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In Europe, ticks are particularly important vectors of pathogens known as tick-borne pathogens (TBP). TBP can influence hosts, including domestic animals and humans as well as ticks. This review focuses on interactions between hard ticks and medically and veterinary significant bacterial pathogens i.e. Borrelia burgdorferi s.l., Anaplasma spp, and Rickettsia spp. The interactions between ticks and bacteria include among others the impact on gene expression and tick behaviour. Infection with TBP may influence tick salivary proteins and midgut receptors. Infection with B. burgdorferi s.l. changes the bahaviour of the tick allowing them for longer questing and increased mobility, while A. phagocytophilum increases survive in low temperatures by upregulating the expression of antifreeze glycoprotein (IAFGP). Whereas Rickettsia spp. increases ticks attraction towards the 900 MHz electromagnetic field.

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

Background: The spread of ticks has also led to the emergence of regional, previously unknown tick-borne diseases (TBDs) that pose an immediate threat to public health systems worldwide. People who spend time or work outdoors are at risk without closer awareness of regional exposures. That is especially true for tourists, who very easily come into contact with ticks and get bitten while hiking and climbing. A regional lack of surveillance, lack of awareness, lack of scientific background, and misdiagnosis makes it hard to assess the actual threat properly., Methods: Therefore, this bibliometric study aims to assess the global research on ticks and some TBDs. Geographical and temporal patterns are elaborated under epidemiological and socioeconomic aspects. That will provide a factual basis for targeted action at the scientific, societal, and policy levels against the growing threat associated with ticks., Results: The USA and Brazil can be identified as the key players in tick research, followed by Russia and some Central European countries. The socioeconomic analysis points to epidemiologically relevant regions, as also shown by comparison with the TBD analysis. A correlation between countries' gross domestic product and publication performance was found. Lack of scientific resources limits the necessary research and surveillance programs., Conclusions: Many regions that are popular travel destinations are threatened by new tick species and thus new health risks. Therefore, outdoor activities in many locations may pose an unknown hazard that requires regionally differentiated scientific investigation and better, globally networked research strategies., Competing Interests: Declaration of competing interest The authors have declared no conflicts of interest., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: Tick-borne diseases, caused by bacterial pathogens, pose a growing threat to public health in Europe. This paper provides an overview of the historical context of the discovery of the most impactful pathogens transmitted by ticks, including Borrelia burgdorferi sensu lato, Rickettsia spp., Anaplasma spp., Francisella spp., Ehrlichia spp., and Neoehrlichia mikurensis. Understanding the historical context of their discovery provides insight into the evolution of our understanding of these pathogens., Methods and Results: Systematic investigation of the prevalence and transmission dynamics of these bacterial pathogens is provided, highlighting the intricate relationships among ticks, host organisms, and the environment. Epidemiology is explored, providing an in-depth analysis of clinical features associated with infections. Diagnostic methodologies undergo critical examination, with a spotlight on technological advancements that enhance detection capabilities. Additionally, the paper discusses available treatment options, addressing existing therapeutic strategies and considering future aspects., Conclusions: By integrating various pieces of information on these bacterial species, the paper aims to provide a comprehensive resource for researchers and healthcare professionals addressing the impact of bacterial tick-borne diseases in Europe. This review underscores the importance of understanding the complex details influencing bacterial prevalence and transmission dynamics to better combat these emerging public health threats., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

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

Background: The composition of the microbial flora associated with ixodid ticks has been studied in several species, revealing the importance of geographical origin, developmental stage(s) and feeding status of the tick, as well as substantial differences between tissues and organs. Studying the microbiome in the correct context and scale is therefore necessary for understanding the interactions between tick-borne pathogens and other microorganisms as well as other aspects of tick biology. Methods: In the present study the microbial flora of whole Ixodes ricinus, I. persulcatus and I. trianguliceps ticks were analyzed with 16S rRNA amplicon sequencing. Additionally, tick organs (midguts, Malpighian tubules, ovaries, salivary glands) from flat and engorged I. ricinus female ticks were examined with the same methodology. Results: The most abundant bacteria belonged to the group of Proteobacteria (Cand. Midichloria mitochondrii and Cand. Lariskella). 16S amplicon sequencing of dissected tick organs provided more information on the diversity of I. ricinus-associated microbial flora, especially when organs were collected from engorged ticks. Bacterial genera significantly associated with tick feeding status as well as genera associated with the presence of tick-borne pathogens were identified. Conclusions: These results contribute to the knowledge of microbial flora associated with ixodid ticks in their northernmost distribution limit in Europe and opens new perspectives for other investigations on the function of these bacteria, including those using other approaches like in vitro cultivation and in vitro models. [ABSTRACT FROM AUTHOR]

Background: Haemaphysalis concinna, carrying multiple pathogens, has attracted increasing attention because of its expanded geographical range and significant role in disease transmission. This study aimed to identify the potential public health risks posed by H. concinna and H. concinna-associated pathogens., Methods: A comprehensive database integrating a field survey, literature review, reference book, and relevant websites was developed. The geographical distribution of H. concinna and its associated pathogens was illustrated using ArcGIS. Meta-analysis was performed to estimate the prevalence of H. concinna-associated microbes. Phylogenetic and geographical methods were used to investigate the role of birds in the transmission of H. concinna-associated microbes. The potential global distribution of H. concinna was predicted by ecological niche modeling., Results: Haemaphysalis concinna was distributed in 34 countries across the Eurasian continent, predominantly in China, Russia, and Central Europe. The tick species carried at least 40 human pathogens, including six species in the Anaplasmataceae family, five species of Babesia, four genospecies in the complex Borrelia burgdorferi sensu lato, ten species of spotted fever group rickettsiae, ten species of viruses, as well as Francisella, Coxiella, and other bacteria. Haemaphysalis concinna could parasitize 119 host species, with nearly half of them being birds, which played a crucial role in the long-distance transmission of tick-borne microbes. Our predictive modeling suggested that H. concinna could potentially survive in regions where the tick has never been previously recorded such as central North America, southern South America, southeast Oceania, and southern Africa., Conclusions: Our study revealed the wide distribution, broad host range, and pathogen diversity of H. concinna. Authorities, healthcare professionals, and the entire community should address the growing threat of H. concinna and associated pathogens. Tick monitoring and control, pathogen identification, diagnostic tools, and continuous research should be enhanced., (© 2024. The Author(s).)

Overseas travel to regions where ticks are found can increase travellers' exposure to ticks and pathogens that may be unfamiliar to medical professionals in their home countries. Previous studies have detailed non-native tick species removed from recently returned travellers, occasionally leading to travel-associated human cases of exotic tick-borne disease. There are 20 species of tick endemic to the UK, yet UK travellers can be exposed to many other non-native species whilst overseas. Here, we report ticks received by Public Health England's Tick Surveillance Scheme from humans with recent travel history between January 2006 and December 2018. Altogether, 16 tick species were received from people who had recently travelled overseas. Confirmed imports (acquired outside of the UK) were received from people who recently travelled to 22 countries. Possible imports (acquired abroad or within the UK) were received from people who had recently travelled to eight European countries. Species-specific literature reviews highlighted nine of the sixteen tick species are known to vector at least one tick-borne pathogen to humans in the country of acquisition, suggesting travellers exposed to ticks may be at risk of being bitten by a species that is a known vector, with implications for novel tick-borne disease transmission to travellers.

This study modelled the probability of introduction of Hyalomma marginatum into Europe by predicting the potential migratory routes of 28 bird species and the probability to carry immatures of the tick. Flyways were modelled as a spatio-temporal feature, at weekly intervals, using satellite-derived data of temperature and vegetal phenology, together with cost surfaces derived from speed and direction of the wind (years 2002-2018). The expected period of activity of tick immatures defined the probability of ticks being carried by birds along the modelled flyways. The probability of moulting of the engorged nymphs was modelled as a linear relationship of the daily sum of temperatures after tick introduction by birds. Positive probabilities of tick introduction extend the known northern range of permanent populations to central and western France, and large portions of central Europe. The flight of birds into an area and thence the risk of introduction of H. marginatum is very heterogeneous, with sites receiving "waves" of different bird species at diverse times of the year. Therefore, there is not a clear period of time for introduction, as it depends on the modelled behaviour of the bird species. The probability of introduction into Baltic and Nordic countries is small. We hypothesise that conditions of a warmer climate might support permanent populations of H. marginatum if a high number of immatures is introduced. Active surveys in risky territories, where the tick is not yet established, are advisable for rapid intervention., (Copyright © 2020 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.)

