Prevalence of Lyme borrelia in Ixodes persulcatus ticks from an area with a confirmed case of Lyme disease

Prevalence of three important tick-borne pathogens in ticks and humans in Shaanxi Province, Northwest China

The investigation of important prevalent tick-borne pathogens is central to the control of tick-borne diseases. To understand the prevalence of Borrelia burgdorferi s.l., Borrelia miyamotoi, and the Alongshan virus in ticks and patients in Shaanxi Province, China, a total of 670 adult ticks and 524 patient blood samples were collected in the region between 2022 and 2023. In this study, PCR was used to estimate the prevalence of the three pathogens. The results revealed that the overall positive rates of B. burgdorferi s.l, B. miyamotoi, and ALSV infection in the collected ticks were 13.58 %, 2.46 %, and 4.17 %, respectively. Three genospecies of B. burgdorferi s.l. were detected in this study, namely, B. garinii, B. afzelii, and B. bavariensis, with positive rates of 4.63 %, 3.58 %, and 5.37 %, respectively. The prevalence rates of B. miyamotoi, ALSV  and B. burgdorferi s.l. in the patients were 0.38 %, 0.95 %, and 15 %, respectively. Moreover, B. burgdorferi s.l. and ALSV coinfection was also detected in three patients. Evolutionary analysis revealed that the isolate of B. miyamotoi belongs to the Asian type (Siberian type) and that of ALSV is closely related to that of Finland. To our knowledge, this is the first report on B. miyamotoi and ALSV detection in both ticks and humans in Shaanxi Province; the prevalence indicates that the regions in this province might be endemic areas. The results also suggest that humans in these regions are at risk of infection with these three tick-borne diseases.

Molecular detection of Borrelia burgdorferi (sensu lato) and Rickettsia spp. in hard ticks distributed in Tokachi District, eastern Hokkaido, Japan

Ticks transmit various pathogens, including parasites, bacteria and viruses to humans and animals. To investigate the ticks and the potentially zoonotic pathogens that they may carry, questing ticks were collected in 2017 from 7 sites in Tokachi District, eastern Hokkaido, Japan. A total of 1563 ticks including adults (male and female), nymphs and larvae were collected. Four species of ticks were identified: Ixodes ovatus, Ixodes persulcatus, Haemaphysalis japonica and Haemaphysalis megaspinosa. Of the 1563 ticks, 1155 were used for DNA extraction. In total, 527 individual tick DNA samples prepared from adults (n = 484), nymphs (n = 41) and larvae (n = 2); and 67 pooled tick DNA samples prepared from larval stages (n = 628) were examined using PCR methods and sequencing to detect Borrelia burgdorferi (sensu lato) and Rickettsia spp. The phylogenetic analysis of Borrelia spp. flaB gene sequences showed the presence of the human pathogenic B. burgdorferi (s.l.) species (Borrelia garinii, Borrelia bavariensis and Borrelia afzelii) in I. persulcatus, whereas the non-pathogenic species Borrelia japonica was found only in I. ovatus. In I. persulcatus, B. garinii and/or its closely related species B. bavariensis was detected in both adults and nymphs at a prevalence of 21.9% whereas B. afzelii was found only in adults (1.8%). The prevalence of B. japonica in adult I. ovatus was 21.8%. Rickettsia species were identified through phylogenetic analysis based on gltA, 16S rRNA, ompB and sca4 genes. Four genotypes were detected in the samples which were classified into three species. The prevalence of human pathogenic Rickettsia helvetica was 26.0% in I. persulcatus adults and nymphs, 55.6% in I. persulcatus larval pools, and 1.7% in H. megaspinosa larval pools. The prevalence of “Candidatus R. tarasevichiae” was 15.4% in I. persulcatus adults and nymphs and 33.3% in I. persulcatus larval pools. The prevalence of “Candidatus R. principis” in H. megaspinosa adults and nymphs was 11.1% whereas it was detected in 3.4% of the H. megaspinosa larval pools. These results indicate that most of the risks of Lyme borreliosis and spotted fever group rickettsiosis infection in eastern Hokkaido, Japan, are restricted to I. persulcatus.

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Four species of ticks were collected in Tokachi District, eastern Hokkaido, Japan.

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Tick DNA samples were subjected to PCR to detect Borrelia spp. and Rickettsia spp.

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Borrelia garinii/Borrelia bavariensis and Borrelia afzelii were detected in Ixodes persulcatus.

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Rickettsia helvetica and “Candidatus R. tarasevichiae” were detected in I. persulcatus.

