Detection of Borrelia burgdorferi sensu lato species in host-seeking Ixodes species ticks in the United States

Lyme disease is the most commonly reported vector-borne disease in the United States and is transmitted by Ixodes scapularis in the eastern US and I. pacificus in the west. The causative agents, Borrelia burgdorferi sensu stricto (Bbss) and B. mayonii belong to the B. burgdorferi sensu lato (Bbsl) species complex. An additional eight species of Bbsl have been identified in Ixodes species ticks in the US, but their geographic distribution, vector associations, human encounter rates and pathogenicity in humans are poorly defined. To better understand the geographic distribution and vector associations of Bbsl spirochetes in frequent and infrequent human-biting Ixodes species ticks in the US, we previously screened 29,517 host-seeking I. scapularis or I. pacificus ticks and 692 ticks belonging to eight other Ixodes species for Borrelia spirochetes using a previously described tick testing algorithm that utilizes a combination of real-time PCR and Sanger sequencing for Borrelia species identification. The assay was designed to detect known human pathogens spread by Ixodes species ticks, but it was not optimized to detect Bbsl co-infections. To determine if such co-infections were overlooked particularly in ticks infected with Bbss, we retested and analyzed a subsample of 845 Borrelia infected ticks using a next generation sequencing multiplex PCR amplicon sequencing (MPAS) assay that can identify Borrelia species and Bbsl co-infections. The assay also includes targets that can molecularly confirm identifications of Ixodes species ticks to better inform pathogen-vector associations. We show that Bbss is the most prevalent species in I. scapularis and I. pacificus; other Bbsl species were rarely detected in I. scapularis and the only Bbsl co-infections identified in I. scapularis were with Bbss and B. mayonii. We detected B. andersonii in I. dentatus in the Mid-Atlantic and Upper Midwest regions, B. kurtenbachii in I. scapularis in the Upper Midwest, B. bissettiae in I. pacificus and I. spinipalpis in the Northwest, and B. carolinensis in I. affinis in the Mid-Atlantic and Southeast, and B. lanei in I. spinipalpis in the Northwest. Twelve of 62 (19.4%) Borrelia-infected I. affinis from the Mid-Atlantic region were co-infected with Bbss and B. carolinensis. Our data support the notion that Bbsl species are maintained in largely independent enzootic cycles, with occasional spill-over resulting in multiple Bbsl species detected in Ixodes species ticks.

Unexpected failure of Ixodes scapularis nymphs to transmit a North American Borrelia bissettiae strain

Globally, the Borrelia burgdorferi (sensu lato) complex comprises more than 21 species of spirochetes. Although the USA is home to a diverse fauna of Lyme disease group Borrelia species, only two are considered responsible for human clinical disease: Borrelia burgdorferi (sensu stricto) and Borrelia mayonii. However, evidence has implicated additional B. burgdorferi (s.l.) species in human illness elsewhere. While much research has focused on the B. burgdorferi (s.s.)-tick interface, tick vectors for most of the other North American Lyme disease group Borrelia species remain experimentally unconfirmed. In this report we document the ability of Ixodes scapularis to acquire but not transmit a single strain of Borrelia bissettiae, a potential human pathogen, in a murine infection model. Pathogen-free I. scapularis larvae were allowed to feed on mice with disseminated B. burgdorferi (s.s.) or B. bissettiae infections. Molted infected nymphs were then allowed to feed on naïve mice to assess transmission to a susceptible host through spirochete culture and qPCR throughout in ticks collected at various developmental stages (fed larvae and nymphs, molted nymphs, and adults). In this study, similar proportions of I. scapularis larvae acquired B. bissettiae and B. burgdorferi (s.s.) but transstadial passage to the nymphal stage was less effective for B. bissettiae. Furthermore, B. bissettiae-infected nymphs did not transmit B. bissettiae infection to naïve susceptible mice as determined by tissue culture and serology. In the tick, B. bissettiae spirochete levels slightly increased from fed larvae to molted and then fed nymphs, yet the bacteria were absent in molted adults. Moreover, in contrast to B. burgdorferi (s.s.), B. bissettiae failed to exponentially increase in upon completion of feeding in our transmission experiment. In this specific model, I. scapularis was unable to support B. bissettiae throughout its life-cycle, and while live spirochetes were detected in B. bissettiae-infected ticks fed on naïve mice, there was no evidence of murine infection. These data question the vector competence of Ixodes scapularis for B. bissettiae. More importantly, this specific B. bissettiae-I. scapularis model may provide a tool for researchers to delineate details on mechanisms involved in Borrelia-tick compatibility.

