Ixodes ricinus and Borrelia prevalence at the Arctic Circle in Norway

Ticks and tick-borne microbes identified through passive and active surveillance in Alaska

Rapid environmental change in Alaska and other regions of the Arctic and sub-Arctic has raised concerns about increasing human exposure to ticks and the pathogens they carry. We tested a sample of ticks collected through a combination of passive and active surveillance from humans, domestic animals, and wildlife hosts in Alaska for a panel of the most common tick-borne pathogens in the contiguous United States to characterize the diversity of microbes present in this region. We tested 189 pooled tick samples collected in 2019-2020 for Borrelia spp., Anaplasma spp., Ehrlichia spp., and Babesia spp. using a multiplex PCR amplicon sequencing assay. We found established populations of Ixodes angustus Neumann (Acari: Ixodidae), Ixodes uriae White (Acari: Ixodidae), and Haemaphysalis leporispalustris Packard (Acari: Ixodidae) in Alaska, with I. angustus found on a variety of hosts including domestic companion animals (dogs and cats), small wild mammals, and humans. Ixodes angustus were active from April through October with peaks in adult and nymphal activity observed in summer months (mainly July). Although no known human pathogens were detected, Babesia microti-like parasites and candidatus Ehrlichia khabarensis were identified in ticks and small mammals. The only human pathogen detected (B. burgdorferi s.s.) was found in a tick associated with a dog that had recently traveled to New York, where Lyme disease is endemic. This study highlights the value of a combined passive and active tick surveillance system to detect introduced tick species and pathogens and to assess which tick species and microbes are locally established.

Does environmental adaptation or dispersal history explain the geographical distribution of Ixodes ricinus and Ixodes persulcatus ticks in Finland?

In Finland, the distribution area of the taiga tick, Ixodes persulcatus (Schulze, 1930), is nested within a broader area of distribution of a congeneric species, the sheep tick, Ixodes ricinus (Linnaeus, 1758) (Acari: Ixodidae). We assess whether distinct environmental adaptations or dispersal history provides a more parsimonious explanation for the differences in the distributions of the two common and medically important ixodids in Finland. We used an innovative spatially constrained randomization procedure to analyze whether crowdsourced occurrence data points of the two tick species had statistically different associations with any of the 28 environmental variables. Using points of presence in a region of species co-occurrence, we built Maxent models to examine whether environmental factors or dispersal history could explain the absence of I. persulcatus in a part of the range of I. ricinus in Finland. Five environmental variables-number of inhabitants, road length, elevation above sea level, proportion of barren bedrock and boulders, and proportion of unsorted glacial deposits-were significant at p ≤ .05, indicating greater between-species difference in original than in the randomized data. Of these variables, only the optimum value for unsorted glacial deposits was higher for I. persulcatus than for I. ricinus. Maxent models also predicted high relative habitat suitability (suitability >80%) for I. persulcatus south of its current, sharply bounded distribution range, suggesting that the species has not fulfilled its distribution potential in Finland. The two most common and medically relevant ixodids in Finland may colonize habitats with different environmental conditions. On the contrary, the recent establishment and ongoing dispersion of I. persulcatus in Fennoscandia rather than environmental conditions cause the southernmost distribution limit of the species in Finland.

Distribution and Characterisation of Tick-Borne Flavi-, Flavi-like, and Phenuiviruses in the Chelyabinsk Region of Russia

In this work, we presented data from a two-year study of flavi-, flavi-like, and phenuiviruses circulation in the population of ixodid ticks in the Chelyabinsk region. We isolated three tick-borne encephalitis virus (TBEV) strains from I. persulcatus, which was not detected in the ticks of the genus Dermacentor. The virus prevalence ranged from 0.66% to 2.28%. The Yanggou tick virus (YGTV) is widespread in steppe and forest-steppe zones and is mainly associated with ticks of the genus Dermacentor. We isolated 26 strains from D. reticulatus, D. marginatus, and I. persulcatus ticks in the HAE/CTVM8 tick cell line. The virus prevalence ranged from 1.58% to 4.18% in D. reticulatus, ranged from 0.78% to 3.93% in D. marginatus, and was 0.66% in I. persulcatus. There was combined focus of TBEV and YGTV in the territory of the Chelyabinsk region. The Alongshan virus (ALSV) was found to be associated with I. persulcatus ticks and is spread in forest zone. We detected 12 amplicons and isolated 7 strains of ALSV in tick cells. The virus prevalence ranged from 1.13% to 6.00%. The phlebovirus Gomselga and unclassified phenuivirus Stavropol were associated with I. persulcatus and D. reticulatus ticks, respectively. Virus prevalence of the unclassified phenuivirus Stavropol in the Chelyabinsk region is lower than that in neighbouring regions.

