Lyme borreliosis in Portugal caused by Borrelia lusitaniae? Clinical report on the first patient with a positive skin isolate

Detection and genetic identification of Borrelia lusitaniae in questing Ixodes inopinatus tick from Tunisia

Background

Until now, there has been limited information on the prevalence and the phylogeny of Borrelia burgdorferi sensu lato in Ixodes ticks in Tunisia, particularly in Ixodes inopinatus.

Methods

The present study aimed to determine the prevalence and the phylogeny of B. burgdorferi s.l., in coexisted I. ricinus and I. inopinatus ticks collected from Northern Tunisia. One hundred questig ticks were collected during winter 2020 by tick-dragging method in Beja gouvernorate located in the north of Tunisia. Real-time PCR panel targeting B. burgdorferi s.l. 23S rRNA gene were performed. Positive DNA samples were subjected to conventional PCRs targeting 457 bp fragment of the Borrelia sp. flagellin (fla) gene using primers FlaF/FlaR. The identified Borrelia sp. isolate underwent partial sequence analysis to determine genospecies and evaluate their phylogenetic position.

Results

The study revealed a prevalence rate of 28% (28/100) for B. burgdorferi sensu lato in the Ixodes ticks. The prevalence rates across tick species and genders did not show significant variations (p > 0.05). Interestingly, the study underlines the coexistence of I. inopinatus and I. ricinus sharing the same geographic areas in Northern Tunisia. Furthermore, DNA of B. lusitaniae was detected in I. inopinatus ticks for the first time in Tunisia. Revealed B. lusitaniae bacterium is similar to previously identified strains in Mediterranean region, but distinct from those isolated exclusively from countries of Eastern and Central Europe, such as Serbia, Romania, and Poland. This study highlights the prevalence of B. burgdorferi s.l. in I. ricinus/I. inopinatus ticks, and reveals B. lusitaniae in I. inopinatus ticks for the first time in Tunisia.

Conclusion

These findings suggest the involvement of I. inopinatus as a potential vector of this pathogenic genospeciess in Tunisia. This may help understanding the ecology of Ixodes ticks, the natural infection and the transmission dynamics of Borrelia species in this country.

Forest Diversity Reduces the Prevalence of Pathogens Transmitted by the Tick Ixodes ricinus

Tick-borne diseases represent the majority of vector-borne human diseases in Europe, with Ixodes ricinus, mostly present in forests, as the main vector. Studies show that vertebrate hosts diversification would decrease the prevalence of these pathogens. However, it is not well known whether habitat diversity can have similar impact on ticks and their infection rates. We measured the presence and abundance of different stages of I. ricinus, and the prevalence of associated pathogens in a large-scale forest experiment in which we manipulated tree diversity and moisture level. We showed that larval abundance was influenced by tree species identity, with larvae being more present in pine plots than in oak plots, while nymph abundance increased with canopy tree density. The proportion of Borrelia burgdorferi s.l.-infected nymphs decreased with increasing tree diversity. Our findings suggest that tree overstorey composition, structure and diversity, can affect tick abundance and pathogen prevalence. They support the idea that forest habitats may have “diluting” or “amplifying” effects on tick-borne diseases with direct relevance for human health.

The Population Structure of Borrelia lusitaniae Is Reflected by a Population Division of Its Ixodes Vector

Populations of vector-borne pathogens are shaped by the distribution and movement of vector and reservoir hosts. To study what impact host and vector association have on tick-borne pathogens, we investigated the population structure of Borrelia lusitaniae using multilocus sequence typing (MLST). Novel sequences were acquired from questing ticks collected in multiple North African and European locations and were supplemented by publicly available sequences at the Borrelia Pubmlst database (accessed on 11 February 2020). Population structure of B. lusitaniae was inferred using clustering and network analyses. Maximum likelihood phylogenies for two molecular tick markers (the mitochondrial 16S rRNA locus and a nuclear locus, Tick-receptor of outer surface protein A, trospA) were used to confirm the morphological species identification of collected ticks. Our results confirmed that B. lusitaniae does indeed form two distinguishable populations: one containing mostly European samples and the other mostly Portuguese and North African samples. Of interest, Portuguese samples clustered largely based on being from north (European) or south (North African) of the river Targus. As two different Ixodes species (i.e., I. ricinus and I. inopinatus) may vector Borrelia in these regions, reference samples were included for I. inopinatus but did not form monophyletic clades in either tree, suggesting some misidentification. Even so, the trospA phylogeny showed a monophyletic clade containing tick samples from Northern Africa and Portugal south of the river Tagus suggesting a population division in Ixodes on this locus. The pattern mirrored the clustering of B. lusitaniae samples, suggesting a potential co-evolution between tick and Borrelia populations that deserve further investigation.

