Prevalence and diversity of Borrelia species in ticks that have bitten humans in Sweden

Coinfection of Babesia and Borrelia in the Tick Ixodes ricinus-A Neglected Public Health Issue in Europe?

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.

Analysis of macerated ticks using Boolean logic gating colorimetric isothermal nucleic acid assays for Lyme Borrelia and Ixodes scapularis ticks

Lyme disease, one of the most common tickborne diseases, has been rapidly spreading in parallel with the expansion of the range of its tick vector. Better tick surveillance efforts are needed to accurately estimate disease risk and to guide public health and clinical management. We have developed two multiplex loop-mediated isothermal amplification (LAMP) reactions coupled with oligonucleotide strand displacement (OSD) probes to identify the tick host, Ixodes scapularis, and the Lyme disease pathogen, Borrelia burgdorferi, they carry. In each multiplex LAMP-OSD assay the co-presence of two target sequences is computed at the DNA level by linking the two corresponding amplicons and detecting the co-product on colorimetric lateral flow dipsticks. In tests with synthetic DNA, the co-presence of as few as four copies of input DNA could be detected, without producing spurious signals. Most importantly, though, the LAMP-OSD assay is amenable to being carried out directly with macerated tick samples, without any sample preparation. In such field conditions, assays performed robustly and demonstrated 97-100% sensitivity and 100% specificity with both field-collected and lab-raised artificially infected ticks. Such easy-to-use, arthropod and pathogen-specific assays would be well suited to field and near patient use without relying on complex instrumentation or infrastructure.

First molecular confirmation of multiple zoonotic vector-borne diseases in pet dogs and cats of Hong Kong SAR

In recent years, the incidence of vector-borne diseases (VBDs) has increased throughout the globe. In particular, tick-borne diseases (e.g., caused by Ehrlichia canis, E. ewingii, Anaplasma phagocytophilum, A. platys, Borrelia burgdorferi sensu stricto (s.s.) and Babesia gibsoni) and mosquito-borne diseases (e.g., caused by Dirofilaria immitis) diseases pose a burden on animal health. Nevertheless, there have been no studies undertaken on the occurrence of VBDs in pet dogs and cats in Hong Kong SAR. This study fills this gap, and is the first to determine the seroprevalence of major VBDs, such as those caused by D. immitis, E. canis, E. ewingii, A. phagocytophilum, A. platys and B. burgdorferi s.s, in dogs and cats through commercially available SNAP 4Dx plus testing. Infection by all these pathogens and Babesia sp. was further assessed through PCR and DNA sequencing. A total of 224 blood samples were collected from domestic dogs (n = 159) and cats (n = 65) in Hong Kong SAR during summer 2022. Hematocrit and platelet counts were determined in each blood sample and other hematological parameters were assessed using an automatic hematology analyzer and vortex the specimen for one to two minutes at or near the highest setting to minimize the clumping. All cat sera samples were negative for tested pathogens, but antibodies against some of the pathogens were detected in dog sera samples. Here, the highest figures were recorded for seroprevalence of E. canis/E. ewingii (10.7%), followed by D. immitis (5.7%), and A. phagocytophilum/A. platys (2.5%). No B. burgdorferi s.s. antibodies were detected in any of the dogs tested. Through molecular diagnostics, we detected the presence of B. gibsoni (3.7%), E. canis (3.1%), D. immitis (5.7%), and A. phagocytophilum (1.3%). Neighbor-Joining phylogenetic trees for vector-borne pathogens (i.e., genus Anaplasma sp.) showed 100% clustering to Japan, the USA and Germany, whereas genus Ehrlichia sp. showed 100% clustering to China, Turkey, Cuba, and Greece. Similarly, genus Babesia sp. clustered 100% to India, Sri Lanka and Austria, while D. immitis clustered in Iraq, South Korea, Portugal, France, the USA and Italy. This study provides the first evidence on the occurrence of tick-borne pathogens in pet dogs in Hong Kong SAR. Based on these findings, it is recommended that appropriate screening should be undertaken in domestic dogs to evaluate the prevalence of these pathogens and promote the timely control of VBDs.

The AxBioTick Study: Borrelia Species and Tick-Borne Encephalitis Virus in Ticks, and Clinical Responses in Tick-Bitten Individuals on the Aland Islands, Finland

The AxBioTick study was initiated to investigate the prevalence of ticks and tick-borne pathogens and their impact on antibody and clinical responses in tick-bitten individuals on the Aland Islands. This geographical area is hyperendemic for both Lyme borreliosis (LB) and Tick-borne encephalitis (TBE). Blood samples and ticks were collected from 100 tick-bitten volunteers. A total of 425 ticks was collected, all determined to Ixodes ricinus using molecular tools. Of them 20% contained Borrelia species, of which B. garinii and B. afzelii were most common. None contained the TBE virus (TBEV). Blood samples were drawn in conjunction with the tick bite, and eight weeks later. Sera were analyzed for Borrelia- and TBEV-specific antibodies using an ELISA and a semiquantitative antibody assay. In total 14% seroconverted in Borrelia C6IgG1, 3% in TBEV IgG, and 2% in TBEV IgM. Five participants developed clinical manifestations of LB. The high seroprevalence of both Borrelia (57%) and TBEV (52%) antibodies are likely attributed to the endemic status of the corresponding infections as well as the TBE vaccination program. Despite the similar prevalence of Borrelia spp. detected in ticks in other parts of Europe, the infection rate in this population is high. The AxBioTick study is continuing to investigate more participants and ticks for co-infections, and to characterize the dermal immune response following a tick bite.

Lyme Neuroborreliosis—Significant Local Variations in Incidence within a Highly Endemic Region in Sweden

The aim of this study was to perform a detailed epidemiological overview of Lyme neuroborreliosis (LNB) 2008–2021 in a highly Lyme borreliosis-endemic area in Sweden using a geographic information system (GIS). Diagnosis of LNB was based on clinical symptoms and analysis of cerebrospinal fluid (CSF) according to European guidelines. From laboratory databases and medical records, we detected all patients with CSF pleocytosis and intrathecal anti-Borrelia antibody production and listed clinical features. The distribution of LNB cases within Kalmar County, Sweden was investigated using GIS. In total, 272 cases of definite LNB were confirmed with an average yearly incidence of 7.8/100,000. Significant differences in incidence were noted between children 0–17 years (16/100,000) and adults 18+ years (5.8/100,000) (p < 0.001), between rural (16/100,000) and urban areas (5.8/100,000) (p < 0.001) and between selected municipalities (p < 0.001). Distinct clinical differences in presentation of LNB were also noted between children and adults. Thus, the incidence of LNB varies significantly locally and in relation to age, and clinical presentation shows differences between children and adults. Surveillance of LNB and knowledge of local epidemiological conditions may facilitate preventive measures.

Epizootiological aspects of natural nidality of Ixodes tick-borne borreliosis in the Moscow region (Russian Federation)

Background and Aim:

At present, tick-borne borreliosis is the most common infectious disease transmitted by ticks in Europe, Asia, and North America. This study aimed to examine the epizootiological aspects of the natural nidality of tick-borne borreliosis in Moscow region (the Russian Federation).

Materials and Methods:

A total of 2,537 ticks representing two species were collected, namely, Ixodes ricinus and Dermacentor reticulatus. The activity, number of ticks, and Borrelia infestation rates were investigated during a high season, that is, from early spring to mid-autumn.

Results:

In May, amount of I. ricinus spp. was found 2.5 times more than those representing D. reticulatus spp. (p≤0.01). In June, August, and September, the amount of I. ricinus was 9.0 (p≤0.0001), 2.0 (p≤0.05), and 5.0 times higher, respectively, compared to D. reticulatus. In the first 10 days of April, the amount of D. reticulatus was 3 times higher than that of I. ricinus (p≤0.02); in the next 10 days, their amounts were equal (p≥0.05) and in the last 10 days the amount of I. ricinus exceeded that of D. reticulatus (p≤0.05) by 1.5 times. In general, Borrelia afzelii, and Borrelia garinii, were detected. In addition, the naturally occurring tick-borne borreliosis pesthole was revealed in the Moscow region.

Conclusion:

Borrelia infection rates for ticks comprise 30%. An increase in Borrelia tick infestation was detected within the vicinity of populated areas. The amount of ticks directly depends on the temperature (20°C-25°C) and moisture (from 50%) values.