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First molecular detection of “Candidatus R. principis” in larvae of Haemaphysalis megaspinosa.

Borreliae Part 1: Borrelia Lyme Group and Echidna-Reptile Group

Simple Summary

Borreliae are spirochaetes, which represent a heterogeneous phylum within bacteria. Spirochaetes are indeed distinguished from other bacteria for their spiral shape, which also characterizes Borreliae. This review describes briefly the organization of the phylum Spirocheteales with a digression about its pathogenicity and historical information about bacteria isolation and characterization. Among spirochaetes, Borrelia genus is here divided into three groups, namely the Lyme group (LG), the Echidna-Reptile group (REPG) and the Relapsing Fever group (RFG). Borreliae Part 1 deals with Lyme group and Echidna-Reptile group Borreliae, while the subject of Borreliae Part 2 is Relapsing Fever group and unclassified Borreliae. Lyme group Borreliae is organized here in sections describing ecology, namely tick vectors and animal hosts, epidemiology, microbiology, and Borrelia genome organization and antigen characterization. Furthermore, the main clinical manifestations in Lyme borreliosis are also described. Although included in the Lyme group due to their particular clinical features, Borrelia causing Baggio Yoshinari syndrome and Borrelia mayonii are described in dedicated paragraphs. The Borrelia Echidna-Reptile group has been recently characterized including spirochaetes that apparently are not pathogenic to humans, but infect reptiles and amphibians. The paragraph dedicated to this group of Borreliae describes their vectors, hosts, geographical distribution and their characteristics.

Abstract

Borreliae are divided into three groups, namely the Lyme group (LG), the Echidna-Reptile group (REPG) and the Relapsing Fever group (RFG). Currently, only Borrelia of the Lyme and RF groups (not all) cause infection in humans. Borreliae of the Echidna-Reptile group represent a new monophyletic group of spirochaetes, which infect amphibians and reptiles. In addition to a general description of the phylum Spirochaetales, including a brief historical digression on spirochaetosis, in the present review Borreliae of Lyme and Echidna-Reptile groups are described, discussing the ecology with vectors and hosts as well as microbiological features and molecular characterization. Furthermore, differences between LG and RFG are discussed with respect to the clinical manifestations. In humans, LG Borreliae are organotropic and cause erythema migrans in the early phase of the disease, while RFG Borreliae give high spirochaetemia with fever, without the development of erythema migrans. With respect of LG Borreliae, recently Borrelia mayonii, with intermediate characteristics between LG and RFG, has been identified. As part of the LG, it gives erythema migrans but also high spirochaetemia with fever. Hard ticks are vectors for both LG and REPG groups, but in LG they are mostly Ixodes sp. ticks, while in REPG vectors do not belong to that genus.

Reconstruction of mitochondrial genomes from raw sequencing data provides insights on the phylogeny of Ixodes ticks and cautions for species misidentification

High-throughput sequencing (HTS) technology has profoundly been involved in sequencing whole genomes of several organisms in a fast and cost-effective manner. Although HTS provides an alternative biomonitoring method to the time-consuming and taxonomy-expertise dependent morphological approach, still we cannot rule out the possibility of the impediment and misidentification biases. In this article we aim to retrieve whole mitochondrial genome (mitogenome) sequences from publicly available raw sequencing data for phylogenetic comparison of Ixodes persulcatus. For this comparison, we sequenced whole mitogenomes of four I. persulcatus ticks from Japan and constructed mitogenomes from raw sequencing data of 74 I. persulcatus ticks from China. Bayesian phylogenetic trees were inferred by the concatenated fifteen mitochondrial genes. We further tested our results by the phylogenetic analysis of cytochrome c oxidase subunit 1 (cox1) gene and internal transcribed spacer 2 (ITS2) sequences. Our findings showed that 70 constructed mitogenomes from China were clustered with the sequenced four mitogenomes of I. persulcatus from Japan. We also revealed that mitogenome sequences retrieved from two data sets CRR142297 and CRR142298 were clustered with Ixodes nipponensis. Moreover, other two mitogenome sequences from CRR142310 and CRR142311 formed a clade with Ixodes pavlovskyi. The phylogenetic analysis of cox1 gene and ITS2 sequences confirmed the identification errors of these four samples. The overall phylogenetics in our study concluded that accurate morphological identification is necessary before implementing HTS to avoid any misidentification biases.

Large erythema migrans lesion in Lyme disease

This study reports a case of Lyme disease with a large erythema migrans in Hokkaido. This image aims at encouraging physicians to consider Lyme disease after tick bites, especially in endemic areas.