Chronic Lyme Disease: An Evidence-Based Definition by the ILADS Working Group

Objective: Chronic Lyme disease has been a poorly defined term and often dismissed as a fictitious entity. In this paper, the International Lyme and Associated Diseases Society (ILADS) provides its evidence-based definition of chronic Lyme disease. Definition: ILADS defines chronic Lyme disease (CLD) as a multisystem illness with a wide range of symptoms and/or signs that are either continuously or intermittently present for a minimum of six months. The illness is the result of an active and ongoing infection by any of several pathogenic members of the Borrelia burgdorferi sensu lato complex (Bbsl). The infection has variable latency periods and signs and symptoms may wax, wane and migrate. CLD has two subcategories, CLD, untreated (CLD-U) and CLD, previously treated (CLD-PT). The latter requires that CLD manifestations persist or recur following treatment and are present continuously or in a relapsing/remitting pattern for a duration of six months or more. Methods: Systematic review of over 250 peer reviewed papers in the international literature to characterize the clinical spectrum of CLD-U and CLD-PT. Conclusion: This evidence-based definition of chronic Lyme disease clarifies the term's meaning and the literature review validates that chronic and ongoing Bbsl infections can result in chronic disease. Use of this CLD definition will promote a better understanding of the infection and facilitate future research of this infection.

Borrelia lusitaniae Infection Mimicking Headache, Neurologic Deficits, and Cerebrospinal Fluid Lymphocytosis

Headache with neurologic deficits and cerebrospinal fluid lymphocytosis (HaNDL) is a rare headache syndrome included in the Classification of Headache of the International Headache Society as a "headache attributed to non-infectious inflammatory intracranial disease." We report one 15-year-old patient with clinical history and cerebrospinal fluid findings compatible with the diagnosis of HaNDL in whom Borrelia lusitaniae was identified in cerebrospinal fluid by polymerase chain reaction.

Europe-Wide Meta-Analysis of Borrelia burgdorferi Sensu Lato Prevalence in Questing Ixodes ricinus Ticks

Lyme borreliosis is the most common zoonotic disease transmitted by ticks in Europe and North America. Despite having multiple tick vectors, the causative agent, Borrelia burgdorferisensu lato, is vectored mainly by Ixodes ricinus in Europe. In the present study, we aimed to review and summarize the existing data published from 2010 to 2016 concerning the prevalence of B. burgdorferi sensu lato spirochetes in questing I. ricinus ticks. The primary focus was to evaluate the infection rate of these bacteria in ticks, accounting for tick stage, adult tick gender, region, and detection method, as well as to investigate any changes in prevalence over time. The data obtained were compared to the findings of a previous metastudy. The literature search identified data from 23 countries, with 115,028 ticks, in total, inspected for infection with B. burgdorferi sensu lato We showed that the infection rate was significantly higher in adults than in nymphs and in females than in males. We found significant differences between European regions, with the highest infection rates in Central Europe. The most common genospecies were B. afzelii and B. garinii, despite a negative correlation of their prevalence rates. No statistically significant differences were found among the prevalence rates determined by conventional PCR, nested PCR, and real-time PCR.IMPORTANCEBorrelia burgdorferisensu lato is a pathogenic bacterium whose clinical manifestations are associated with Lyme borreliosis. This vector-borne disease is a major public health concern in Europe and North America and may lead to severe arthritic, cardiovascular, and neurological complications if left untreated. Although pathogen prevalence is considered an important predictor of infection risk, solitary isolated data have only limited value. Here we provide summarized information about the prevalence of B. burgdorferi sensu lato spirochetes among host-seeking Ixodes ricinus ticks, the principal tick vector of borreliae in Europe. We compare the new results with previously published data in order to evaluate any changing trends in tick infection.