Pathogens in Ixodes persulcatus and Ixodes ricinus ticks (Acari, Ixodidae) in Karelia (Russia)

Ixodid ticks (Acarina, Ixodidae) are vectors of dangerous human infections. The main tick species that determine the epidemiological situation for tick-borne diseases in northern Europe are Ixodes ricinus and Ixodes persulcatus. In recent years, significant changes in the number and distribution of these species have been observed, accompanied by an expansion of the sympatric range. This work summarizes the data of long-term studies carried out in Karelia since 2007 on the infection of I. persulcatus and I. ricinus ticks with various pathogens, including new viruses with unclear pathogenic potential. As a result, tick-borne encephalitis virus (TBEV, Siberian genotype), Alongshan virus, several representatives of the family Phenuiviridae, Borrelia afzelii, Borrelia garinii, Ehrlichia muris, Candidatus Rickettsia tarasevichiae and Candidatus Lariskella arthropodarum were identified. Data were obtained on the geographical and temporal variability of tick infection rates with these main pathogens. The average infection rates of I. persulcatus with TBEV and Borrelia burgdorferi sensu lato were 4.4% and 23.4% and those of I. ricinus were 1.1% and 11.9%, respectively. We did not find a correlation between the infection rate of ticks with TBEV, B. burgdorferi s.l. and Ehrlichia muris/chaffeensis with the sex of the vector. In general, the peculiarities of the epidemiological situation in Karelia are determined by the wide distribution and high abundance of I. persulcatus ticks and by their relatively high infection rate with TBEV and B. burgdorferi s.l. in most of the territory, including the periphery of the range.

LOUPING-ILL VIRUS SEROSURVEY OF WILLOW PTARMIGAN (LAGOPUS LAGOPUS LAGOPUS) IN NORWAY

In Norway, the Willow Ptarmigan (Lagopus lagopus lagopus) is experiencing population declines and is nationally Red Listed as Near Threatened. Although disease has not generally been regarded as an important factor behind population fluctuations for Willow Ptarmigan in Norway, disease occurrence has been poorly investigated. Both louping-ill virus (LIV) and the closely related tick-borne encephalitis virus are found along the southern part of the Norwegian coast. We assessed whether and where Norwegian Willow Ptarmigan populations have been infected with LIV. We expected to find infected individuals in populations in the southernmost part of the country. We did not expect to find infected individuals in populations further north and at higher altitudes because of the absence of the main vector, the sheep tick (Ixodes ricinus). We collected serum samples on Nobuto filter paper and used a hemagglutination inhibition assay for antibodies against LIV. We collected data at both local and country-wide levels. For local sampling, we collected and analyzed 87 hunter-collected samples from one of the southernmost Willow Ptarmigan populations in Norway. Of these birds, only three positives (3.4%) were found. For the country-wide sampling, we collected serum samples from 163 Willow Ptarmigan carcasses submitted from selected locations all over the country. Of these birds, 32% (53) were seropositive for LIV or a cross-reacting virus. Surprisingly, we found seropositive individuals from locations across the whole country, including outside the known distribution of the sheep tick. These results suggest that either LIV or a cross-reacting virus infects ptarmigan in large parts of Norway, including at high altitudes and latitudes.

High-elevational occurrence of two tick species, Ixodes ricinus and I. trianguliceps, at their northern distribution range

BACKGROUND

During the last decades a northward and upward range shift has been observed among many organisms across different taxa. In the northern hemisphere, ticks have been observed to have increased their latitudinal and altitudinal range limit. However, the elevational expansion at its northern distribution range remains largely unstudied. In this study we investigated the altitudinal distribution of the exophilic Ixodes ricinus and endophilic I. trianguliceps on two mountain slopes in Norway by assessing larval infestation rates on bank voles (Myodes glareolus).