Humans infested with Ixodes ricinus are exposed to a diverse array of tick-borne pathogens in Serbia

Tick-borne pathogens (TBPs) pose a major threat to human health in Europe and the whole northern hemisphere. Despite a high prevalence of TBPs in Ixodes ricinus ticks, knowledge on the incidence of tick-borne diseases in humans infested by this tick species is limited. This study was conducted in the year 2019 on patients who presented themselves to the Pasteur Institute Novi Sad with tick infestations. Ticks (n = 31) feeding on human (n = 30) and blood samples from the same individuals were collected by physicians and a microfluidic real-time high-throughput PCR system was used to test the genomic DNA of the samples for the presence of 27 bacterial and eight parasitic microorganisms in Serbia. Except for one Rhipicephalus sanguineus s.l. adult male tick, all ticks infesting humans were morphologically identified as I. ricinus. A high proportion of ticks (74 %, 23/31) were infected with at least one of the tested TB microorganisms, being Rickettsia helvetica (54 %, 17/31) the most common pathogen, but Borrelia afzelii (9 %, 3/31), Anaplasma phagocytophilum (6 %, 2/31), Borrelia miyamotoi (6 %, 2/31), and Francisella like-endosymbiont (6 %, 2/31), Borrelia valaisiana (3 %, 1/31), Borrelia lusitaniae (3 %, 1/31), Rickettsia felis (3 %, 1/31) and Rickettsia aeschlimannii (3 %, 1/31) were also identified. Despite the high infection rate of TBPs in ticks, only two human blood samples (6 %, 2/30) tested positive for the presence of TBPs, one patient (code H12, 67 years old female) was diagnosed with Borrelia spp. and the other patient was diagnosed (code H17, 71 years old female) with R. felis infection. The tick infesting patient H12 tested positive for B. afzelii, and R. helvetica and the tick infesting patient H17 tested positive for R. felis. Upon clinical examination, both patients were diagnosed with erythema migrans. No additional discomfort was reported by the patient and no additional pathology was observed by the physician. We concluded that humans bitten by I. ricinus in Serbia are exposed to a diverse array of TBPs with clinical impact in the Serbian cohort studied.

Cytokine Expression Patterns and Single Nucleotide Polymorphisms (SNPs) in Patients with Chronic Borreliosis

(1) Background: Genetically based hyperinflammation may play a role in pathogen defense. We here questioned whether alterations in circulating monocytes/macrophages, inflammatory biomarkers and a functional SNP (single nucleotide polymorphisms) of the Interleukin-6 (IL-6) promotor might play a role in patients with persistent, and treatment resistant borreliosis. (2) Methods: Leukocyte subpopulations were studied by flow cytometry; plasma cytokines were determined by a chemiluminescence based ELISA (Immulite^®), and genotypes of the IL-6 promotor SNP rs1800795 were determined by pyrosequencing. (3) Results: In a cohort of n = 107 Lyme borreliosis patients, who concomitantly manifested either malignant diseases (group 1), autoimmune disorders (group 2), neurological diseases (group 3), or morbidities caused by multiple other infectious complications (group 4), we found decreased numbers of anti-inflammatory CD163-positive macrophages, elevated concentrations of inflammatory cytokines, and an imbalance of IL-6 promotor SNP rs1800795 genotypes. The most prominently upregulated cytokines were IL-1β, and IL-8. (4) Conclusions: Increased pro-inflammatory phenotypes identified by monocyte/macrophage subtypes and concomitantly increased cytokines appear to be valid to monitor disease activity in patients with persistent Lyme borreliosis. Patterns may vary by additional co-morbidities. In patients with autoimmune diseases, increased frequencies of a heterozygous IL-6 promotor SNP rs1800795 were identified. This functional SNP may guide chronic inflammation, impacting other cytokines to trigger trigger chronicity and therapeutic resistance in Lyme borreliosis.