Lyme borreliosis, the most common vector-borne disease in Europe and North America, is attracting growing concern due to its expanding geographic range. The growth in incidence and geographic spread is largely attributed to climate and land-use changes that support the tick vector and thereby increase disease risk. Despite a wide range of symptoms displayed by Lyme borreliosis patients, the demographic patterns in clinical manifestations and seasonal case timing have not been thoroughly investigated and may result from differences in exposure, immunity and pathogenesis. We analysed 25 years of surveillance data from Norway, supplemented by population demography data, using a Bayesian modelling framework. The analyses aimed to detect differences in case seasonality and clinical manifestations of Lyme borreliosis across age and sex differentiated patient groups. The results showed a bimodal pattern of incidence over age, where children (0-9 years) had the highest incidence, young adults (20-29 years) had low incidence and older adults had a second incidence peak in the ages 70-79 years. Youth (0-19 years) presented with a higher proportion of neuroborreliosis cases and a lower proportion of arthritic manifestations compared to adults (20+ years). Adult males had a higher overall incidence than adult females and a higher proportion of arthritis cases. The seasonal timing of Lyme borreliosis consistently occurred around 4.4 weeks earlier in youth compared to adults, regardless of clinical manifestation. All demographic groups exhibited a shift towards an earlier seasonal timing over the 25-year study period, which appeared unrelated to changes in population demographics. However, the disproportionate incidence of Lyme borreliosis in seniors requires increased public awareness and knowledge about this high-risk group as the population continues to age concurrently with disease emergence. Our findings highlight the importance of considering patient demographics when analysing the emergence and seasonal patterns of vector-borne diseases using long-term surveillance data., (© 2023 The Authors. Zoonoses and Public Health published by Wiley-VCH GmbH.)

Ixodes ricinus nymphs and adults removed from humans, and larvae and nymphs from birds, have been analysed for infection with Babesia species and Borrelia species previously in separately published studies. Here, we use the same data set to explore the coinfection pattern of Babesia and Borrelia species in the ticks. We also provide an overview of the ecology and potential public health importance in Sweden of I. ricinus infected both with zoonotic Babesia and Borrelia species. Among 1952 nymphs and adult ticks removed from humans, 3.1% were PCR-positive for Babesia spp. Of these Babesia-positive ticks, 43% were simultaneously Borrelia-positive. Among 1046 immatures of I. ricinus removed from birds, 2.5% were Babesia-positive, of which 38% were coinfected with Borrelia species. This study shows that in I. ricinus infesting humans or birds in Sweden, potentially zoonotic Babesia protozoa sometimes co-occur with human-pathogenic Borrelia spp. Diagnostic tests for Babesia spp. infection are rarely performed in Europe, and the medical significance of this pathogen in Europe could be underestimated. [ABSTRACT FROM AUTHOR]

In Europe, Ixodes ricinus tick is the vector of Lyme disease spirochetes and their relatives (Borreliella genus) and Borrelia miyamotoi. However, a newly described tick I. inopinatus with similar biological features and separated from I. ricinus may act as a vector for different Borrelia species. To date, eleven Borreliella species were detected in the natural populations of I. ricinus. Recently, two North American species have been detected in ticks parasitizing bats and red foxes in Europe, i.e., B. lanei and B. californiensis pointing to the necessity for searching for them in natural tick populations. In this study, using the coxI molecular marker only I. ricinus was identified in field-collected ticks with the exception of individual specimens of Haemaphysalis concinna. Using the flaB gene and mag-trnI intergenic spacer as molecular markers 14 Borreliaceae species have been detected with various frequencies in different parts of northern Poland. Among infected ticks, the most frequent were Borreliella (Bl.) afzelii (29.4%) and Bl. garinii (20.0%), followed by Bl. spielmanii, Bl. valaisiana, Bl. lanei, Bl. californiensis, B. miyamotoi, Bl. burgdorferi, Bl. carolinensis, Bl. americana, B. turcica, Bl. lusitaniae, Bl. bissettiae and Bl. finlandensis. Three of the above-mentioned species, i.e., Bl. lanei, Bl. californiensis and B. turcica were detected in this study for the first time in the natural ixodid tick population in Europe. The existence of the newly detected spirochetes increases their total diversity in Europe and points to the necessity of careful identification and establishment of the actual distribution of all Borreliaceae species transmitted by I. ricinus. [ABSTRACT FROM AUTHOR]

Hyalomma marginatum is an important tick species which is the main vector of Crimean–Congo haemorrhagic fever and spotted fever. The species is predominantly distributed in parts of southern Europe, North Africa and West Asia. However, due to ongoing climate change and increasing reports of H. marginatum in central and northern Europe, the expansion of this range poses a potential future risk. In this study, an ecological niche modelling approach to model the current and future climatic suitability of H. marginatum was followed. Using high-resolution climatic variables from the Chelsa dataset and an updated list of locations for H. marginatum , ecological niche models were constructed under current environmental conditions using MaxEnt for both current conditions and future projections under the ssp370 and ssp585 scenarios. Models show that the climatically suitable region for H. marginatum matches the current distributional area in the Mediterranean basin and West Asia. When applied to future projections, the models suggest a considerable expansion of H. marginatum 's range in the north in Europe as a result of rising temperatures. However, a decline in central Anatolia is also predicted, potentially due to the exacerbation of drought conditions in that region.

Jingmen tick virus (JMTV), belonging to the Flaviviridae family, is a novel segmented RNA virus identified in 2014 in the Jingmen region of Hubei Province, China. Up to now, JMTV has been detected in a variety of countries or regions in Asia, Europe, Africa, and the Americas, involving a wide range of arthropods and mammals, and even humans. The JMTV genome is composed of four linear RNA segments, two of which are derived from flaviviruses, while the other two segments are unique to JMTV and has no matching virus. Currently, JMTV has been shown to have a pathogenic effect on humans. Humans who had been infected would develop viremia and variable degrees of clinical symptoms. However, the pathogenic mechanism of JMTV has not been elucidated yet. Therefore, it is crucial to strengthen the epidemiological surveillance and laboratory studies of JMTV., Competing Interests: The authors declare no conflict of interest.

Background: Lyme borreliosis (LB) is the most common vector-borne disease in Europe. Monitoring changes in the prevalence of different Borrelia species in ticks may be an important indicator of risk assessment and of differences in pathogenicity in humans. The objective of our study was to assess the prevalence, co-infection and distribution of Borrelia and Babesia species in ticks removed from humans in a large sample collected during a study period of 4 years. Methods: The ticks were collected throughout Poland from March to November over 4-year period from 2016 to 2019. All ticks (n = 1953) were morphologically identified in terms of species and developmental stage. Molecular screening for Borrelia and Babesia by amplification of the flagellin gene (flaB) or 18S rRNA marker was performed. Pathogen identity was confirmed by Sanger sequencing or PCR–restriction fragment length polymorphism analysis. Results: The ticks removed from humans in Poland during this study belonged to two species: Ixodes ricinus (97%) and Dermacentor reticulatus (3%). High Borrelia prevalence (25.3%), including B. miyamotoi (8.4%), was confirmed in Ixodes ricinus ticks removed from humans, as was the change in frequency of occurrence of Borrelia species during the 4-year study. Despite Babesia prevalence being relatively low (1.3%), the majority of tested isolates are considered to be pathogenic to humans. Babesia infection was observed more frequently among Borrelia-positive ticks (2.7%) than among ticks uninfected with Borrelia (0.8%). The most frequent dual co-infections were between Borrelia afzelii and Babesia microti. The presence of Borrelia was also confirmed in D. reticulatus (12.7%); however the role of these ticks in spirochete transmission to susceptible hosts is still unclear. Conclusions: Although the overall risk of developing LB after a tick bite is low in Europe, knowledge of the prevalence and distribution of Borrelia and Babesia species in ticks might be an important indicator of the risk of both these tick-borne diseases. [ABSTRACT FROM AUTHOR]

