Relative density of host-seeking ticks in different habitat types of south-western Slovakia

The Role of Environmental Factors in Lyme Disease Transmission in the European Union: A Systematic Review

BACKGROUND

Lyme disease (LD) is an emergent vector-borne disease caused by Borrelia spp. and transmitted through infected ticks, mainly Ixodes spp. Our objective was to determine meteorological and environmental factors associated with LD transmission in Europe and the effect of climate change on LD.

MATERIALS AND METHODS

A systematic review following the PRISMA guidelines was performed. We selected studies on LD transmission in the European Union (EU) and the European Economic Area (EEA) published between 2000 and 2022. The protocol was registered in the PROSPERO database.

RESULTS

We included 81 studies. The impact of environmental, meteorological or climate change factors on tick vectors was studied in 65 papers (80%), and the impact on human LD cases was studied in 16 papers (19%), whereas animal hosts were only addressed in one study (1%). A significant positive relationship was observed between temperature and precipitation and the epidemiology of LD, although contrasting results were found among studies. Other positive factors were humidity and the expansion of anthropized habitats.

CONCLUSIONS

The epidemiology of LD seems to be related to climatic factors that are changing globally due to ongoing climate change. Unfortunately, the complete zoonotic cycle was not systematically analyzed. It is important to adopt a One Health approach to understand LD epidemiology.

Ticks and Chlamydia-Related Bacteria in Swiss Zoological Gardens Compared to in Contiguous and Distant Control Areas

Ticks are vectors of numerous agents of medical importance and may be infected by various Chlamydia-related bacteria, such as members of Parachlamydiaceae and Rhabdochlamydiaceae families, which are sharing the same biphasic life cycle with the pathogenic Chlamydia. However, the veterinary importance of ticks and of their internalized pathogens remains poorly studied. Thus, we wondered (i) whether the prevalence of ticks was higher in zoological gardens than in control areas with similar altitude, vegetation, humidity and temperature, and (ii) whether the presence of Chlamydia-related bacteria in ticks may vary according to the environment in which the ticks are collected. A total of 212 Ixodes ricinus ticks were collected, and all were tested for the presence of DNA from any member of the Chlamydiae phylum using a pan-Chlamydiae quantitative PCR (qPCR). We observed a higher prevalence of ticks outside animal enclosures in both zoos, compared to in enclosures. Tick prevalence was also higher outside zoos, compared to in enclosures. With 30% (3/10) of infected ticks, the zoological gardens presented a prevalence of infected ticks that was higher than that in contiguous areas (13.15%, 10/76), and higher than the control distant areas (8.65%, 9/104). In conclusion, zoological gardens in Switzerland appear to contain fewer ticks than areas outside zoological gardens. However, ticks from zoos more often contain Chlamydia-like organisms than ticks from contiguous or distant control areas.

Spatial and Temporal Variability in Prevalence Rates of Members of the Borrelia burgdorferi Species Complex in Ixodes ricinus Ticks in Urban, Agricultural and Sylvatic Habitats in Slovakia