Phylogeography of Borrelia spirochetes in Ixodes pacificus and Ixodes spinipalpis ticks highlights differential acarological risk of tick-borne disease transmission in northern versus southern California

The common human-biting tick, Ixodes pacificus, is the primary vector of the Lyme disease spirochete, Borrelia burgdorferi sensu stricto (ss) in western North America and has been found to harbor other closely-related spirochetes in the Borrelia burgdorferi sensu lato (sl) complex. Between 2008–2015, 11,066 adult and 3,815 nymphal I. pacificus and five adult and 144 nymphal Ixodes spinpalpis, a commonly collected wildlife tick, were collected from 42 California counties. Borrelia burgdorferi sl was detected in 1.2% and 3.8% I. pacificus adults and nymphs, respectively. Results from this study indicate genetic diversity and geographic structure of B. burgdorferi sl in California I. pacificus ticks, by sequence comparison of the16S rRNA gene, with B. burgdorferi ss, the agent of Lyme disease, found only in I. pacificus collected from the north and central coastal and Sierra Nevada foothill regions; B. burgdorferi ss was not detected in ticks tested from southern California. In contrast, Borrelia bissettiae, a member of the B. burgdorferi sl complex, was detected in both I. pacificus and I. spinipalpis, in the coastal region of both northern and southern California, but was absent from ticks in the Sierra Nevada foothills. In a similar pattern to B. bissettiae, Borrelia americana (a member of the B. burgdorferi sl complex) was detected in a single adult I. pacificus from the north coast and two I. spinipalpis nymphs from south-coastal California. This study highlights that the geographic area of Lyme disease acarological risk in California is the north-central and Sierra Nevada foothill regions of the state with little to no risk in the southern regions of the state.

Metabolic differentiation of early Lyme disease from southern tick-associated rash illness (STARI)

Lyme disease, the most commonly reported vector-borne disease in the United States, results from infection with Borrelia burgdorferi. Early clinical diagnosis of this disease is largely based on the presence of an erythematous skin lesion for individuals in high-risk regions. This, however, can be confused with other illnesses including southern tick-associated rash illness (STARI), an illness that lacks a defined etiological agent or laboratory diagnostic test, and is coprevalent with Lyme disease in portions of the eastern United States. By applying an unbiased metabolomics approach with sera retrospectively obtained from well-characterized patients, we defined biochemical and diagnostic differences between early Lyme disease and STARI. Specifically, a metabolic biosignature consisting of 261 molecular features (MFs) revealed that altered N-acyl ethanolamine and primary fatty acid amide metabolism discriminated early Lyme disease from STARI. Development of classification models with the 261-MF biosignature and testing against validation samples differentiated early Lyme disease from STARI with an accuracy of 85 to 98%. These findings revealed metabolic dissimilarity between early Lyme disease and STARI, and provide a powerful and new approach to inform patient management by objectively distinguishing early Lyme disease from an illness with nearly identical symptoms.

Spatial clustering of Borrelia burgdorferi sensu lato within populations of Allen's chipmunks and dusky-footed woodrats in northwestern California

