The Impacts of Climate Change on Ticks and Tick-Borne Disease Risk

First detection of Bandavirus dabieense in ticks collected from migratory birds in the Republic of Korea

The causative agent of severe fever with thrombocytopenia syndrome (SFTS) is Bandavirus dabieense, an emerging tick-borne zoonotic pathogen. Migratory birds have often been suggested as potential carriers of ticks that can transmit Bandavirus dabieense; however, their role remains unclear. The Republic of Korea (ROK) holds an important position as a stopover on the East Asian-Australasian Flyway. The present study aimed to investigate the potential involvement of migratory birds in the transmission of the SFTS virus (SFTSV) in the ROK. A total of 4,497 ticks were collected across various regions, including Heuksando and Daecheongdo, in the ROK, from bird migration seasons in 2022 and 2023. Genetic analysis of the SFTSV was performed for 96 ticks collected from 20 different species of migratory birds. Polymerase chain reaction (PCR) fragments of SFTSV were detected in one Haemaphysalis concinna nymph collected from a Black-faced Bunting (Emberiza spodocephala) and one Ixodes turdus nymph collected from an Olive-backed Pipit (Anthus hodgsoni) on Daecheongdo and Heuksando, respectively, during their northward migration in two spring seasons. This finding suggests that migratory birds can be considered as possible carriers and long-distance dispersers of ticks and associated tick-borne diseases. This study highlights the importance of clarifying the role and impact of migratory birds in the rapid expansion of tick-borne diseases, facilitating enhanced preparedness and the development of mitigation measures against emerging SFTS across and beyond East Asia.

Sample-to-answer direct real-time PCR detection of Anaplasma phagocytophilum, Ehrlichia spp., and Babesia spp. infections in whole-blood specimens

Emerging tick-borne illnesses, such as anaplasmosis, babesiosis, or ehrlichiosis, are caused by obligate intracellular pathogens that have clinically comparable presentations. Diagnostics used in laboratories today are serologic assays and blood smear analyses, which have known diagnostic limits. This study evaluated the performance of a sample-to-answer direct real-time PCR laboratory-developed test for the multiplex qualitative detection of Anaplasma, Babesia, and Ehrlichia DNA in whole-blood specimens. Compared to two standard-of-care (SOC) methods, the DiaSorin tick-borne laboratory-developed test for Anaplasma detection demonstrated a positive percent agreement (PPA) and negative percent agreement (NPA) of 100% (95% CI, 0.80 to 1.0) and 89% (95% CI, 0.74 to 0.97), respectively with a discordant rate of 9.3% against microscopy. After discordant resolution, the NPA increased to 100%. For Babesia, the test demonstrated a PPA of 100% (95% CI, 0.90 to 1.0) and NPA of 100% (95% CI, 0.90 to 1.0). Compared to a SOC PCR method Anaplasma samples showed a PPA of 100% (95% CI, 0.66 to 1.0) and NPA of 100% (95% CI, 0.90 to 1.0). Ehrlichia results showed a PPA of 100% (95% CI, 0.69 to 1.0) and NPA of 100% (95% CI, 0.90 to 1.0). The total percent agreement was 98% (95% CI, 0.95 to 0.99) with a κ statistic of 0.95 (95% CI, 0.90 to 0.99) or almost perfect agreement compared to SOC methods. This laboratory-developed test for detecting Anaplasma, Babesia, and Ehrlichia DNA provides rapid and reliable detection of tick-borne infections without nucleic acid extraction.

IMPORTANCE

This work demonstrates that detection of tick-borne illnesses, such as anaplasmosis, babesiosis, or ehrlichiosis, can be performed directly from whole blood with no extraction. The assay described here has a high positive and negative percent agreement with existing methods and is used as the standard of care. An increasing incidence of tick-borne illness combined with shortage of well-trained technologists to perform traditional manual testing, testing options that can be adapted to various lab settings, are of the utmost importance.

The influence of forest habitat type on Ixodes ricinus infections with Rickettsia spp. in south-western Poland

This study investigates the prevalence of Rickettsia spp. in Ixodes ricinus tick populations in different forest habitat types (broadleaf forest, mixed broadleaf and coniferous forest, and coniferous forest) in south-western Poland. During the survey periods from April to June 2018 and 2019 a total of 494 I. ricinus ticks, including 374 nymphs, 60 females and 60 males, were tested for Rickettsia infections by nested PCR targeting the gltA gene. The overall infection rate was 42.3%; however, we observed statistically significant year-to-year variation. Infection rates varied between tick developmental stages and were significantly influenced by forest habitat type. As assessed by a generalized linear mixed model (GLMM), the highest infection rates were observed in mixed broadleaf and coniferous forests, while coniferous forests had a significant negative effect on infection prevalence. DNA sequencing of selected samples confirmed the predominance of Rickettsia helvetica (91.2%) and less frequent Rickettsia monacensis (8.8%). This study suggests that the forest habitat types can influence Rickettsia spp. infection in tick populations; however, a comprehensive understanding of all factors influencing the level of infection requires future study.

Hard Ticks as Vectors: The Emerging Threat of Tick-Borne Diseases in India

Hard ticks (Ixodidae) play a critical role in transmitting various tick-borne diseases (TBDs), posing significant global threats to human and animal health. Climatic factors influence the abundance, diversity, and vectorial capacity of tick vectors. It is imperative to have a comprehensive understanding of hard ticks, pathogens, eco-epidemiology, and the impact of climatic changes on the transmission dynamics of TBDs. The distribution and life cycle patterns of hard ticks are influenced by diverse ecological factors that, in turn, can be impacted by changes in climate, leading to the expansion of the tick vector's range and geographical distribution. Vector competence, a pivotal aspect of vectorial capacity, involves the tick's ability to acquire, maintain, and transmit pathogens. Hard ticks, by efficiently feeding on diverse hosts and manipulating their immunity through their saliva, emerge as competent vectors for various pathogens, such as viruses, parasites and bacteria. This ability significantly influences the success of pathogen transmission. Further exploration of genetic diversity, population structure, and hybrid tick vectors is crucial, as they play a substantial role in influencing vector competence and complicating the dynamics of TBDs. This comprehensive review deals with important TBDs in India and delves into a profound understanding of hard ticks as vectors, their biology, and the factors influencing their vector competence. Given that TBDs continue to pose a substantial threat to global health, the review emphasizes the urgency of investigating tick control strategies and advancing vaccine development. Special attention is given to the pivotal role of population genetics in comprehending the genetic diversity of tick populations and providing essential insights into their adaptability to environmental changes.

Epidemiology of Anaplasma species amongst cattle in Africa from 1970 to 2022: A systematic review and meta-analysis

Tick-borne pathogens of the genus Anaplasma cause anaplasmosis in livestock and humans, impacting health and livelihoods, particularly in Africa. A comprehensive review on the epidemiology of Anaplasma species is important to guide further research and for implementation of control approaches. We reviewed observational studies concerning Anaplasma species amongst cattle in Africa. Peer-reviewed studies published in PubMed, Google Scholar, and Web of Science - from database inception to 2022 - were searched. The quality of individual studies was assessed using the Joanna Briggs Institute Critical Appraisal Tool and the pooled prevalences by diagnostic method were estimated using random-effects models. Heterogeneity across the studies was tested and quantified using the Cochran's Q statistic and the I2 statistic. Potential sources of heterogeneity were investigated by subgroup analysis. A total of 1117 records were retrieved and at the end of the screening, 149 records (155 studies) were eligible for this meta-analysis. The occurrence of Anaplasma species was reported in 31/54 countries in all regions. Seven recognised species (A. marginale, A. centrale, A. phagocytophilum, A. platys, A. capra, A. bovis, A. ovis) and nine uncharacterised genotypes (Anaplasma sp. Hadesa; Anaplasma sp. Saso; Anaplasma sp. Dedessa; Anaplasma sp. Mymensingh; Anaplasma sp. Lambwe-1; Candidatus Anaplasma africae; Anaplasma sp.; Candidatus Anaplasma boleense) were reported in African cattle. Anaplasma marginale was the most frequently reported (n=144/155 studies) and the most prevalent species (serology methods 56.1%, 45.9-66.1; direct detection methods 19.9%, 15.4-24.7), followed by A. centrale (n=26 studies) with a prevalence of 8.0% (95% CI: 4.8-11.9) and A. platys (n=19 studies) with prevalence of 9.7% (95% CI: 5.4-15.2). Anaplasma marginale, A. centrale and A. platys were reported in all Africa's regions, while A. ovis and A. capra were reported only in the northern and central regions. The uncharacterised Anaplasma taxa were mostly detected in the eastern and southern regions. Subgroup analysis showed that significant determinants for A. marginale exposure (serology) were geographical region (p=0.0219), and longitude (p=0.0336), while the technique employed influenced (p<0.0001) prevalence in direct detection approaches. Temperature was the only significant variable (p=0.0269) for A. centrale. These findings show that various Anaplasma species, including those that are zoonotic, circulate in African cattle. There is need for more genetic and genome data, especially for unrecognised species, to facilitate effective identification, improve livestock and minimise the health risk in human populations. Additional epidemiological data including pathogen occurrence, tick vectors and host range, as well as pathogenicity are essential.