Establishment of Amblyomma americanum populations and new records of Borrelia burgdorferi-infected Ixodes scapularis in South Dakota

Tick-borne diseases are an emerging public health threat in the United States, but surveillance is lacking in some regions. To advance current knowledge of the ecology of ticks and tick-borne diseases in South Dakota, we conducted a survey in the summer of 2019, focusing on the eastern counties of the state. We collected and identified 266 ticks and a subset were tested for the presence of Borrelia burgdorferi by polymerase chain reaction (PCR). Dermacentor variabilis, a ubiquitous species in the state, was the most commonly identified tick, present in all counties surveyed. However, we also identified 15 Amblyomma americanum from three different locations, providing the first evidence of established populations in the state and expanding the range of this species. In addition, we identified 22 Ixodes scapularis from five different locations, confirming a previous report of an established population in the state. Two adult I. scapularis from two different sites were found to harbor B. burgdorferi, including an individual from Lincoln County, suggesting the ongoing presence of the pathogen in tick populations in the state and representing its southwestern-most detection in the midwest United States. These findings provide important information for assessing and monitoring the public health risk from tick-borne diseases in an area where surveillance is lacking.

The raccoon dog (Nyctereutes procyonoides) as a reservoir of zoonotic diseases in Denmark

Raccoon dogs have successfully invaded Europe, including Denmark. Raccoon dogs are potential vectors and reservoir hosts of several zoonotic pathogens and thus have the potential for posing a threat to both human and animal health. This study includes analysis of four zoonotic parasites, 16 tick-borne pathogens and two pathogen groups from 292 raccoon dogs collected from January 2018 to December 2018. The raccoon dogs were received as a part of the Danish national wildlife surveillance program and were hunted, found dead or road killed. The raccoon dogs were screened for Alaria alata and Echinococcus multilocularis eggs in faeces by microscopy and PCR, respectively, Trichinella spp. larvae in muscles by digestion, antibodies against Toxoplasma gondii by ELISA and screening of ticks for pathogens by fluidigm real-time PCR. All raccoon dogs tested negative for E. multilocularis and Trichinella spp., while 32.9% excreted A. alata eggs and 42.7% were T. gondii sero-positive. Five tick-borne pathogens were identified in ticks collected from 15 raccoon dogs, namely Anaplasma phagocytophilum (20.0%), Babesia venatorum (6.7%), Borrelia miyamotoi (6.7%), Neoehrlichia mikurensis (6.7%) and Rickettsia helvetica (60.0%). We identified raccoon dogs from Denmark as an important reservoir of T. gondii and A. alata infection to other hosts, including humans, while raccoon dogs appear as a negligible reservoir of E. multilocularis and Trichinella spp. infections. Our results suggest that raccoon dogs may be a reservoir of A. phagocytophilum.

Laboratory Methods for Detection of Infectious Agents and Serological Response in Humans With Tick-Borne Infections: A Systematic Review of Evaluations Based on Clinical Patient Samples

Background: For the most important and well-known infections spread by Ixodes ticks, Lyme borreliosis (LB) and tick-borne encephalitis (TBE), there are recommendations for diagnosis and management available from several health authorities and professional medical networks. However, other tick-borne microorganisms with potential to cause human disease are less known and clear recommendations on diagnosis and management are scarce. Therefore, we performed a systematic review of published studies and reviews focusing on evaluation of laboratory methods for clinical diagnosis of human tick-borne diseases (TBDs), other than acute LB and TBE. The specific aim was to evaluate the scientific support for laboratory diagnosis of human granulocytic anaplasmosis, rickettsiosis, neoehrlichiosis, babesiosis, hard tick relapsing fever, tularemia and bartonellosis, as well as tick-borne co-infections and persistent LB in spite of recommended standard antibiotic treatment.

Methods: We performed a systematic literature search in 11 databases for research published from 2007 through 2017, and categorized potentially relevant references according to the predefined infections and study design. An expert group assessed the relevance and eligibility and reviewed the articles according to the QUADAS (diagnostic studies) or AMSTAR (systematic reviews) protocols, respectively. Clinical evaluations of one or several diagnostic tests and systematic reviews were included. Case reports, non-human studies and articles published in other languages than English were excluded.

Results: A total of 48 studies fulfilled the inclusion criteria for evaluation. The majority of these studies were based on small sample sizes. There were no eligible studies for evaluation of tick-borne co-infections or for persistent LB after antibiotic treatment.

Conclusions: Our findings highlight the need for larger evaluations of laboratory tests using clinical samples from well-defined cases taken at different time-points during the course of the diseases. Since the diseases occur at a relatively low frequency, single-center cross-sectional studies are practically not feasible, but multi-center case control studies could be a way forward.

Long-term study of Borrelia and Babesia prevalence and co-infection in Ixodes ricinus and Dermacentor recticulatus ticks removed from humans in Poland, 2016-2019

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.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04849-5.

Human Borrelia miyamotoi Infection, Austria

We report a human case of Borrelia miyamotoi infection diagnosed in Austria. Spirochetes were detected in Giemsa-stained blood smears. The presence of B. miyamotoi in the patient’s blood was confirmed by PCR, and phylogenetic analysis identified an infection with a strain from Europe.

Are other tick-borne infections overlooked in patients investigated for Lyme neuroborreliosis? A large retrospective study from South-eastern Sweden

In Europe, the hard tick Ixodes ricinus is considered the most important vector of human zoonotic diseases. Human pathogenic agents spread by I. ricinus in Sweden include Borrelia burgdorferi sensu lato (s.l.), Anaplasma phagocytophilum, Rickettsia helvetica, the recently described Neoehrlichia mikurensis, Borrelia miyamotoi, tick-borne encephalitis virus (TBEV), and Babesia spp. (Babesia microti, Babesia venatorum and Babesia divergens). Since these pathogens share the same vector, co-infections with more than one tick-borne pathogen may occur and thus complicate the diagnosis and clinical management of the patient due to possibly altered symptomatology. Borrelia burgdorferi s.l., TBEV and B. miyamotoi are well-known to cause infections of the central nervous system (CNS), whereas the abilities of other tick-borne pathogens to invade the CNS are largely unknown. The aim of this study was to investigate the presence and clinical impact of tick-borne pathogens other than B. burgdorferi s.l. in the cerebrospinal fluid (CSF) and serum samples of patients who were under investigation for Lyme neuroborreliosis (LNB) in a tick-endemic region of South-eastern Sweden. CSF and serum samples from 600 patients, recruited from the Regions of Östergötland County, Jönköping County and Kalmar County in South-eastern Sweden and investigated for LNB during the period of 2009-2013, were retrospectively collected for analysis. The samples were analysed by real-time PCR for the presence of nucleic acid from B. burgdorferi s.l., B. miyamotoi, A. phagocytophilum, Rickettsia spp., N. mikurensis, TBEV and Babesia spp. Serological analyses were conducted in CSF and serum samples for all patients regarding B. burgdorferi s.l., and for the patients with CSF mononuclear pleocytosis, analyses of antibodies to B. miyamotoi, A. phagocytophilum, spotted fever group (SFG) rickettsiae, TBEV and B. microti in serum were performed. The medical charts of all the patients with CSF mononuclear pleocytosis and patients with positive PCR findings were reviewed. Of the 600 patients, 55 (9%) presented with CSF mononuclear pleocytosis, 13 (2%) of whom had Borrelia-specific antibodies in the CSF. One patient was PCR-positive for N. mikurensis, and another one was PCR-positive for Borrelia spp. in serum. No pathogens were detected by PCR in the CSF samples. Four patients had serum antibodies to B. miyamotoi, four patients to A. phagocytophilum, five patients to SFG rickettsiae, and six patients to TBEV. One patient, with antibodies to SFG rickettsiae, had both clinical and laboratory signs suggestive of a current infection. Nine patients had serum antibodies to more than one pathogen, although none of these was assessed as a current co-infection. We can conclude from this study that tick-borne co-infections are uncommon in patients who are being investigated for suspected LNB in South-eastern Sweden, an area endemic for borreliosis and TBE.