The ecology of Lyme borreliosis is complex in northwestern California, with several potential reservoir hosts, tick vectors, and genospecies of Borrelia burgdorferi sensu lato. The primary objective of this study was to determine the fine-scale spatial distribution of different genospecies in four rodent species, the California ground squirrel (Otospermophilus beecheyi), northern flying squirrel (Glaucomys sabrinus), dusky-footed woodrat (Neotoma fuscipes), and Allen's chipmunk (Neotamias senex). Rodents were live-trapped between June 2004 and May 2005 at the Hoopa Valley Tribal Reservation (HVTR) in Humboldt County, California. Ear-punch biopsies obtained from each rodent were tested by polymerase chain reaction (PCR) and sequencing analysis. The programs ArcGIS and SaTScan were used to examine the spatial distribution of genospecies. Multinomial log-linear models were used to model habitat and host-specific characteristics and their effect on the presence of each borrelial genospecies. The Akaike information criterion (AICc) was used to compare models and determine model fit. Borrelia burgdorferi sensu stricto was primarily associated with chipmunks and B. bissettiae largely with woodrats. The top model included the variables "host species", "month", and "elevation" (weight = 0.84). Spatial clustering of B. bissettiae was detected in the northwestern section of the HVTR, whereas B. burgdorferi sensu stricto was clustered in the southeastern section. We conclude that the spatial distribution of these borreliae are driven at least in part by host species, time-of-year, and elevation.

Cerebrospinal Fluid B-lymphocyte Chemoattractant CXCL13 in the Diagnosis of Acute Lyme Neuroborreliosis in Children

BACKGROUND

Current markers of Lyme neuroborreliosis (LNB) in children have insufficient sensitivity in the early stage of disease. The B-lymphocyte chemoattractant CXCL13 in the cerebrospinal fluid (CSF) may be useful in diagnosing LNB, but its specificity has not been evaluated in studies including children with clinically relevant differential diagnoses. The aim of this study was to elucidate the diagnostic value of CSF CXCL13 in children with symptoms suggestive of LNB.

METHODS

Children with symptoms suggestive of LNB were included prospectively into predefined groups with a high or low likelihood of LNB based on CSF pleocytosis and the detection of Borrelia antibodies or other causative agents. CSF CXCL13 levels were compared between the groups, and receiver-operating characteristic analyses were performed to indicate optimal cutoff levels to discriminate LNB from non-LNB conditions.

RESULTS

Two hundred and ten children were included. Children with confirmed LNB (n=59) and probable LNB (n=18) had higher CSF CXCL13 levels than children with possible LNB (n=7), possible peripheral LNB (n=7), non-Lyme aseptic meningitis (n=12), non-meningitis (n=91) and negative controls (n=16). Using 18 pg/mL as a cutoff level, both the sensitivity and specificity of CSF CXCL13 for LNB (confirmed and probable) were 97%. Comparing only children with LNB and non-Lyme aseptic meningitis, the sensitivity and specificity with the same cutoff level were 97% and 83%, respectively.

CONCLUSION

CSF CXCL13 is a sensitive marker of LNB in children. The specificity to discriminate LNB from non-Lyme aseptic meningitis may be more moderate, suggesting that CSF CXCL13 should be used together with other variables in diagnosing LNB in children.