Accounting for missing ticks: Use (or lack thereof) of hierarchical models in tick ecology studies

Ixodid (hard) ticks play important ecosystem roles and have significant impacts on animal and human health via tick-borne diseases and physiological stress from parasitism. Tick occurrence, abundance, activity, and key life-history traits are highly influenced by host availability, weather, microclimate, and landscape features. As such, changes in the environment can have profound impacts on ticks, their hosts, and the spread of diseases. Researchers recognize that spatial and temporal factors influence activity and abundance and attempt to account for both by conducting replicate sampling bouts spread over the tick questing period. However, common field methods notoriously underestimate abundance, and it is unclear how (or if) tick studies model the confounding effects of factors influencing activity and abundance. This step is critical as unaccounted variance in detection can lead to biased estimates of occurrence and abundance. We performed a descriptive review to evaluate the extent to which studies account for the detection process while modeling tick data. We also categorized the types of analyses that are commonly used to model tick data. We used hierarchical models (HMs) that account for imperfect detection to analyze simulated and empirical tick data, demonstrating that inference is muddled when detection probability is not accounted for in the modeling process. Our review indicates that only 5 of 412 (1 %) papers explicitly accounted for imperfect detection while modeling ticks. By comparing HMs with the most common approaches used for modeling tick data (e.g., ANOVA), we show that population estimates are biased low for simulated and empirical data when using non-HMs, and that confounding occurs due to not explicitly modeling factors that influenced both detection and abundance. Our review and analysis of simulated and empirical data shows that it is important to account for our ability to detect ticks using field methods with imperfect detection. Not doing so leads to biased estimates of occurrence and abundance which could complicate our understanding of parasite-host relationships and the spread of tick-borne diseases. We highlight the resources available for learning HM approaches and applying them to analyzing tick data.

Does bird life-history influence the prevalence of ticks? A citizen science study in North East Spain

After mosquitoes, ticks are among the most important vector of pathogens of concern for animal and public health, but unless mosquitoes ticks remain attached to their hosts for long time periods providing an opportunity to analyse their role in the dispersal and dynamics of different zoonotic pathogens. Given their interest in public health it is important to understand which factors affect their incidence in different hosts and to stablish effective surveillance programs to determine the risk of transmission and spill-over of zoonotic pathogens. Taking benefit of a large network of volunteer ornithologists, we analysed the life-history traits associated to the presence of ticks using information of 620,609 individuals of 231 avian species. Bird phylogeny, locality and year explained a large amount of variance in tick prevalence. Non-colonial species non breeding in grasslands and non-spending the non-breeding season as gregarious groups or isolated individuals (e.g. thrushes, quails and finches) had the higher prevalence of ticks and appear as good candidates for zoonosis surveillance programs based on the analyses of ticks collected from wild birds. Ringers underestimated tick prevalence but can be considered as an important source of information of ticks for public and animal health surveillance programs if properly trained for the detection and collection of the different tick development phases.

Distribution and pathogen prevalence of field-collected ticks from south-western Korea: a study from 2019 to 2022

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.

Initial study and phylogenetic analysis of hard ticks (Acari: Ixodidae) in Nantong, China along the route of avian migration

The growing concern about migratory birds potentially spreading ticks due to global warming has become a significant issue. The city of Nantong in this study is situated along the East Asia-Australasian Flyway (EAAF), with numerous wetlands serving as roosting sites for migratory birds. We conducted an investigation of hard ticks and determined the phylogenetic characteristics of tick species in this city. We utilized three different genes for our study: the mitochondrial cytochrome oxidase subunit 1 (COX1) gene, the second internal transcribed spacer (ITS2), and the mitochondrial small subunit rRNA (12 S rRNA) gene. The predominant tick species were Haemaphysalis flava (H. flava) and Haemaphysalis longicornis (H. longicornis). Additionally, specimens of Haemaphysalis campanulata (H. campanulata) and Rhipicephalus sanguineus (R. sanguineus) were collected. The H. flava specimens in this study showed a close genetic relationship with those from inland provinces of China, as well as South Korea and Japan. Furthermore, samples of H. longicornis exhibited a close genetic relationship with those from South Korea, Japan, Australia, and the USA, as well as specific provinces in China. Furthermore, R. sanguineus specimens captured in Nantong showed genetic similarities with specimens from Egypt, Nigeria, and Argentina.

Tick species diversity and potential distribution alternation of dominant ticks under different climate scenarios in Xinjiang, China

Ticks are a hematophagous parasite and a vector of pathogens for numerous human and animal diseases of significant importance. The expansion of tick distribution and the increased risk of tick-borne diseases due to global climate change necessitates further study of the spatial distribution trend of ticks and their potential influencing factors. This study constructed a dataset of tick species distribution in Xinjiang for 60 years based on literature database retrieval and historical data collection (January 1963-January 2023). The distribution data were extracted, corrected, and deduplicated. The dominant tick species were selected for analysis using the MaxEnt model to assess their potential distribution in different periods under the current and BCC-CSM2.MR mode scenarios. The results indicated that there are eight genera and 48 species of ticks in 108 cities and counties of Xinjiang, with Hyalomma asiaticum, Rhipicephalus turanicus, Dermacentor marginatus, and Haemaphysalis punctatus being the top four dominant species. The MaxEnt model analysis revealed that the suitability areas of the four dominant ticks were mainly distributed in the north of Xinjiang, in areas such as Altay and Tacheng Prefecture. Over the next four periods, the medium and high suitable areas within the potential distribution range of the four tick species will expand towards the northwest. Additionally, new suitability areas will emerge in Altay, Changji Hui Autonomous Prefecture, and other local areas. The 60-year tick dataset in this study provides a map of preliminary tick distribution in Xinjiang, with a diverse array of tick species and distribution patterns throughout the area. In addition, the MaxEnt model revealed the spatial change characteristics and future distribution trend of ticks in Xinjiang, which can provide an instrumental data reference for tick monitoring and tick-borne disease risk prediction not only in the region but also in other countries participating in the Belt and Road Initiative.

Investigating the pathogens associated with Dermacentor nuttalli and its global distribution: A study integrating metagenomic sequencing, meta-analysis and niche modeling

Dermacentor nuttalli, a member of family Ixodidae and genus Dermacentor, is predominantly found in North Asia. It transmits various pathogens of human and animal diseases, such as Lymphocytic choriomeningitis mammarenavirus and Brucella ovis, leading to severe symptoms in patients and posing serious hazards to livestock husbandry. To profile pathogen abundances of wild D. nuttalli, metagenomic sequencing was performed of four field-collected tick samples, revealing that Rickettsia, Streptomyces, and Pseudomonas were the most abundant bacterial genera in D. nuttalli. Specifically, four nearly complete Rickettsia genomes were assembled, closely relative to Rickettsia conorii subsp. raoultii. Then, a comprehensive meta-analysis was performed to evaluate its potential threats based on detected pathogens and geographical distribution positions reported in literature, reference books, related websites, and field surveys. At least 48 pathogens were identified, including 20 species of bacteria, seven species of eukaryota, and 21 species of virus. Notably, Rickettsia conorii subsp. raoultii, Coxiella burnetii, and Brucella ovis displayed remarkably high positivity rates, which were known to cause infectious diseases in both humans and livestock. Currently, the primary distribution of D. nuttalli spans China, Mongolia, and Russia. However, an additional 14 countries in Asia and America that may also be affected by D. nuttalli were identified in our niche model, despite no previous reports of its presence in these areas. This study provides comprehensive data and analysis on the pathogens carried by D. nuttalli, along with documented and potential distribution, suggesting an emerging threat to public health and animal husbandry. Therefore, there is a need for heightened surveillance and thorough investigation of D. nuttalli.