BackgroundTick-borne encephalitis (TBE) is a disease which can lead to severe neurological symptoms, caused by the TBE virus (TBEV). The natural transmission cycle occurs in foci and involves ticks as vectors and several key hosts that act as reservoirs and amplifiers of the infection spread. Recently, the incidence of TBE in Europe has been rising in both endemic and new regions.AimIn this study we want to provide comprehensive understanding of the main ecological and environmental factors that affect TBE spread across Europe.MethodsWe searched available literature on covariates linked with the circulation of TBEV in Europe. We then assessed the best predictors for TBE incidence in 11 European countries by means of statistical regression, using data on human infections provided by the European Surveillance System (TESSy), averaged between 2017 and 2021.ResultsWe retrieved data from 62 full-text articles and identified 31 different covariates associated with TBE occurrence. Finally, we selected eight variables from the best model, including factors linked to vegetation cover, climate, and the presence of tick hosts.DiscussionThe existing literature is heterogeneous, both in study design and covariate types. Here, we summarised and statistically validated the covariates affecting the variability of TBEV across Europe. The analysis of the factors enhancing disease emergence is a fundamental step towards the identification of potential hotspots of viral circulation. Hence, our results can support modelling efforts to estimate the risk of TBEV infections and help decision-makers implement surveillance and prevention campaigns.

For more than three decades, it has been recognized that Ixodes ricinus ticks occur in urban green space in Europe and that they harbour multiple pathogens linked to both human and animal diseases. Urban green space use for health and well‐being, climate mitigation or biodiversity goals is promoted, often without consideration for the potential impact on tick encounters or tick‐borne disease outcomes. This review synthesizes the results of over 100 publications on questing I. ricinus and Borrelia spp. infections in ticks in urban green space in 24 European countries. It presents data on several risk indicators for Lyme borreliosis and highlights key research gaps and recommendations for future studies. Across Europe, mean density of I. ricinus in urban green space was 6.9 (range; 0.1–28.8) per 100 m2 and mean Borrelia prevalence was 17.3% (range; 3.1%–38.1%). Similar density estimates were obtained for nymphs, which had a Borrelia prevalence of 14.2% (range; 0.5%–86.7%). Few studies provided data on both questing nymph density and Borrelia prevalence, but those that did found an average of 1.7 (range; 0–5.6) Borrelia‐infected nymphs per 100 m2 of urban green space. Although a wide range of genospecies were reported, Borrelia afzelii was the most common in most parts of Europe, except for England where B. garinii was more common. The emerging pathogen Borrelia miyamotoi was also found in several countries, but with a much lower prevalence (1.5%). Our review highlights that I. ricinus and tick‐borne Borrelia pathogens are found in a wide range of urban green space habitats and across several seasons. The impact of human exposure to I. ricinus and subsequent Lyme borreliosis incidence in urban green space has not been quantified. There is also a need to standardize sampling protocols to generate better baseline data for the density of ticks and Borrelia prevalence in urban areas. [ABSTRACT FROM AUTHOR]

Crimean-Congo hemorrhagic fever (CCHF) is the most widely distributed tick-borne viral infection in the world. Strikingly, reported mortality rates for CCHF are extremely variable, ranging from 5% to 80% (Whitehouse, 2004). CCHF virus (CCHFV, Nairoviridae ) exhibits extensive genomic sequence diversity across strains (Deyde et al., 2006; Sherifi et al., 2014). It is currently unknown if genomic diversity is a factor contributing to variation in its pathogenicity. We obtained complete genome sequences of CCHFV directly from the tick reservoir. These new strains belong to a solitary lineage named Europe 2 that is circumstantially reputed to be less pathogenic than the epidemic strains from Europe 1 lineage. We identified a single tick-specific amino acid variant in the viral glycoprotein region that dramatically reduces its fusion activity in human cells, providing evidence that a glycoprotein precursor variant, present in ticks, has severely impaired function in human cells., Competing Interests: BH, FS, VO, AK, MM, CD, SN, CS, SJ, ÉB No competing interests declared

Ticks are known to transmit pathogens which threaten the health and welfare of companion animals and man globally. In the present study, mainly adult ticks were collected from dogs and cats presented at their local veterinary practice in Hungary, France, Italy, Belgium (dogs only) and Germany (cats only), and identified based on tick morphology. If more than one tick was collected from a host animal, ticks were pooled by tick species for DNA extraction and subsequent PCR examination for the presence of tick-borne pathogens. Out of 448 tick samples, 247 (95 from dogs and 152 from cats) were Ixodes ricinus, 26 (12 from dogs and 14 from cats) were I. hexagonus, 59 (43 from dogs and 16 from cats) were Dermacentor reticulatus and 116 (74 from dogs and 42 from cats) were Rhipicephalus sanguineus sensu lato (s.l.). In 17% of the I. ricinus samples Anaplasma phagocytophilum was found. Borrelia spp. were mainly identified in I. ricinus collected from cats (18%) and to a lesser extent in dog-sourced ticks (1%), with Borrelia afzelii (n = 11), B. garinii (n = 7), B. valaisiana (n = 5), B. lusitaniae (n = 3) and B. burgdorferi sensu stricto (n = 3) being identified. One I. hexagonus sample collected from a cat in France tested positive for B. afzelii. Babesia canis was detected in 20% of the D. reticulatus samples, mainly from Hungary. Rhipicephalus sanguineus s.l. was found positive for Hepatozoon canis (3%), A. platys (5%) and three Rickettsia species (7%; R. massiliae; R. raoultii and R. rhipicephali). Furthermore, a total of 66 R. sanguineus s.l. ticks were subjected to molecular analysis and were identified as R. sanguineus sp. II-temperate lineage, with seven haplotypes recorded. Amongst them, the most prevalent sequence types were haplotype XIII (n = 24; 69%) and haplotype XIV (n = 16; 52%) in France and in Italy, respectively, found both in cats and dogs. Although differences related to both country and host, were observed, the results of this study indicate that cats and dogs are exposed to tick-borne pathogen infected ticks, which may represent a medical risk to these host animals., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Background: Lyme borreliosis (LB), a tick bite-transmitted infection caused by Borrelia burgdorferi sensu lato ( Bbsl ) complex spirochetes, is the most common tickborne disease in Europe. Studies in European countries have reported LB seroprevalence (prevalence of antibodies to Bbsl infection) and diagnostic strategies used for testing. We conducted a systematic literature review to summarize contemporary LB seroprevalence in Europe. Methods: PubMed, Embase, and CABI Direct (Global Health) databases were searched from 2005 to 2020 to identify studies reporting LB seroprevalence in European countries. Reported single-tier and two-tier test results were summarized; algorithms (standard or modified) were used to interpret final test results from studies that used two-tier testing. Results: The search yielded 61 articles from 22 European countries. Studies used a range of diagnostic testing methods and strategies (48% single-tier, 46% standard two-tier, and 6% modified two-tier). In 39 population-based studies, of which 14 were nationally representative, seroprevalence estimates ranged from 2.7% (Norway) to 20% (Finland). There was substantial heterogeneity among studies in terms of design, cohort types, periods sampled, sample sizes, and diagnostics, which limited cross-study comparisons. Nevertheless, among studies that reported seroprevalence in persons with greater exposure to ticks, LB seroprevalence was higher among these groups than in the general population (40.6% vs. 3.9%). Furthermore, among studies that used two-tier testing, general population LB seroprevalence was higher in Western Europe (13.6%) and Eastern Europe (11.1%) than in Northern Europe (4.2%) and Southern Europe (3.9%). Conclusion: Despite variations in LB seroprevalence between and within European subregions and countries, high seroprevalence was observed in certain geographic regions and particular risk groups, suggesting significant disease burden and supporting the need for improved, targeted public health interventions such as vaccination. Harmonized approaches to serologic testing and more nationally representative seroprevalence studies are needed to better understand the prevalence of Bbsl infection in Europe.