Enzootic origins for clinical manifestations of Lyme borreliosis

Both early localized and late disseminated forms of Lyme borreliosis are caused by Borrelia burgdorferi senso lato. Differentiating between the spirochetes that only cause localized skin infection from those that cause disseminated infection, and tracing the group of medically-important spirochetes to a specific vertebrate host species, are two critical issues in disease risk assessment and management. Borrelia burgdorferi senso lato isolates from Lyme borreliosis cases with distinct clinical manifestations (erythema migrans, neuroborreliosis, acrodermatitis chronica atrophicans, and Lyme arthritis) and isolates from Ixodes ricinus ticks feeding on rodents, birds and hedgehogs were typed to the genospecies level by sequencing part of the intergenic spacer region. In-depth molecular typing was performed by sequencing eight additional loci with different characteristics (plasmid-bound, regulatory, and housekeeping genes). The most abundant genospecies and genotypes in the clinical isolates were identified by using odds ratio as a measure of dominance. Borrelia afzelii was the most common genospecies in acrodermatitis patients and engorged ticks from rodents. Borrelia burgdorferi senso stricto was widespread in erythema migrans patients. Borrelia bavariensis was widespread in neuroborreliosis patients and in ticks from hedgehogs, but rare in erythema migrans patients. Borrelia garinii was the dominant genospecies in ticks feeding on birds. Spirochetes in ticks feeding on hedgehogs were overrepresented in genotypes of the plasmid gene ospC from spirochetes in erythema migrans patients. Spirochetes in ticks feeding on hedgehogs were overrepresented in genotypes of ospA from spirochetes in acrodermatitis patients. Spirochetes from ticks feeding on birds were overrepresented in genotypes of the plasmid and regulatory genes dbpA, rpoN and rpoS from spirochetes in neuroborreliosis patients. Overall, the analyses of our datasets support the existence of at least three transmission pathways from an enzootic cycle to a clinical manifestation of Lyme borreliosis. Based on the observations with these nine loci, it seems to be justified to consider the population structure of B. burgdorferi senso lato as being predominantly clonal.

Natural foci of Borrelia lusitaniae in a mountain region of Central Europe

Lyme borreliosis is the most prevalent tick-borne disease in Europe. It is caused by spirochaetes of the Borrelia burgdorferi sensu lato (s.l.) complex and transmitted to humans by ticks of the genus Ixodes. Borrelia afzelii, Borrelia garinii, and Borrelia valaisiana are the most common genospecies in Central Europe. In contrast, Borrelia lusitaniae predominates in Mediterranean countries such as Portugal, Morocco, and Tunisia. In Slovakia, its prevalence is low and restricted to only a few sites. The aim of our research was to study the expansion of ticks into higher altitudes in the ecosystem of the Malá Fatra mountains (north Slovakia) and their infection with B. burgdorferi s.l. pathogens. Questing ticks were collected by flagging in seven years (2004, 2006-2011) at three different altitudes: low (630-660 m above sea level (ASL)), intermediate (720-750 m ASL), and high (1040-1070 m ASL). Tick abundance was highest at the lowest altitude and lowest at the highest altitude. The average infection prevalence of B. burgdorferi s.l. in nymphs and adults was 16.8% and 36.2%, respectively. The number of infected ticks decreased from 38.5% at the lowest altitude to 4.4% at the highest altitude. B. lusitaniae was the most frequently found genospecies (>60% of the ticks found positive for B. burgdorferi s.l.) in all sites in all the studied years with the exception of 2008 when B. afzelii predominated (62%). Our study confirms the spread of Ixodes ricinus ticks to higher altitudes in Slovakia. The discovery that our mountain study sites were a natural foci of B. lusitaniae was unexpected because this genospecies is usually associated with lizards and xerothermic habitats.