New hard tick (Acari: Ixodidae) reports and detection of Rickettsia in ticks from Sierra Nevada de Santa Marta, Colombia

The Sierra Nevada de Santa Marta (SNSM), located in northern Colombia, is considered a geographical island with high levels of biodiversity and endemism. However, little is known about tick species and their associated microorganisms at the SNSM. In this study we sampled host-seeking ticks in areas of the town of Minca within the SNSM. We collected 47 ticks identified as Amblyomma pacae, Amblyomma longirostre, Amblyomma ovale, Amblyomma mixtum, Haemaphysalis juxtakochi, Ixodes sp. cf. Ixodes affinis and Ixodes sp. Of these ticks, we tested for Rickettsia spp. by amplifying the gltA, SCA1, and 16S rRNA genes via PCR. Rickettsia amblyommatis was detected in one pool of 3 larvae and in a female of A. pacae. Additonally, we isolated Rickettsia sp. belonging to the group of spotted fevers in larvae of A. longirostre. This study reports new findings of six species of ticks and two species of Rickettsia within the SNSM.

A Set of Diagnostic Tests for Detection of Active Babesia duncani Infection

Human babesiosis is a rapidly emerging and potentially fatal tick-borne disease caused by intraerythrocytic apicomplexan parasites of the Babesia genus. Among the various species of Babesia that infect humans, B. duncani has been found to cause severe and life-threatening infections. Detection of active B. duncani infection is critical for accurate diagnosis and effective management of the disease. While molecular assays for the detection of B. duncani infection in blood are available, a reliable strategy to detect biomarkers of active infection has not yet been developed. Here, we report the development of the first B. duncani antigen capture assays that rely on the detection of two B. duncani -exported immunodominant antigens, BdV234 and BdV38. The assays were validated using blood samples from cultured parasites in human erythrocytes and B. duncani -infected laboratory mice at different parasitemia levels and following therapy. The assays display high specificity with no cross-reactivity with B. microti , B. divergens , Babesia MO1, or P. falciparum. The assay also demonstrates high sensitivity, detecting as low as 115 infected erythrocytes/µl of blood. Screening of 1,731 blood samples from diverse biorepositories, including previously identified Lyme and/or B. microti positive human samples and new specimens from field mice, showed no evidence of B. duncani infection in these samples. The assays could be useful in diverse diagnostic scenarios, including point-of-care testing for early B. duncani infection detection in patients, field tests for screening reservoir hosts, and high-throughput screening such as blood collected for transfusion.

Short summary

We developed two ELISA-based assays, BdACA38 and BdACA234, for detecting B. duncani , a potentially fatal tick-borne parasite causing human babesiosis. The assays target two immunodominant antigens, BdV234 and BdV38, demonstrating high specificity (no cross-reactivity with other Babesia species or Plasmodium falciparum ) and sensitivity (detecting as low as 115 infected erythrocytes/µl). The assays were validated using in vitro-cultured parasites and infected mice. Screening diverse blood samples showed no evidence of B. duncani active infection among 1,731 human and field mice blood samples collected from the north-eastern, midwestern, and western US. These assays offer potential in diverse diagnostic scenarios, including early patient detection, reservoir animal screening, and transfusion-transmitted babesiosis prevention.

Nationwide survey of ticks on domesticated animals in Taiwan: Revealing the hidden threat to animal and public health

Ticks are not only bloodsucking ectoparasites but also important vectors of tick-borne diseases (TBDs), posing significant threats to public and animal health. Domesticated animals serve as critical hosts for numerous ticks, highlighting the importance of understanding tick infestations in Taiwan. To address this knowledge gap, we conducted a nationwide survey to identify ticks on domesticated animals and associated environments in 2018 and 2019. A total of 6,205 ticks were collected from 1,337 host animals, revealing the presence of seven tick species, with Rhipicephalus microplus, and Rhipicephalus sanguineus being the dominant species. High infestation rates and widespread distribution of ticks were observed on domesticated animals, especially on dogs and cattle (yellow cattle and angus cattle), and the neighbouring grassland of yellow cattle. While this study has certain limitations, it provides valuable insights into the distribution and prevalence of ticks on domesticated animals in Taiwan and their implications for controlling TBDs. Further research is needed to comprehensively understand the complex interactions among ticks, hosts and pathogens.

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

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

Diversity of species and geographic distribution of tick-borne viruses in China

Introduction

Tick-borne pathogens especially viruses are continuously appearing worldwide, which have caused severe public health threats. Understanding the species, distribution and epidemiological trends of tick-borne viruses (TBVs) is essential for disease surveillance and control.

Methods

In this study, the data on TBVs and the distribution of ticks in China were collected from databases and literature. The geographic distribution of TBVs in China was mapped based on geographic locations of viruses where they were prevalent or they were detected in vector ticks. TBVs sequences were collected from The National Center for Biotechnology Information and used to structure the phylogenetic tree.

Results

Eighteen TBVs from eight genera of five families were prevalent in China. Five genera of ticks played an important role in the transmission of TBVs in China. According to phylogenetic analysis, some new viral genotypes, such as the Dabieshan tick virus (DTV) strain detected in Liaoning Province and the JMTV strain detected in Heilongjiang Province existed in China.

Discussion

TBVs were widely distributed but the specific ranges of viruses from different families still varied in China. Seven TBVs belonging to the genus Orthonairovirus of the family Nairoviridae such as Nairobi sheep disease virus (NSDV) clustered in the Xinjiang Uygur Autonomous Region (XUAR) and northeastern areas of China. All viruses of the family Phenuiviridae except Severe fever with thrombocytopenia syndrome virus (SFTSV) were novel viruses that appeared in the last few years, such as Guertu virus (GTV) and Tacheng tick virus 2 (TcTV-2). They were mainly distributed in the central plains of China. Jingmen tick virus (JMTV) was distributed in at least fourteen provinces and had been detected in more than ten species of tick such as Rhipicephalus microplus and Haemaphysalis longicornis, which had the widest distribution and the largest number of vector ticks among all TBVs. Parainfluenza virus 5 (PIV5) and Lymphatic choriomeningitis virus (LCMV) were two potential TBVs in Northeast China that could cause serious diseases in humans or animals. Ixodes persulcatus carried the highest number of TBVs, followed by Dermacentor nuttalli and H. longicornis. They could carry as many as ten TBVs. Three strains of Tick-borne encephalitis (TBEV) from Inner Mongolia Province clustered with ones from Russia, Japan and Heilongjiang Province, respectively. Several SFTSV strains from Zhejiang Province clustered with strains from Korea and Japan. Specific surveillance of dominant TBVs should be established in different areas in China.

Predicting current and future potential distributions of the greater bandicoot rat (Bandicota indica) under climate change conditions

BACKGROUND

Rodent infestation is a global problem. Rodents cause huge harm to agriculture, forestry, and animal husbandry around the world and spread various zoonoses. In this study, we simulated the potentially suitable habitats of Bandicota indica and predicted the impact of future climate change on its distribution under different socio-economic pathway scenarios of CMIP6 using a parameter-optimized maximum entropy (MaxEnt) model.

RESULTS

The average area under the receiver operating characteristic curve (AUC) value (0.958 ± 0.006) after ten repetitions proved the high accuracy of the MaxEnt model. Model results show that the annual mean temperature (≥ 15.93 °C), isothermality (28.52-80.49%), annual precipitation (780.13-3863.13 mm), precipitation of the warmest quarter (≥ 204.37 mm), and nighttime light (≥ 3.38) were important limiting environmental variables for the distribution of B. indica. Under current climate conditions, the projected potential suitable habitats for B. indica were mainly in India, China, Myanmar, Thailand, and Vietnam, which cover a total area of 301.70 × 104  km2 . The potentially suitable areas of B. indica in the world will expand under different future climate change scenarios by 1.61-17.65%.

CONCLUSIONS

These results validate the potential influence of climate change on the distribution of B. indica and aid in understanding the linkages between B. indica niches and the relevant environment, thereby identifying urgent management areas where interventions may be necessary to develop feasible early warning and prevention strategies to protect against this rodent's spread. © 2023 Society of Chemical Industry.