Tick-borne diseases are a major health problem worldwide and could become even more important in Europe in the future. Due to changing climatic conditions, ticks are assumed to be able to expand their ranges in Europe towards higher latitudes and altitudes, which could result in an increased occurrence of tick-borne diseases. There is a great interest to identify potential (new) areas of distribution of vector species in order to assess the future infection risk with vector-borne diseases, improve surveillance, to develop more targeted monitoring program, and, if required, control measures. Based on an ecological niche modelling approach we project the climatic suitability for the three tick species Ixodes ricinus, Dermacentor reticulatus and Dermacentor marginatus under current and future climatic conditions in Europe. These common tick species also feed on humans and livestock and are vector competent for a number of pathogens. For niche modelling, we used a comprehensive occurrence data set based on several databases and publications and six bioclimatic variables in a maximum entropy approach. For projections, we used the most recent IPCC data on current and future climatic conditions including four different scenarios of socio-economic developments. Our models clearly support the assumption that the three tick species will benefit from climate change with projected range expansions towards north-eastern Europe and wide areas in central Europe with projected potential co-occurrence. A higher tick biodiversity and locally higher abundances might increase the risk of tick-borne diseases, although other factors such as pathogen prevalence and host abundances are also important. [ABSTRACT FROM AUTHOR]

The finding of immature stages of some Hyalomma spp. feeding on migratory birds in Europe is unexceptional. The reports of adults of Hyalomma in Europe (incl. the British Isles) after successful molting from immatures have increased in recent years. It has been claimed that the warming of the target territory could favor the populations of these invasive ticks. Although evaluations of the impact on health or measures of adaptation are on their way, the climate niches of these species remain undefined, preventing preventive policies. This study delineates such niches for both Hyalomma marginatum (2,729 collection points) and Hyalomma rufipes (2,573 collections) in their distribution area, together with 11,669 points in Europe where Hyalomma spp. are believed to be absent in field surveys. Niche is defined from daily data of temperature, evapotranspiration, soil humidity and air saturation deficit (years 1970-2006). A set of eight variables (annual/seasonal accumulated temperature and vapor deficit) has the maximum discriminatory power separating the niches of both Hyalomma and a negative dataset, with an accuracy near 100%. The sites supporting H. marginatum or H. rufipes seem to be controlled by the joint action of the amount of water in the air (accounting for mortality) and the accumulated temperature (regulating development). The use of accumulated annual temperature as the only variable for predictive purposes of colonization of Hyalomma spp. looks unreliable, as far as values of water in air are excluded., (© 2023. The Author(s).)

Background: Hepatozoon spp. are tick-borne parasites causing subclinical to clinical disease in wild and domestic animals. Aim of this study was to determine Hepatozoon prevalence and species distribution among wild mammals and ticks in Europe., Methods: Samples of wild mammals and ticks, originating from Austria, Bosnia and Herzegovina, Croatia, Belgium and the Netherlands, were tested with PCR to amplify a ~ 670-bp fragment of the small subunit ribosomal RNA gene., Results: Of the 2801 mammal samples that were used for this study, 370 (13.2%) tested positive. Hepatozoon canis was detected in samples of 178 animals (3 Artiodactyla, 173 Carnivora, 1 Eulipotyphia, 1 Lagomorpha), H. martis in 125 (3 Artiodactyla, 122 Carnivora), H. sciuri in 13 (all Rodentia), Hepatozoon sp. in 47 (among which Hepatozoon sp. Vole isolate, all Rodentia) and H. ayorgbor in 4 (all Rodentia). Regarding origin, 2.9% (6/208) tested positive from Austria, 2.8% (1/36) from Bosnia and Herzegovina, 14.6% (173/1186) from Croatia and 13.9% (190/1371) from Belgium/the Netherlands. Of the 754 ticks collected, 0.0% (0/35) Hyalomma sp., 16.0% (4/25) Dermacentor spp., 0.0% (0/23) Haemaphysalis spp., 5.3% (24/50) Ixodes and 1.4% (3/221) Rhipicephalus spp. tested positive for Hepatozoon (4.2%; 32/754), most often H. canis (n = 22)., Conclusions: Hepatozoon canis is most present in mammals (especially in Carnivora such as gray wolves and golden jackals) and ticks, followed by H. martis, which was found merely in stone martens and pine martens. None of the rodent-associated Hepatozoon spp. were detected in the ticks, suggesting the possible implication of other arthropod species or non-vectorial routes in the transmission cycle of the hemoprotozoans in rodents. Our findings of H. canis in ticks other than R. sanguineus add to the observation that other ticks are also involved in the life cycle of Hepatozoon. Now that presence of Hepatozoon has been demonstrated in red foxes, gray wolves, mustelids and rodents from the Netherlands and/or Belgium, veterinary clinicians should be aware of the possibility of spill-over to domestic animals, such as dogs., (© 2023. The Author(s).)

Background: Among live wild mammals adapted to urban and peri-urban habitats in Europe, members of the families Felidae, Mustelidae and Sciuridae deserve special attention as pathogen reservoirs because all of these families include members that are kept as pets. We report here the results of our study on two important groups of tick-borne protozoan parasites in ticks and tissues of wild cats, mustelids and red squirrels. Methods: DNA was extracted from the tissues of carnivores (wild cats, mustelids; n = 16) and red squirrels (n = 4), as well as from ixodid ticks (n = 89) collected from these hosts. These DNA extracts were screened for piroplasms and Hepatozoon spp. using conventional PCR analysis and sequencing. In addition, 53 pooled samples of 259 questing Haemaphysalis concinna ticks were evaluated for the presence of Hepatozoon DNA, followed by phylogenetic analyses. Results: One wild cat was found to be coinfected with Cytauxzoon europaeus and a new genotype of Hepatozoon felis, and two additional wild cats were infected with H. felis from a different phylogenetic group. In mustelids, Hepatozoon martis and two further Hepatozoon genotypes were detected. The latter clustered separately, close to others reported from eastern Asia. In addition, Hepatozoon sciuri was detected in red squirrels. Morphologic and molecular analyses verified eight tick species. One wild cat was infected with a H. felis genotype that was significantly different from that in Ixodes ricinus females infesting this cat. Only three pools of questing H. concinna nymphs tested positive for Hepatozoon, one of which contained H. martis. Conclusions: This study provides the first evidence of the occurrence of any Cytauxzoon species and of three Hepatozoon species in Hungary. In addition to H. martis, two further mustelid-associated Hepatozoon genotypes were detected, one of which was new in terms of phylogenetic and broader geographical contexts. This may be the first indication that H. felis genotypes from both of its phylogenetic groups occur in Europe. This also appears to be the first evidence of H. felis and C. europaeus coinfection in felids in Europe, and of autochthonous H. felis infection in wild cats north of the Mediterranean Basin. New tick–host associations were also observed in this study. Based on the results, H. felis and H. martis might survive transstadially in I. ricinus and H. concinna, respectively. [ABSTRACT FROM AUTHOR]

Introduction and Objective: Vector diseases are common in Europe, including Poland. Every year, 77,000 Europeans are infected with transmissive diseases as a result of contact with infected vectors. In Poland, ticks are vectors of great epidemiological importance. The most important etiological factors causing disease in humans and transmitted by ticks include bacteria of the genus Borrelia and the species Francisella tularensis, Anaplasma phagophytophilum and Coxiella burnetii; as well as tick-borne encephalitis viruses. The level of the number of diagnosed cases of vector diseases in humans is influenced by environmental conditions, the most important of which is the COVID-19 pandemic that has been spreading for two years., Objective: The aim of the review was to assess knowledge about tick-borne diseases in humans, as well as etiological factors, epidemiology of these diseases in Poland and other European countries. Infection with pathogens can occur both during recreation in nature and during work related to a profession. Professional groups include those particularly exposed to contact with vectors and pathogens - foresters, farmers and soldiers., Review Methods: A comprehensive assessment was conducted of extant publications., Brief Description of the State of Knowledge: The results of the literature research revealed that in recent years an increase in the number of people suffering from tick-borne diseases has been recorded, possibly influenced by the changing climate. The vector diseases of the greatest importance for the inhabitants of Poland include Lyme disease and tick-borne encephalitis., Summary: Soldiers, as a professional group who perform their duties in an environment where there is a high risk of exposure to infected ticks, are particularly at risk of acquiring transmission of vector diseases.

