading pathways linking climate, land cover, landscape structure, and host biodiversity to pathogen prevalence. Genospecies exhibited distinct biogeographic patterns shaped by vector-host specificity, with Ixodes ricinus dominating transmission in Europe and I. persulcatus in Asia. Borrelia afzelii prevalence was associated with climate, forest fragmentation, and landscape heterogeneity, and exhibited a negative association with rodent species richness at the continental scale. Borrelia garinii showed no host diversity effects but responded directly to temperature and landscape structure, reflecting reliance on highly mobile avian hosts. These findings reveal fundamental transmission heterogeneity among genospecies arising from divergent host-reservoir ecologies, with critical implications for disease control. Effective surveillance must integrate genospecies-specific ecology with landscape management to align biodiversity conservation, climate adaptation, and public health.

Babesiosis is a tick-borne infection caused by intraerythrocytic Babesia parasites and may result in severe hemolytic anemia and systemic complications. Coinfection with other Ixodes-borne pathogens may further complicate diagnosis and management. We report a 45-year-old immunocompetent man working as a landscaper in Connecticut who presented with syncope following two weeks of fever, fatigue, diaphoresis, arthralgias, jaundice, and dark urine. Laboratory evaluation revealed profound hemolytic anemia with a hemoglobin of 6.8 g/dL, elevated lactate dehydrogenase (LDH), undetectable haptoglobin, reticulocytosis, and stage 1 acute kidney injury. Peripheral blood smear demonstrated characteristic Maltese cross formations, with approximately 0.6% parasitemia, and polymerase chain reaction (PCR) testing confirmed Babesia microti and Borrelia burgdorferi coinfection. Direct antiglobulin testing for immunoglobulin G (IgG) was negative. The patient required intensive care monitoring and transfusion and improved following treatment with atovaquone, azithromycin, and doxycycline. Subsequent outpatient evaluation identified asymptomatic Strongyloides stercoralis infection, which was treated with ivermectin. This finding was clinically significant because warm autoimmune hemolytic anemia is a recognized complication of babesiosis and may require corticosteroid therapy, which can precipitate potentially life-threatening Strongyloides hyperinfection in patients with occult infection. This case highlights that severe babesiosis may occur despite low-level parasitemia and emphasizes the importance of recognizing coinfections and obtaining a detailed occupational and environmental exposure history, particularly when future immunosuppressive therapy may be considered.

Tick-borne diseases are emerging worldwide due to the expanding distribution of tick vectors and represent an increasing public health concern. This study investigated the occurrence of major tick-borne pathogens in ticks collected from wild animals in Valle d'Aosta Region (Northwestern Italy) between 2017 and 2022. Tick pools were screened for Anaplasma spp., Borrelia burgdorferi s.l., Coxiella burnetii, Rickettsia spp., and Tick-Borne Encephalitis virus (TBEV). Most collected ticks were morphologically identified as Ixodes ricinus. Overall, 15.2% of the 158 analyzed pools tested positive for at least one pathogen. Rickettsia spp. was the most frequently detected pathogen (10.7%), with multiple species identified, including R. helvetica, R. monacensis, R. slovaca, and R. raoultii. Anaplasma phagocytophilum was detected in ticks collected from wild ungulates, whereas Borrelia burgdorferi s.l. was only occasionally identified. No samples tested positive for TBEV or C. burnetii. Rickettsia spp. positivity was higher in ticks collected from ungulates and in I. ricinus, although these differences were not statistically significant. These findings provide new insights into tick ecology in Alpine ecosystems, highlighting the circulation of potentially zoonotic pathogens and the altitudinal presence of ticks in the Alps up to 1800-2300 m a.s.l. The study contributes valuable epidemiological data and supports the need for continued surveillance within a One Health framework.

Ticks are among the most important arthropod vectors affecting human and animal health worldwide. We present a set of globally harmonized indicators integrating hazard, exposure, and vulnerability associated with human-biting ticks and with two major tick-borne pathogens, Borrelia burgdorferi sensu lato (Lyme borreliosis), and Orthonairovirus haemorrhagiae (Crimean-Congo haemorrhagic fever virus, CCHFV). Hazard indices were derived from the distributions of confirmed vector tick species. Exposure was incorporated through rural human population density, livestock density, and the abundance of competent vertebrate reservoirs and/or amplification hosts, as applicable. Vulnerability was assessed using country-level indicators related to healthcare accessibility, socioeconomic development, and demographic dependency. The indices show spatially structured global patterns. Tick hazard is concentrated in eastern North America, Europe, Central and East Asia; Africa displays fragmented but substantial hotspots. The B. burgdorferi s.l. index is restricted to the Northern Hemisphere, following the distribution of Ixodes spp. and associated reservoir communities, with highest exposure in Europe and North America. The CCHFV index is confined to the Old World, extending from the Mediterranean region through the Middle East and Central Asia into Sub-Saharan Africa, reflecting the distribution of Hyalomma ticks and ungulates. The vulnerability indicators highlight regional patterns of high exposure and limited adaptive capacity, particularly in Sub-Saharan Africa and parts of the Middle East. Our framework provides the first global set of harmonized, high-resolution indices integrating vector ecology, reservoir communities, exposure, and vulnerability for major tick-borne diseases of humans. It offers a flexible platform for comparative epidemiology, surveillance prioritization, and public health decision-making at multiple administrative scales.

Anaplasma phagocytophilum is a tick-borne bacterium and the causative agent of human granulocytic anaplasmosis. Two major variants have been identified in North America: a human pathogenic variant (Ap-ha) that is maintained by small mammals and a nonpathogenic variant (Ap-v1) that is maintained by white-tailed deer (Odocoileus virginianus). Despite white-tailed deer being recognized as the main reservoir of Ap-v1, few studies have directly demonstrated transmission of Ap-v1 from white-tailed deer to feeding I. scapularis ticks, and transmission to feeding larvae remains undescribed. In this study, we collected samples from an outdoor white-tailed deer research facility during an I. scapularis larval questing season in the eastern United States to investigate the variants infecting white-tailed deer and acquisition by feeding larvae. Although both variants were present in questing ticks onsite, white-tailed deer were persistently infected with only Ap-v1 and transferred this variant to feeding I. scapularis larvae with high efficiency. These results support the concept that white-tailed deer play a role in the maintenance of Ap-v1 in nature and highlight the utility of captive white-tailed deer research facilities for studying vector-pathogen-host biology.