Evaluation of the association between climate warming and the spread and proliferation of Ixodes scapularis in northern states in the Eastern United States

Ixodes scapularis (the blacklegged tick) is widely distributed in forested areas across the eastern United States. The public health impact of I. scapularis is greatest in the north, where nymphal stage ticks commonly bite humans and serve as primary vectors for multiple human pathogens. There were dramatic increases in the tick's distribution and abundance over the last half-century in the northern part of the eastern US, and climate warming is commonly mentioned as a primary driver for these changes. In this review, we summarize the evidence for the observed spread and proliferation of I. scapularis being driven by climate warming. Although laboratory and small-scale field studies have provided insights into how temperature and humidity impact survival and reproduction of I. scapularis, using these associations to predict broad-scale distribution and abundance patterns is more challenging. Numerous efforts have been undertaken to model the distribution and abundance of I. scapularis at state, regional, and global scales based on climate and landscape variables, but outcomes have been ambiguous. Across the models, the functional relationships between seasonal or annual measures of heat, cold, precipitation, or humidity and tick presence or abundance were inconsistent. The contribution of climate relative to landscape variables was poorly defined. Over the last half-century, climate warming occurred in parallel with spread and population increase of the white-tailed deer, the most important reproductive host for I. scapularis adults, in the northern part of the eastern US. There is strong evidence for white-tailed deer playing a key role to facilitate spread and proliferation of I. scapularis in the US over the last century. However, due to a lack of spatially and temporally congruent data, climate, landscape, and host variables are rarely included in the same models, thus limiting the ability to evaluate their relative contributions or interactions in defining the geographic range and abundance patterns of ticks. We conclude that the role of climate change as a key driver for geographic expansion and population increase of I. scapularis in the northern part of the eastern US over the last half-century remains uncertain.

The impact of anthropogenic climate change on pediatric viral diseases

The adverse effects of climate change on human health are unfolding in real time. Environmental fragmentation is amplifying spillover of viruses from wildlife to humans. Increasing temperatures are expanding mosquito and tick habitats, introducing vector-borne viruses into immunologically susceptible populations. More frequent flooding is spreading water-borne viral pathogens, while prolonged droughts reduce regional capacity to prevent and respond to disease outbreaks with adequate water, sanitation, and hygiene resources. Worsening air quality and altered transmission seasons due to an increasingly volatile climate may exacerbate the impacts of respiratory viruses. Furthermore, both extreme weather events and long-term climate variation are causing the destruction of health systems and large-scale migrations, reshaping health care delivery in the face of an evolving global burden of viral disease. Because of their immunological immaturity, differences in physiology (e.g., size), dependence on caregivers, and behavioral traits, children are particularly vulnerable to climate change. This investigation into the unique pediatric viral threats posed by an increasingly inhospitable world elucidates potential avenues of targeted programming and uncovers future research questions to effect equitable, actionable change. IMPACT: A review of the effects of climate change on viral threats to pediatric health, including zoonotic, vector-borne, water-borne, and respiratory viruses, as well as distal threats related to climate-induced migration and health systems. A unique focus on viruses offers a more in-depth look at the effect of climate change on vector competence, viral particle survival, co-morbidities, and host behavior. An examination of children as a particularly vulnerable population provokes programming tailored to their unique set of vulnerabilities and encourages reflection on equitable climate adaptation frameworks.

Understanding the connections between climate change, air pollution, and human health in Africa: Insights from a literature review

Climate change and air pollution are two interconnected global challenges that have profound impacts on human health. In Africa, a continent known for its rich biodiversity and diverse ecosystems, the adverse effects of climate change and air pollution are particularly concerning. This review study examines the implications of air pollution and climate change for human health and well-being in Africa. It explores the intersection of these two factors and their impact on various health outcomes, including cardiovascular disease, respiratory disorders, mental health, and vulnerable populations such as children and the elderly. The study highlights the disproportionate effects of air pollution on vulnerable groups and emphasizes the need for targeted interventions and policies to protect their health. Furthermore, it discusses the role of climate change in exacerbating air pollution and the potential long-term consequences for public health in Africa. The review also addresses the importance of considering temperature and precipitation changes as modifiers of the health effects of air pollution. By synthesizing existing research, this study aims to shed light on complex relationships and highlight the key findings, knowledge gaps, and potential solutions for mitigating the impacts of climate change and air pollution on human health in the region. The insights gained from this review can inform evidence-based policies and interventions to mitigate the adverse effects on human health and promote sustainable development in Africa.

Strains of Anaplasma phagocytophilum from horses in Ohio are related to isolates from humans in the northeastern USA

IMPORTANCE

The tick-borne obligatory intracellular bacterium Anaplasma phagocytophilum infects humans as well as domesticated and wild animals, causing a febrile disease collectively called granulocytic anaplasmosis. The epidemiology and the host species specificity and zoonotic potential of A. phagocytophilum strains remain unclear. In this study, ankA (encoding ankyrin A) and p44 gene sequences of A. phagocytophilum were determined in clinical specimens from horses in Ohio and compared with those found in A. phagocytophilum strains from various hosts and geographic regions. With increasing numbers of seropositive horses, the study points out the unrecognized prevalence and uncharacterized strains of A. phagocytophilum infection in horses and the importance of A. phagocytophilum molecular testing for the prevention of equine and human granulocytic anaplasmosis.

Tick-Borne Diseases of Humans and Animals in West Africa

Ticks are a significant group of arthropod vectors that transmit a large variety of pathogens responsible for human and animal diseases worldwide. Ticks are the second biggest transmitters of vector-borne diseases, behind mosquitoes. However, in West Africa, there is often only limited knowledge of tick-borne diseases. With the scarcity of appropriate diagnostic services, the prevalence of tick-borne diseases is generally underestimated in humans. In this review, we provide an update on tick-borne pathogens reported in people, animals and ticks in West Africa by microscopic, immunological and molecular methods. A systematic search was conducted in PubMed and Google Scholar. The selection criteria included all studies conducted in West Africa reporting the presence of Rickettsia, Borrelia, Anaplasma, Ehrlichia, Bartonella, Coxiella burnetii, Theileria, Babesia, Hepatozoon and Crimean-Congo haemorrhagic fever viruses in humans, animals or ticks. Our intention is to raise awareness of tick-borne diseases amongst human and animal health workers in West Africa, and also physicians working with tourists who have travelled to the region.

Transcriptome analysis of Haemaphysalis flava female using Illumina HiSeq 4000 sequencing: de novo assembly, functional annotation and discovery of SSR markers

BACKGROUND

Ticks are ectoparasites capable of directly damaging their hosts and transmitting vector-borne diseases. The ixodid tick Haemaphysalis flava has a broad distribution that extends from East to South Asia. This tick is a reservoir of severe fever with thrombocytopenia syndrome virus (SFTSV) that causes severe hemorrhagic disease, with cases reported from China, Japan and South Korea. Recently, the distribution of H. flava in South Korea was found to overlap with the occurrence of SFTSV.

METHODS

This study was undertaken to discover the molecular resources of H. flava female ticks using the Illumina HiSeq 4000 system, the Trinity de novo sequence assembler and annotation against public databases. The locally curated Protostome database (PANM-DB) was used to screen the putative adaptation-related transcripts classified to gene families, such as angiotensin-converting enzyme, aquaporin, adenylate cyclase, AMP-activated protein kinase, glutamate receptors, heat shock proteins, molecular chaperones, insulin receptor, mitogen-activated protein kinase and solute carrier family proteins. Also, the repeats and simple sequence repeats (SSRs) were screened from the unigenes using RepeatMasker (v4.0.6) and MISA (v1.0) software tools, followed by the designing of SSRs flanking primers using BatchPrimer 3 (v1.0) software.

RESULTS

The transcriptome produced a total of 69,822 unigenes, of which 46,175 annotated to the homologous proteins in the PANM-DB. The unigenes were also mapped to the EuKaryotic Orthologous Groups (KOG), Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) specializations. Promiscuous presence of protein kinase, zinc finger (C2H2-type), reverse transcriptase, and RNA recognition motif domains was observed in the unigenes. A total of 3480 SSRs were screened, of which 1907 and 1274 were found as tri- and dinucleotide repeats, respectively. A list of primer sequences flanking the SSR motifs was detailed for validation of polymorphism in H. flava and the related tick species.

CONCLUSIONS

The reference transcriptome information on H. flava female ticks will be useful for an enriched understanding of tick biology, its competency to act as a vector and the study of species diversity related to disease transmission.

It's about time: small mammal communities and Lyme disease emergence

Theory predicts that biodiversity changes due to climate warming can mediate the rate of disease emergence. The mechanisms linking biodiversity-disease relationships have been described both theoretically and empirically but remain poorly understood. We investigated the relations between host diversity and abundance and Lyme disease risk in southern Quebec, a region where Lyme disease is rapidly emerging. We found that both the abundance of small mammal hosts and the relative abundance of the tick's natural host, the white-footed mouse (Peromyscus leucopus), influenced measures of disease risk in tick vectors (Borrelia burgdorferi infection abundance and prevalence in tick vectors). Our results suggest that the increase in Lyme disease risk is modulated by regional processes involving the abundance and composition of small mammal assemblages. However, the nature and strength of these relationships was dependent both on time and geographic area. The strong effect of P. leucopus abundance on disease risk we report here is of significant concern, as this competent host is predicted to increase in abundance and occurrence in the region, with the northern shift in the range of North American species under climate warming.