Lyme borreliosis (LB) is the most prevalent tick-borne human infection in Europe, with increasing incidence during the latest decades. Abundant populations of Ixodes ricinus, the main vector of the causative agent, spirochetes from the Borrelia burgdorferi sensu lato (Bbsl) complex, have been observed in urban and suburban areas of Europe, in general, and Slovakia, particularly. Understanding the spread of infectious diseases is crucial for implementing effective control measures. Global changes affect contact rates of humans and animals with Borrelia-infected ticks and increase the risk of contracting LB. The aim of this study was to investigate spatial and temporal variation in prevalence of Bbsl and diversity of its species in questing I. ricinus from three sites representing urban/suburban, natural and agricultural habitat types in Slovakia. Ixodes ricinus nymphs and adults were collected by dragging the vegetation in green areas of Bratislava town (urban/suburban habitat), in the Small Carpathians Mountains (natural habitat) (south-western Slovakia) and in an agricultural habitat at Rozhanovce in eastern Slovakia. Borrelia presence in ticks was detected by PCR and Bbsl species were identified by restriction fragment length polymorphism (RFLP). Borrelia burgdorferi s.l. species in coinfected ticks were identified by reverse line blot. Significant spatial and temporal variability in prevalence of infected ticks was revealed in the explored habitats. The lowest total prevalence was detected in the urban/suburban habitat, whereas higher prevalence was found in the natural and agricultural habitat. Six Bbsl species were detected by RFLP in each habitat type -B. burgdorferi sensu stricto (s.s.), B. afzelii, B. garinii, B. valaisiana, B. lusitaniae and B. spielmanii. Coinfections accounted for 3% of the total infections, whereby B. kurtenbachii was identified by RLB and sequencing in mixed infection with B. burgdorferi s.s, B. garinii and B. valaisiana. This finding represents the first record of B. kurtenbachii in questing I. ricinus in Slovakia and Europe. Variations in the proportion of Bbsl species were found between nymphs and adults, between years and between habitat types. Spatial variations in prevalence patterns and proportion of Bbsl species were also confirmed between locations within a relatively short distance in the urban habitat. Habitat-related and spatial variations in Borrelia prevalence and distribution of Bbsl species are probably associated with the local environmental conditions and vertebrate host spectrum. Due to the presence of Borrelia species pathogenic to humans, all explored sites can be ranked as areas with high epidemiological risk.

Distribution of ticks in the Western Palearctic: an updated systematic review (2015-2021)

BACKGROUND

The distributions of ticks and tick-borne pathogens are thought to have changed rapidly over the last two decades, with their ranges expanding into new regions. This expansion has been driven by a range of environmental and socio-economic factors, including climate change. Spatial modelling is being increasingly used to track the current and future distributions of ticks and tick-borne pathogens and to assess the associated disease risk. However, such analysis is dependent on high-resolution occurrence data for each species. To facilitate such analysis, in this review we have compiled georeferenced tick locations in the Western Palearctic, with a resolution accuracy under 10 km, that were reported between 2015 and 2021 METHODS: The PubMed and Web of Science databases were searched for peer-reviewed papers documenting the distribution of ticks that were published between 2015 and 2021, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The papers were then screened and excluded in accordance with the PRISMA flow chart. Coordinate-referenced tick locations along with information on identification and collection methods were extracted from each eligible publication. Spatial analysis was conducted using R software (version 4.1.2).

RESULTS

From the 1491 papers identified during the initial search, 124 met the inclusion criteria, and from these, 2267 coordinate-referenced tick records from 33 tick species were included in the final dataset. Over 30% of articles did not record the tick location adequately to meet inclusion criteria, only providing a location name or general location. Among the tick records, Ixodes ricinus had the highest representation (55%), followed by Dermacentor reticulatus (22.1%) and Ixodes frontalis (4.8%). The majority of ticks were collected from vegetation, with only 19.1% collected from hosts.

CONCLUSIONS

The data presented provides a collection of recent high-resolution, coordinate-referenced tick locations for use in spatial analyses, which in turn can be used in combination with previously collated datasets to analyse the changes in tick distribution and research in the Western Palearctic. In the future it is recommended that, where data privacy rules allow, high-resolution methods are routinely used by researchers to geolocate tick samples and ensure their work can be used to its full potential.

Borrelia spirochetes in European exotic farm animals

Ticks transmit a broad spectrum of pathogens, threatening both animal and human health. Tick survival and proliferation are strongly dependent on host selection and suitability. The hard tick Ixodes ricinus, which is widespread throughout most of Europe, is a host generalist capable of feeding on many different vertebrate species. Pasture-kept exotic farm animals may be at a high risk for tick and tick-borne pathogens infestations but research characterizing this is currently lacking. This study focused on the detection of Borrelia spirochetes (including Borrelia miyamotoi) in exotic farm animals. Using nested-PCR with Borrelia-specific primers, 121 serum samples from 54 exotic farm animals of several species bred in four different farms in Bohemia and Moravia (Czechia) were tested. Positive samples were sequenced for the identification of Borrelia species. The prevalence of Borrelia DNA in the samples ranged from 13 to 67%, depending on the sampling site. The sequencing results confirmed the DNA presence of multiple spirochete species from the Borrelia burgdorferi sensu lato complex. Only one sample from an ostrich (Struthio camelus) was found to be positive for Borrelia myiamotoi. The results show that exotic farm animals can serve as hosts for hard ticks and can be infected by Borrelia spirochetes, transmitted by hard ticks. Therefore, these animals could play a relevant role in maintaining Borrelia spirochetes in nature.