METHODS

During 2017 and 2018, 1325 bank voles were captured during the spring, summer and autumn at ten trapping stations ranging from 100 m to 1000 m.a.s.l. in two study areas in southern Norway. We used generalized logistic regression models to estimate the prevalence of infestation of both tick species along gradients of altitude, considering study area, collection year and season, temperature, humidity and altitude interactions as extrinsic variables, and host body mass and sex as intrinsic predictor variables.

RESULTS

We found that both I. ricinus and I. trianguliceps infested bank voles at altitudes up to 1000 m.a.s.l., which is a substantial increase in altitude compared to previous findings for I. ricinus in this region. The infestation rates declined more rapidly with increasing altitude for I. ricinus compared to I. trianguliceps, indicating that the endophilic ecology of I. trianguliceps may provide shelter from limiting factors tied to altitude. Seasonal effects limited the occurrence of I. ricinus during autumn, but I. trianguliceps was found to infest rodents at all altitudes during all seasons of both years.

CONCLUSIONS

This study provides new insights into the altitudinal distribution of two tick species at their northern distribution range, one with the potential to transmit zoonotic pathogens to both humans and livestock. With warming temperatures predicted to increase, and especially so in the northern regions, the risk of tick-borne infections is likely to become a concern at increasingly higher altitudes in the future.

Low prevalence of tick-borne encephalitis virus antibodies in Norwegian blood donors

BACKGROUND

Tick-borne encephalitis (TBE) constitutes a public health concern in Europe. Certain coastal municipalities in southern Norway are considered TBE risk areas and in the last two years, there have been increasing numbers of TBE cases. Since the majority of infections are claimed to be asymptomatic, the aim of the current study was to assess the seroprevalence of antibodies to tick-borne encephalitis virus (TBEV) among unvaccinated adults living in a TBE endemic area in Norway.

METHODS

One thousand one hundred and twenty-three blood donors living in Vestfold and Telemark county were included and associated sera were analysed for TBEV IgG antibodies. Information regarding tick bites, previous flavivirus exposure and knowledge regarding TBE and TBE prevention were obtained through a questionnaire.

RESULTS

Fifty-eight samples were reactive by ELISA, of which 21 (36.2%) were confirmed by a TBEV-specific serum neutralization test. Of the 21 blood donors with neutralizing TBEV antibodies detected, 17 reported previous TBE vaccination. Thus, only four blood donors (0.4%) had TBEV neutralizing antibodies consistent with previously undergone TBEV infection. Regarding TBE awareness, half of the blood donors were familiar with TBE, but only 35% were aware of a preventive TBE vaccine.

CONCLUSIONS

Our study indicates low prevalence of subclinical TBEV infections among blood donors living in Vestfold and Telemark county and there is a lack of awareness among general public.

A Mini-Review of Ixodes Ticks Climate Sensitive Infection Dispersion Risk in the Nordic Region

Climate change in the Nordic countries is projected to lead to both wetter and warmer seasons. This, in combination with associated vegetation changes and increased animal migration, increases the potential incidence of tick-borne diseases (TBD) where already occurring, and emergence in new places. At the same time, vegetation and animal management influence tick habitat and transmission risks. In this paper, we review the literature on Ixodes ricinus, the primary vector for TBD. Current and projected distribution changes and associated disease transmission risks are related to climate constraints and climate change, and this risk is discussed in the specific context of reindeer management. Our results indicate that climatic limitations for vectors and hosts, and environmental and societal/institutional conditions will have a significant role in determining the spreading of climate-sensitive infections (CSIs) under a changing climate. Management emerges as an important regulatory "tool" for tick and/or risk for disease transfer. In particular, shrub encroachment, and pasture and animal management, are important. The results underscore the need to take a seasonal view of TBD risks, such as (1) grazing and migratory (host) animal presence, (2) tick (vector) activity, (3) climate and vegetation, and (4) land and animal management, which all have seasonal cycles that may or may not coincide with different consequences of climate change on CSI migration. We conclude that risk management must be coordinated across the regions, and with other land-use management plans related to climate mitigation or food production to understand and address the changes in CSI risks.