Temporal tendency, seasonality and relationship with climatic factors of Crimean-Congo Hemorrhagic Fever cases (East of Turkey: 2012-2021)

Crimean-Congo Hemorrhagic Fever continues to be an important public health problem by expanding its borders. To evaluate the temporal trend, seasonality, and relationship with the climatic factors of Crimean-Congo Hemorrhagic Fever. Study data included cases treated in two different tertiary healthcare institutions between 2012 and 2021. The demographic characteristics of the cases and the dates of admission to the hospital were determined, and they were matched with the average of the measurements (temperature, cumulative precipitation, relative humidity, wind speed) of two different meteorology stations in the study area. By calculating the crude incidence rates, the trend in years was investigated. Estimates were created by removing the incidence rates, seasonality, and trend components using the additive decomposition technique. The temporal relationship between incidence rates and climatic factors was evaluated with the help of the Autoregressive Distributed Lag Bound Test. Toda Yamamoto test was used for causality verification. The mean age of the cases (n = 974) included in the study was 47.6 ± 17.7 years, and the majority (57.3%) were in the group above 45 years of age. 56.6% of the cases were male and there was a male predominance in all age groups. Incidence rates ranged from 5.5 to 23.1/100,000 over the ten-year period and there was a significant upward trend (R2 = 0.691, p = 0.003). Cases of Crimean-Congo Hemorrhagic Fever that started in March, peaked in July and ended in October, showed a clear seasonality. A cointegration relationship was observed between case incidence rates and air temperature, cumulative precipitation, and relative humidity (p < 0.05 for all). Climatic factors can only indirectly affect the occurrence of Crimean-Congo Hemorrhagic Fever cases. However, climatic conditions that become progressively more favorable for vector ticks lead to the spread of the disease. The control measures to be taken should be prepared by considering the changing climatic conditions and prioritizing the risk groups. There is a need for information and awareness-raising studies about climate change and the growing dangers associated with it, also outside of endemic regions.

Genome-informed investigation of the molecular evolution and genetic reassortment of severe fever with thrombocytopenia syndrome virus

BACKGROUND

Severe fever with thrombocytopenia syndrome virus (SFTSV) is a viral pathogen causing significant clinical signs from mild fever with thrombocytopenia to severe hemorrhages. World Health Organization has paid special attention to the dramatic increase in human SFTS cases in China, Japan, and South Korea since the 2010s. The present study investigated the molecular evolution and genetic reassortment of SFTSVs using complete genomic sequences.

METHODS/PRINCIPAL FINDING

We collected the complete genome sequences of SFTSVs globally isolated until 2019 (L segment, n = 307; M segment, n = 326; and S segment, n = 564) and evaluated the evolutionary profiles of SFTSVs based on phylogenetic and molecular selection pressure analyses. By employing a time-scaled Bayesian inference method, we found the geographical heterogeneity of dominant SFTSV genotypes in China, Japan, and South Korea around several centuries before and locally spread by tick-born spillover with infrequent long-distance transmission. Purifying selection predominated the molecular evolution of SFTSVs with limited gene reassortment and fixed substitution, but almost all three gene segments appeared to harbor at least one amino acid residue under positive selection. Specifically, the nonstructural protein and glycoprotein (Gn/Gc) genes were preferential selective targets, and the Gn region retained the highest number of positively selected residues.

CONCLUSION/SIGNIFICANCE

Here, the large-scale genomic analyses of SFTSVs improved prior knowledge of how this virus emerged and evolved in China, Japan, and South Korea. Our results highlight the importance of SFTSV surveillance in both human and non-human reservoirs at the molecular level to fight against fatal human infection with the virus.

A Longitudinal Study of a Large Clinical Cohort of Patients with Lyme Disease and Tick-Borne Co-Infections Treated with Combination Antibiotics

The rising prevalence of tick-borne infections (TBIs) necessitates further attention. This study retrospectively investigated the types of TBIs, symptoms, and if combination antibiotics were helpful within a patient cohort at an infectious disease clinic in Ireland. In this chart audit of 301 individuals (184 female, 117 male) tested for TBIs, 140 (46.51%) had positive antibody responses for TBIs from an ELISA (enzyme-linked immunoassay) that was based on a modified two-tiered testing protocol. A total of 93 (66.43%) patients had positive antibody responses to one TBI: 83 (59.29%) for Borrelia, 7 (5.00%) for Rickettsia, and 1 (0.71%) each for either Babesia, Bartonella, or Ehrlichia. The remaining 47 (33.57%) patients were infected with multiple TBIs. These patients were treated with combination antibiotics and monitored at two subsequent follow-ups. Only 2 of 101 patients (1.98%) had discontinued treatment by the second follow-up. In the first follow-up with 118 patients, 70 (59.32%) reported pain and 48 (40.68%) had neurological symptoms. In the next follow-up of 101 patients, 41 (40.59%) had pain while 30 (29.70%) had neurological symptoms. There were statistically significant reductions in the incidence of pain (41.43%) and neurological (37.50%) symptoms between follow-ups. Thus, our study demonstrates that combination antibiotics effectively relieve TBI symptoms with good patient tolerance.

Invasive hematophagous arthropods and associated diseases in a changing world

Biological invasions have increased significantly with the tremendous growth of international trade and transport. Hematophagous arthropods can be vectors of infectious and potentially lethal pathogens and parasites, thus constituting a growing threat to humans-especially when associated with biological invasions. Today, several major vector-borne diseases, currently described as emerging or re-emerging, are expanding in a world dominated by climate change, land-use change and intensive transportation of humans and goods. In this review, we retrace the historical trajectory of these invasions to better understand their ecological, physiological and genetic drivers and their impacts on ecosystems and human health. We also discuss arthropod management strategies to mitigate future risks by harnessing ecology, public health, economics and social-ethnological considerations. Trade and transport of goods and materials, including vertebrate introductions and worn tires, have historically been important introduction pathways for the most prominent invasive hematophagous arthropods, but sources and pathways are likely to diversify with future globalization. Burgeoning urbanization, climate change and the urban heat island effect are likely to interact to favor invasive hematophagous arthropods and the diseases they can vector. To mitigate future invasions of hematophagous arthropods and novel disease outbreaks, stronger preventative monitoring and transboundary surveillance measures are urgently required. Proactive approaches, such as the use of monitoring and increased engagement in citizen science, would reduce epidemiological and ecological risks and could save millions of lives and billions of dollars spent on arthropod control and disease management. Last, our capacities to manage invasive hematophagous arthropods in a sustainable way for worldwide ecosystems can be improved by promoting interactions among experts of the health sector, stakeholders in environmental issues and policymakers (e.g. the One Health approach) while considering wider social perceptions.

Mechanistic movement models to predict geographic range expansions of ticks and tick-borne pathogens: Case studies with Ixodes scapularis and Amblyomma americanum in eastern North America

The geographic range of the blacklegged tick, Ixodes scapularis, is expanding northward from the United States into southern Canada, and studies suggest that the lone star tick, Amblyomma americanum, will follow suit. These tick species are vectors for many zoonotic pathogens, and their northward range expansion presents a serious threat to public health. Climate change (particularly increasing temperature) has been identified as an important driver permitting northward range expansion of blacklegged ticks, but the impacts of host movement, which is essential to tick dispersal into new climatically suitable regions, have received limited investigation. Here, a mechanistic movement model was applied to landscapes of eastern North America to explore 1) relationships between multiple ecological drivers and the speed of the northward invasion of blacklegged ticks infected with the causative agent of Lyme disease, Borrelia burgdorferi sensu stricto, and 2) its capacity to simulate the northward range expansion of infected blacklegged ticks and uninfected lone star ticks under theoretical scenarios of increasing temperature. Our results suggest that the attraction of migratory birds (long-distance tick dispersal hosts) to resource-rich areas during their spring migration and the mate-finding Allee effect in tick population dynamics are key drivers for the spread of infected blacklegged ticks. The modeled increases in temperature extended the climatically suitable areas of Canada for infected blacklegged ticks and uninfected lone star ticks towards higher latitudes by up to 31% and 1%, respectively, and with an average predicted speed of the range expansion reaching 61 km/year and 23 km/year, respectively. Differences in the projected spatial distribution patterns of these tick species were due to differences in climate envelopes of tick populations, as well as the availability and attractiveness of suitable habitats for migratory birds. Our results indicate that the northward invasion process of lone star ticks is primarily driven by local dispersal of resident terrestrial hosts, whereas that of blacklegged ticks is governed by long-distance migratory bird dispersal. The results also suggest that mechanistic movement models provide a powerful approach for predicting tick-borne disease risk patterns under complex scenarios of climate, socioeconomic and land use/land cover changes.