The parasitoid wasp, Ixodiphagus hookeri (Hymenoptera: Encyrtidae), is the natural enemy of a wide range of hard and soft tick species. While these encyrtid wasps are supposed to be distributed worldwide, only a few studies report on their actual distribution around the globe. Within a shotgun sequencing-based metagenome analysis, the occurrence of I. hookeri was screened at multiple Ixodes ricinus (Acari: Ixodidae) tick sampling points in Hungary to contribute to the assessment of the distribution patterns of the parasitoid wasps in Central Europe. To our knowledge, the first report of the species in Hungary and the description of the southernmost I. hookeri associated geoposition in Central Europe took place within our study. I. hookeri infested I. ricinus nymphs were detected at five sampling points in Hungary. The results show that the exact distribution range of I. hookeri is still barely studied. At the same time, unprecedented public health issues being brought about by climate change might require steps toward the exploitation of the tick biocontrol potential and as an ecological bioindicator role of the parasitoid wasp in the future., (© 2023. The Author(s).)

In the literature, 114 species of arthropods associated to Microtus oeconomus have been reported in the entire area of their occurrence. There are eight species of hard ticks, 52 species of gamasid and chigger mites, 47 species of fleas and seven species of sucking lice. In general, the dominant parasites of the Palearctic and Nearctic root vole populations are either western or entire Palearctic species. The analysis of the geographical range of their occurrence indicates that most of them occur both in Europe and Asia. Throughout Europe, Asia and America (Holarctic realm), root voles share 13 species of mites, seven species of fleas, and three species of sucking lice. Ectoparasite species split between two continents, most of them are found in both Europe and Asia (Palearctic region). Here belong three species of ixodid ticks, sixteen species of mites, seven species of fleas and two species of sucking lice. In Asia and the North American continents (Holarctic realm excluding Europe) populations of root voles share only one tick species, two species of mites, three species of fleas and one species of sucking lice. Of the parasitic species found only in Western Palearctic, excluding Asia, root voles are infested by three ixodid tick species, 14 mite species, and 13 flea species. Among the parasitic arthropods affecting root vole only in Eastern Palearctic, excluding Europe, one tick species, four mite species and seven flea species occur. There are only three mite species, ten flea and one sucking louse species on voles that inhabit North America (Nearctic region). Associated arthropods are obligate and facultative parasites or nidicolic and edaphic species. Seasonal changes in numbers of ticks, parasitic mites, sucking lice, fleas have also been observed. [ABSTRACT FROM AUTHOR]

We collected 1,671 Dermacentor reticulatus ticks from 17 locations in the Czech Republic, Slovakia, and Hungary. We found 47.9% overall prevalence of Rickettsia species in ticks over all locations. Sequence analysis confirmed that all tested samples belonged to R. raoultii, the causative agent of tick-borne lymphadenopathy. [ABSTRACT FROM AUTHOR]

Lyme borreliosis is the most common vector-borne zoonosis in the northern hemisphere, and the pathogens causing Lyme borreliosis have distinct, incompletely described transmission cycles involving multiple host groups. The mammal community in Fennoscandia differs from continental Europe, and we have limited data on potential competent and incompetent hosts of the different genospecies of Borrelia burgdorferi sensu lato (sl) at the northern distribution ranges where Lyme borreliosis is emerging. We used qPCR to determine presence of B. burgdorferi sl in tissue samples (ear) from 16 mammalian species and questing ticks from Norway, and we sequenced the 5S-23 S rDNA intergenic spacer region to determine genospecies from 1449 qPCR-positive isolates obtaining 423 sequences. All infections coming from small rodents and shrews were linked to the genospecies B. afzelii, while B. burgdorferi sensu stricto (ss) was only found in red squirrels (Sciurus vulgaris). Red squirrels were also infected with B. afzelii and B. garinii. There was no evidence of B. burgdorferi sl infection in moose (Alces alces), red deer (Cervus elaphus) or roe deer (Capreolus capreolus), confirming the role of cervids as incompetent hosts. In infected questing ticks in the two western counties, B. afzelii (67% and 75%) dominated over B. garinii (27% and 21%) and with only a few recorded B. burgdorferi ss and B. valaisiana. B. burgdorferi ss were more common in adult ticks than in nymphs, consistent with a reservoir in squirrels. Our study identifies potential competent hosts for the different genospecies, which is key to understand transmission cycles at high latitudes of Europe.

The red fox (Vulpes vulpes) is the most widespread free-living carnivore in the world. Over the years, foxes have been recognized as hosts for a number of tick-borne pathogens. However, their role as reservoirs for zoonotic tick-borne diseases is poorly understood. The aim of our study was to investigate tick-borne pathogens in the red fox population in the Czech Republic. Out of 117 red foxes, 110 (94.02%) individuals tested positive for the presence of at least one pathogen by the combined PCR and sequencing approach. Hepatozoon canis was the most frequently detected pathogen (n = 95; 81.2%), followed by Babesia vulpes (n = 75; 64.1%). Babesia canis was not detected in our study. Four (3.42%) red foxes were positive for Candidatus Neoehrlichia sp., 3 (2.56%) for Anaplasma phagocytophilum, and one red fox (0.85%) tested positive for the presence of Ehrlichia sp. DNA. Overall, DNA of spirochetes from the Borrelia burgdorferi s.l. complex was detected in 8.6% of the foxes and B. miyamotoi in 5.12% of the samples. As a carnivore found in all ecosystems of Central Europe, foxes obviously contribute to transmission of tick-borne pathogens such as A. phagocytophilum, B. burgdorferi s.l., and B. myiamotoi. In addition, foxes apparently harbour a community of pathogens, associated with this host in local ecological context, dominated by H. canis and B. vulpes (possibly also Candidatus Neoehrlichia sp.). These species have the potential to spread to the domestic dog population and should be included in the differential diagnosis of febrile diseases with hematologic abnormalities in dogs., Competing Interests: Declaration of Competing Interest The authors declare no conflicts of interest., (Copyright © 2022. Published by Elsevier GmbH.)

Background: The bacteria of the group Borrelia burgdorferi s.l. are the etiological agents of Lyme borreliosis in humans, transmitted by bites of ticks. Improvement of control measures requires a solid framework of the environmental traits driving its prevalence in ticks., Methods: We updated a previous meta-analysis of the reported prevalence of Borrelia burgdorferi s.l. in questing nymphs of Ixodes ricinus with a literature search from January 2010-June 2017. This resulted in 195 new papers providing the prevalence of Bb for 926 geo-referenced records. Previously obtained data (878 records, years 2000-2010) were appended for modelling. The complete dataset contains data from 82,004 questing nymphs, resulting in 558 records of B. afzelii, 404 of B. burgdorferi s.s. (only 80 after the year 2010), 552 of B. garinii, 78 of B. lusitaniae, 61 of B. spielmanii, and 373 of B. valaisiana. We associated the records with explicit coordinates to environmental conditions and to a categorical definition of European landscapes (LANMAP2) looking for a precise definition of the environmental niche of the most reported species of the pathogen, using models based on different classification methods., Results: The most commonly reported species are B. afzelii, B. garinii and B. valaisiana largely overlapping across Europe. Prevalence in ticks is associated with portions of the environmental niche. Highest prevalence occurs in areas of 280°-290° (Kelvin) of mean annual temperature experiencing a small amplitude, steady spring slope, together with high mean values and a moderate spring rise of vegetation vigor. Low prevalence occurs in sites with low and a noteworthy annual amplitude of temperature and the Normalized Difference Vegetation Index (colder areas with abrupt annual changes of vegetation). Models based on support vector machines provided a correct classification rate of the habitat and prevalence of 89.5%. These results confirm the association of prevalence of the three most commonly reported species of B. burgdorferi s.l. in Europe to parts of the environmental niche and provide a statistically tractable framework for analyzing trends under scenarios of climate change.