Spatial tick bite exposure and associated risk factors in Scandinavia

Tick-borne diseases are emerging and re-emerging threats causing public health concerns in Europe and North America. Prevention and control requires understanding of human exposure and behaviour. The aim was to measure exposure to tick bites across Scandinavia, its spatial distribution and the associated risk factors. Methods We sent a web-based survey to a randomly chosen population and analysed answers by Principal Component Analysis and Chi-Square. Individual responses were aggregated at the municipality level to assess the spatial distribution of bites. Results Nearly 60% of adults reported bites at low levels (1-5 bites); however, the majority were not in their resident municipality. We found two spatial profiles: In their home municipalities, people were most often bitten in less, but not the least, urbanized areas. When visiting other municipalities, people were most frequently bitten in peri-urban areas. Running/walking in the forest, gardening, and paddling/rowing were activities most strongly associated with bites. Conclusion Tick bites affect the entire Scandinavian population, with a higher risk in Sweden compared to Denmark and Norway. The frequency of observation of ticks in the environment or on pets might be used as a proxy for the actual risk of exposure to tick bites. Our results indicates that urban-dwelling outdoor enthusiasts and inhabitants of rural areas must be equally targeted for prevention campaigns.

The distribution limit of the common tick, Ixodes ricinus, and some associated pathogens in north-western Europe

In north-western Europe, the common tick, Ixodes ricinus, is widely established, its distribution appears to be increasing and the spread of tick-borne diseases is of increasing concern. The project 'Flått i Nord' (Ticks in northern Norway) commenced in spring 2009 with the intention of studying the tick's distribution and that of its pathogens in northern Norway. Several methods were used: cloth-dragging, collecting from trapped small mammals, and collecting from pets. Since 2010, the occurrence of ticks in the region of northern Norway was determined directly by cloth-dragging 167 times in 109 separate locations between the latitudes of 64 °N and 70 °N (included seven locations in the northern part of Trøndelag County). The northernmost location of a permanent I. ricinus population was found to be Nordøyvågen (66.2204 °N, 12.59 °E) on the Island of Dønna. In a sample of 518 nymphal and adult ticks, the Borrelia prevalence collected close to this distribution limit varied but was low (1-15 %) compared with the locations in Trøndelag, south of the study area (15-27 %). Five specimens (1 %) were positive for Rickettsia helvetica. The length of the vegetation growing season (GSL) can be used as an approximate index for the presence of established populations of I. ricinus. The present study suggests that the threshold GSL for tick establishment is about 170 days, because the median GSL from 1991 to 2015 was 174-184 days at sites with permanent tick populations, showing a clear increase compared with the period 1961-1990. This apparent manifestation of climate change could explain the northward extension of the range of I. ricinus.

Cervids as sentinel-species for tick-borne encephalitis virus in Norway - A serological study

Tick-borne encephalitis virus (TBEV) is the causative agent of tick-borne encephalitis (TBE). TBEV is one of the most important neurological pathogens transmitted by tick bites in Europe. The objectives of this study were to investigate the seroprevalence of TBE antibodies in cervids in Norway and the possible emergence of new foci, and furthermore to evaluate if cervids can function as sentinel animals for the distribution of TBEV in the country. Serum samples from 286 moose, 148 roe deer, 140 red deer and 83 reindeer from all over Norway were collected and screened for TBE immunoglobulin G (IgG) antibodies with a modified commercial enzyme-linked immunosorbent assay (ELISA) and confirmed by TBEV serum neutralisation test (SNT). The overall seroprevalence against the TBEV complex in the cervid specimens from Norway was 4.6%. The highest number of seropositive cervids was found in south-eastern Norway, but seropositive cervids were also detected in southern- and central Norway. Antibodies against TBEV detected by SNT were present in 9.4% of the moose samples, 1.4% in red deer, 0.7% in roe deer, and nil in reindeer. The majority of the positive samples in our study originated from areas where human cases of TBE have been reported in Norway. The study is the first comprehensive screening of cervid species in Norway for antibodies to TBEV, and shows that cervids are useful sentinel animals to indicate TBEV occurrence, as supplement to studies in ticks. Furthermore, the results indicate that TBEV might be spreading northwards in Norway. This information may be of relevance for public health considerations and supports previous findings of TBEV in ticks in Norway.