Failure of the Asian longhorned tick, Haemaphysalis longicornis, to serve as an experimental vector of the Lyme disease spirochete, Borrelia burgdorferi sensu stricto

The invasive, human-biting Asian longhorned tick, Haemaphysalis longicornis, was detected in New Jersey in the eastern United States in August of 2017 and by November of 2018 this tick had been recorded from 45 counties across 9 states, primarily along the Eastern Seaboard. The establishment of H. longicornis in the United States has raised the questions of how commonly it will bite humans and which native pathogens may naturally infect this tick. There also is a need for experimental vector competence studies with native pathogens to determine if H. longicornis can acquire a given pathogen while feeding, pass it transstadially, and then transmit the pathogen in the next life stage. In this experimental study, we evaluated the vector competence of a population of H. longicornis originating from the United States (New York) for a native isolate (B31) of the Lyme disease spirochete, Borrelia burgdorferi sensu stricto (s.s.). In agreement with a previous experimental study on the vector competence of H. longicornis for Borrelia garinii, we found that uninfected H. longicornis larvae could acquire B. burgdorferi s.s. while feeding on infected Mus musculus mice (infection prevalence >50% in freshly fed larvae) but that the infection was lost during the molt to the nymphal stage. None of 520 tested molted nymphs were found to be infected, indicating that transstadial passage of B. burgdorferi s.s. is absent or rare in H. longicornis; and based on the potential error associated with the number of nymphs testing negative in this study, we estimate that the upper 95% limit for infection prevalence was 0.73%. An Ixodes scapularis process control showed both effective acquisition of B. burgdorferi s.s. from infected mice by uninfected larvae and transstadial passage to the nymphal stage (infection prevalence of 80-82% for both freshly fed larvae and molted nymphs). We also observed that although H. longicornis larvae could be compelled to feed on mice by placing the ticks within feeding capsules, attachment and feeding success was minimal (<0.5%) when larvae were placed freely on the fur of the mice. We conclude that H. longicornis is unlikely to contribute more than minimally, if at all, to transmission of Lyme disease spirochetes in the United States.

Prevalence and Identification of Borrelia burgdorferi Sensu Lato Genospecies in Ticks from Northeastern China

Lyme disease is considered as one of important tick-transmitted zoonosis in northeastern China, where the causative agents, the Borrelia burgdorferi sensu lato (s.l.) complex, remain poorly characterized. The purpose of the present study was to determine the prevalence and genospecies of B. burgdorferi s.l. in ticks in northeastern China. In May, 2015, a total of 2785 unfed adult ticks were collected in the Jilin and Heilongjiang provinces of northeastern China, with the predominant tick species of Ixodes persulcatus (59.9%), followed by Haemaphysalis concinna (14.8%), Haemaphysalis longicornis (8.9%), Dermacentor nuttalli (9.4%), and Dermacentor silvarum (7.0%). Only I. persulcatus was tested positive for Borrelia spirochetes DNA by PCR, targeting the 5S-23S rRNA intergenic spacer and 16S rRNA genes, with a prevalence of 1.9%. Phylogenetic analysis based on the partial 5S-23S rRNA intergenic spacer and 16S rRNA genes showed that these positive samples were grouped into four pathogenic genospecies for humans, including Borrelia garinii (2.8%), Borrelia afzelii (0.2%), Borrelia bavariensis (0.1%), and Borrelia bissettii (0.1%). These results showed that B. garinii is the predominant genospecies and I. persulcatus is the main tick host and carrier in northeastern China. To our knowledge, B. bissettii were detected for the first time in China.

A case of Lyme disease in a Japanese woman

This report presents the case of a Japanese patient who developed Lyme disease. The patient was a 44-year-old woman who had general fatigue and the inability to open her mouth. She was initially suspected of having mild tetanus with lockjaw; however, she reported a past history of a tick bite while camping in the USA and had erythema migrans 2 months before this visit. Finally, Lyme disease was serologically confirmed. A few cases of Lyme disease are annually reported in Japan; however, this infectious disease should also be suspected.