Under-diagnosis of vector-borne diseases among individuals suspected of having Scrub Typhus in South Korea

Due to environmental and ecological changes and suitable habitats, the occurrence of vector-borne diseases is increasing. We investigated the seroprevalence of four major vector-borne pathogens in human patients with febrile illness who were clinically suspected of having Scrub Typhus (ST) caused by Orientia tsutsugamushi. A total of 187 samples (182 patient whole blood and sera samples, including 5 follow-up) were collected. Antibodies to Anaplasma phagocytophilum, Ehrlichia chaffeensis, Borrelia burgdorferi, and Bartonella henselae were tested by using indirect immunofluorescence assays. Molecular diagnoses were performed using real-time PCR. Of the 182 cases, 37 (20.3%) cases were designated as confirmed cases of ST, and the remaining 145 (79.7%) cases as other febrile diseases (OFDs). The seroprevalence of A. phagocytophilum, E. chaffeensis, B. burgdorferi, and B. henselae was 51.4% (19/37), 10.8% (4/37), 86.5% (32/37), and 10.8% (4/37) among the ST group, and 42.8% (62/145), 10.4% (19/145), 57.7% (105/145), and 15.9% (29/145) among the OFD group, respectively. There were no significant differences in the seroprevalence between the ST and the OFD groups. Considering the co-occurrence, 89.0% (162/182) had at least one antibody to tick-borne pathogens, 37.0% (60/162) were positive for two pathogens, 17.3% (28/162) for three pathogens, and 6.2% (10/162) for four pathogens. In real-time PCR, O. tsutsugamushi was positive in 16 cases [15 (40.5%) in ST group and 1 (2.2%) in OFD group], and the four other pathogens were negative in all cases except one confirmed as anaplasmosis. In evaluating the five follow-up samples, the appearance of new antibodies or an increase in the pre-existing antibody titers was detected. Our data highlighted that acute febrile illness and manifestations suggestive of a vector-borne infection must be recognized and further considered for coinfections in clinical practice and the laboratory.

Human-biting ticks and zoonotic tick-borne pathogens in North Africa: diversity, distribution, and trans-Mediterranean public health challenges

North Africa is home to more than 200 million people living across five developing economies (Egypt, Libya, Tunisia, Algeria, and Morocco) and two Spanish exclaves (Ceuta and Melilla), many of whom are impacted by ticks and tick-borne zoonoses. Populations in Europe are also increasingly vulnerable to North African ticks and tick-borne zoonoses due to a combination of climate change and the movement of ticks across the Mediterranean on migratory birds, human travellers, and trafficked wildlife. The human-biting ticks and tick-borne zoonoses in North Africa are reviewed along with their distribution in the region. We also assess present and future challenges associated with ticks and tick-borne zoonoses in North African and highlight opportunities for collaboration and coordination between governments in Europe and North Africa to address public health challenges posed by North African ticks and tick-borne zoonoses.

Immunization against arthropod protein impairs transmission of rickettsial pathogen from ticks to the vertebrate host

Human anaplasmosis caused by Anaplasma phagocytophilum is one of the most common tick-borne diseases in the United States. The black-legged ticks, Ixodes scapularis, vector and transmit this bacterium to humans. In this study, we provide evidence that targeting I. scapularis membrane-bound organic anion transporting polypeptide 4056 (IsOATP4056) with an anti-vector vaccine affects transmission of A. phagocytophilum from ticks to the vertebrate host. Anaplasma phagocytophilum induces expression of IsOATP4056 in ticks and tick cells. Increased membrane localization of IsOATP4056 was evident in A. phagocytophilum-infected tick cells. Treatment with high dose (10 µg/ml) but not low dose (5 µg/ml) of EL-6 antibody that targets the largest extracellular loop of IsOATP4056 showed cytotoxic effects in tick cells but not in human keratinocyte cell line (HaCaT). Passive immunization, tick-mediated transmission and in vitro studies performed with mice ordered from two commercial vendors and with tick cells showed that EL-6 antibody not only impairs A. phagocytophilum transmission from ticks to the murine host but also aids in the reduction in the bacterial loads within engorged ticks and in tick cells by activation of arthropod Toll pathway. Furthermore, reduced molting efficiency was noted in ticks fed on EL-6 antibody-immunized mice. Collectively, these results provide a good candidate for the development of anti-tick vaccine to target the transmission of A. phagocytophilum and perhaps other tick-borne pathogens of medical importance.

Molecular characterisation of three Ixodes (Pholeoixodes) species (Ixodida, Ixodidae) and the first record of Ixodes (Pholeoixodes) kaiseri from Slovakia

A study of ticks on wildlife was carried out in the area of Levice, Bratislava, Stupava, and Vrbovce (south-western Slovakia) during 2021 and 2022. Overall, 512 ticks were collected from 51 individuals of six wild mammalian species. Eight tick species were identified, namely Dermacentorreticulatus, D.marginatus, Haemaphysalisinermis, H.concinna, Ixodesricinus, I.hexagonus, and two Ixodes spp. Ixodeshexagonus were collected from northern white-breasted hedgehogs (Erinaceusroumanicus), females belonging to Ixodes spp. were collected from red fox (Vulpesvulpes) and nymphs from European badger (Melesmeles). Ixodeshexagonus and the Ixodes spp. were identified morphologically and molecularly based on sequences of fragments of two mitochondrial genes, COI and 16S rRNA. Molecular analysis of Ixodes spp. confirmed the identity of Ixodeskaiseri Arthur, 1957 and I.canisuga (Johnston, 1849). Sequence analyses show that the I.kaiseri isolate from Slovakia is identical to I.kaiseri isolates from Romania, Poland, Germany, Turkey, and Croatia. We demonstrate for the first time the presence of I.kaiseri in Slovakia using both morphological and molecular methods.

T Cells in Tick-Borne Flavivirus Encephalitis: A Review of Current Paradigms in Protection and Disease Pathology

The family Flaviviridae is comprised of a diverse group of arthropod-borne viruses that are the etiological agents of globally relevant diseases in humans. Among these, infection with several of these flaviviruses-including West Nile virus (WNV), Zika virus (ZIKV), Japanese encephalitis virus (JEV), tick-borne encephalitis virus (TBEV), and Powassan virus (POWV)-can result in neuroinvasive disease presenting as meningitis or encephalitis. Factors contributing to the development and resolution of tick-borne flavivirus (TBEV, POWV) infection and neuropathology remain unclear, though many recently undertaken studies have described the virus-host interactions underlying encephalitic disease. With access to neural tissues despite the selectively permeable blood-brain barrier, T cells have emerged as one notable contributor to neuroinflammation. The goal of this review is to summarize the recent advances in tick-borne flavivirus immunology-particularly with respect to T cells-as it pertains to the development of encephalitis. We found that although T cell responses are rarely evaluated in a clinical setting, they are integral in conjunction with antibody responses to restricting the entry of TBFV into the CNS. The extent and means by which they can drive immune pathology, however, merits further study. Understanding the role of the T cell compartment in tick-borne flavivirus encephalitis is instrumental for improving vaccine safety and efficacy, and has implications for treatments and interventions for human disease.

Human Borrelia miyamotoi Infection in North America

Borrelia miyamotoi is an emerging pathogen that causes a febrile illness and is transmitted by the same hard-bodied (ixodid) ticks that transmit several other pathogens, including Borrelia species that cause Lyme disease. B. miyamotoi was discovered in 1994 in Ixodes persulcatus ticks in Japan. It was first reported in humans in 2011 in Russia. It has subsequently been reported in North America, Europe, and Asia. B. miyamotoi infection is widespread in Ixodes ticks in the northeastern, northern Midwestern, and far western United States and in Canada. In endemic areas, human B. miyamotoi seroprevalence averages from 1 to 3% of the population, compared with 15 to 20% for B. burgdorferi. The most common clinical manifestations of B. miyamotoi infection are fever, fatigue, headache, chills, myalgia, arthralgia, and nausea. Complications include relapsing fever and rarely, meningoencephalitis. Because clinical manifestations are nonspecific, diagnosis requires laboratory confirmation by PCR or blood smear examination. Antibiotics are effective in clearing infection and are the same as those used for Lyme disease, including doxycycline, tetracycline, erythromycin, penicillin, and ceftriaxone. Preventive measures include avoiding areas where B. miyamotoi-infected ticks are found, landscape management, and personal protective strategies such as protective clothing, use of acaricides, and tick checks with rapid removal of embedded ticks.