Predicting the spatial abundance of Ixodes ricinus ticks in southern Scandinavia using environmental and climatic data

Recently, focus on tick-borne diseases has increased as ticks and their pathogens have become widespread and represent a health problem in Europe. Understanding the epidemiology of tick-borne infections requires the ability to predict and map tick abundance. We measured Ixodes ricinus abundance at 159 sites in southern Scandinavia from August-September, 2016. We used field data and environmental variables to develop predictive abundance models using machine learning algorithms, and also tested these models on 2017 data. Larva and nymph abundance models had relatively high predictive power (normalized RMSE from 0.65–0.69, R² from 0.52–0.58) whereas adult tick models performed poorly (normalized RMSE from 0.94–0.96, R² from 0.04–0.10). Testing the models on 2017 data produced good results with normalized RMSE values from 0.59–1.13 and R² from 0.18–0.69. The resulting 2016 maps corresponded well with known tick abundance and distribution in Scandinavia. The models were highly influenced by temperature and vegetation, indicating that climate may be an important driver of I. ricinus distribution and abundance in Scandinavia. Despite varying results, the models predicted abundance in 2017 with high accuracy. The models are a first step towards environmentally driven tick abundance models that can assist in determining risk areas and interpreting human incidence data.

First evidence of Ixodiphagus hookeri (Hymenoptera: Encyrtidae) parasitization in Finnish castor bean ticks (Ixodes ricinus)

Ixodiphagus hookeri (Hymenoptera: Encyrtidae) is a parasitoid wasp specialized in parasitizing the larvae and nymphs of ticks (Acari: Ixodidae). As parasitized ticks die prior to reproduction, I. hookeri is seen as a prime biological control agent candidate. Despite this, little is known of their occurrence or ecology in northern Europe. The main aim of the current study was to determine whether adult wasps or parasitized ticks can be found from a tick-infested island in southwestern Finland, using field collections and molecular methods. Following the initial discovery of an adult I. hookeri female on Seili Island, we set out to collect further specimens via sweep netting and Malaise trappings between May and October 2017. Furthermore, 1310 Ixodes ricinus (1220 nymphs, 90 adults) collected from the island during 2012-2014 were screened for I. hookeri DNA using qPCR. Whereas no further wasp specimens could be collected via sweep netting or Malaise trappings, I. hookeri DNA was consistently detected in I. ricinus nymphs (annual minimum infection rates in 2012, 2013, and 2014: 2.3, 0.4, and 0.5%, respectively), whereas all adult samples were negative. Although the annually repeated detections of parasitized ticks suggest that the wasp inhabits the island, further field and molecular surveys are needed to more comprehensively determine the status and stability of the population.

Detection of Candidatus Neoehrlichia mikurensis in Norway up to the northern limit of Ixodes ricinus distribution using a novel real time PCR test targeting the groEL gene

BACKGROUND

Candidatus Neoehrlichia mikurensis is an emerging tick-borne pathogen. It is widely distributed in Ixodes ricinus ticks in Europe, but knowledge of its distribution in Norway, where I. ricinus reaches its northern limit, is limited. In this study we have developed a real time PCR test for Ca. N. mikurensis and used it to investigate the distribution of Ca. N. mikurensis in Norway.

RESULTS

Real time PCR targeting the groEL gene was developed and shown to be highly sensitive. It was used to detect Ca. N. mikurensis in 1651 I. ricinus nymphs and adults collected from twelve locations in Norway, from the eastern Oslo Fjord in the south to near the Arctic Circle in the north. The overall prevalence was 6.5% and varied locally between 0 and 16%. Prevalence in adults and nymphs was similar, suggesting that ticks acquire Ca. N. mikurensis predominantly during their first blood meal. In addition, 123 larvae were investigated; Ca. N. mikurensis was not found in larvae, suggesting that transovarial transmission is rare or absent. Sequence analysis suggests that a single variant dominates in Norway.

CONCLUSIONS

Ca. N. mikurensis is widespread and common in ticks in Norway and reaches up to their northern limit near the Arctic Circle. Ticks appear to acquire Ca. N. mikurensis during their first blood meal. No evidence for transovarial transmission was found.