Borrelia Diversity and Co-infection with Other Tick Borne Pathogens in Ticks

Identifying Borrelia burgdorferi as the causative agent of Lyme disease in 1981 was a watershed moment in understanding the major impact that tick-borne zoonoses can have on public health worldwide, particularly in Europe and the USA. The medical importance of tick-borne diseases has long since been acknowledged, yet little is known regarding the occurrence of emerging tick-borne pathogens such as Borrelia spp., Anaplasma phagocytophilum, Rickettsia spp., Bartonella spp., “Candidatus Neoehrlichia mikurensis”, and tick-borne encephalitis virus in questing ticks in Romania, a gateway into Europe. The objective of our study was to identify the infection and co-infection rates of different Borrelia genospecies along with other tick-borne pathogens in questing ticks collected from three geographically distinct areas in eastern Romania. We collected 557 questing adult and nymph ticks of three different species (534 Ixodes ricinus, 19 Haemaphysalis punctata, and 4 Dermacentor reticulatus) from three areas in Romania. We analyzed ticks individually for the presence of eight different Borrelia genospecies with high-throughput real-time PCR. Ticks with Borrelia were then tested for possible co-infections with A. phagocytophilum, Rickettsia spp., Bartonella spp., “Candidatus Neoehrlichia mikurensis”, and tick-borne encephalitis virus. Borrelia spp. was detected in I. ricinus ticks from all sampling areas, with global prevalence rates of 25.8%. All eight Borrelia genospecies were detected in I. ricinus ticks: Borrelia garinii (14.8%), B. afzelii (8.8%), B. valaisiana (5.1%), B. lusitaniae (4.9%), B. miyamotoi (0.9%), B. burgdorferi s.s (0.4%), and B. bissettii (0.2%). Regarding pathogen co-infection 64.5% of infected I. ricinus were positive for more than one pathogen. Associations between different Borrelia genospecies were detected in 9.7% of ticks, and 6.9% of I. ricinus ticks tested positive for co-infection of Borrelia spp. with other tick-borne pathogens. The most common association was between B. garinii and B. afzelii (4.3%), followed by B. garinii and B. lusitaniae (3.0%). The most frequent dual co-infections were between Borrelia spp. and Rickettsia spp., (1.3%), and between Borrelia spp. and “Candidatus Neoehrlichia mikurensis” (1.3%). The diversity of tick-borne pathogens detected in this study and the frequency of co-infections should influence all infection risk evaluations following a tick bite.

Molecular Testing in Emerging Infectious Diseases

It was widely believed in the late 1960s that infectious diseases had been conquered by vaccines and antibiotics and humans were no longer under threat by microbial pathogens. Yet, since that time more than 60 pathogens have been discovered that can cause serious emerging infectious diseases. Molecular methods have played critical roles in the discovery, monitoring, and clinical diagnostics of emerging pathogens. In this chapter, we present well-recognized emerging pathogens. We provide examples of the utility of molecular assays in research and clinical care of emerging infectious diseases. We also discuss some theoretical and practical limitations of molecular tests and the future prospects of expanding molecular diagnostics for emerging pathogens based on new advances of knowledge and technologies.

Stable Transmission of Borrelia burgdorferi Sensu Stricto on the Outer Banks of North Carolina

The spirochaete (Borrelia burgdorferi) associated with Lyme disease was detected in questing ticks and rodents during a period of 18 years, 1991-2009, at five locations on the Outer Banks of North Carolina. The black-legged tick (Ixodes scapularis) was collected at varied intervals between 1991 and 2009 and examined for B. burgdorferi. The white-footed mouse (Peromyscus leucopus), house mouse (Mus musculus) marsh rice rat (Oryzomys palustris), marsh rabbit (Sylvilagus palustris), eastern cottontail (Sylvilagus floridanus) and six-lined racerunner (Cnemidophorus sexlineatus) were live-trapped, and their tissues cultured to isolate spirochaetes. Borrelia burgdorferi isolates were obtained from questing adult I. scapularis and engorged I. scapularis removed from P. leucopus, O. palustris and S. floridanus. The prevalence of B. burgdorferi infection was variable at different times and sites ranging from 7 to 14% of examined questing I. scapularis. Mitochondrial (16S) rRNA gene phylogenetic analysis from 65 adult I. scapularis identified 12 haplotypes in two major clades. Nine haplotypes were associated with northern/Midwestern I. scapularis populations and three with southern I. scapularis populations. Sixteen isolates obtained from tick hosts in 2005 were confirmed to be B. burgdorferi by amplifying and sequencing of 16S rRNA and 5S-23S intergenic spacer fragments. The sequences had 98-99% identity to B. burgdorferi sensu stricto strains B31, JD1 and M11p. Taken together, these studies indicate that B. burgdorferi sensu stricto is endemic in questing I. scapularis and mammalian tick hosts on the Outer Banks of North Carolina.