Bartonella, Rickettsia, Babesia, and Hepatozoon Species in Fleas (Siphonaptera) Infesting Small Mammals of Slovakia (Central Europe)

Fleas (Siphonaptera) as obligate, blood-feeding ectoparasites are, together with ticks, hosted by small mammals and can transmit causative agents of serious infections. This study aimed to determine and characterize the presence and genetic diversity of Bartonella, Rickettsia, and apicomplexan parasites (Babesia, Hepatozoon) in fleas feeding on small mammals from three different habitat types (suburban, natural, and rural) in Slovakia. The most common pathogen in the examined fleas was Bartonella spp. (33.98%; 95% CI: 30.38-37.58), followed by Rickettsia spp. (19.1%; 95% CI: 16.25-22.24) and apicomplexan parasites (4.36%; 95% CI: 2.81-5.91). Bartonella strains belonging to B. taylorii, B. grahamii, B. elizabethae, Bartonella sp. wbs11, and B. rochalimae clades were identified in Ctenophthalmus agyrtes, C. congener, C. assimilis, C. sciurorum, C. solutus, C. bisoctodentatus, Palaeopsylla similis, Megabothris turbidus, and Nosopsyllus fasciatus within all habitats. The presence of Rickettsia helvetica, R. monacensis, and rickettsiae, belonging to the R. akari and R. felis clusters, and endosymbionts with a 96-100% identity with the Rickettsia endosymbiont of Nosopsyllus laeviceps laeviceps were also revealed in C. agyrtes, C. solutus, C. assimilis, C. congener, M. turbidus, and N. fasciatus. Babesia and Hepatozoon DNA was detected in the fleas from all habitat types. Hepatozoon sp. was detected in C. agyrtes, C. assimilis, and M. turbidus, while Babesia microti was identified from C. agyrtes, C. congener, and P. similis. The present study demonstrated the presence of zoonotic pathogens in fleas, parasitizing the wild-living small mammals of southwestern and central Slovakia and widens our knowledge of the ecology and genomic diversity of Bartonella, Rickettsia, Babesia, and Hepatozoon.

Questing Ixodes ricinus ticks and Borrelia spp. in urban green space across Europe: A review

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.

Ticks and their epidemiological role in Slovakia: from the past till present

In Slovakia, 22 tick species have been found to occur to date. Among them, Ixodes ricinus, Dermacentor reticulatus, D. marginatus and marginally Haemaphysalis concinna, H. inermis and H. punctata have been identified as the species of public health relevance. Ticks in Slovakia were found to harbour and transmit zoonotic and/or potentially zoonotic agents such as tick-borne encephalitis virus (TBEV), spirochaetes of the Borrelia burgdorferi sensu lato (s.l.) complex, the relapsing fever sprirochaete Borrelia miyamotoi, bacteria belonging to the orders Rickettsiales (Rickettsia spp., Anaplasma phagocytophilum, Neoehrlichia mikurensis), Legionellales (Coxiella burnetii), and Thiotrichales (Francisella tularensis), and Babesia spp. parasites (order Piroplasmida). Ixodes ricinus is the principal vector of the largest variety of microorganisms including viruses, bacteria and piroplasms. TBEV, B. burgdorferi s.l., rickettsiae of the spotted fever group, C. burnetii and F. tularensis have been found to cause serious diseases in humans, whereas B. miyamotoi, A. phagocytophilum, N. mikurensis, Babesia microti, and B. venatorum pose lower or potential risk to humans. Distribution of TBEV has a focal character. During the last few decades, new tick-borne encephalitis (TBE) foci and their spread to new areas have been registered and TBE incidence rates have increased. Moreover, Slovakia reports the highest rates of alimentary TBE infections among the European countries. Lyme borreliosis (LB) spirochaetes are spread throughout the distribution range of I. ricinus. Incidence rates of LB have shown a slightly increasing trend since 2010. Only a few sporadic cases of human rickettsiosis, anaplasmosis and babesiosis have been confirmed thus far in Slovakia. The latest large outbreaks of Q fever and tularaemia were recorded in 1993 and 1967, respectively. Since then, a few human cases of Q fever have been reported almost each year. Changes in the epidemiological characteristics and clinical forms of tularaemia have been observed during the last few decades. Global changes and development of modern molecular tools led to the discovery and identification of emerging or new tick-borne microorganisms and symbionts with unknown zoonotic potential. In this review, we provide a historical overview of research on ticks and tick-borne pathogens in Slovakia with the most important milestones and recent findings, and outline future directions in the investigation of ticks as ectoparasites and vectors of zoonotic agents and in the study of tick-borne diseases.