Tick-borne viruses are responsible for various symptoms in humans and animals, ranging from simple fever to neurological disorders or haemorrhagic fevers. The Kemerovo virus (KEMV) is a tick-borne orbivirus, and it has been suspected to be responsible for human encephalitis cases in Russia and central Europe. It has been isolated from Ixodes persulcatus and Ixodes ricinus ticks. In a previous study, we assessed the vector competence of I. ricinus larvae from Slovakia for KEMV, using an artificial feeding system. In the current study, we used the same system to infect different tick population/species, including I. ricinus larvae from France and nymphs from Slovakia, and I. persulcatus larvae from Russia. We successfully confirmed the first two criteria of vector competence, namely, virus acquisition and trans-stadial transmission, for both tick species that we tested. The estimated infection rates of engorged and moulted ticks suggest specificities between viral strains and tick species/developmental stages.

When studying a vector-borne disease, an eco-epidemiological approach is vital for a comprehensive understanding of how the pathogen circulates amongst populations. Equine piroplasmosis (EP), a tick-borne disease caused by the protozoans Babesia caballi and Theileria equi, is endemic in the Mediterranean basin of Europe and causes both animal health and economic issues for the equine sector. With no vaccine available, defining the episystem of the disease can help to identify which components of the host-pathogen-vector-environment system to target to improve preventive measures. In this systematic literature review, we collected relevant data on the eco-epidemiology of EP in Europe. The 62 studies remaining after the selection procedure explored potential vectors, indicators of parasite circulation and putative risk factors of EP. Eight hard tick species were identified as potential vectors of one or both piroplasm species. Meta-analyses were then conducted on prevalence and seroprevalence data in equids in European countries, demonstrating an estimated seroprevalence of 30% and 8% and prevalence of 25% and 2% for T. equi and B. caballi, respectively. Finally, herd management practices and environmental risk factors analysed in studies showed no real consensus between studies, but revealed a general trend highlighting age and exposure to ticks as risk factors, and vaccination as a protective factor. Through this study, we point out that only a few studies have focused on disease management practices and even fewer have studied the effect of environmental parameters on equid infections. Further investigation in these areas is required to better characterize the eco-epidemiology of EP and risk factors associated with this disease., (© 2021 Wiley-VCH GmbH.)

Ticks are a major group of arthropod vectors, characterized by the diversity of pathogens they transmit, by their impact on human and animal health, and by their socioeconomic implication especially in countries of the Southern Hemisphere. In Europe, Ixodes is the most important tick due to its wide distribution in the ecosystems and the variety of transmitted pathogens, in particular Borrelia (responsible for Lyme borreliosis), but also the tick-borne encephalitis virus. Their increased presence in the environment since the beginning of the 20th century is undeniable, because of major modifications in the biodiversity caused by humans. Increasing the awareness of health professionals and the general population is required to achieve better control of these infections. Thus, "a better understanding of these tick-borne diseases for a better control" is a simple but effective approach, considering their ubiquity in the environment and their particular mode of pathogen transmission (long-lasting blood meal for hard ticks and delayed transmission for bacteria and parasites). Finally, these ectoparasites are problematic due to the potential allergic reactions and other damages caused by their saliva, in humans and animals., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

Ticks are one of the important groups of parasites, whose populations have increased in Europe in the last 20 years and, as vectors of many emerging diseases, are a major threat to human and animal health. Bosnia and Herzegovina has both climate and environmental conditions favorable for ticks. Given this risk, the aim of this study was to identify tick species currently present in this country and to compare the findings with previous studies, in order to update information on their spatial distribution and other parameters of occurrence. From March 2017 to April 2020, ticks were collected in 42 sampling areas (municipalities) throughout the country. Prespecified identification keys were used for identifying the ticks to the species level. A total of 6193 tick specimens from the Ixodidae family were collected from animal hosts or from vegetation. Ixodes ricinus was the most dominant tick species found. However, our results indicate a decrease in the relative contribution of this tick species to the overall abundance of tick populations. Dermacentor marginatus, which almost doubled in abundance compared to earlier studies, is the second most common tick species. We further confirmed the presence of Dermacentor reticulatus, Rhipicephalus bursa, Rhipicephalus sanguineus sensu lato, Hyalomma marginatum and Haemaphysalis punctata. Ixodes hexagonus, Ixodes canisuga and Haemaphysalis concinna, which were previously reported at low abundance were not found amongst our specimens., (Copyright © 2021 The Authors. Published by Elsevier GmbH.. All rights reserved.)

Anaplasma phagocytophilum causes a multi-organ non-specific febrile illness referred to as human granulocytic anaplasmosis. The epidemiologic risk of the pathogen is underestimated despite human encroachment into the natural habitats of ticks. In this study, we performed a systematic review and meta-analysis to determine the global infection rates and distribution of A. phagocytophilum in tick vectors. We pooled data using the random-effects model, assessed individual study quality using the Joanna Briggs Institute critical appraisal instrument for prevalence studies and determined heterogeneity and across study bias using Cochran's Q-test and Egger's regression test respectively. A total of 126 studies from 33 countries across 4 continents reported A. phagocytophilum estimated infection rate of 4.76% (9453/174,967; 95% CI: 3.96, 5.71). Estimated IRs across sub-groups varied significantly (p <0.05) with a range of 1.95 (95% CI: 0.63, 5.86) to 7.15% (95% CI: 5.31, 9.56). Country-based IRs ranged between 0.42 (95% CI: 0.22, 0.80) in Belgium and 37.54% (95% CI: 0.72, 98.03) in Norway. The highest number of studies on A. phagocytophilum were in Europe (82/126) by continent and the USA (33/126) by country. The risk of transmitting this pathogens from ticks to animals and humans exist and therefore, we recommend the use of chemical and biological control measures as well as repellents and protective clothing by occupationally exposed individuals to curtail further transmission of the pathogen to humans and animals., (Copyright © 2022. Published by Elsevier B.V.)

Background: Parasites may actively seek for hosts and may use a number of adaptive strategies to promote their reproductive success and host colonization. These strategies will necessarily influence their host specificity and seasonality. Ticks are important ectoparasites of vertebrates, which (in addition to directly affecting their hosts) may transmit a number of pathogens. In Europe, three hard tick species (Ixodidae: Ixodes ariadnae, I. simplex and I. vespertilionis) and at least two soft tick species (Argasidae: Argas transgariepinus and A. vespertilionis) are specialized for bats. Methods: Here we report data on the host range of these ticks and the seasonality of tick infestation on wild caught bats in south-east Europe. We collected 1803 ticks from 30 species of bats living in underground shelters (caves and mines) from Romania and Bulgaria. On the basis of tick–host associations, we tested several hypotheses on host–parasite evolutionary adaptations regulating host specificity, seasonality and sympatric speciation. Results: We observed significant differences in host specificity and seasonality of abundance between the morphologically different bat specialist ticks (I. simplex and I. vespertilionis) likely caused by their host choice and their respective host-seeking behavior. The two highly generalist, but morphologically similar tick species (I. ariadnae and I. vespertilionis) showed temporal differences in occurrence and activity, thus exploiting significantly different host communities while occurring in geographical sympatry. Conclusions: We conclude that bat-specialist ticks show a wide range of adaptations to their hosts, with differences in specificity, seasonality of occurrence, the prevalence and intensity of infestation and all these contribute to a successful division of temporal niches of ticks sharing morphologically similar hosts occurring in geographical sympatry. [ABSTRACT FROM AUTHOR]

In recent years, the media and internet have been the stage of a campaign of scientific disinformation led by patient advocacy groups, supported by some « experts » in the field, demanding recognition of health problems attributed to Lyme disease. The controversy has led several professional societies and leading scientific journals in Europe and the United States to reaffirm their position and update their recommendations. Tick bites are common in our area, and medical practitioners must know their potential complications, respond to questions from worried patients, and confront their own doubts and uncertainties. This article aims to give an update on current knowledge of tick-borne diseases based on a number of common assumptions., Competing Interests: Les auteurs n’ont déclaré aucun conflit d’intérêts en relation avec cet article.