First Record of a Suspected Human-Pathogenic Borrelia Species in Populations of the Bat Tick Carios vespertilionis in Sweden

The bat tick Cariosvespertilionis has been reported from Sweden to occasionally feed on humans resulting in disease symptoms. The aim of this study was to investigate C. vespertilionis as a potential vector and reservoir of Borrelia species. In 2015 and 2018 in south-central Sweden, C. vespertilionis ticks were collected from a wooden bat box harboring Soprano pipistrelle bats, Pipistrellus pygmaeus. In addition, one C. vespertilionis tick found inside a house in southern Sweden in 2019 was collected. Ticks were screened for Borrelia spp. using a genus-specific quantitative PCR assay. The Borrelia species of the positive specimens were determined by conventional PCR followed by DNA sequencing and phylogenetic analyses. A total of 24% (22 of 92) of the analyzed C. vespertilionis ticks were Borrelia-positive. Phylogenetic analyses indicate that the bacteria belong to the relapsing fever group of borreliae; some of them appear to be identical with Borrelia sp. CPB1, a spirochete only found twice before-in the United Kingdom and in France. Our results also indicate a temporal and spatial distribution of this Borrelia species. Since C. vespertilionis occasionally bites humans, and since it exhibits a high prevalence of Borrelia bacteria, it is possible that it presents a risk of human disease. Further studies are needed to characterize Borrelia sp. CPB1 to determine if it is human-pathogenic and to determine if C. vespertilionis is a vector and/or reservoir of this agent.

Lyme neuroborreliosis in Swedish children-PCR as a complementary diagnostic method for detection of Borrelia burgdorferi sensu lato in cerebrospinal fluid

The aim of this study was to evaluate polymerase chain reaction (PCR) as a diagnostic method for the detection of Borrelia burgdorferi s.l. in CSF of Swedish children with LNB. This study was performed retrospectively on CSF and serum samples collected from children evaluated for LNB (n = 233) and controls with other specific neurological disorders (n = 59) in a Swedish Lyme endemic area. For anti-Borrelia antibody index, the IDEIA Lyme Neuroborreliosis kit (Oxoid) was used. Two in-house real-time PCR assays targeting the 16S rRNA gene were evaluated (TaqMan® and LUX™). Among patients classified as LNB cases (n = 102), five children (5%) were Borrelia PCR-positive in CSF with the TaqMan® assay. In the Non-LNB group (n = 131), one patient was Borrelia PCR positive with the TaqMan® assay. Among controls (n = 59), all CSF samples were PCR negative. When amplifying and sequencing ospA, we found B. garinii (n = 2), B. afzelii (n = 2), B. bavariensis (n = 1), and one untypable (n = 1). With the LUX™ technology, all CSF samples were PCR negative. The TaqMan® assay could detect only few cases (n = 6) of B. burgdorferi s.l. in CSF among children with LNB and the sensitivity was very low (5%). However, using larger CSF volumes and centrifugation of samples, the PCR technique could still be useful as a complementary diagnostic method when evaluating LNB. Furthermore, detection of spirochete DNA in clinical matrices, including CSF, is the method of choice for studying epidemiological aspects of LNB, a tick-borne emerging disease.

Migratory birds as disseminators of ticks and the tick-borne pathogens Borrelia bacteria and tick-borne encephalitis (TBE) virus: a seasonal study at Ottenby Bird Observatory in South-eastern Sweden

Background

Birds can act as reservoirs of tick-borne pathogens and can also disperse pathogen-containing ticks to both nearby and remote localities. The aims of this study were to estimate tick infestation patterns on migratory birds and the prevalence of different Borrelia species and tick-borne encephalitis virus (TBEV) in ticks removed from birds in south-eastern Sweden.

Methods

Ticks were collected from resident and migratory birds captured at the Ottenby Bird Observatory, Öland, Sweden, from March to November 2009. Ticks were molecularly identified to species, and morphologically to developmental stage, and the presence of Borrelia bacteria and TBEV was determined by quantitative real-time PCR.

Results

A total of 1339 ticks in the genera Haemaphysalis, Hyalomma, and Ixodes was recorded of which I. ricinus was the most abundant species. Important tick hosts were the European robin (Erithacus rubecula), Blackbird (Turdus merula), Tree pipit (Anthus trivialis), Eurasian wren (Troglodytes troglodytes), Common redstart (Phoenicurus phoenicurus), Willow warbler (Phylloscopus trochilus), and Common whitethroat (Sylvia communis). Borrelia bacteria were detected in 25% (285/1,124) of the detached ticks available for analysis. Seven Borrelia species (B. afzelii, B. burgdorferi (s.s.), B. garinii, B. lusitaniae, B. turdi, B. valaisiana, and B. miyamotoi) were identified. B. turdi was recorded for the first time in ticks in Sweden. The number of Borrelia cells per tick ranged from 2.0 × 10⁰ to 7.0 × 10⁵. B. miyamotoi-containing ticks contained a significantly higher median number of Borrelia cells than B. burgdorferi (s.l.)-containing ticks. B. garinii and B. miyamotoi were the most prevalent Borrelia species in tick larvae. Larvae of I. ricinus with B. garinii were removed from seven bird species, particularly S. communis and A. trivialis, which may suggest that the larvae had contracted the Borrelia bacteria from or via these birds. Also, a high percentage of tick larvae containing B. miyamotoi was removed from E. rubecula. All ticks were negative for TBEV.

Conclusions

The results corroborate the view that the contributions of birds to human disease are substantial, particularly as blood hosts for ticks and for their short-, medium-, and long-distance dispersal. Moreover, several ground-foraging bird species appear to be important for the maintenance and dispersal of Borrelia species. The absence of TBEV in the ticks conforms to other similar studies.

Spatial patterns of pathogen prevalence in questing Ixodes ricinus nymphs in southern Scandinavia, 2016

Tick-borne pathogens cause diseases in animals and humans, and tick-borne disease incidence is increasing in many parts of the world. There is a need to assess the distribution of tick-borne pathogens and identify potential risk areas. We collected 29,440 tick nymphs from 50 sites in Scandinavia from August to September, 2016. We tested ticks in a real-time PCR chip, screening for 19 vector-associated pathogens. We analysed spatial patterns, mapped the prevalence of each pathogen and used machine learning algorithms and environmental variables to develop predictive prevalence models. All 50 sites had a pool prevalence of at least 33% for one or more pathogens, the most prevalent being Borrelia afzelii, B. garinii, Rickettsia helvetica, Anaplasma phagocytophilum, and Neoehrlichia mikurensis. There were large differences in pathogen prevalence between sites, but we identified only limited geographical clustering. The prevalence models performed poorly, with only models for R. helvetica and N. mikurensis having moderate predictive power (normalized RMSE from 0.74-0.75, R2 from 0.43-0.48). The poor performance of the majority of our prevalence models suggest that the used environmental and climatic variables alone do not explain pathogen prevalence patterns in Scandinavia, although previously the same variables successfully predicted spatial patterns of ticks in the same area.

Lyme Borreliosis with Scalp Eschar Mimicking Rickettsial Infection, Austria

We report on a patient in Austria with scalp eschar and neck lymphadenopathy. Rickettsial etiology was excluded by culture, PCR, and serologic tests. Borrelia afzelii was identified from the eschar swab by PCR. Lyme borreliosis can mimic rickettsiosis; appropriate tests should be included in the diagnostic workup of patients with eschars.

Large-scale countrywide screening for tick-borne pathogens in field-collected ticks in Latvia during 2017-2019

Background

Tick-borne diseases are of substantial concern worldwide in both humans and animals. Several hard tick species are of medical and veterinary interest in Europe, and changes in the range of tick species can affect the spread of zoonotic pathogens. The aim of the present study was to map the current prevalence and distribution pattern of ticks and related tick-borne pathogens in Latvia, a Baltic state in northern Europe.

Methods

Nearly 4600 Ixodes ricinus, I. persulcatus and Dermacentor reticulatus tick samples were collected in all regions of Latvia during 2017–2019 and were screened by molecular methods to reveal the prevalence and distribution pattern of a wide spectrum of tick-borne pathogens.