Role of Zoo-Housed Animals in the Ecology of Ticks and Tick-Borne Pathogens-A Review

Ticks are ubiquitous ectoparasites, feeding on representatives of all classes of terrestrial vertebrates and transmitting numerous pathogens of high human and veterinary medical importance. Exotic animals kept in zoological gardens, ranches, wildlife parks or farms may play an important role in the ecology of ticks and tick-borne pathogens (TBPs), as they may serve as hosts for local tick species. Moreover, they can develop diseases of varying severity after being infected by TBPs, and theoretically, can thus serve as reservoirs, thereby further propagating TBPs in local ecosystems. The definite role of these animals in the tick-host-pathogen network remains poorly investigated. This review provides a summary of the information currently available regarding ticks and TBPs in connection to captive local and exotic wildlife, with an emphasis on zoo-housed species.

Long-term monitoring of the seasonal density of questing ixodid ticks in Vienna (Austria): setup and first results

The first long-term monitoring to document both activity and density of questing ixodid ticks in Vienna, Austria, is introduced. It was started in 2017 and is planned to run over decades. Such long-term monitorings are needed to quantify possible effects of climate change or to develop tick density forecast models. The monthly questing tick density at three sites has been observed by using a standardized sampling method by dragging an area of [Formula: see text] at each occasion. Popular recreational areas were chosen as study sites. These are the Prater public park, the wooded Kahlenberg, and a wildlife garden in Klosterneuburg. First results show a 3-year time series of nymphs and adults of the Ixodes ricinus species complex and Haemaphysalis concinna for the period 2017-2019. Whereas questing nymphs of the I. ricinus species complex were collected from February to November, H. concinna nymphs were only dragged from May to October. The peak of nymphal activity of the I. ricinus species complex was in May, that of H. concinna in August. In addition, a brief overview is given about ticks and tick-borne pathogens occurring in urban and suburban areas of Vienna.

Isolation and partial characterisation of a novel Trypanosoma from the tick Ixodes ricinus

Trypanosomes have long been recognised as being amongst the most important protozoan parasites of vertebrates, from both medical and veterinary perspectives. Whilst numerous insect species have been identified as vectors, the role of ticks is less well understood. Here we report the isolation and partial molecular characterisation of a novel trypanosome from questing Ixodes ricinus ticks collected in Slovakia. The trypanosome was isolated in tick cell culture and then partially characterised by microscopy and amplification of fragments of the 18S rRNA and 24Sα rDNA genes. Analysis of the resultant sequences suggests that the trypanosome designated as Trypanosoma sp. Bratislava1 may be a new species closely related to several species or strains of trypanosomes isolated from, or detected in, ticks in South America and Asia, and to Trypanosoma caninum isolated from dogs in Brazil. This study highlights the potential involvement of ixodid ticks in the epidemiology of trypanosomes, as well as the use of tick cell lines for isolation of such tick-borne protozoa. Further studies are required to investigate the epidemiology, transmission and life cycle of this putative novel species.