Long-term dynamics of Ixodes persulcatus (Acari: Ixodidae) abundance in the north-west of its range (Karelia, Russia)

The article presents the results of long-term observations of variations in the abundance of Ixodes persulcatus, carried out since 1982, in the middle taiga subzone of Karelia. Adult questing ticks were collected from vegetation following standard flagging procedures. The time series was evaluated by singular spectrum analysis. Correlation coefficients were calculated for the observed tick abundances and meteorological data (mean daily air temperature and precipitation) for the current year and preceding years. Analysis of the time series revealed the trend and harmonic components with periods of 8, 2.5 and 4 years. Around 83% of the total variance is explained by the first principal component, which governs the general vector of change-a gradual reduction in I. persulcatus abundance from 2003 to 2017. Correlations between tick abundance and climatic indices were observed in all years and were associated with both temperature and precipitation. The greatest number of significant coefficients was obtained for correlations between tick abundance and weather conditions in the preceding season. An equation was suggested where tick abundance is described by a linear function with four variables: mean air temperature in April and July, total precipitation in February, and annual number of days with temperatures above 5 °С. Thus, the observed long-term dynamics are characterized by the following key patterns: a sharp population rise early in the 2000s, some recent decline (stabilization) of the abundance, the presence of quasi-periodic cycles, and a close correlation between tick abundance and climatic variables.

"Candidatus Neoehrlichia mikurensis" in Ixodes ricinus ticks collected near the Arctic Circle in Norway

BACKGROUND

"Candidatus Neoehrlichia mikurensis" is a gram-negative bacterium belonging to the family Anaplasmataceae that, in Europe, is transmitted by Ixodes ricinus ticks. "Candidatus N. mikurensis" can cause a severe systemic inflammatory syndrome, neoehrlichiosis, mostly in persons with other underlying diseases. To date, "Ca. N. mikurensis" has been found in ticks in different countries in Asia and Europe, but never as far north as at the Arctic Circle.

METHODS

A total of 1104 I. ricinus ticks collected from vegetation and from animals in northern Norway (64-68°N) were analysed for the prevalence of "Ca. N. mikurensis". Of them, 495 ticks were collected from vegetation by flagging and 609 ticks were collected from dogs and cats. Total nucleic acid extracted from the ticks were converted to cDNA and analyzed with real-time PCR targeting the 16S rRNA gene of "Ca. N. mikurensis". Positive samples were further analysed by nested PCR and sequencing.

RESULTS

"Candidatus N. mikurensis" was detected in 11.2% of all collected I. ricinus ticks in northern Norway. The prevalence differed between ticks collected from vegetation (18.2%; 90/495) compared to ticks collected from dogs and cats (5.6%; 34/609). The ticks from dogs and cats were collected in Brønnøy area and seven additional districts further north. The prevalence of "Ca. N. mikurensis" in these ticks differed between geographical localities, with the highest prevalence in the Brønnøy area.

CONCLUSIONS

The detection of "Ca. N. mikurensis" in I. ricinus ticks from the Arctic Circle in northern Norway indicates potential risk for tick-bitten humans at this latitude to be infected with "Ca. N. mikurensis".

Emergence of tick-borne diseases at northern latitudes in Europe: a comparative approach

The factors that drive the emergence of vector-borne diseases are difficult to identify due to the complexity of the pathogen-vector-host triad. We used a novel comparative approach to analyse four long-term datasets (1995-2015) on the incidence of tick-borne diseases in humans and livestock (Lyme disease, anaplasmosis and babesiosis) over a geographic area that covered the whole of Norway. This approach allowed us to separate general (shared vector) and specific (pathogen reservoir host) limiting factors of tick-borne diseases, as well as the role of exposure (shared and non-shared pathogens in different hosts). We found broadly similar patterns of emergence across the four tick-borne diseases. Following initial increases during the first decade of the time series, the numbers of cases peaked at slightly different years and then stabilized or declined in the most recent years. Contrasting spatial patterns of disease incidence were consistent with exposure to ticks being an important factor influencing disease incidence in livestock. Uncertainty regarding the reservoir host(s) of the pathogens causing anaplasmosis and babesiosis prevented a firm conclusion regarding the role of the reservoir host-pathogen distribution. Our study shows that the emergence of tick-borne diseases at northern latitudes is linked to the shared tick vector and that variation in host-pathogen distribution and exposure causes considerable variation in emergence.