Results

New localities of D. reticulatus occurrence were found in western and central Latvia, including the Riga region, indicating that the northern border of D. reticulatus in Europe has moved farther to the north. Among the analyzed ticks, 33.42% carried at least one tick-borne pathogen, and 5.55% of tick samples were positive for two or three pathogens. A higher overall prevalence of tick-borne pathogens was observed in I. ricinus (34.92%) and I. persulcatus (31.65%) than in D. reticulatus (24.2%). The molecular analysis revealed the presence of tick-borne encephalitis virus, Babesia spp., Borrelia spp., Anaplasma phagocytophilum and Rickettsia spp. Overall, 15 and 7 tick-borne pathogen species were detected in Ixodes spp. and D. reticulatus ticks, respectively. This is the first report of Borrelia miyamotoi in Latvian field-collected ticks.

Conclusions

This large-scale countrywide study provides a snapshot of the current distribution patterns of Ixodes and Dermacentor ticks in Latvia and gives us a reliable overview of tick-borne pathogens in Latvian field-collected ticks.

Two Cases of Borrelia miyamotoi Meningitis, Sweden, 2018

We report 2 human cases of Borrelia miyamotoi disease diagnosed in Sweden, including 1 case of meningitis in an apparently immunocompetent patient. The diagnoses were confirmed by 3 different independent PCR assays and DNA sequencing from cerebrospinal fluid, supplemented by serologic analyses.

A new Borrelia on the block: Borrelia miyamotoi - a human health risk?

Background

Borrelia miyamotoi clusters phylogenetically among relapsing fever borreliae, but is transmitted by hard ticks. Recent recognition as a human pathogen has intensified research into its ecology and pathogenic potential.

Aims

We aimed to provide a timely critical integrative evaluation of our knowledge on B. miyamotoi, to assess its public health relevance and guide future research.

Methods

This narrative review used peer-reviewed literature in English from January 1994 to December 2018.

Results

Borrelia miyamotoi occurs in the world’s northern hemisphere where it co-circulates with B. burgdorferi sensu lato, which causes Lyme disease. The two borreliae have overlapping vertebrate and tick hosts. While ticks serve as vectors for both species, they are also reservoirs for B. miyamotoi. Three B. miyamotoi genotypes are described, but further diversity is being recognised. The lack of sufficient cultivable isolates and vertebrate models compromise investigation of human infection and its consequences. Our understanding mainly originates from limited case series. In these, human infections mostly present as influenza-like illness, with relapsing fever in sporadic cases and neurological disease reported in immunocompromised patients. Unspecific clinical presentation, also occasionally resulting from Lyme- or other co-infections, complicates diagnosis, likely contributing to under-reporting. Diagnostics mainly employ PCR and serology. Borrelia miyamotoi infections are treated with antimicrobials according to regimes used for Lyme disease.

Conclusions

With co-infection of tick-borne pathogens being commonplace, diagnostic improvements remain important. Developing in vivo models might allow more insight into human pathogenesis. Continued ecological and human case studies are key to better epidemiological understanding, guiding intervention strategies.

Clinical/serological outcome in humans bitten by Babesia species positive Ixodes ricinus ticks in Sweden and on the Åland Islands

The risk of contracting babesiosis after a tick bite in Sweden and on the Åland Islands, Finland, is unknown. We investigated clinical and serological outcomes in people bitten by Ixodes ricinus ticks positive for Babesia species. Ticks, blood and questionnaires were obtained from study participants in Sweden and on the Åland Islands. Sixty-five of 2098 (3.1 %) ticks were positive by real-time PCR. Three Babesia species were detected, Babesia microti (n = 33), B. venatorum (n = 27) and B. capreoli (n = 5), the latter species not known to cause human infection. Half (46 %) of the Babesia PCR-positive ticks also contained Borrelia spp. Fifty-three participants bitten by a Babesia PCR-positive tick and a control group bitten by a Babesia PCR-negative tick were tested for B. microti IgG antibodies by IFA. The overall seroprevalence was 4.4 %, but there was no significant difference between the groups. None of the participants seroconverted and no participant with a Babesia PCR-positive tick sought medical care or reported symptoms suggestive of babesiosis. Given the prevalence of Babesia in I. ricinus ticks in southern Sweden and on the Åland Islands, babesiosis should be considered a possible diagnosis in symptomatic residents who seek medical care following tick exposure.

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.

Complement activation in individuals with previous subclinical Lyme borreliosis and patients with previous Lyme neuroborreliosis

Lyme borreliosis (LB) is caused by Borrelia burgdorferi and infection may lead to not only a large variety of clinical manifestations but also a subclinical outcome. The aim of the present study was to investigate if there is a constitutional difference in complement activation between individuals with previous subclinical Lyme borreliosis (SB) and patients previously diagnosed with Lyme neuroborreliosis (LNB).

Lepirudin plasma for activation studies was collected from 60 SB individuals and from 22 patients pre-diagnosed with LNB. The plasma was incubated with live Borrelia spirochetes of two strains (complement sensitive B. garinii Lu59 and complement resistant B. afzelii ACA1).

Complement factor C3 was measured in non-activated lepirudin plasma with immune-nephelometry and C3a and sC5b-9 generated during complement activation were measured by enzyme-linked immunosorbent assay.

We found that the complement sensitive Lu59 induced higher complement activation than the complement resistant ACA1 when measuring activation products C3a and sC5b-9 in SB and LNB patients, p < 0.0001. No significant difference was found between SB and LNB patients in systemic levels of C3. Furthermore, SB individuals generated a higher activation of C3 cleavage to C3a (C3a/C3 ratio) than LNB patients after activation with ACA1, p < 0.001, but no significant differences were found in response to Lu59. In conclusion, Lu59 induced higher complement activation than ACA1 and individuals with previous SB showed increased generation of C3a compared with patients with previous LNB. In our study population, this mechanism could lead to less elimination of spirochetes in LNB patients and thereby be a factor contributing to the clinical outcome.

Molecular detection of avian spirochete Borrelia anserina in Argas persicus ticks in Algeria

Argasid ticks are one of the most important poultry ectoparasites. They affect poultry directly through blood meal and indirectly through the transmission of pathogens essentially Borrelia anserina, agent of avian borreliosis, one of the most widespread poultry diseases in the world, and is of great economic importance. This study was conducted between April 2014 and March 2015 in the region of Ksar El Boukhari, Algeria, in order to investigate the presence of soft ticks in laying hen farms and to detect B. anserina bacteria using molecular tools. DNA was extracted and screened for the presence of Borrelia spp. DNA by real-time polymerase chain reaction (qPCR). Borrelia spp. screening was performed using primers and probe targeting the 16S rRNA gene. A total of 83 traditional laying hen farms were visited, of which 39 (46.98 %) were found infested with A. persicus tick. Molecular analysis revealed that 2/34 (5.88 %) of ticks were infected by B. anserina. None of the ticks tested were positive for Rickettsia spp., and Coxiella burnetii. These results constitute the first report in Algeria of A. persicus harboring B. anserina.

Borrelia prevalence and species distribution in ticks removed from humans in Germany, 2013-2017