Ixodes ricinus is the most abundant tick species and an important vector of pathogens in Germany and in large parts of Europe. A few other ixodid tick species, e.g., Dermacentor reticulatus, may also be of eco-epidemiological relevance. As ticks are not only found in natural but also in suburban areas (parks, gardens), the present study investigated whether ticks occur on and near football grounds thus posing a potential risk to players and visitors. Thirty-two football grounds from all 16 German federal states were selected, mainly situated adjacent to a green area (forest, park). Ticks were collected by the conventional flagging method in spring 2018, and nymphs and adults were counted and morphologically determined. Altogether 807 nymphal and adult ticks were collected from 29 football grounds: 714 I. ricinus, 64 Ixodes inopinatus, 2 Ixodes frontalis, 24 Ixodes sp. ticks, and 3 D. reticulatus. Ixodes inopinatus was found in 13 out of 16 German states. Three ticks were even found on the turf of two football fields. It can be concluded that ticks occur quite frequently and sometimes in high abundance near football grounds situated close or adjacent to a forest or a park.

Entomopathogenic fungi of the genus Beauveria and Metarhizium play an important role in controlling the population of arthropods. However, the data on their effectiveness against ticks focus mainly on species that do not occur in Europe. The aim of the study was to assess the effectiveness of entomopathogenic fungi against two of the most important tick species in Europe: Ixodes ricinus and Dermacentor reticulatus. In our study, the majority of tested entomopathogenic fungi strains showed potential efficacy against both tick species; however, D. reticulatus was less susceptible in comparison to I. ricinus. The observed mortality of ticks was up to 100% by using all commercial strains as well as three out of nine of the environmental strains. Among all tested fungi, the most effective against both tick species was environmental strain Metarhizium anisopliae LO4(1) with LC50 values: 2.6 × 103 cfu/ml–5.7 × 105 cfu/ml. Botanigard proved to be more effective than MET52 with LC50 values: 6.8 × 103 cfu/ml–3.3 × 106 cfu/ml. The conducted bioassays indicate the potential possibility of using the environmental isolates of entomopathogenic fungi, as well as commercial strains in control of local populations of I. ricinus and D. reticulatus; however, the possibility of using them in vivo requires more research. [ABSTRACT FROM AUTHOR]

The Maltese Archipelago is situated in the middle of the Mediterranean Basin, between Europe and Africa, therefore representing an important stopover site for migratory birds between these two continents. Despite this, up-to-date information is not available on tick species associated with birds in Malta. Therefore, in this study, birds mist-netted for ringing by BirdLife Malta were examined for the presence of ticks between September, 2019 and May, 2021. Ticks were identified morphologically and molecularly, using three genetic markers. During the study period, 57 individuals of 22 bird species were found tick-infested, from which altogether 113 ixodid ticks were collected. The majority of developmental stages were nymphs, but 13 larvae and one female were also found. These ticks belonged to nine species: Ixodes cumulatimpunctatus (n=1), Ixodes ricinus (n=2), Ixodes acuminatus (n=2), Ixodes frontalis (n=5), Ixodes festai (n=1), one species of the Amblyomma marmoreum complex (n=8), Hyalomma rufipes (n=78), Hyalomma marginatum (n=7) and Hyalomma lusitanicum (n=1). Eight Hyalomma sp. ticks could only be identified on the genus level. Regarding seasonality, all Palearctic Ixodes species were carried by birds exclusively in the autumn (i.e., north to south), whereas H. rufipes (with predominantly Afrotropical distribution) was exclusively collected in the spring (i.e., carried south to north). Two tick species that occurred on birds in Malta, i.e., a species of the A. marmoreum complex and I. cumulatimpunctatus are only indigenous in the Afrotropical zoogeographic region. This is the first finding of the latter tick species in Europe, and four tick species were identified for the first time in Malta. In conclusion, the diversity of tick species regularly arriving in Europe from Africa is most likely higher than reflected by data obtained in Mediterranean countries of mainland Europe. Most notably, ticks of the genus Amblyomma appear to be underrepresented in previous datasets. Ticks of the subgenus Afrixodes (represented by I. cumulatimpunctatus) might also be imported into Europe by migratory birds., (Copyright © 2022. Published by Elsevier GmbH.)

Worldwide, ticks are important vectors of human and animal pathogens. Besides Lyme Borreliosis, a variety of other bacterial and protozoal tick-borne infections are of medical interest in Europe. In this study, 553 questing and feeding Ixodes ricinus (n = 327) and Dermacentor reticulatus ticks (n = 226) were analysed by PCR for Borrelia, Rickettsia, Anaplasma, Coxiella, Francisella and Babesia species. Overall, the pathogen prevalence in ticks was 30.6% for I. ricinus and 45.6% for D. reticulatus. The majority of infections were caused by members of the spotted-fever group rickettsiae (24.4%), 9.4% of ticks were positive for Borrelia burgdorferi sensu lato, with Borrelia afzelii being the most frequently detected species (40.4%). Pathogens with low prevalence rates in ticks were Anaplasma phagocytophilum (2.2%), Coxiella burnetii (0.9%), Francisella tularensis subspecies (0.7%), Bartonella henselae (0.7%), Babesia microti (0.5%) and Babesia venatorum (0.4%). On a regional level, hotspots of pathogens were identified for A. phagocytophilum (12.5-17.2%), F. tularensis ssp. (5.5%) and C. burnetii (9.1%), suggesting established zoonotic cycles of these pathogens at least at these sites. Our survey revealed a high burden of tick-borne pathogens in questing and feeding I. ricinus and D. reticulatus ticks collected in different regions in Belarus, indicating a potential risk for humans and animals. Identified hotspots of infected ticks should be included in future surveillance studies, especially when F. tularensis ssp. and C. burnetii are involved.

Ixodes ricinus, the most common species of tick in Europe, is known to transmit major pathogens to animals and humans such as Babesia spp. or Borrelia spp. Its abundance and distribution have been steadily increasing in Europe during recent decades, due to global environmental changes. Indeed, as ticks spend most of their life in the environment, their activity and life cycle are highly dependent on environmental conditions and therefore, on climate or habitat changes. Simultaneously, wild ungulates have expanded their range and increased dramatically in abundance worldwide, in particular roe deer (Capreolus capreolus), allowing tick populations to grow and spread. Currently, tick infestation on newborn wild ungulates is poorly documented. However, newborn ungulates are considered more sensitive to tick bites and pathogen transmission because of their immature immune systems. Thus, improving knowledge about the factors influencing tick infestation on newborns is essential to better understand their health risks. This study was conducted at Trois-Fontaines Forest, Champagne-Ardenne, France (1992–2018). Based on a long-term monitoring of roe deer fawns, we used a novel Bayesian model of the infestation of fawns to identify which biotic or abiotic factors were likely to modify the level of infestation by ticks of 965 fawns over time. We show that tick burden increased faster during the first days of life of the fawns and became constant when fawns were five days old and more, which could be explained by the depletion of questing ticks or the turnover of ticks feeding on fawns. Moreover, despite the known positive influence of humidity on tick activity, the tick burdens were weakly related to this parameter. Our results demonstrate that tick infestation was highly variable among years, particularly between 2000–2009. We hypothesize that this results from a modification of habitat caused by Hurricane Lothar. [ABSTRACT FROM AUTHOR]