First evidence of established populations of the taiga tick Ixodes persulcatus (Acari: Ixodidae) in Sweden

Background

The tick species Ixodes ricinus and I. persulcatus are of exceptional medical importance in the western and eastern parts, respectively, of the Palaearctic region. In Russia and Finland the range of I. persulcatus has recently increased. In Finland the first records of I. persulcatus are from 2004. The apparent expansion of its range in Finland prompted us to investigate if I. persulcatus also occurs in Sweden.

Methods

Dog owners and hunters in the coastal areas of northern Sweden provided information about localities where ticks could be present. In May-August 2015 we used the cloth-dragging method in 36 localities potentially harbouring ticks in the Bothnian Bay area, province Norrbotten (NB) of northern Sweden. Further to the south in the provinces Västerbotten (VB) and Uppland (UP) eight localities were similarly investigated.

Results

Ixodes persulcatus was detected in 9 of 36 field localities in the Bothnian Bay area. Nymphs, adult males and adult females (n = 46 ticks) of I. persulcatus were present mainly in Alnus incana - Sorbus aucuparia - Picea abies - Pinus sylvestris vegetation communities on islands in the Bothnian Bay. Some of these I. persulcatus populations seem to be the most northerly populations so far recorded of this species. Dog owners asserted that their dogs became tick-infested on these islands for the first time 7–8 years ago. Moose (Alces alces), hares (Lepus timidus), domestic dogs (Canis lupus familiaris) and ground-feeding birds are the most likely carriers dispersing I. persulcatus in this area. All ticks (n = 124) from the more southern provinces of VB and UP were identified as I. ricinus.

Conclusions

The geographical range of the taiga tick has recently expanded into northern Sweden. Increased information about prophylactic, anti-tick measures should be directed to people living in or visiting the coastal areas and islands of the Baltic Bay.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-016-1658-3) contains supplementary material, which is available to authorized users.

Ticks and associated pathogens collected from cats in Sicily and Calabria (Italy)

Background

Limited information is available about the species of ticks infesting the cat and the pathogens that they harbor. The aims of the present study were to identify the species of ticks removed from cats living in Sicily and Calabria (Italy) and to detect DNA of vector-borne pathogens in the same ticks.

Findings

Morphological identification of 132 adult ticks collected throughout the year from cats was carried out. Real-time PCRs for Hepatozoon felis, Piroplasmid, Ehrlichia/Anaplasma spp., Rickettsia spp., Bartonella spp., Mycoplasma spp. and Leishmania infantum were performed from each individual tick.

Ticks belonging to Rhipicephalus (R. sanguineus sensu lato, R. pusillus) and Ixodes (I. ricinus, I. ventalloi) genera were identified. Ixodes ventalloi was the most frequently found tick species (47 %).

The positivity rate to at least one pathogen was 14.4 % (19/132 ticks). Leishmania infantum, Rickettsia spp. (R. monacensis and R. helvetica), Bartonella spp. (B. clarridgeiae), Piroplasmid (Babesia vogeli), and Ehrlichia/Anaplasma spp. (E. canis) DNAs were amplified in 8.3, 5.3, 1.5, 0.75 and 0.75 % of ticks, respectively. Hepatozoon felis, Anaplasma spp. and hemotropic Mycoplasma spp. DNAs were not detected. Four (21.1 %) out of nineteen positive ticks were co-infected.

Conclusions

This study provides novel data about ticks infesting cats and the DNA of pathogens that they harbor. In Southern Italy, anti-tick prophylaxis should be implemented throughout the year in cats without neglecting winter time.

Detection of Anaplasma phagocytophilum in Ixodes ricinus ticks from Norway using a realtime PCR assay targeting the Anaplasma citrate synthase gene gltA

Background

A TaqMan real-time PCR assay targeting the Anaplasma citrate synthase gene, gltA, was developed and used for detection of Anaplasma phagocytophilum in 765 Ixodes ricinus ticks collected from dogs and cats in northern Norway (n = 669) and Telemark county in southern Norway (n = 96).