Tick Populations and Molecular Analysis of Anaplasma Species in Ticks from the Republic of Korea

The present study was performed to survey the dominant tick populations and molecularly determine the pathogenic agents of anaplasmosis in ticks from Gyeongsang, Republic of Korea. A total of 3825 questing ticks were collected by the flagging method from 12 sites near animal farms in Gyeongsang from March to October 2021. A molecular genomic study was performed with ticks stored in 70% ethanol to detect Anaplasma genes by the previously described method. The monthly incidence of ticks varied by developmental stages, i.e., nymphs, adults, and larvae, and each of their populations peaked in May, March, and October, respectively. The predominant tick species were Haemaphysalis longicornis, Haemaphysalis sp., Haemaphysalis flava, Ixodes nipponensis, and Amblyomma testudinarium in order. To determine the Anaplasma infection rate, collected ticks were pooled into 395 groups. The minimum infection rate (MIR) of Anaplasma was 0.7% (27 pools). That of A. phagocytophilum was highest (23 pools, MIR 0.6%), followed by A. phagocytophilum-like Anaplasma spp. clade B (2 pools, MIR 0.1%), A. bovis (1 pool, MIR 0.1%), and A. capra (1 pool, MIR 0.1%), respectively. In this study, five species of ticks, including unidentified Haemaphysalis species, were collected in 12 survey sites in Gyeongsang, but their prevalence was somewhat different according to the tick species and survey sites. Further, the incidence rate (6.8%) of 4 Anaplasma spp. was not as high in tick pools. However, the results of this study may offer a basis for future epidemiological research and risk assessment of tick-borne diseases.

Biodiversity in the Lyme-light: ecological restoration and tick-borne diseases in Europe

Biodiversity loss and the emergence of zoonotic diseases are two major global challenges. An urgent question is how ecosystems and wildlife communities can be restored whilst minimizing the risk of zoonotic diseases carried by wildlife. Here, we evaluate how current ambitions to restore Europe's natural ecosystems may affect the hazard of diseases vectored by the tick Ixodes ricinus at different scales. We find that effects of restoration efforts on tick abundance are relatively straightforward but that the interacting effects of vertebrate diversity and abundance on pathogen transmission are insufficiently known. Long-term integrated surveillance of wildlife communities, ticks, and their pathogens is needed to understand their interactions and to prevent nature restoration from increasing tick-borne disease (TBD) hazard.

Impact of green space connectivity on urban tick presence, density and Borrelia infected ticks in different habitats and seasons in three cities in southern England

Understanding the effects of local habitat and wider landscape connectivity factors on tick presence, nymph density and Borrelia species (spp.) prevalence in the tick population is important for identifying the public health risk from Lyme borreliosis. This multi-city study collected data in three southern England cities (Bath, Bristol, and Southampton) during spring, summer, and autumn in 2017. Focusing specifically on urban green space used for recreation which were clearly in urbanised areas, 72 locations were sampled. Additionally, geospatial datasets on urban green space coverage within 250 m and 1 km of sampling points, as well as distance to woodland were incorporated into statistical models. Distance to woodland was negatively associated with tick presence and nymph density, particularly during spring and summer. Furthermore, we observed an interaction effect between habitat and season for tick presence and nymph density, with woodland habitat having greater tick presence and nymph density during spring. Borrelia spp. infected Ixodes ricinus were found in woodland, woodland edge and under canopy habitats in Bath and Southampton. Overall Borrelia spp. prevalence in nymphs was 2.8%, similar to wider UK studies assessing prevalence in Ixodes ricinus in rural areas. Bird-related Borrelia genospecies dominated across sites, suggesting bird reservoir hosts may be important in urban green space settings for feeding and infecting ticks. Whilst overall density of infected nymphs across the three cities was low (0.03 per 100 m²), risk should be further investigated by incorporating data on tick bites acquired in urban settings, and subsequent Lyme borreliosis transmission.

Molecular epidemiology of Theileria species in ticks and its potential threat to livestock in the Republic of Korea

The purpose of this study was to investigate molecular epidemiology of Theileria spp. in ticks in Korea and assess their potential threat from wildlife animals to domestic animals. A total of 21152 hard ticks were collected from Chungcheong and Jeolla provinces of Korea from March to October 2021. Tick species were identified by microscopy and Theileria spp. were screened by nested PCR targeting 18S rRNA. Haemaphysalis spp. were the most abundant tick species, followed by H. longicornis, H. flava, Amblyomma testudinarium, and Ixodes nipponensis. Of the collected ticks, 6914 ticks (541 pools) were screened, and PCR showed 211 positive pools (39.0%; MIR: 3.05). The PCR and phylogenetic analysis identified two Theileria species, T. luwenshuni and Theileria sp., with T. luwenshuni (162/211, 76.78%; MIR: 2.34) being more abundant than Theileria sp. (36/211, 17.06%; MIR: 0.52); co-infection of the two species were noted (13/211, 6.16%; MIR: 0.19). Among the tick species, H. longicornis, especially nymphs, showed the highest prevalence. Regarding season, the highest prevalence was observed in May. Considering the tick and Theileria species identified in this study, H. longicornis nymph and cervine play a critical role in maintaining Theileria spp. in Korea and could be a potential threat to domestic animals, including deer and goats. In addition, there are significant correlations among tick distribution, region, season, and prevalence of Theileria.

Unravelling the Diversity of Microorganisms in Ticks from Australian Wildlife

Ticks and tick-borne pathogens pose a significant threat to the health and welfare of humans and animals. Our knowledge about pathogens carried by ticks of Australian wildlife is limited. This study aimed to characterise ticks and tick-borne microorganisms from a range of wildlife species across six sites in Victoria, Australia. Following morphological and molecular characterisation (targeting 16S rRNA and cytochrome c oxidase I), tick DNA extracts (n = 140) were subjected to microfluidic real-time PCR-based screening for the detection of microorganisms and Rickettsia-specific real-time qPCRs. Five species of ixodid ticks were identified, including Aponomma auruginans, Ixodes (I.) antechini, I. kohlsi, I. tasmani and I. trichosuri. Phylogenetic analyses of 16S rRNA sequences of I. tasmani revealed two subclades, indicating a potential cryptic species. The microfluidic real-time PCR detected seven different microorganisms as a single (in 13/45 ticks) or multiple infections (27/45). The most common microorganisms detected were Apicomplexa (84.4%, 38/45) followed by Rickettsia sp. (55.6%, 25/45), Theileria sp. (22.2% 10/45), Bartonella sp. (17.8%, 8/45), Coxiella-like sp. (6.7%, 3/45), Hepatozoon sp. (2.2%, 1/45), and Ehrlichia sp. (2.2%, 1/45). Phylogenetic analyses of four Rickettsia loci showed that the Rickettsia isolates detected herein potentially belonged to a novel species of Rickettsia. This study demonstrated that ticks of Australian wildlife carry a diverse array of microorganisms. Given the direct and indirect human-wildlife-livestock interactions, there is a need to adopt a One Health approach for continuous surveillance of tick-associated pathogens/microorganisms to minimise the associated threats to animal and human health.

Knowledge, Attitudes, and Behaviors Regarding Lyme Borreliosis Prevention in the Endemic Area of Northeastern Poland

(1) Background: The incidence of Lyme borreliosis (LB) is increasing in Europe. The new LB vaccine is still in clinical development, thus the dissemination of knowledge about the disease is essential. We assessed the knowledge, attitudes and preventive practices (KAP) against tick-borne diseases (TBDs) of people living in the endemic area in northeastern Poland. (2) Methods: We surveyed 406 adults using a 37-item anonymous paper survey. The data were analyzed with regression models. (3) Results: The two most popular knowledge sources were the Internet and doctors, selected by 77.8% and 53.4%, respectively. Respondents felt moderately knowledgeable about TBDs and tick bite prophylaxis (median scores 5/10, and 6/10, respectively), considered TBDs to be a significant health threat (median 8/10), attributed high risk to tick mouthparts remaining in the skin after tick removal (median 10/10), and shared multiple misconceptions regarding LB transmission, symptoms, and management. General knowledge scores (GKS) about TBDs and tick protection practices scores (TPS) were moderate (65.0%; IQR, 55.8−71.7%, 63.6%; 54.5−72.7%, respectively). Only 48.0% had a positive attitude towards TBE vaccination. A recent tick-bite was associated with higher GKS (OR, 2.55; 95% CI, 1.27−5.10; p = 0.008), higher TPS (OR 4.76, 95% CI, 2.0−11.1; p < 0.001), and a positive attitude towards TBE vaccine (OR 2.10, 1.07−4.10, p = 0.030). A positive vaccine attitude was also associated with obtaining TBD knowledge from doctors and other verified sources (OR, 2.654, 1.66−4.23; p < 0.001). Age, place of residence, and frequent exposure to ticks in green areas were not associated with GKS, TPS, nor vaccine attitude. (4) Conclusions: Increased risk perceptions are associated with adoption of behaviors preventing TBDs. Medical professionals play an important role in communicating knowledge about TBDs. There is a need to revise current communication strategies with respect to tick bites and prevention of LB and other TBDs.