Background: The tick Ixodes ricinus is an important vector of tick-borne diseases including Lyme borreliosis. In continental Europe, the nymphal stage of I. ricinus often has a bimodal phenology with a large spring peak and a smaller fall peak. There is consensus about the origin of the spring nymphal peak, but there are two alternative hypotheses for the fall nymphal peak. In the direct development hypothesis, larvae quest as nymphs in the fall of the same year that they obtained their larval blood meal. In the developmental diapause hypothesis, larvae overwinter in the engorged state and quest as nymphs one year after they obtained their larval blood meal. These two hypotheses make different predictions about the time lags that separate the larval blood meal and the density of questing nymphs (DON) in the spring and fall., Methods: Inter-annual variation in seed production (masting) by deciduous trees is a time-lagged index for the density of vertebrate hosts (e.g., rodents) which provide blood meals for larval ticks. We used a long-term data set on the masting of the European beech tree and a 15-year study on the DON at 4 different elevation sites in western Switzerland to differentiate between the two alternative hypotheses for the origin of the fall nymphal peak., Results: Questing I. ricinus nymphs had a bimodal phenology at the three lower elevation sites, but a unimodal phenology at the top elevation site. At the lower elevation sites, the DON in the fall was strongly correlated with the DON in the spring of the following year. The inter-annual variation in the densities of I. ricinus nymphs in the fall and spring was best explained by a 1-year versus a 2-year time lag with the beech tree masting index. Fall nymphs had higher fat content than spring nymphs indicating that they were younger. All these observations are consistent with the direct development hypothesis for the fall peak of I. ricinus nymphs at our study site. Our study provides new insight into the complex bimodal phenology of this important disease vector., Conclusions: Public health officials in Europe should be aware that following a strong mast year, the DON will increase 1 year later in the fall and 2 years later in the spring. Studies of I. ricinus populations with a bimodal phenology should consider that the spring and fall peak in the same calendar year represent different generations of ticks., (© 2021. The Author(s).)

Ticks are hematophagous arthropods that transmit a number of pathogens while feeding. Among these is tick-borne encephalitis virus (TBEV), a flavivirus transmitted by Ixodes ricinus ticks in the temperate zone of Europe. The infection results in febrile illness progressing to encephalitis and meningitis with a possibility of fatality or long-term neurological sequelae. The composition of tick saliva plays an essential role in the initial virus transmission during tick feeding. Ticks secrete a diverse range of salivary proteins to modulate the host response, such as lipocalins to control the itch and inflammatory response, and both proteases and protease inhibitors to prevent blood coagulation. Here, the effect of viral infection of adult females of Ixodes ricinus was studied with the goal of determining how the virus alters the tick sialome to modulate host tissue response at the site of infection. Uninfected ticks or those infected with TBEV were fed on mice and removed and dissected one- and 3-h post-attachment. RNA from the salivary glands of these ticks, as well as from unfed ticks, was extracted and subjected to next-generation sequencing to determine the expression of key secreted proteins at each timepoint. Genes showing statistically significant up- or down-regulation between infected and control ticks were selected and compared to published literature to ascertain their function. From this, the effect of tick viral infection on the modulation of the tick-host interface was determined. Infected ticks were found to differentially express a number of uncategorized genes, proteases, Kunitz-type serine protease inhibitors, cytotoxins, and lipocalins at different timepoints. These virus-induced changes to the tick sialome may play a significant role in facilitating virus transmission during the early stages of tick feeding. [ABSTRACT FROM AUTHOR]

Pathogen species often consist of genetically distinct strains, which can establish mixed infections or coinfections in the host. In coinfections, interactions between pathogen strains can have important consequences for their transmission success. We used the tick-borne bacterium Borrelia afzelii, which is the most common cause of Lyme disease in Europe, as a model multi-strain pathogen to investigate the relationship between coinfection, competition between strains, and strain-specific transmission success. Mus musculus mice were infected with one or two strains of B. afzelii, strain transmission success was measured by feeding ticks on mice, and the distribution of each strain in six different mouse organs and the ticks was measured using qPCR. Coinfection and competition reduced the tissue infection prevalence of both strains and changed their bacterial abundance in some tissues. Coinfection and competition also reduced the transmission success of the B. afzelii strains from the infected hosts to feeding ticks. The ability of the B. afzelii strains to establish infection in the host tissues was strongly correlated with their transmission success to the tick vector. Our study demonstrates that coinfection and competition between pathogen strains inside the host tissues can have major consequences for their transmission success., (© 2021. The Author(s).)

Members of the Orthonairovirus genus (family Nairoviridae) include many tick-borne viruses of significant human and animal health impact, with several recently-documented pathogenic viruses lacking sufficient epidemiological information. We screened 215 adult ticks of seven species collected in Bulgaria, Georgia, Latvia and Poland for orthonairoviruses, followed by nanopore sequencing (NS) for genome characterization. Initial generic amplification revealed Sulina virus (SULV, Orthonairovirus sulinaense), for which an updated amplification assay was used, revealing an overall prevalence of 2.7% in Ixodes ricinus ticks from Latvia. Three complete and additional partial SULV genomes were generated, that consistently formed a separate, distinct clade with further intragroup divergence in the maximum likelihood analyses. Comparisons with previously described viruses from Romania exhibited similar genome topologies, albeit with divergent motifs and cleavage sites on the glycoprotein precursor. Preliminary evidence of recombination involving the S segment was documented, in addition to variations in predicted viral glycoproteins. Generic screening further identified Tacheng tick virus 1 (TCTV1, Orthonairovirus tachengense), with documented human infections, in Dermacentor reticulatus ticks from Poland, with a prevalence of 0.9%. Subsequent NS and assembly provided the first complete TCTV1 genome outside of China, where it was originally described. Phylogenetic analysis of virus genome segments revealed TCTV1-Poland as a discrete taxon within the TCTV1 cluster in the Orthonairovirus genus, representing a geographically segregated clade. Comparable genome topology with TCTV1 from China was observed, aside from minor variations in the M segment. Similar to SULV, TCTV1 exhibited several mismatches on previously described screening primer binding sites, likely to prevent amplification. These findings indicate presence of novel TCTV1 and SULV clades in Eastern Europe, confirming the expansion of orthonairoviruses with pathogenic potential., Competing Interests: Declaration of competing interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

As evidence of global changes is accumulating, scientists are challenged to detect distribution changes of vectors, reservoirs and pathogens caused by anthropogenic and/or environmental changes. Statistical and mathematical distribution models are emerging for ixodid hard ticks whereas no prediction has ever been developed for argasid ones. These last organisms remain unknown and under-reported; they differ from hard ticks by many structural, biological and ecological properties, which complicate direct adaptation of hard tick models. However, investigations on bibliographic resources concerning these ticks suggest that distribution modelling based on natural niche concept and using environmental factors especially climate is also possible, bearing in mind the scale of prediction and their specificities including their nidicolous lifestyle, an indiscriminate host feeding and a short bloodmeal duration, as well as a flexible development cycle through diapause periods.

Background: Rickettsia spp. are human pathogens that cause a number of diseases and are transmitted by arthropods, such as ixodid ticks. Estonia is one of few regions where the distribution area of two medically important tick species, Ixodes persulcatus and I. ricinus, overlaps. The nidicolous rodent-associated Ixodes trianguliceps has also recently been shown to be present in Estonia. Although no data are available on human disease(s) caused by tick-borne Rickettsia spp. in Estonia, the presence of three Rickettsia species in non-nidicolous ticks has been previously reported. The aim of this study was to detect, identify and partially characterize Rickettsia species in nidicolous and non-nidicolous ticks attached to rodents in Estonia., Results: Larvae and nymphs of I. ricinus (n = 1004), I. persulcatus (n = 75) and I. trianguliceps (n = 117), all removed from rodents and shrews caught in different parts of Estonia, were studied for the presence of Rickettsia spp. by nested PCR. Ticks were collected from 314 small animals of five species [Myodes glareolus (bank voles), Apodemus flavicollis (yellow necked mice), A. agrarius (striped field mice), Microtus subterranius (pine voles) and Sorex araneus (common shrews)]. Rickettsial DNA was detected in 8.7% (103/1186) of the studied ticks. In addition to identifying R. helvetica, which had been previously found in questing ticks, we report here the first time that the recently described I. trianguliceps-associated Candidatus Rickettsia uralica has been identified west of the Ural Mountains.