Research paper on abiotic factors and their influence on Ixodes ricinus activity-observations over a two-year period at several tick collection sites in Germany

Tick-borne diseases are a public health issue. To predict vector tick abundance and activity, it is necessary to understand the driving factors for these variables. In this study, the activity of Ixodes ricinus was investigated in forest and meadow habitats in Germany with a focus on abiotic factors. Ixodes ricinus adults, nymphs and larvae were caught by flagging over a period of 2 years. Microclimatic and weather conditions were recorded at the collection sites. Statistical models were applied to describe correlations between abiotic factors and tick activity in univariable and multivariable analyses. Tick activity was observed in a broad range of air temperature between 3 and 28 °C, and air humidity varied between 35 and 95%. In general, tick activity of nymphs and larvae was higher in forest habitats than that in meadows. With the exception of a single specimen of Dermacentor reticulatus, all ticks were Ixodes ricinus, most of them nymphs (63.2% in 2009 and 75.2% in 2010). For the latter, a negative binomial mixed-effects model fitted best to the observed parameters. The modelling results showed an activity optimum between 20 and 23 °C for air temperature and between 13 and 15 °C for ground temperature. In univariable analyses, the collection site, month, season, ground and air temperature were significant factors for the number of ticks caught and for all life stages. In the multivariable analysis, temperature, season and habitat turned out to be key drivers. Ixodes ricinus positive for RNA of tick-borne encephalitis virus was only found at a single sampling site. The results of this study can be used in risk assessments and to parameterise predictive models.

Presence of Roe Deer Affects the Occurrence of Anaplasma phagocytophilum Ecotypes in Questing Ixodes ricinus in Different Habitat Types of Central Europe

The way in which European genetic variants of Anaplasma phagocytophilum circulate in their natural foci and which variants cause disease in humans or livestock remains thus far unclear. Red deer and roe deer are suggested to be reservoirs for some European A. phagocytophilum strains, and Ixodes ricinus is their principal vector. Based on groEL gene sequences, five A. phagocytophilum ecotypes have been identified. Ecotype I is associated with the broadest host range, including strains that cause disease in domestic animals and humans. Ecotype II is associated with roe deer and does not include zoonotic strains. In the present study, questing I. ricinus were collected in urban, pasture, and natural habitats in the Czech Republic, Germany, and Slovakia. A fragment of the msp2 gene of A. phagocytophilum was amplified by real-time PCR in DNA isolated from ticks. Positive samples were further analyzed by nested PCRs targeting fragments of the 16S rRNA and groEL genes, followed by sequencing. Samples were stratified according to the presence/absence of roe deer at the sampling sites. Geographic origin, habitat, and tick stage were also considered. The probability that A. phagocytophilum is a particular ecotype was estimated by a generalized linear model. Anaplasma phagocytophilum was identified by genetic typing in 274 I. ricinus ticks. The majority belonged to ecotype I (63.9%), 28.5% were ecotype II, and both ecotypes were identified in 7.7% of ticks. Ecotype II was more frequently identified in ticks originating from a site with presence of roe deer, whereas ecotype I was more frequent in adult ticks than in nymphs. Models taking into account the country-specific, site-specific, and habitat-specific aspects did not improve the goodness of the fit. Thus, roe deer presence in a certain site and the tick developmental stage are suggested to be the two factors consistently influencing the occurrence of a particular A. phagocytophilum ecotype in a positive I. ricinus tick.

Ticks and tick-borne diseases in the city: Role of landscape connectivity and green space characteristics in a metropolitan area