The importance of lizards and small mammals as reservoirs for Borrelia lusitaniae in Portugal

Borrelia lusitaniae is a pathogen frequent in the Mediterranean area. Apart from lizards, evidence for birds and small mammals as competent reservoirs for this genospecies has been occasional. We collected questing ticks, skin biopsies and Ixodes sp. ticks feeding on lizards, birds and small mammals in a B. burgdorferi s.l. (sensu lato) enzootic area to assess their importance in the maintenance of B. lusitaniae. Borrelia lusitaniae was the most prevalent genospecies in questing ticks and was commonly found in larvae feeding on Psammodromus algirus. One biopsy infected with B. lusitaniae was collected from the tail of one Podarcis hispanica, which suggests systemic infection. Ixodes ricinus larvae feeding on Apodemus sylvaticus were infected with B. lusitaniae but with a lower prevalence. Our results reinforce the importance of lizards as reservoirs for B. lusitaniae, suggesting that P. algirus, in particular, acts as main reservoir for B. lusitaniae in Portugal.

Exploring gaps in our knowledge on Lyme borreliosis spirochaetes--updates on complex heterogeneity, ecology, and pathogenicity

The Lyme borreliosis complex is a heterogeneous group of tick-borne spirochaetes of the genus Borrelia (Spirochaetales: Spirochaetaceae) that are distributed all over the temperate zone of the northern hemisphere. Due to the usage of new methods for phylogenetic analysis, this group has expanded rapidly during the past 5 years. Along with this development, the number of Borrelia spp. regarded as pathogenic to humans also increased. Distribution areas as well as host and vector ranges of Lyme borreliosis agents turned out to be much wider than previously thought. Furthermore, there is evidence that ticks, reservoir hosts, and patients can be coinfected with multiple Borrelia spp. or other tick-borne pathogens, which indicates a need to establish new and well-defined diagnostic and therapeutic standards for Lyme borreliosis. This review gives a broad overview on the occurrence of Lyme borreliosis spirochaetes worldwide with particular emphasis on their vectors and vertebrate hosts as well as their pathogenic potential and resultant problems in diagnosis and treatment. Against the background that many issues regarding distribution, species identity, ecology, pathogenicity, and coinfections are still unsolved, the purpose of this article is to reveal directions for future research on the Lyme borreliosis complex.

Molecular diagnosis of Borrelia bacteria for the diagnosis of Lyme disease

INTRODUCTION

Lyme borreliosis is the most common vector-borne disease in the temperate climate zone of Europe and the US, and its frequency is increasing. Serology is often negative in the early stage of Lyme borreliosis and cannot distinguish between active and past infection. Culture is cumbersome and not very sensitive, and polymerase chain reaction (PCR) for the diagnosis of Lyme borreliosis has been described over the last 20 years, with varying results.

AREAS COVERED

In this article, all of the major studies in which PCR has been used to diagnose Lyme borreliosis in humans are critically reviewed. However, this article does not include studies that consisted of fewer than 10 patients, nor does it include studies that have inadequate descriptions of the patient population.

EXPERT OPINION

There is a lack of standardized protocols, and preamplification procedures have not been standardized. Nested PCRs seem to perform best, but are prone to contamination. PCR on skin biopsies can be used to diagnose early Lyme borreliosis in patients with atypical forms of erythema migrans. PCR also has diagnostic potential in Lyme arthritis and early neuroborreliosis. Blood and urine should not used for PCR. For future development, preamplification procedures should be optimized using materials from experimentally infected animals. Multi-center studies should follow to evaluate these optimized tests.

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

Members of the genus Borrelia are among the most common infectious agents causing tick-borne disease in humans worldwide. Here, we developed a Light Upon eXtension (LUX) real-time PCR assay that can detect and quantify Borrelia species in ticks that have fed on humans, and we applied the assay to 399 such ticks. Borrelia PCR-positive ticks were identified to species level by sequencing the products of conventional PCR performed using Borrelia group-specific primers. There was a 19% prevalence of Borrelia spp. in the detached ticks, and the number of spirochetes per Borrelia PCR-positive tick ranged from 2.0 × 10(2) to 4.9 × 10(5), with a median of 7.8 × 10(3) spirochetes. Adult ticks had a significantly larger number of spirochetes, with a median of 8.4 × 10(3) compared to the median of nymphs of 4.4 × 10(3). [corrected] Adult ticks also exhibited a higher prevalence of Borrelia (33%) than nymphs (14%). Among the identified species, Borrelia afzelii was found to predominate (61%) and was followed by B. garinii (23%), B. valaisiana (13%), B. burgdorferi sensu stricto (1%), B. lusitaniae (1%), and B. miyamotoi-like (1%). Also, 3% of the ticks were coinfected with multiple strains of B. afzelii. Notably, this is the first report of B. lusitaniae being detected in ticks in Sweden. Our LUX real-time PCR assay proved to be more sensitive than a corresponding TaqMan assay. In conclusion, the novel LUX real-time PCR method is a rapid and sensitive tool for detection and quantification of Borrelia spp. in ticks.