Lyme borreliosis caused by spirochaetes of the Borrelia burgdorferi sensu lato (s.l.) complex is the most common tick-borne disease in Europe. In addition, the relapsing-fever spirochaete Borrelia miyamotoi, which has been associated with febrile illness and meningoencephalitis in immunocompromised persons, is present in Europe. This study investigated Borrelia prevalence and species distribution in ticks removed from humans and sent as diagnostic material to the Institute for Parasitology, University of Veterinary Medicine Hannover, in 2013-2017. A probe-based real-time PCR was carried out and Borrelia-positive samples were subjected to species determination by reverse line blot (RLB), including a B. miyamotoi-specific probe. The overall Borrelia-infection rate as determined by real-time PCR was 20.02 % (510/2547, 95 % CI: 18.48-21.63 %), with annual prevalences ranging from 17.17 % (90/524, 95 % CI: 14.04-20.68 %) in 2014 to 24.12 % (96/398, 95 % CI: 19.99-28.63 %) in 2015. In total, 271/475 (57.1 %) positive samples available for RLB were successfully differentiated. Borrelia afzelii was detected in 30.53 % of cases (145/475, 95 % CI: 26.41-34.89), followed by B. garinii/B. bavariensis (13.26 % [63/475], 95 % CI: 10.34-16.65). Borrelia valaisiana occurred in 5.89 % (28/475, 95 % CI: 3.95-8.41), B. spielmanii in 4.63 % (22/475, 95 % CI: 2.93-6.93), B. burgdorferi sensu stricto (s.s.)/B. carolinensis in 2.32 % (11/475, 95 % CI: 1.16-4.11), B. lusitaniae in 0.63 % (3/475, 95 % CI: 0.13-1.83) and B. bisettiae in 0.42 % (2/475, 95 % CI: 0.05-1.51) of positive ticks. Borrelia kurtenbachii was not detected, while B. miyamotoi was identified in 7.37 % (35/475, 95 % CI: 5.19-10.10) of real-time PCR-positive samples. Sanger sequencing of B. garinii/B. bavariensis-positive ticks revealed that the majority were B. garinii-infections (50/52 successfully amplified samples), while only 2 ticks were infected with B. bavariensis. Furthermore, 6/12 B. burgdorferi s.s./B. carolinensis-positive samples could be differentiated; all of them were identified as B. burgdorferi sensu stricto. Thirty-nine ticks (8.21 %, 95 % CI: 5.90-11.05) were coinfected with two different species. Comparison of the species distribution between ticks removed from humans in 2015 and questing ticks collected in the same year and the same area revealed a significantly higher B. afzelii-prevalence in diagnostic tick samples than in questing ticks, confirming previous observations. The obtained data indicate that Borrelia prevalence fluctuated in the same range as observed in a previous study, analysing the period from 2006 to 2012. Detection of B. miyamotoi in 7.37 % of Borrelia-positive samples points to the fact that clinicians should be aware of this pathogen as a differential diagnosis in cases of febrile illness.

First records of tick-borne pathogens in populations of the taiga tick Ixodes persulcatus in Sweden

Background

The common tick Ixodes ricinus and the taiga tick I. persulcatus are the main tick vectors of Borrelia spirochaetes, TBE virus (TBEV) and of several other zoonotic pathogens in the western and eastern areas, respectively of the Palaearctic region. Recently, populations of the taiga tick were, for the first time, detected in northern Sweden. This prompted us to investigate if they harbour human pathogens.

Methods

A total of 276 I. persulcatus ticks (136 males, 126 females and 14 nymphs) and one I. ricinus nymph was collected by the cloth-dragging method in northern Sweden in July–August 2015 and May–July 2016. In addition, 8 males and 10 females of I. persulcatus were collected from two dogs (16 and 2 ticks, respectively) in two of the localities. All ticks were microscopically and molecularly identified to developmental stage and species and screened for B. burgdorferi (sensu lato), B. miyamotoi, Anaplasma phagocytophilum, Rickettsia spp., Neoehrlichia mikurensis, Babesia spp. and TBEV using real-time PCR followed by species identification by sequencing the PCR-products of conventional PCR assays.

Results

Of the ticks collected by the cloth-dragging method, 55% (152/277) were positive for Borrelia. There was no significant difference between the proportions of Borrelia-infected nymphs (33%, 5/15) and Borrelia-infected adult ticks (56%, 147/262), and no significant difference between the proportions of Borrelia-infected males (54%, 74/136) and Borrelia-infected females (58%, 73/126). Three different Borrelia species were identified. Borrelia afzelii was the predominant species and detected in 46% of all Borrelia-infected ticks followed by B. garinii, 35%, B. valaisiana, 1%, and mixed infections of different Borrelia species, 1%; 17% of all Borrelia-infections were untypeable. One I. persulcatus female contained Rickettsia helvetica, and one nymph contained Rickettsia sp. Of the 277 ticks analysed, all were negative for A. phagocytophilum, Babesia spp., Borrelia miyamotoi, N. mikurensis and TBEV. The ticks collected from the two dogs were negative for all pathogens examined except for Borrelia spp., that was detected in 5 out of 16 ticks removed from one of the dogs.

Conclusions

To our knowledge, this is the first time that I. persulcatus from Sweden has been analysed for the presence of tick-borne pathogens. The examined tick populations had a low diversity of tick-borne pathogens but a high prevalence of B. burgdorferi (s.l.).

Emerging tick-borne pathogens in the Nordic countries: A clinical and laboratory follow-up study of high-risk tick-bitten individuals

Despite the presence of several microorganisms, other than Borrelia burgdorferi sensu lato (Bbsl) and TBE virus, in Ixodes ricinus ticks from the Nordic countries, data is lacking on their pathogenic potential in humans. In this study, we wanted to investigate the aetiology and clinical manifestations of tick-transmitted infections in individuals seeking medical care following a tick-bite. The sampling frame was participants of a large-scale, prospective, multi-centre, follow-up study of tick-bitten volunteers recruited in Sweden, Finland and Norway in the years 2007-2015. Participants who sought medical care during the three-month follow-up period and from whom blood samples were collected during this healthcare visit (n = 92) were tested, using PCR, for exposure to spotted fever group (SFG) Rickettsia spp., Anaplasma phagocytophilum and Babesia spp. Moreover, 86 of these individuals had two serum samples, collected three months apart, tested serologically for six tick-borne microorganisms. The selected organisms - Bbsl, SFG rickettsiae, Anaplasma phagocytophilum, TBE virus, Babesia microti and Bartonella henselae - have all been detected in field-collected ticks from the Nordic countries. Medical records were reviewed and questionnaires were completed to determine clinical manifestations. We found Lyme borreliosis to be the most common tick-transmitted infection as seen in 46 (54%) of the 86 participants with available medical records. Among the 86 participants with paired sera, serological or molecular evidence of recent exposure to other microorganisms than Bbsl could be demonstrated in eight (9%). Five participants (6%) exhibited serological evidence of recent concomitant exposure to more than one tick-borne microorganism. Clinical presentations were mild with one exception (TBE). In conclusion, our data suggest a low risk of infection with tick-borne microorganisms, other than Bbsl, in immunocompetent tick-bitten persons from the examined regions, a low occurrence of co-infection and mostly mild or no overt clinical signs of infection in immunocompetent persons exposed to the studied agents.

Simultaneous Occurrence of Borrelia miyamotoi, Borrelia burgdorferi Sensu Lato, Anaplasma phagocytophilum and Rickettsia helvetica in Ixodes ricinus Ticks in Urban Foci in Bratislava, Slovakia

BACKGROUND

Questing Ixodes ricinus ticks were collected in two urban parks (Železná studienka and Horský park) of the capital city of Slovakia, Bratislava, during two consecutive years in 2011 and 2012. A total of 932 ticks were analyzed for the presence of tick-borne agents: B. miyamotoi, B. burgdorferi s.l., A. phagocytophilum and R. helvetica.

RESULTS

PCR analysis confirmed the presence of all pathogens at both localities. The overall infection prevalence of B. miyamotoi, B. burgdorferi s.l., A. phagocytophilum and R. helvetica was 0.75, 13.2, 5.6 and 8.9%, respectively. B. burgdorferi s.l. positive samples were represented by six genospecies. The most frequent one was B. afzelii followed by B. garinii and B. valaisiana.

CONCLUSION

Our study confirms the presence of I. ricinus ticks and at least nine tick-borne bacterial agents in city forest parks, which are used for recreational purposes. Ordination analysis revealed significant differences in the composition of pathogens with respect to study site location, time of season and ambient temperature, despite the fact that both sites are located relatively close to one another within the city.

High seroprevalence of Babesia antibodies among Borrelia burgdorferi-infected humans in Sweden

In northern Europe, tick-borne diseases such as Lyme borreliosis (LB) and tick-borne encephalitis (TBE) are well known. The actual incidence of Babesia infections, however, has remained elusive. In this study, the prevalence of antibodies against two Babesia spp. was investigated in a cohort of patients that were seropositive for Borrelia (B.) burgdorferi sensu lato (s.l.). Data were compared to a control group of healthy individuals. Sera were collected from 283 individuals residing in the southernmost region of Sweden, Skåne County. Almost one third of the sera were from patients with a confirmed seropositive reaction against B. burgdorferi s.l. All sera samples were assessed for IgG antibodies against Babesia (Ba.) microti and Ba. divergens by indirect fluorescent antibody (IFA) assays. Seropositive IgG titers for at least one of the Babesia spp. was significantly more common (p < 0.05) in individuals seropositive for Borrelia (16.3%) compared to the healthy control group (2.5%). Our findings suggest that Babesia infections may indeed be quite common among individuals who have been exposed to tick bites. Furthermore, the results indicate that human babesiosis should be considered in patients that show relevant symptoms; particularly for splenectomized and other immunocompromised individuals. Finally, the data challenges current blood transfusion procedures and highlights the current lack of awareness of the parasite in northern Europe.