Green spaces in the city are important for human wellbeing, but are also zones in which humans can become infected with zoonotic diseases. Therefore, there is a need to understand how infection risk is related to green space characteristics, wildlife communities and connectivity with rural areas hosting reservoir populations of hosts. Our hypothesis is that wildlife hosts in urban green spaces, and thereby the prevalence of questing ticks and their Lyme disease causing pathogens (Borrelia burgdorferi s.l.), can be partly predicted based on green space characteristics as well as measures of connectivity to known source areas. We sampled ticks in twenty-two green spaces during Spring (2014 and 2016) and Autumn 2016, located along an urbanization gradient in Antwerp (Belgium). More than 18,000 m² was sampled, with tick densities ranging from 0 to 386 individuals/100 m². We estimated connectivity using the least-cost algorithm as either the cost distance to the nearest green space, or to a known population of roe deer (Capreolus capreolus), known to be an important tick propagation host. Both connectivity measures turned out to be correlated, reflecting a gradient in green space isolation from the periphery to the urban center. In 87% of plots where ticks were trapped, at least one Borrelia-infected tick was found. The overall Borrelia-prevalence in nymphs was 17.8%, in adults 32.6%. Density of infected ticks decreased with urbanization and increased with connectivity. Nymphs in larger green spaces were more likely to be infected. While density and infection prevalence for adults increased with the amount of neighboring agricultural land, the larval density and nymphal infection prevalence decreased. Interestingly, the proportion of Borrelia genospecies associated with birds or mammals was comparable in rural and (sub)urban areas (bird/mammal: 0.38), suggesting that even in small green spaces Borrelia infections can persist in local host populations.

Diverse tick-borne microorganisms identified in free-living ungulates in Slovakia

BACKGROUND

Free-living ungulates are hosts of ixodid ticks and reservoirs of tick-borne microorganisms in central Europe and many regions around the world. Tissue samples and engorged ticks were obtained from roe deer, red deer, fallow deer, mouflon, and wild boar hunted in deciduous forests of south-western Slovakia. DNA isolated from these samples was screened for the presence of tick-borne microorganisms by PCR-based methods.

RESULTS

Ticks were found to infest all examined ungulate species. The principal infesting tick was Ixodes ricinus, identified on 90.4% of wildlife, and included all developmental stages. Larvae and nymphs of Haemaphysalis concinna were feeding on 9.6% of wildlife. Two specimens of Dermacentor reticulatus were also identified. Ungulates were positive for A. phagocytophilum and Theileria spp. Anaplasma phagocytophilum was found to infect 96.1% of cervids, 88.9% of mouflon, and 28.2% of wild boar, whereas Theileria spp. was detected only in cervids (94.6%). Importantly, a high rate of cervids (89%) showed mixed infections with both these microorganisms. In addition to A. phagocytophilum and Theileria spp., Rickettsia helvetica, R. monacensis, unidentified Rickettsia sp., Coxiella burnetii, "Candidatus Neoehrlichia mikurensis", Borrelia burgdorferi (s.l.) and Babesia venatorum were identified in engorged I. ricinus. Furthermore, A. phagocytophilum, Babesia spp. and Theileria spp. were detected in engorged H. concinna. Analysis of 16S rRNA and groEL gene sequences revealed the presence of five and two A. phagocytophilum variants, respectively, among which sequences identified in wild boar showed identity to the sequence of the causative agent of human granulocytic anaplasmosis (HGA). Phylogenetic analysis of Theileria 18S rRNA gene sequences amplified from cervids and engorged I. ricinus ticks segregated jointly with sequences of T. capreoli isolates into a moderately supported monophyletic clade.

CONCLUSIONS

The findings indicate that free-living ungulates are reservoirs for A. phagocytophilum and Theileria spp. and engorged ixodid ticks attached to ungulates are good sentinels for the presence of agents of public and veterinary concern. Further analyses of the A. phagocytophilum genetic variants and Theileria species and their associations with vector ticks and free-living ungulates are required.

Effect of Climate and Land Use on the Spatio-Temporal Variability of Tick-Borne Bacteria in Europe

The incidence of tick-borne diseases caused by Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum and Rickettsia spp. has been rising in Europe in recent decades. Early pre-assessment of acarological hazard still represents a complex challenge. The aim of this study was to model Ixodes ricinus questing nymph density and its infection rate with B. burgdorferi s.l., A. phagocytophilum and Rickettsia spp. in five European countries (Italy, Germany, Czech Republic, Slovakia, Hungary) in various land cover types differing in use and anthropisation (agricultural, urban and natural) with climatic and environmental factors (Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Land Surface Temperature (LST) and precipitation). We show that the relative abundance of questing nymphs was significantly associated with climatic conditions, such as higher values of NDVI recorded in the sampling period, while no differences were observed among land use categories. However, the density of infected nymphs (DIN) also depended on the pathogen considered and land use. These results contribute to a better understanding of the variation in acarological hazard for Ixodes ricinus transmitted pathogens in Central Europe and provide the basis for more focused ecological studies aimed at assessing the effect of land use in different sites on tick–host pathogens interaction.