Borrelia burgdorferi sensu lato in Ixodes cf. neuquenensis and Ixodes sigelos ticks from the Patagonian region of Argentina

This study was conducted to detect Borrelia burgdorferi sensu lato infection in ixodid ticks from the Patagonia region in the south of Argentina. Therefore, ticks were collected on rodents in the provinces of Chubut, Río Negro and Santa Cruz. These ticks were identified as nymphs of Ixodes cf. neuquenensis and Ixodes sigelos. The B. burgdorferi s.l. infection was tested by a battery of PCR methods targeting the gene flagellin (fla) and the rrfA-rrlB intergenic spacer region (IGS). Three pools of I. sigelos nymphs from Chubut and Santa Cruz provinces as well as one pool of I. cf. neuquenensis nymphs from Río Negro province were tested positive in the fla-PCR. The samples of I. sigelos were also positive for the IGS-PCR. Phylogenetically, the haplotypes found in the positive ticks belong to the B. burgdorferi s.l. complex, and they were closely related to Borrelia chilensis, a genospecies isolated from Ixodes stilesi in Chile. The pathogenic relevance of the Borrelia genospecies detected in both I. neuquenensis and I. sigelos is unknown.

Seroprevalence of Borrelia burgdorferi antibodies in white-tailed deer from Texas

Lyme Disease is caused by the bacterial pathogen Borrelia burgdorferi, and is transmitted by the tick-vector Ixodes scapularis. It is the most prevalent arthropod-borne disease in the United States. To determine the seroprevalence of B. burgdorferi antibodies in white-tailed deer (Odocoileus virginianus) from Texas, we analyzed serum samples (n = 1493) collected during the 2001–2015 hunting seasons, using indirect ELISA. Samples with higher sero-reactivity (0.803 and above) than the negative control group (0.662) were further tested using a more specific standardized western immunoblot assay to rule out false positives. Using ELISA, 4.7% of the samples were sero-reactive against B. burgdorferi, and these originated in two eco-regions in Texas (Edwards Plateau and South Texas Plains). However, only 0.5% of the total samples were sero-reactive by standardized western immunoblot assay. Additionally, both ELISA and standardized western immunoblot assay results correlated with an increased incidence in human Lyme Disease cases reported in Texas. This is the first longitudinal study to demonstrate fluctuation in sero-reactivity of white-tailed deer to B. burgdorferi sensu stricto antigens in southern United States. Future ecological and geographical studies are needed to assess the environmental factors governing the prevalence of Lyme Disease in non-endemic areas of the southern United States.

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White-tailed deer serum samples were analyzed for anti Borrelia burgdorferi IgG.

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This is the first 15-year longitudinal study reported in Texas, and provides data previously unavailable within the study of Lyme disease ecology.

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White-tailed deer population density might be critical to sero-prevalence.

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Further pathogenic landscape studies on Lyme disease in Texas are recommended.

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Databased Lyme disease ecology models in Texas can be developed.

Prevalence of the Lyme Disease Spirochete, Borrelia burgdorferi, in Blacklegged Ticks, Ixodes scapularis at Hamilton-Wentworth, Ontario

Lyme disease has emerged as a major health concern in Canada, where the etiological agent, Borrelia burgdorferi sensu lato (s.l.), a spirochetal bacterium, is typically spread by the bite of certain ticks. This study explores the presence of B. burgdorferi s.l. in blacklegged ticks, Ixodes scapularis, collected at Dundas, Ontario (a locality within the region of Hamilton-Wentworth). Using passive surveillance, veterinarians and pet groomers were asked to collect blacklegged ticks from dogs and cats with no history of travel. Additionally, I. scapularis specimens were submitted from local residents and collected by flagging. Overall, 12 (41%) of 29 blacklegged ticks were infected with B. burgdorferi s.l. Using polymerase chain reaction (PCR) and DNA sequencing, two borrelial amplicons were characterized as B. burgdorferi sensu stricto (s.s.), a genospecies pathogenic to humans and certain domestic animals. Notably, three different vertebrate hosts each had two engorged I. scapularis females removed on the same day and, likewise, one cat had three repeat occurrences of this tick species. These multiple infestations suggest that a population of I. scapularis may be established in this area. The local public health unit has been underreporting the presence of B. burgdorferi s.l.-infected I. scapularis in the area encompassing Dundas. Our findings raise concerns about the need to erect tick warning signs in parkland areas. Veterinarians, medical professionals, public health officials, and the general public must be vigilant that Lyme disease-carrying blacklegged ticks pose a public health risk in the Dundas area and the surrounding Hamilton-Wentworth region.