Tick-borne pathogens in tick species infesting humans in Sibiu County, central Romania

Romania has a highly diverse tick fauna. Consequently, a high diversity of tick-transmitted pathogens might be a potential threat to humans. However, only a limited number of tick species regularly infest humans, and pathogens present in such species are therefore of particular interest from a medical perspective. In this study, 297 ticks were collected from humans during 2013 and 2014. Ixodes ricinus was the predominant tick species, accounting for 272 specimens or 91.6% of the ticks in the study. Nevertheless, other tick species were also found to infest humans: Dermacentor marginatus constituted 7% of the ticks found on humans (21/297), Haemaphysalis punctata 1% (3/297), and Haemaphysalis concinna 0.3% (1/297). Ticks were tested by PCR for a wide range of tick-borne pathogens. In total, 11.8% of the ticks carried human pathogenic bacteria, while no viral or protozoan pathogens were detected. The most frequently detected pathogen was Rickettsia spp., occurring in 5.4% of the ticks (16/297) and comprising three species: Rickettsia (R.) raoultii, R. monacensis, and R. helvetica. Borrelia s.l. occurred in 3% (9/297) of the ticks. "Candidatus Neoehrlichia mikurensis" occurred in 1.7% (5/297) and Anaplasma phagocytophilum in 1.3% (4/297). Anaplasma bovis was detected in an H. punctata and Borrelia miyamotoi in an I. ricinus. These results point to the need for further studies on the medical importance of tick-borne pathogens in Romania.

Comparison of phenoxymethylpenicillin, amoxicillin, and doxycycline for erythema migrans in general practice. A randomized controlled trial with a 1-year follow-up

OBJECTIVES

To compare the three most commonly used antibiotics for erythema migrans (EM) in Norwegian primary care.

METHODS

A randomized, parallel, controlled trial was carried out. Treatments were open to the patients, but blinded for the GPs and investigators. Patients eligible for inclusion were aged ≥18 years and clinically diagnosed with EM. Block randomization was processed in blocks of six. Patients were assigned to receive one of three antibiotic treatments for 14 days: phenoxymethylpenicillin (PCV), amoxicillin, or doxycycline. The primary outcome was the duration of EM in days in the three treatment groups. Patients kept a diary for the 14 days of treatment, in which they registered concomitant symptoms and side effects. The patients consulted their GP after 14 days of treatment and had a 1-year follow-up to monitor any development of disseminated Lyme borreliosis (LB). EMs with a duration of more than 14 days were followed until resolution. ClinicalTrials.govNCT01368341 and EU Clinical Trials Register 2010-023747-15.

RESULTS

One hundred and eighty eight patients (PCV: n = 56, amoxicillin: n = 64, doxycycline: n = 68) were included by 44 Norwegian general practitioners (GPs) from June 2011 to November 2013. Follow-up was completed by December 2014. The median duration of EM was altogether 14 days (range 3-293). For the PCV group median duration was 14 days (range 5-91), for amoxicillin 13 days (range 4-179) and for doxycycline 14 days (range 3-293). The duration of EM did not differ significantly between the three antibiotic groups (p 0.277). None of the patients developed disseminated LB within the 1-year follow-up.

CONCLUSIONS

We did not find 14 days of PCV, doxycycline, and amoxicillin treatments to differ in effectiveness or safety in the treatment of clinically diagnosed EM in primary care.

Subclinical Lyme borreliosis is common in south-eastern Sweden and may be distinguished from Lyme neuroborreliosis by sex, age and specific immune marker patterns

BACKGROUND

Determinants of a subclinical course of Lyme borreliosis (LB) remain largely unknown. The aim of this study was to assess the extent, sex and age profiles of subclinical Borrelia seroconversion in a LB endemic area in Sweden and to map blood cellular Borrelia-specific immune marker patterns in individuals with a previous subclinical LB course compared with patients previously diagnosed with Lyme neuroborreliosis (LNB).

METHODS

A large group of 1113 healthy blood donors was screened for multiple IgG anti-Borrelia antibodies and asked to complete a health inquiry regarding previous LB. A group of subjects with anti-Borrelia-specific IgG antibodies but no previous history of LB (subclinical LB, n = 60) was identified together with 22 cases of previous LNB. Whole Borrelia spirochetes, strains B. afzelii ACA1 and B. garinii Ip90, were used for ex vivo whole blood stimulations, whereas outer surface protein enriched fractions of the same strains were used for stimulation of peripheral blood mononuclear cells (PBMCs). An extensive panel of immune markers was analysed in the supernatants after stimulation using multiplex bead arrays, and Borrelia-specific secretion was determined by subtracting the spontaneous secretion.

RESULTS

A total of 125/1113 blood donors reported previous clinical LB. In contrast, 66 donors denied previous LB but showed multiple IgG anti-Borrelia antibodies; these were defined as subclinical subjects, of whom 60 were available for further studies. The subclinical subjects consisted of significantly more men and had a younger age compared with the LNB patients (p ≤ 0.01). Discriminant analysis revealed a distinct pattern of sex, age and PBMC B. garinii-specific levels of IL-10, IL-17A and CCL20 discriminating subclinical subjects from LNB patients.

CONCLUSIONS

This study confirms that subclinical Borrelia seroconversion is common in south-eastern Sweden. The findings further suggest that male sex, younger age together with B. gariniii induced levels of IL-10, IL-17A and CCL20 may be associated with a subclinical course.

First report of Borrelia miyamotoi in an Ixodes ricinus tick in Augsburg, Germany

Borrelia miyamotoi, a spirochete found in the hard tick Ixodes ricinus, is thought to cause relapsing fever. The disease caused by this bacterium can manifest with high fever, fatigue and other symptoms. It may also lead to central nervous system involvement with symptoms similar to meningoencephalitis. DNA from ticks from the greater Augsburg region in Germany was subjected to qPCR for Borrelia spp., followed by nested PCR and subsequent sequencing for species identification of the qPCR positive samples. From 112 ticks, 20 were found to be positive for Borrelia. The DNA sequenced showed 50% Borrelia afzelli, 15% Borrelia garinii, 5% Borrelia valaisiana and one sequence was identified as Borrelia miyamotoi. The positive identification of Borrelia miyamotoi is unlikely to be due to contamination. In conclusion, Borrelia miyamotoi has been found in a tick in the Augsburg region for the first time. This follows on from previous reports of a low incidence of this bacterium in southern Germany around Lake Constance and in the Munich region. This infectious agent should be taken into account when patients present with recurring fever or neurological symptoms which cannot be otherwise explained. Tick-borne relapsing fever should now be considered as a cause of such symptoms and medical professionals should contemplate differential Borrelia testing when presented with corresponding symptoms.

Human Tick-Borne Encephalitis and Characterization of Virus from Biting Tick

We report a case of human tick-borne encephalitis (TBE) in which the TBE virus was isolated from the biting tick. Viral growth and sequence were characterized and compared with those of a reference strain. Virus isolation from ticks from patients with TBE may offer a new approach for studies of epidemiology and pathogenicity.

Ticks and the city - are there any differences between city parks and natural forests in terms of tick abundance and prevalence of spirochaetes?

BACKGROUND

Ixodes ricinus ticks are commonly encountered in either natural or urban areas, contributing to Lyme disease agents Borreliella [(Borrelia burgdorferi (sensu lato)] spp. and Borrelia miyamotoi enzootic cycles in cities. It is an actual problem whether urbanization affects pathogen circulation and therefore risk of infection. The aim of the study was to evaluate main tick-borne disease risk factors in natural, endemic areas of north-east (NE) Poland (Białowieża) and urban areas of central Poland (Warsaw), measuring tick abundance/density, prevalence of infection with spirochaetes and diversity of these pathogens in spring-early summer and late summer-autumn periods between 2012 and 2015.