Seasonal cycles of the TBE and Lyme borreliosis vector Ixodes ricinus modelled with time-lagged and interval-averaged predictors

Ticks of the species Ixodes ricinus (L.) are the major vectors for tick-borne diseases in Europe. The aim of this study was to quantify the influence of environmental variables on the seasonal cycle of questing I. ricinus. Therefore, an 8-year time series of nymphal I. ricinus flagged at monthly intervals in Haselmühl (Germany) was compiled. For the first time, cross correlation maps were applied to identify optimal associations between observed nymphal I. ricinus densities and time-lagged as well as temporal averaged explanatory variables. To prove the explanatory power of these associations, two Poisson regression models were generated. The first model simulates the ticks of the entire time series flagged per 100 m[Formula: see text], the second model the mean seasonal cycle. Explanatory variables comprise the temperature of the flagging month, the relative humidity averaged from the flagging month and 1 month prior to flagging, the temperature averaged over 4-6 months prior to the flagging event and the hunting statistics of the European hare from the preceding year. The first model explains 65% of the monthly tick variance and results in a root mean square error (RMSE) of 17 ticks per 100 m[Formula: see text]. The second model explains 96% of the tick variance. Again, the accuracy is expressed by the RMSE, which is 5 ticks per 100 m[Formula: see text]. As a major result, this study demonstrates that tick densities are higher correlated with time-lagged and temporal averaged variables than with contemporaneous explanatory variables, resulting in a better model performance.

Diversity and prevalence of Bartonella species in small mammals from Slovakia, Central Europe

Wild-living rodents are important hosts for zoonotic pathogens. Bartonella infections are widespread in rodents; however, in Slovakia, knowledge on the prevalence of these bacteria in small mammals is limited. We investigated the prevalence and diversity of Bartonella species in the spleens of 640 rodents of six species (Apodemus flavicollis, Apodemus sylvaticus, Myodes glareolus, Microtus arvalis, Microtus subterraneus, and Micromys minutus) and in the European mole (Talpa europaea) from three different habitat types in south-western and central Slovakia. Overall, the prevalence of Bartonella spp. in rodents was 64.8%; a rate of 73.8% was found in natural habitat (deciduous forest), 56.0% in suburban forest park and 64.9% in rural habitat. Bartonella spp. were detected in 63.0% of A. flavicollis, 69% of My. glareolus and 61.1% of M. arvalis and in T. europaea. However, Bartonella were not found in the other examined rodents. Molecular analyses of the 16S-23S rRNA intergenic spacer region revealed the presence of four different Bartonella spp. clusters. We identified B. taylorii, B. rochalimae, B. elizabethae, B. grahamii and Bartonella sp. wbs11 in A. flavicollis and My. glareolus. Bartonella genotypes ascribed to B. taylorii and B. rochalimae were found in M. arvalis. B. taylorii was identified in T. europaea. Questing Ixodes ricinus ticks that were collected at the study sites were not infected with Bartonella. This study improves our understanding of the ecoepidemiology of Bartonella spp. in Europe and underlines the necessity for further research on Bartonella-host-vector associations and their consequences on animal and human health in Slovakia.

Molecular evidence of Rickettsia spp. in ixodid ticks and rodents in suburban, natural and rural habitats in Slovakia

BACKGROUND

Natural foci of tick-borne spotted fever group (SFG) rickettsiae of public health concern have been found in Slovakia, but the role of rodents in their circulation is unclear. Ticks (Ixodes ricinus, Ixodes trianguliceps, Dermacentor marginatus, Dermacentor reticulatus, Haemaphysalis concinna and Haemaphysalis inermis) and tissues of rodents (Apodemus flavicollis, Apodemus sylvaticus, Myodes glareolus, Microtus arvalis, Microtus subterraneus and Micromys minutus) were examined for the presence of SFG rickettsiae and Coxiella burnetii by molecular methods. Suburban, natural and rural habitats were monitored to acquire information on the role of ticks and rodents in the agents' maintenance in various habitat types of Slovakia.