Lyme neuroborreliosis-epidemiology, diagnosis and management

Lyme disease, caused by the Borrelia burgdorferi bacterium, is the most common vector-borne disease in the northern hemisphere. The clinical presentation varies with disease stage, and neurological manifestations (often referred to as Lyme neuroborreliosis) are reported in up to 12% of patients with Lyme disease. Most aspects of the epidemiology, clinical manifestation and treatment of Lyme neuroborreliosis are well known and accepted; only the management of so-called chronic Lyme disease is surrounded by considerable controversy. This term is used for disparate patient groups, including those who have untreated late-stage infection (for example, late neuroborreliosis), those with subjective symptoms that persist after treatment (termed 'post-treatment Lyme disease syndrome' [PTLDS]), and those with unexplained subjective complaints that may or may not be accompanied by positive test results for B. burgdorferi infection in serum (here called 'chronic Lyme disease'). The incidence of PTLDS is still a matter of debate, and its pathogenesis is unclear, but there is evidence that these patients do not have ongoing B. burgdorferi infection and, thus, do not benefit from additional antibiotic therapy. Chronic Lyme disease lacks an accepted clinical definition, and most patients who receive this diagnosis have other illnesses. Thus, a careful diagnostic work-up is needed to ensure proper treatment.

Borrelia burgdorferi not confirmed in human-biting Amblyomma americanum ticks from the southeastern United States

The predominant human-biting tick throughout the southeastern United States is Amblyomma americanum. Its ability to transmit pathogens causing Lyme disease-like illnesses is a subject of ongoing controversy. Results of previous testing by the Department of Defense Human Tick Test Kit Program and other laboratories indicated that it is highly unlikely that A. americanum transmits any pathogen that causes Lyme disease. In contrast, a recent publication by Clark and colleagues (K. L. Clark, B. Leydet, and S. Hartman, Int. J. Med. Sci. 10:915-931, 2013) reported detection of Lyme group Borrelia in A. americanum using a nested-flagellin-gene PCR. We evaluated this assay by using it and other assays to test 1,097 A. americanum ticks collected from humans. Using the Clark assay, in most samples we observed nonspecific amplification and nonrepeatability of results on subsequent testing of samples. Lack of reaction specificity and repeatability is consistent with mispriming, likely due to high primer concentrations and low annealing temperatures in this protocol. In six suspect-positive samples, Borrelia lonestari was identified by sequencing of an independent gene region; this is not a Lyme group spirochete and is not considered zoonotic. B. burgdorferi was weakly amplified from one pool using some assays, but not others, and attempts to sequence the amplicon of this pool failed, as did attempts to amplify and sequence B. burgdorferi from the five individual samples comprising this pool. Therefore, B. burgdorferi was not confirmed in any sample. Our results do not support the hypothesis that A. americanum ticks are a vector for Lyme group Borrelia infections.

Prevalence of Borrelia burgdorferi-infected ticks from wildlife hosts, a response to Norris et al

In a recent Letter to the Editor, Norris et al. questioned the validity of some of our data reported by Feria-Arroyo et al. The main issue investigated by us was the potential impact of climate change on the probable distribution of the tick vector Ixodes scapularis in the Texas-Mexico transboundary region. As an ancillary issue, an analysis of sequence data for the intergenic spacer of Borrelia burgdorferi was conducted. In the present letter, we provide further evidence supporting our original results, and advocate that extensive study of the population genetics of B. burgdorferi is needed in the Texas-Mexico transboundary region.