METHODS

Questing I. ricinus ticks were collected from three urban sites in Warsaw, central Poland and three natural sites in Białowieża, NE Poland. A total of 2993 ticks were analyzed for the presence of Borreliella spp. and/or Borrelia miyamotoi DNA by PCR. Tick abundance was analyzed by General Linear Models (GLM). Prevalence and distribution of spirochaetes was analyzed by Maximum Likelihood techniques based on log-linear analysis of contingency tables (HILOGLINEAR). Species typing and molecular phylogenetic analysis based on the sequenced flaB marker were carried out.

RESULTS

Overall 4617 I. ricinus ticks were collected (2258 nymphs and 2359 adults). We report well established population of ticks in urban areas (10.1 ± 0.9 ticks/100 m²), as in endemic natural areas with higher mean tick abundance (16.5 ± 1.5 ticks/100 m²). Tick densities were the highest in spring-early summer in both types of areas. We observed no effect of the type of area on Borreliella spp. and B. miyamotoi presence in ticks, resulting in similar prevalence of spirochaetes in urban and natural areas [10.9% (95% CI: 9.7-12.2%) vs 12.4% (95% CI: 10.1-15.1%), respectively]. Prevalence of spirochaetes was significantly higher in the summer-autumn period than in the spring-early summer [15.0% (95% CI: 12.8-17.5%) vs 10.4% (95% CI: 9.2-11.6%), respectively]. We have detected six species of bacteria present in both types of areas, with different frequencies: dominance of B. afzelii (69.3%) in urban and B. garinii (48.1%) in natural areas. Although we observed higher tick densities in forests than in maintained parks, the prevalence of spirochaetes was significantly higher in the latter [9.8% (95% CI: 8.6-11.0%) vs 17.5% (95% CI: 14.4-20.5%)].

CONCLUSIONS

Surprisingly, a similar risk of infection with Borreliella spp. and/or B. miyamotoi was discovered in highly- and low-transformed areas. We suggest that the awareness of presence of these disease agents in cities should be raised.

Molecular detection of Borrelia burgdorferi sensu lato - An analytical comparison of real-time PCR protocols from five different Scandinavian laboratories

Introduction

Lyme borreliosis (LB) is the most common tick transmitted disease in Europe. The diagnosis of LB today is based on the patient´s medical history, clinical presentation and laboratory findings. The laboratory diagnostics are mainly based on antibody detection, but in certain conditions molecular detection by polymerase chain reaction (PCR) may serve as a complement.

Aim

The purpose of this study was to evaluate the analytical sensitivity, analytical specificity and concordance of eight different real-time PCR methods at five laboratories in Sweden, Norway and Denmark.

Method

Each participating laboratory was asked to analyse three different sets of samples (reference panels; all blinded) i) cDNA extracted and transcribed from water spiked with cultured Borrelia strains, ii) cerebrospinal fluid spiked with cultured Borrelia strains, and iii) DNA dilution series extracted from cultured Borrelia and relapsing fever strains. The results and the method descriptions of each laboratory were systematically evaluated.

Results and conclusions

The analytical sensitivities and the concordance between the eight protocols were in general high. The concordance was especially high between the protocols using 16S rRNA as the target gene, however, this concordance was mainly related to cDNA as the type of template. When comparing cDNA and DNA as the type of template the analytical sensitivity was in general higher for the protocols using DNA as template regardless of the use of target gene. The analytical specificity for all eight protocols was high. However, some protocols were not able to detect Borrelia spielmanii, Borrelia lusitaniae or Borrelia japonica.

Infection of Ixodes ricinus by Borrelia burgdorferi sensu lato in peri-urban forests of France

Lyme borreliosis is the most common tick-borne disease in the northern hemisphere. In Europe, it is transmitted by Ixodes ticks that carry bacteria belonging to the Borrelia burgdorferi sensu lato complex. The objective of this work was to explore eco-epidemiological factors of Lyme borreliosis in peri-urban forests of France (Sénart, Notre-Dame and Rambouillet). We investigated whether the introduction of Tamias sibiricus in Sénart could alter the density of infected ticks. Moreover, the density and tick infection were investigated according to the tree species found in various patches of Sénart forest. For this purpose, ticks were sampled during 3 years. In the Sénart forest, the density of nymph and adult ticks showed no significant difference between 2008, 2009 and 2011. The nymph density varied significantly as a function of the month of collection. Regarding the nymphs, a higher rate of infection and infected density were found in 2009. Plots with chipmunks (C) presented a lower density of both nymphs and adult ticks than plots without chipmunks (NC) did. A higher rate of infection of nymphs with Borrelia was seen in C plots. The prevalence of the various species of Borrelia was also found to vary between C and NC plots with the year of the collect. The presence of chestnut trees positively influenced the density of both nymphs and adults. The infected nymph density showed a significant difference depending on the peri-urban forest studied, Sénart being higher than Rambouillet. The prevalence of Borrelia species also differed between the various forests studied. Concerning the putative role that Tamias sibiricus may play in the transmission of Borrelia, our results suggest that its presence is correlated with a higher rate of infection of questing ticks by Borrelia genospecies and if its population increases, it could play a significant role in the risk of transmission of Lyme borreliosis.

Crowdsourcing-based nationwide tick collection reveals the distribution of Ixodes ricinus and I. persulcatus and associated pathogens in Finland

A national crowdsourcing-based tick collection campaign was organized in 2015 with the objective of producing novel data on tick distribution and tick-borne pathogens in Finland. Nearly 20 000 Ixodes ticks were collected. The collected material revealed the nationwide distribution of I. persulcatus for the first time and a shift northwards in the distribution of I. ricinus in Finland. A subset of 2038 tick samples containing both species was screened for Borrelia burgdorferi sensu lato (the prevalence was 14.2% for I. ricinus and 19.8% for I. persulcatus), B. miyamotoi (0.2% and 0.4%, respectively) and tick-borne encephalitis virus (TBEV; 0.2% and 3.0%, respectively). We also report new risk areas for TBEV in Finland and, for the first time, the presence of B. miyamotoi in ticks from mainland Finland. Most importantly, our study demonstrates the overwhelming power of citizen science in accomplishing a collection effort that would have been impossible with the scientific community alone.

Borrelia miyamotoi and Co-Infection with Borrelia afzelii in Ixodes ricinus Ticks and Rodents from Slovakia

Borrelia miyamotoi causes relapsing fever in humans. The occurrence of this spirochete has been reported in Ixodes ricinus and wildlife, but there are still gaps in the knowledge of its eco-epidemiology and public health impact. In the current study, questing I. ricinus (nymphs and adults) and skin biopsies from rodents captured in Slovakia were screened for the presence of B. miyamotoi and Borrelia burgdorferi s.l. DNA. The prevalence of B. miyamotoi and B. burgdorferi s.l. in questing ticks was 1.7 and 16.9%, respectively. B. miyamotoi was detected in Apodemus flavicollis (9.3%) and Myodes glareolus (4.4%). In contrast, B. burgdorferi s.l. was identified in 11.9% of rodents, with the highest prevalence in Microtus arvalis (68.4%) and a lower prevalence in Apodemus spp. (8.4%) and M. glareolus (12.4%). Borrelia afzelii was the prevailing genospecies infecting questing I. ricinus (37.9%) and rodents (72.2%). Co-infections of B. miyamotoi and B. burgdorferi s.l. were found in 24.1 and 9.3% of the questing ticks and rodents, respectively, whereas the proportion of ticks and rodents co-infected with B. miyamotoi and B. afzelii was 6.9 and 7.0%, respectively. The results suggest that B. miyamotoi and B. afzelii share amplifying hosts. The sequences of the B. miyamotoi glpQ gene fragment from our study showed a high degree of identity with sequences of the gene amplified from ticks and human patients in Europe. The results seem to suggest that humans in Slovakia are at risk of contracting tick-borne relapsing fever, and in some cases together with Lyme borreliosis.