Is there a Lyme-like disease in Australia? Summary of the findings to date

Lyme Borreliosis is a common tick-borne disease of the northern hemisphere caused by the spirochaetes of the Borrelia burgdorferi sensu lato (B. burgdorferi s. l.) complex. It results in multi-organ disease with arthritic, cardiac, neurological and dermatological manifestations. In the last twenty-five years there have been over 500 reports of an Australian Lyme-like syndrome in the scientific literature. However, the diagnoses of Lyme Borreliosis made in these cases have been primarily by clinical presentation and laboratory results of tentative reliability and the true cause of these illnesses remains unknown. A number of animals have been introduced to Australia that may act as B. burgdorferi s. l. reservoirs in Lyme-endemic countries, and there are some Australian Ixodes spp. and Haemaphysalis spp. ticks whose geographical distribution matches that of the Australian Lyme-like cases. Four published studies have searched for Borrelia in Australian ticks, with contradicting results. The cause of the potential Lyme-like disease in Australia remains to be defined. The evidence to date as to whether these illnesses are caused by a Borrelia species, another tick borne pathogen or are due to a novel or unrelated aetiology is summarised in this review.

Serological survey of Borrelia infection of dogs in Sapporo, Japan, where Borrelia garinii infection was previously detected

A serological survey of Borrelia infection of dogs was performed in Sapporo, Japan, where Borrelia garinii infection in dogs was detected in 2011. A total of 314 serum samples were collected from dogs that visited three animal hospitals in Sapporo from 2012 to 2014. The two-step evaluation method, involving screening ELISA followed by Western blot analysis, was used to detect antibodies against Borrelia species. A total of 34 samples were positive by ELISA. Among those 34 samples, 32 were positive for Borrelia spp. by Western blot. These findings suggest that the 32 dogs (10.2%) generated antibodies against Borrelia burgdorferi sensu lato, such as B. garinii or B. afzelii. Antibody positivity was 7.6% and 13.3% for dogs living in urban and rural areas, respectively. Dogs with a history of tick infestation showed a positive rate of 16.7%, which was higher, although not significantly, than the 6.7% among dogs without a history.

Identification and the preliminary in vitro characterization of IRIS homologue from salivary glands of Ixodes persulcatus Schulze

Ixodes ricinus immunosuppressor (Iris) is a tick salivary gland protein derived from I. ricinus. In this study, Iris homolog was identified in the salivary glands of Ixodes persulcatus, which is the specific vector of the Lyme disease agent in Japan. The homolog was named Ipis-1. To investigate the function of Ipis-1, we prepared a recombinant Ipis-1 expressed in COS-7 cells as a rabbit IgG Fc-fused protein (Ipis-1-Ig). Cell proliferation assay and IFN-γ ELISA showed that Ipis-1-Ig inhibits the proliferation and IFN-γ production of bovine peripheral blood mononuclear cells (PBMCs). Notably, Ipis-1-Ig inhibited the cell proliferation and production of IFN-γ in bovine PBMCs even when CD14(+) cells were depleted, suggesting that Ipis could directly interact with T cells and inhibit their functions. In conclusion, Ipis could contribute to the establishment of environments suitable for tick blood feeding and pathogen transmission by suppressing the function of immune cells.

An investigation of binding ability of Ixodes persulcatus Schulze Salp15 with Lyme disease spirochetes

Salp15, a 15-kDa tick salivary gland protein, has several suppressive modes of activity against host immunity and plays a critical role in the transmission of Lyme disease spirochetes in Ixodes scapularis and Ixodes ricinus, major vectors of Lyme disease in North America and Western Europe. Salp15 adheres to Borrelia burgdorferi and specifically interacts with its outer surface protein C (OspC), protecting the spirochete from antibody-mediated cytotoxicity and facilitating infection in the mice. Recently, we identified two Salp15 homologues, IperSalp15-1 and IperSalp15-2, in Ixodes persulcatus, a vector for Lyme disease in Japan. Here we describe the function of IperSalp15 in the transmission of Lyme borreliosis. To investigate the function of IperSalp15, recombinant IperSalp15-1 and IperSalp15-2 were prepared in bacterial and insect cells. Both were identified in the sera of tick-immunized hamsters, indicating that these are secretory proteins in exposed host animals. Solid-phase overlay and indirect fluorescence assays showed that IperSalp15 binds to OspC from B. burgdorferi, Borrelia garinii, and Borrelia afzelii. Importantly, this binding likely protected the spirochete from antibody-mediated cytotoxicity in vitro. In addition, IperSalp15 tended to facilitate infection in mice. Thus, further characterization of tick molecules, including IperSalp15, could lead to the development of new strategies to prevent the transmission of tick-borne diseases.