Epitope profiling of monoclonal antibodies to the immunodominant antigen BmGPI12 of the human pathogen Babesia microti

The significant rise in the number of tick-borne diseases represents a major threat to public health worldwide. One such emerging disease is human babesiosis, which is caused by several protozoan parasites of the Babesia genus of which B. microti is responsible for most clinical cases reported to date. Recent studies have shown that during its intraerythrocytic life cycle, B. microti exports several antigens into the mammalian host using a novel vesicular-mediated secretion mechanism. One of these secreted proteins is the immunodominant antigen BmGPI12, which has been demonstrated to be a reliable biomarker of active B. microti infection. The major immunogenic determinants of this antigen remain unknown. Here we provide a comprehensive molecular and serological characterization of a set of eighteen monoclonal antibodies developed against BmGPI12 and a detailed profile of their binding specificity and suitability in the detection of active B. microti infection. Serological profiling and competition assays using synthetic peptides identified five unique epitopes on the surface of BmGPI12 which are recognized by a set of eight monoclonal antibodies. ELISA-based antigen detection assays identified five antibody combinations that specifically detect the secreted form of BmGPI12 in plasma samples from B. microti-infected mice and humans but not from other Babesia species or P. falciparum.

Tick Control in a Connected World: Challenges, Solutions, and Public Policy from a United States Border Perspective

Ticks are able to transmit the highest number of pathogen species of any blood-feeding arthropod and represent a growing threat to public health and agricultural systems worldwide. While there are numerous and varied causes and effects of changes to tick-borne disease (re)emergence, three primary challenges to tick control were identified in this review from a U.S. borders perspective. (1) Climate change is implicated in current and future alterations to geographic ranges and population densities of tick species, pathogens they can transmit, and their host and reservoir species, as highlighted by Ixodes scapularis and its expansion across southern Canada. (2) Modern technological advances have created an increasingly interconnected world, contributing to an increase in invasive tick species introductions through the increased speed and frequency of trade and travel. The introduction of the invasive Haemaphysalis longicornis in the eastern U.S. exemplifies the challenges with control in a highly interconnected world. (3) Lastly, while not a new challenge, differences in disease surveillance, control, and management strategies in bordering countries remains a critical challenge in managing ticks and tick-borne diseases. International inter-agency collaborations along the U.S.-Mexico border have been critical in control and mitigation of cattle fever ticks (Rhipicephalus spp.) and highlight the need for continued collaboration and research into integrated tick management strategies. These case studies were used to identify challenges and opportunities for tick control and mitigation efforts through a One Health framework.

Thrombospondin-Related Anonymous Protein (TRAP) Family Expression by Babesia bovis Life Stages within the Mammalian Host and Tick Vector

The tick-transmitted disease bovine babesiosis causes significant economic losses in many countries around the world. Current control methods include modified live-attenuated vaccines that have limited efficacy. Recombinant proteins could provide effective, safe, and low-cost alternative vaccines. We compared the expression of the Babesia bovis thrombospondin-related anonymous protein (TRAP) family from parasites in bovine blood, in vitro induced sexual stages, and kinetes from tick hemolymph. Quantitative PCR showed that in blood and sexual stages, TRAP3 was highly transcribed as compared to the other TRAPs. In contrast, the TRAP1 gene was highly transcribed in kinetes as compared to the other TRAPs. Fixed immunofluorescence assays showed that TRAP2, 3, and 4 proteins were expressed by both blood and sexual stages. Conversely, TRAP1 protein, undetected on blood and induced sexual stages, was the only family member expressed by kinetes. Live IFA revealed that TRAP2, 3, and 4 proteins were expressed on the surface of both B. bovis blood and sexual stages. Modeling of B. bovis TRAP1 and TRAP4 tertiary structure demonstrated both proteins folded the metal-ion-dependent adhesion site (MIDAS) domain structure of Plasmodium TRAP. In conclusion, TRAP proteins may serve as potential vaccine targets to prevent infection of bovine and ticks with B. bovis essential for controlling the spread of bovine babesiosis.

Global Change and Emerging Infectious Diseases

Our world is undergoing rapid planetary changes driven by human activities, often mediated by economic incentives and resource management, affecting all life on Earth. Concurrently, many infectious diseases have recently emerged or spread into new populations. Mounting evidence suggests that global change-including climate change, land-use change, urbanization, and global movement of individuals, species, and goods-may be accelerating disease emergence by reshaping ecological systems in concert with socioeconomic factors. Here, we review insights, approaches, and mechanisms by which global change drives disease emergence from a disease ecology perspective. We aim to spur more interdisciplinary collaboration with economists and identification of more effective and sustainable interventions to prevent disease emergence. While almost all infectious diseases change in response to global change, the mechanisms and directions of these effects are system specific, requiring new, integrated approaches to disease control that recognize linkages between environmental and economic sustainability and human and planetary health.

A Review on Climate, Air Pollution, and Health in North Africa

PURPOSE OF REVIEW

The aim of this review is to summarize and provide clear insights into studies that evaluate the interaction between air pollution, climate, and health in North Africa.

RECENT FINDINGS

Few studies have estimated the effects of climate and air pollution on health in North Africa. Most of the studies highlighted the evidence of the link between climate and air pollution as driving factors and increased mortality and morbidity as health outcomes. Each North African country prioritized research on a specific health factor. It was observed that the health outcome from each driving factor depends on the studied area and data availability. The latter is a major challenge in the region. As such, more studies should be led in the future to cover more areas in North Africa and when more data are available. Data availability will help to explore the applicability of different tools and techniques new to the region. This review explores studies related to climate and air pollution, and their possible impacts on health in North Africa. On one hand, air quality studies have focused mainly on particulate matter exceedance levels and their long-term exposure impacts, namely, morbidity and mortality. The observed differences between the various studies are mainly due to the used exposure-response function, the studied population, background emissions, and natural emission from the Sahara Desert that characterize the region. On the other hand, climate studies have focused primarily on the impact of heat waves, vector-borne disease, and mental disorders. More than half of these studies have been on leishmaniasis disease. The review revealed unbalanced and insufficient research on health impacts from air pollution episodes and climate extremes across the region.

A Powassan virus domain III nanoparticle immunogen elicits neutralizing and protective antibodies in mice

Powassan virus (POWV) is an emerging tick borne flavivirus (TBFV) that causes severe neuroinvasive disease. Currently, there are no approved treatments or vaccines to combat POWV infection. Here, we generated and characterized a nanoparticle immunogen displaying domain III (EDIII) of the POWV E glycoprotein. Immunization with POWV EDIII presented on nanoparticles resulted in significantly higher serum neutralizing titers against POWV than immunization with monomeric POWV EDIII. Furthermore, passive transfer of EDIII-reactive sera protected against POWV challenge in vivo. We isolated and characterized a panel of EDIII-specific monoclonal antibodies (mAbs) and identified several that potently inhibit POWV infection and engage distinct epitopes within the lateral ridge and C-C' loop of the EDIII. By creating a subunit-based nanoparticle immunogen with vaccine potential that elicits antibodies with protective activity against POWV infection, our findings enhance our understanding of the molecular determinants of antibody-mediated neutralization of TBFVs.

Climate Changes Exacerbate the Spread of Ixodes ricinus and the Occurrence of Lyme Borreliosis and Tick-Borne Encephalitis in Europe-How Climate Models Are Used as a Risk Assessment Approach for Tick-Borne Diseases

Climate change has influenced the transmission of a wide range of vector-borne diseases in Europe, which is a pressing public health challenge for the coming decades. Numerous theories have been developed in order to explain how tick-borne diseases are associated with climate change. These theories include higher proliferation rates, extended transmission season, changes in ecological balances, and climate-related migration of vectors, reservoir hosts, or human populations. Changes of the epidemiological pattern have potentially catastrophic consequences, resulting in increasing prevalence of tick-borne diseases. Thus, investigation of the relationship between climate change and tick-borne diseases is critical. In this regard, climate models that predict the ticks’ geographical distribution changes can be used as a predicting tool. The aim of this review is to provide the current evidence regarding the contribution of the climatic changes to Lyme borreliosis (LB) disease and tick-borne encephalitis (TBE) and to present how computational models will advance our understanding of the relationship between climate change and tick-borne diseases in Europe.