Inadequate binding of immune regulator factor H is associated with sensitivity of Borrelia lusitaniae to human complement

Spirochetes belonging to the Borrelia burgdorferi sensu lato complex differ in resistance to complement-mediated killing by human serum. Here, we characterize complement sensitivity of a panel of B. lusitaniae isolates derived from ticks collected in Germany and Portugal as well as one patient-derived isolate, PoHL. All isolates are highly susceptible to complement-mediated lysis in human serum and activate complement predominantly by the alternative pathway, leading to an increased deposition of complement components C3, C6, and the terminal complement complex. Interestingly, serum-sensitive B. lusitaniae isolates were able to bind immune regulator factor H (CFH), and some strains also bound CFH-related protein 1 (CFHR1) and CFHR2. Moreover, CFH bound to the surface of B. lusitaniae was inefficient in mediating C3b conversion. Furthermore, the identification and characterization of a potential CFH-binding protein, OspE, revealed that this molecule possesses a significantly reduced binding capacity for CFH compared to that of CFH-binding OspE paralogs expressed by various serum-resistant Borrelia species. This finding suggests that a reduced binding capability of CFH is associated with an increased serum sensitivity of B. lusitaniae to human complement.

Establishment of a minor groove binder-probe based quantitative real time PCR to detect Borrelia burgdorferi sensu lato and differentiation of Borrelia spielmanii by ospA-specific conventional PCR

BACKGROUND

Borrelia burgdorferi sensu lato (sl), the causative agent of Lyme borreliosis, is transmitted by ticks of the genus Ixodes as vector. For identification of Borrelia infections in ticks a TaqMan minor groove binder (MGB) probe-based quantitative real time PCR (qPCR) was established targeting the 5S-23S intergenic spacer. Extension to a duplex qPCR included an Ixodes spp. positive control to verify successful DNA isolation. Besides qPCR, an ospA-specific conventional PCR for species-specific identification of B. spielmanii was established. Afterwards 1000 I. ricinus flagged in the city of Hanover, Germany, were investigated for B. burgdorferi sl infections followed by species identification. Furthermore, I. hexagonus ticks were investigated to proof applicability of the PCRs.

RESULTS

Quantitative real time PCR (qPCR) identifying B. burgdorferi sl in ticks was able to detect 1-10 copies per reaction. B. spielmanii ospA-specific conventional PCR was also highly specific and showed no cross reactions with the other tested Borrelia species. From 1000 hanoveranian ticks 24.3% were positive compared to only 7.4% positives by dark-field microscopy. Related to tick stage 1.7% larvae, 18.1% nymphs, and 34.6% adults were positive. The most frequent species was B. garinii, followed by B. afzelii, B. spielmanii, B. valaisiana and B. burgdorferi sensu stricto (ss). 70.6% of I. ricinus were mono-infected, whereas 28.0% and 1.4% were infected with two and three Borrelia species, respectively. From 232 I. hexagonus collected from hedgehogs in different sites of Germany, qPCR detected 5.7% to be infected with B. burgdorferi sl, which were identified as B. afzelii, B. garinii and B. spielmanii.

CONCLUSIONS

The evaluated qPCR to detect B. burgdorferi sl in Ixodes spp. is highly specific and sensitive. As a duplex qPCR including detection of Ixodes spp. DNA it is the first DNA based technique incorporating a control for successful DNA isolation from the vector tick. Establishment of a B. spielmanii specific conventional PCR filled the gap in PCR identification of principal European Borrelia genospecies. Practical application showed that all European pathogenic Borrelia spp. were present in I. ricinus flagged in recreational areas of the city of Hanover and confirmed I. hexagonus as reservoir for pathogenic Borrelia spp.