Relevance of chronic lyme disease to family medicine as a complex multidimensional chronic disease construct: a systematic review

Lyme disease has become a global public health problem and a prototype of an emerging infection. Both treatment-refractory infection and symptoms that are related to Borrelia burgdorferi infection remain subject to controversy. Because of the absence of solid evidence on prevalence, causes, diagnostic criteria, tools and treatment options, the role of autoimmunity to residual or persisting antigens, and the role of a toxin or other bacterial-associated products that are responsible for the symptoms and signs, chronic Lyme disease (CLD) remains a relatively poorly understood chronic disease construct. The role and performance of family medicine in the detection, integrative treatment, and follow-up of CLD are not well studied either. The purpose of this paper is to describe insights into the complexity of CLD as a multidimensional chronic disease construct and its relevance to family medicine by means of a systematic literature review.

The Western progression of lyme disease: infectious and Nonclonal Borrelia burgdorferi Sensu Lato populations in Grand Forks County, North Dakota

Scant attention has been paid to Lyme disease, Borrelia burgdorferi, Ixodes scapularis, or reservoirs in eastern North Dakota despite the fact that it borders high-risk counties in Minnesota. Recent reports of B. burgdorferi and I. scapularis in North Dakota, however, prompted a more detailed examination. Spirochetes cultured from the hearts of five rodents trapped in Grand Forks County, ND, were identified as B. burgdorferi sensu lato through sequence analyses of the 16S rRNA gene, the 16S rRNA gene-ileT intergenic spacer region, flaB, ospA, ospC, and p66. OspC typing revealed the presence of groups A, B, E, F, L, and I. Two rodents were concurrently carrying multiple OspC types. Multilocus sequence typing suggested the eastern North Dakota strains are most closely related to those found in neighboring regions of the upper Midwest and Canada. BALB/c mice were infected with B. burgdorferi isolate M3 (OspC group B) by needle inoculation or tick bite. Tibiotarsal joints and ear pinnae were culture positive, and B. burgdorferi M3 was detected by quantitative PCR (qPCR) in the tibiotarsal joints, hearts, and ear pinnae of infected mice. Uninfected larval I. scapularis ticks were able to acquire B. burgdorferi M3 from infected mice; M3 was maintained in I. scapularis during the molt from larva to nymph; and further, M3 was transmitted from infected I. scapularis nymphs to naive mice, as evidenced by cultures and qPCR analyses. These results demonstrate that isolate M3 is capable of disseminated infection by both artificial and natural routes of infection. This study confirms the presence of unique (nonclonal) and infectious B. burgdorferi populations in eastern North Dakota.

A comparison of lyme disease serologic test results from 4 laboratories in patients with persistent symptoms after antibiotic treatment

BACKGROUND

As the incidence of Lyme disease (LD) has increased, a number of "Lyme specialty laboratories" have emerged, claiming singular expertise in LD testing. We investigated the degree of interlaboratory variability of several LD serologic tests-whole cell sonicate (WCS) enzyme-linked immunosorbent assay (ELISA), immunoglobulin M (IgM) and immunoglobulin G (IgG) Western blots (WBs), and an ELISA based on the conserved sixth region of variable major protein-like sequence expressed (C6)-that were performed at 1 university laboratory, 1 commercial laboratory, and 2 laboratories that specialize in LD testing.

METHODS

Serum samples from 37 patients with posttreatment Lyme syndrome, as well as 40 medically healthy controls without prior LD, were tested independently at the 4 laboratories.

RESULTS

In general, there was little difference among the laboratories in the percentage of positive test results on the ELISAs and IgG WBs, although the number of discordant results was often high. When in-house criteria for positivity were used at the 2 specialty laboratories, specificity at 1 laboratory declined considerably on both the IgM and IgG WBs. The Centers for Disease Control and Prevention (CDC) 2-tiered criteria improved overall concordance. At the 2 laboratories that performed the C6 ELISA, the percentage of positive tests was comparable to that of the WCS ELISA while providing higher specificity. The IgM WB performed poorly in our patient population of individuals with later-stage illness, a result consistent with previous studies.

CONCLUSIONS

Although there was surprisingly little difference among the laboratories in percentage of positive results on most assays using CDC criteria, interlaboratory variability was considerable and remains a problem in LD testing.