RESULTS

The overall prevalence of rickettsial infection in questing I. ricinus and D. marginatus was 6.6% and 21.4%, respectively. Rickettsia helvetica, R. monacensis and non-identified rickettsial species were detected in I. ricinus, whereas R. slovaca and R. raoultii were identified in D. marginatus. Rickettsia spp.-infected I. ricinus occurred during the whole tick questing period. Rickettsia helvetica dominated (80.5%) followed by R. monacensis (6.5%). The species were present in all studied habitats. Rickettsia slovaca (66.7%) and R. raoultii (33.3%) were identified in D. marginatus from the rural habitat. Apodemus flavicollis was the most infested rodent species with I. ricinus, but My. glareolus carried the highest proportion of Rickettsia-positive I. ricinus larvae. Only 0.5% of rodents (A. flavicollis) and 5.2% of engorged I. ricinus removed from My. glareolus, A. flavicollis and M. arvalis were R. helvetica- and R. monacensis-positive. Coxiella burnetii was not detected in any of the tested samples. We hypothesize that rodents could play a role as carriers of infected ticks and contribute to the maintenance of rickettsial pathogens in natural foci.

CONCLUSIONS

Long-term presence of SFG Rickettsia spp. was confirmed in questing ticks from different habitat types of Slovakia. The results suggest a human risk for infection with the pathogenic R. helvetica, R. monacensis, R. slovaca and R. raoultii.

Babesia spp. in ticks and wildlife in different habitat types of Slovakia

BACKGROUND

Babesiosis is an emerging and potentially zoonotic disease caused by tick-borne piroplasmids of the Babesia genus. New genetic variants of piroplasmids with unknown associations to vectors and hosts are recognized. Data on the occurrence of Babesia spp. in ticks and wildlife widen the knowledge on the geographical distribution and circulation of piroplasmids in natural foci. Questing and rodent-attached ticks, rodents, and birds were screened for the presence of Babesia-specific DNA using molecular methods. Spatial and temporal differences of Babesia spp. prevalence in ticks and rodents from two contrasting habitats of Slovakia with sympatric occurrence of Ixodes ricinus and Haemaphysalis concinna ticks and co-infections of Candidatus N. mikurensis and Anaplasma phagocytophilum were investigated.

RESULTS

Babesia spp. were detected in 1.5 % and 6.6 % of questing I. ricinus and H. concinna, respectively. Prevalence of Babesia-infected I. ricinus was higher in a natural than an urban/suburban habitat. Phylogenetic analysis showed that Babesia spp. from I. ricinus clustered with Babesia microti, Babesia venatorum, Babesia canis, Babesia capreoli/Babesia divergens, and Babesia odocoilei. Babesia spp. amplified from H. concinna segregated into two monophyletic clades, designated Babesia sp. 1 (Eurasia) and Babesia sp. 2 (Eurasia), each of which represents a yet undescribed novel species. The prevalence of infection in rodents (with Apodemus flavicollis and Myodes glareolus prevailing) with B. microti was 1.3 % in an urban/suburban and 4.2 % in a natural habitat. The majority of infected rodents (81.3 %) were positive for spleen and blood and the remaining for lungs and/or skin. Rodent-attached I. ricinus (accounting for 96.3 %) and H. concinna were infected with B. microti, B. venatorum, B. capreoli/B. divergens, Babesia sp. 1 (Eurasia), and Babesia sp. 2 (Eurasia). All B. microti and B. venatorum isolates were identical to known zoonotic strains from Europe. Less than 1.0 % of Babesia-positive ticks and rodents carried Candidatus N. mikurensis or A. phagocytophilum.

CONCLUSION

Our findings suggest that I. ricinus and rodents play important roles in the epidemiology of zoonotic Babesia spp. in south-western Slovakia. Associations with vertebrate hosts and the pathogenicity of Babesia spp. infecting H. concinna ticks need to be further explored.