Diversity of Borrelia genospecies in Ixodes ricinus ticks in a Lyme borreliosis endemic area in Switzerland identified by using new probes for reverse line blotting

In Europe, 7 Borrelia species belonging to the Borrelia burgdorferi sensu lato complex have been reported in Ixodes ricinus ticks. In addition, another Borrelia, related to the relapsing fever spirochaetes, has also been described. In the present study, we designed probes for reverse line blotting allowing detection and identification of all these Borrelia species after amplification of the variable spacer region between the 23S and 5S ribosomal genes. These new probes allowed us investigate the diversity of Borrelia in 915 I. ricinus collected on the south-facing slope of Chaumont (Switzerland). Among the 159 infected ticks, 7 Borrelia species were identified, and B. spielmanii and relapsing fever-like (RFL) spirochaetes were identified in this area for the first time. B. valaisiana and B. spielmanii were significantly less present in male than in female or nymphal ticks. Mixed infection with RFL spirochaetes and Lyme borreliosis spirochaetes were detected in 4 ticks. In addition, the set of probes could identify the recently described species, B. bavariensis.

Human Lyme disease vaccines: past and future concerns

The development of a vaccine for Lyme disease was intensely pursued in the 1990s. However, citing a lack of demand, the first human Lyme disease vaccine was withdrawn from the market less than 5 years after its approval. The public's concerns about the vaccine's safety also likely contributed to the withdrawal of the vaccine. Nearly a decade later, no vaccine for human Lyme disease exists. The expansion of Lyme disease's endemic range, as well as the difficulty of diagnosing infection and the disease's steady increase in incidence in the face of proven preventative measures, make the pursuit of a Lyme disease vaccine a worthwhile endeavor. Many believe that the negative public perception of the Lyme disease vaccine will have tarnished any future endeavors towards its development. Importantly, many of the drawbacks of the Lyme disease vaccine were apparent or foreseeable prior to its approval. These pitfalls must be confronted before the construction of a new, effective and safe human Lyme disease vaccine.

Biological aspects of Lyme disease spirochetes: unique bacteria of the Borrelia burgdorferi species group

BACKGROUND

Borrelia burgdorferi sensu lato is a group of at least twelve closely related species some of which are responsible for Lyme disease, the most frequent zoonosis in Europe and the USA. Many of the biological features of Borrelia are unique in prokaryotes and very interesting not only from the medical viewpoint but also from the view of molecular biology.

METHODS

Relevant recent articles were searched using PubMed and Google search tools.

RESULTS AND CONCLUSION

This is a review of the biological, genetic and physiological features of the spirochete species group, Borrelia burgdorferi sensu lato. In spite of a lot of recent articles focused on B. burgdorferi sensu lato, many features of Borrelia biology remain obscure. It is one of the main reasons for persisting problems with prevention, diagnosis and therapy of Lyme disease. The aim of the review is to summarize ongoing current knowledge into a lucid and comprehensible form.

Borrelia bissettii isolates induce pathology in a murine model of disease

The spirochete Borrelia burgdorferi is a tick-borne pathogen that causes Lyme disease. Although B. burgdorferi sensu lato is a diverse group of bacteria, only three genospecies, B. burgdorferi sensu stricto, Borrelia afzelii, and Borrelia garinii, are known to be pathogenic and commonly recognized to cause human disease. To assess the potential of another common genospecies, Borrelia bissettii, to induce disease, a mouse model was employed. Two Colorado isolates of B. bissettii (CO-Bb) induced lesions of the bladder, heart, and femorotibial joint 8 weeks after inoculation into mice. In contrast, two British Columbia (BC-Bb) isolates, could not be cultured or amplified by PCR from target organs, and did not induce lesions. Consistent with pathology and culture results, the antibody response in mice to BC-Bb was minimal compared to CO-Bb, indicating either transient localized infection or rapid immune clearance of BC-Bb. Although sequence analysis of the rrf (5S)-rrl (23S) intergenic spacer region indicated 99% homology between CO-Bb and BC-Bb, polyacrylamide gel electrophoresis (PAGE) analysis indicated five distinct protein differences between these low-passage isolates. These studies support the prospect that B. bissettii may indeed be the causative agent of Lyme borreliosis cases in Eastern Europe, associated with the atypical Borrelia strain 25015, and in other regions. To our knowledge, this is the first evidence that B. bissettii can induce pathology in a vertebrate host.