Rhipicephalus microplus and Ixodes ovatus cystatins in tick blood digestion and evasion of host immune response

BACKGROUND

Cystatins are a group of cysteine protease inhibitors responsible for physiological proteolysis regulation and present in a wide range of organisms. Studies about this class of inhibitors in parasites have contributed to clarify their roles in important physiological processes, like blood digestion and modulation of host immune response during blood feeding. Thus, cystatins are a subject of research on the development of new parasite control methods. Additionally, the characterization of proteins shared by different parasite species represents a valuable strategy to find potential targets in multi-species control methods. However, cystatin functions in ticks remain undetermined, especially in Rhipicephalus microplus and Ixodes ovatus, two species that affect livestock and human health, respectively.

METHODS

Here we report the inhibitory profile of two R. microplus (BrBmcys2b and BrBmcys2c) and one I. ovatus (JpIocys2a) cystatins to commercial cathepsins B, C, and L. The presence of native cystatins in R. microplus tissues was analyzed using sera against recombinant BrBmcys2b and BrBmcys2c. Also, a peptide from JpIocys2a was synthesized for rabbit immunization, and this serum was used to analyze the cross antigenicity between R. microplus and I. ovatus cystatins.

RESULTS

Enzymatic inhibition profile of tick cystatins shows a distinct modulation for cathepsins related to tick blood digestion and evasion of host immune response. Furthermore, BrBmcys2b was detected in saliva and different tissues along tick stages, while BrBmcys2c was detected mainly in gut from partially engorged R. microplus females, demonstrating a distinct pattern of cystatin expression, secretion and traffic between tick tissues. Moreover, phylogenetic analysis suggests that JpIocys2a belongs to the group of tick gut secreted cystatins. Finally, cross-antigenicity assays revealed that antibodies against the JpIocys2a peptide recognize native and recombinant R. microplus cystatins.

CONCLUSION

The presence of these proteins in different tissues and their ability to differentially inhibit cathepsins suggest distinct roles for JpIocys2a, BrBmcys2b, and BrBmcys2c in blood digestion, egg and larvae development, and modulation of host immune response in tick physiology. The cross-antigenicity between native and recombinant cystatins supports further experiments using JpIocys2a, BrBmcys2b, and BrBmcys2c as vaccine antigens.

Epidemiological features and clinical manifestations of Lyme borreliosis in Korea during the period 2005-2012

Lyme borreliosis is one of the most common tick-borne infections in the northern hemisphere. However, the epidemiological features and clinical manifestations of this disease in Korea are unknown. The present study is the first to investigate the characteristics of Lyme borreliosis in Korea. We traced suspected cases of Lyme borreliosis during the period 2005-2012. Of the 16 identified patients with the disease, 11 had acquired autochthonous infection within Korea, while 5 patients were infected outside Korea. The history of past exposure was investigated in 8 of the 11 patients with autochthonous infection; 5 of these 8 patients (62.5%) were suspected to have acquired the infection in the northeastern alpine region. Clinically, of 11 patients with autochthonous infection, 6 (54.5%) showed early skin manifestations, 4 (36.4%) showed neurological manifestations, and 1 (9.1%) showed acrodermatitis chronica atrophicans. In conclusion, Lyme borreliosis could be endemic in the northeastern alpine region of Korea, and neurological and early skin manifestations are likely to be the major clinical characteristics of autochthonous Lyme borreliosis in Korea.

A relapsing fever group Borrelia sp. similar to Borrelia lonestari found among wild sika deer (Cervus nippon yesoensis) and Haemaphysalis spp. ticks in Hokkaido, Japan

A relapsing fever Borrelia sp. similar to Borrelia lonestari (herein referred to as B. lonestari-like) was detected from wild sika deer (Cervus nippon yesoensis) and Haemaphysalis ticks in the eastern part of Hokkaido, Japan. The total prevalence of this Borrelia sp. in tested deer blood samples was 10.6% using conventional PCR and real-time PCR. The prevalence was significantly higher in deer fawns compared to adults (21.9% and 9.4%, respectively). Additionally, there was significant regional difference between our two sampling areas, Shiretoko and Shibetsu with 17% and 2.8% prevalence, respectively. Regional differences were also found in tick species collected from field and on deer. In the Shiretoko region, Haemaphysalis spp. were more abundant than Ixodes spp., while in Shibetsu, Ixodes spp. were more abundant. Using real-time PCR analysis, B. lonestari-like was detected from 2 out of 290 adult Haemaphysalis spp. ticks and 4 out of 76 pools of nymphs. This is the first report of a B. lonestari-like organism in Haemaphysalis spp. ticks, and the first phylogenetic analysis of this B. lonestari-like organism in Asia. Based on our results, Haemaphysalis spp. are the most likely candidates to act as a vector for B. lonestari-like; furthermore, regional variation of B. lonestari-like prevalence in sika deer may be dependent on the population distribution of these ticks.