Host Immune Evasion by Lyme and Relapsing Fever Borreliae: Findings to Lead Future Studies for Borrelia miyamotoi

The emerging pathogen, Borrelia miyamotoi, is a relapsing fever spirochete vectored by the same species of Ixodes ticks that carry the causative agents of Lyme disease in the US, Europe, and Asia. Symptoms caused by infection with B. miyamotoi are similar to a relapsing fever infection. However, B. miyamotoi has adapted to different vectors and reservoirs, which could result in unique physiology, including immune evasion mechanisms. Lyme Borrelia utilize a combination of Ixodes-produced inhibitors and native proteins [i.e., factor H-binding proteins (FHBPs)/complement regulator-acquiring surface proteins, p43, BBK32, BGA66, BGA71, CD59-like protein] to inhibit complement, while some relapsing fever spirochetes use C4b-binding protein and likely Ornithodoros-produced inhibitors. To evade the humoral response, Borrelia utilize antigenic variation of either outer surface proteins (Osps) and the Vmp-like sequences (Vls) system (Lyme borreliae) or variable membrane proteins (Vmps, relapsing fever borreliae). B. miyamotoi possesses putative FHBPs and antigenic variation of Vmps has been demonstrated. This review summarizes and compares the common mechanisms utilized by Lyme and relapsing fever spirochetes, as well as the current state of understanding immune evasion by B. miyamotoi.

Progress in the molecular diagnosis of Lyme disease

INTRODUCTION

Current laboratory testing of Lyme borreliosis mostly relies on serological methods with known limitations. Diagnostic modalities enabling direct detection of pathogen at the onset of the clinical signs could overcome some of the limitations. Molecular methods detecting borrelial DNA seem to be the ideal solution, although there are some aspects that need to be considered. Areas covered: This review represent summary and discussion of the published data obtained from literature searches from PubMed and The National Library of Medicine (USA) together with our own experience on molecular diagnosis of Lyme disease. Expert commentary: Molecular methods are promising and currently serve as supporting diagnostic testing in Lyme borreliosis. Since the field of molecular diagnostics is under rapid development, molecular testing could become an important diagnostic modality.

Oligoarthritis caused by Borrelia bavariensis, Austria, 2014

A case of Lyme oligoarthritis occurred in an 11-year-old boy in Vienna, Austria. DNA of Borrelia bavariensis was detected by PCR in 2 aspirates obtained from different joints. Complete recovery was achieved after a 4-week course with amoxicillin. Lyme arthritis must be considered in patients from Europe who have persisting joint effusions.

Prevalence of Borrelia miyamotoi in Ixodes persulcatus in Irkutsk City and its neighboring territories, Russia

Adult Ixodes persulcatus were collected in highly populated districts in Irkutsk city, Russia, and in popular recreational and professional areas in its neighboring territories. Borrelia miyamotoi infection in I. persulcatus was examined using multiplex Taqman-PCR targeting 16S rDNA, and nested PCR and sequencing analyses targeting flaB and 16S rDNA. B. miyamotoi and Lyme disease Borrelia species were detected in 13 (infection rate, 2.9%) and 77 (17.3%) out of 445 I. persulcatus ticks, respectively, collected from 4 sites around the Baikal Lake. The 16S rDNA and flaB sequences of these amplicons were closely related to those of B. miyamotoi detected and/or isolated from I. persulcatus in Japan and Far Eastern Russia, and clustered separately from those of Europe and North America. These results indicate that additional surveillance for B. miyamotoi infection is needed in order to determine how it affects human health in Irkutsk City and its neighboring territories.

A prospective study on the incidence of Borrelia burgdorferi sensu lato infection after a tick bite in Sweden and on the Åland Islands, Finland (2008-2009)

Lyme borreliosis (LB) is a common and increasing tick-borne disease in Europe. The risk of acquiring a Borrelia infection after a tick bite is not fully known. Therefore, we investigated the incidence of Borrelia infection after a bite by a Borrelia-infected tick and if the Borrelia load and/or the duration of tick-feeding influenced the risk of infection. During 2008-2009, ticks and blood samples were collected from 1546 tick-bitten persons from Sweden and the Åland Islands, Finland. Follow-up blood samples were taken 3 months after the tick bite. The duration of tick feeding was microscopically estimated and Borrelia was detected and quantified in ticks by real-time PCR. Anti-Borrelia antibodies were detected in sera using ELISA tests and immunoblot. Five percent (78/1546) of the study participants developed Borrelia infection (LB diagnosis and/or seroconversion) after a tick bite (45% bitten by Borrelia-infected ticks and 55% bitten by uninfected ticks). Of these, 33 developed LB (whereof 9 also seroconverted) while 45 participants seroconverted only. Experience of non-specific symptoms was more frequently reported by Borrelia-infected participants compared to uninfected participants. All who seroconverted removed "their" ticks significantly later than those who did not. The Borrelia load in the ticks did not explain the risk of seroconversion. Regional and sex differences in the Borrelia seroprevalence were found. The risk of developing a Borrelia infection after a bite by a Borrelia-infected tick is small but increases with the duration of tick feeding.

Disease Risk & Landscape Attributes of Tick-Borne Borrelia Pathogens in the San Francisco Bay Area, California

Habitat heterogeneity influences pathogen ecology by affecting vector abundance and the reservoir host communities. We investigated spatial patterns of disease risk for two human pathogens in the Borrelia genus–B. burgdorferi and B. miyamotoi–that are transmitted by the western black-legged tick, Ixodes pacificus. We collected ticks (349 nymphs, 273 adults) at 20 sites in the San Francisco Bay Area, California, USA. Tick abundance, pathogen prevalence and density of infected nymphs varied widely across sites and habitat type, though nymphal western black-legged ticks were more frequently found, and were more abundant in coast live oak forest and desert/semi-desert scrub (dominated by California sagebrush) habitats. We observed Borrelia infections in ticks at all sites where we able to collect >10 ticks. The recently recognized human pathogen, B. miyamotoi, was observed at a higher prevalence (13/349 nymphs = 3.7%, 95% CI = 2.0–6.3; 5/273 adults = 1.8%, 95% CI = 0.6–4.2) than recent studies from nearby locations (Alameda County, east of the San Francisco Bay), demonstrating that tick-borne disease risk and ecology can vary substantially at small geographic scales, with consequences for public health and disease diagnosis.

Babesia species in questing Ixodes ricinus, Sweden

Babesiosis is an emerging tick-transmitted zoonosis in large parts of the world. In Sweden, the occurrence and diversity of Babesia species is largely unknown. In order to estimate the exposure to Babesia from infected ticks, we collected questing Ixodes ricinus from several sites across southern Sweden during two consecutive field seasons and investigated the occurrence of Babesia species. We report for the first time the occurrence of the zoonotic species Babesia venatorum in Swedish ticks, with a prevalence of 1%. We also detected B. microti (prevalence 3.2%) and B. divergens (prevalence 0.2%). The incidence of Babesia in questing ticks is substantially lower than that of several other tick-borne diseases in Sweden. Nevertheless, babesiosis should not be neglected as a possible diagnosis following tick bites in humans and animals in Sweden.

Low risk of seroconversion or clinical disease in humans after a bite by an Anaplasma phagocytophilum-infected tick

The risk of contracting human granulocytic anaplasmosis (HGA) after a tick bite is mainly unknown. In this study we investigated the clinical and serological response in 30 humans bitten by ticks positive for Anaplasma phagocytophilum (Group A), 30 humans bitten by Borrelia burgdorferi sensu lato (s.l.)-positive ticks (Group B), and 30 humans bitten by ticks negative for both A. phagocytophilum and B. burgdorferi s.l. (Group C). Ticks, blood samples and questionnaires were collected from tick-bitten humans at 34 primary healthcare centres in Sweden and in the Åland Islands, Finland, at the time of the tick bite and after three months. A total of 2553 ticks detached from humans in 2007-2009 were analyzed by polymerase chain reaction, and 31 (1.2%) were positive for A. phagocytophilum, 556 (21.8%) were positive for B. burgdorferi s.l., and eight (0.3%) were co-infected by A. phagocytophilum and B. burgdorferi s.l. The overall prevalence of Anaplasma IgG antibodies in the included participants (n=90) was 17%, and there was no significant difference between the groups A-C. Only one of the participants (in Group C) showed a four-fold increase of IgG antibodies against A. phagocytophilum at the three-month follow-up, but reported no symptoms. The frequency of reported symptoms did not differ between groups A-C, and was unrelated to the findings of A. phagocytophilum and B. burgdorferi s.l. in the detached ticks. We conclude that the risk for HGA or asymptomatic seroconversion after a tick bite in Sweden or in the Åland Islands is low, even if the tick is infected by A. phagocytophilum.