Results

Among the ticks from northern Norway the prevalence of A. phagocytophilum was 3.0 %, while the prevalence in southern Norway was 2.1 % (p = 0.63). The gltA PCR assay showed a high analytical sensitivity (30 genomic units) and efficiency (98.5 %), and its utility in clinical diagnostics should be evaluated in future studies.

Conclusion

This is the first report of A. phagocytophilum occurrence in ticks collected north of the Arctic Circle in Norway. The prevalence is comparable to that found in Telemark county in southern Norway.

Comparison of Two Commercial Tick-Borne Encephalitis Virus IgG Enzyme-Linked Immunosorbent Assays

Despite the availability of protective vaccines, tick-borne encephalitis virus (TBEV) infections have been increasingly reported to the European Centre for Disease Prevention and Control in the past 2 decades. Since the diagnosis of TBEV exposure relies on serological testing, we compared two commercial enzyme-linked immunosorbent assays (ELISAs), i.e., Immunozym FSME IgG assay (ELISA-1) and Euroimmun FSME Vienna IgG assay (ELISA-2). Both assays use whole TBEV antigens, but they differ in viral strains (Neudoerfl for ELISA-1 and K23 for ELISA-2) and cutoff values. In testing of samples from 398 healthy blood donors, ELISA-1 showed higher reactivity levels than ELISA-2 (P < 0.001), suggesting different assay properties. This finding was supported by Bland-Altman analysis of the optical density at 450 nm (OD450) (mean bias, +0.32 [95% limits of agreement, -0.31 to +0.95]) and persisted after transformation into Vienna units. Concordant results were observed for 276 sera (69%) (44 positive and 232 negative results). Discordant results were observed for 122 sera (31%); 15 were fully discordant, all being ELISA-1 positive and ELISA-2 negative, and 107 were partially discordant (101 being ELISA-1 indeterminate and ELISA-2 negative and 6 having positive or indeterminate reactivity in both ELISAs). Neutralization testing at a 1:10 dilution yielded positive results for 33 of 44 concordant positive sera, 1 of 15 fully discordant sera, and 1 of 33 partially discordant sera. Indirect immunofluorescence testing revealed high antibody titers of ≥100 for yellow fever virus in 18 cases and for dengue virus in one case, suggesting that cross-reactivity contributed to the ELISA-1 results. We conclude that (i) cross-reactivity among flaviviruses remains a limitation of TBEV serological testing, (ii) ELISA-2 revealed reasonable sensitivity and specificity for anti-TBEV IgG population screening of human sera, and (iii) neutralization testing is most specific and should be reserved for selective questions.

Evaluation of microbial communities and symbionts in Ixodes ricinus and ungulate hosts (Cervus elaphus and Ovis aries) from shared habitats on the west coast of Norway

Recent reports suggest a potential for transmission of a newly discovered rickettsial endosymbiont, Midichloria mitochondrii, to animals and humans from feeding ticks (Ixodes ricinus). Using molecular methods; I. ricinus, sheep and red deer in Anaplasma phagocytophilum-endemic areas of Norway, were examined to see if they were infected by M. mitochondrii or related organisms like Wolbachia pipientis and Rickettsia spp. A total of 532 ticks collected from pastures, 76 blood samples from grazing lambs and 12 organ samples from hunted deer, were analyzed during the study. All larval pools, 60.4% pooled nymphs and 35.1% of adult ticks were positive for M. mitochondrii. There was a significant difference between geographical areas in the prevalence of M. mitochondrii infection among nymphs. A total of 2.2% pooled nymphs and 5.3% adult ticks were positive for A. phagocytophilum. Eleven percent of pooled nymphs were positive for Borrelia spp, 2.2% of pooled nymphs and 3.5% of adult ticks were positive for Rickettsia spp. and none of the ticks were positive for W. pipientis. The prevalence of A. phagocytophilum infection was 54% and 75% in grazing lambs and deer, respectively. No animals were positive for Borrelia spp., M. mitochondrii, Rickettsia spp. or W. pipientis. The reported findings suggest that M. mitochondrii is widespread in tick populations at different geographical sites, and may appear in co-infection with A. phagocytophilum, Borrelia spp. and Rickettsia spp. in ticks.