Estimating the Frequency of Lyme Disease Diagnoses, United States, 2010-2018

Molecular Detection of Tick-Borne Pathogens in American Bison (Bison bison) at El Uno Ecological Reserve, Janos, Chihuahua, Mexico

American bison (Bison bison) is listed as near-threatened and in danger of extinction in Mexico. Recent studies have demonstrated the presence of several emerging pathogens at the Janos Biosphere Reserve (JBR), inhabited by one wild herd of American bison. Blood samples were collected from 26 American bison in the JBR. We tested for the presence of Anaplasma marginale, Babesia bigemina, B. bovis, Borrelia burgdorferi sensu lato, and Rickettsia rickettsii DNA using nested and semi-nested PCR protocols performing duplicates in two different laboratories. Results showed three animals (11.5%) positive for B. burgdorferi s. l., three more (11.5%) for Rickettsia rickettsii, and four (19.2%) for B. bovis. Two individuals were co-infected with B. burgdorferi s. l. and B. bovis. We found no animals positive for A. marginale and B. bigemina. This is the first report in America of R. rickettsii in American bison. American bison has been described as an important reservoir for pathogens of zoonotic and veterinary importance; thus, the presence of tick-borne pathogen DNA in the JBR American bison indicates the importance of continuous wildlife health surveys.

Electrocardiogram as a Lyme Disease Screening Test

OBJECTIVE

To examine the association between electrocardiographic (ECG) evidence of carditis at the time of Lyme disease evaluation and a diagnosis of Lyme disease.

STUDY DESIGN

We performed an 8-center prospective cohort study of children undergoing emergency department evaluation for Lyme disease limited to those who had an ECG obtained by their treating clinicians. The study cardiologist reviewed all ECGs flagged as abnormal by the study sites to assess for ECG evidence of carditis. We defined Lyme disease as the presence of an erythema migrans lesion or a positive 2-tier Lyme disease serology. We used logistic regression to measure the association between Lyme disease and atrioventricular (AV) block or any ECG evidence of carditis.

RESULTS

Of the 546 children who had an ECG obtained, 214 (39%) had Lyme disease. Overall, 42 children had ECG evidence of carditis, of whom 24 had AV block (20 first-degree). Of the patients with ECG evidence of carditis, only 21 (50%) had any cardiac symptoms. The presence of AV block (OR 4.7, 95% CI 1.8-12.1) and any ECG evidence of carditis (OR 2.3, 95% CI 1.2-4.3) were both associated with diagnosis of Lyme disease.

CONCLUSIONS

ECG evidence of carditis, especially AV block, was associated with a diagnosis of Lyme disease. ECG evidence of carditis can be used as a diagnostic biomarker for Lyme disease to guide initial management while awaiting Lyme disease test results.

Citizen Science Provides an Efficient Method for Broad-Scale Tick-Borne Pathogen Surveillance of Ixodes pacificus and Ixodes scapularis across the United States

Tick-borne diseases have expanded over the last 2 decades as a result of shifts in tick and pathogen distributions. These shifts have significantly increased the need for accurate portrayal of real-time pathogen distributions and prevalence in hopes of stemming increases in human morbidity. Traditionally, pathogen distribution and prevalence have been monitored through case reports or scientific collections of ticks or reservoir hosts, both of which have challenges that impact the extent, availability, and accuracy of these data. Citizen science tick collections and testing campaigns supplement these data and provide timely estimates of pathogen prevalence and distributions to help characterize and understand tick-borne disease threats to communities. We utilized our national citizen science tick collection and testing program to describe the distribution and prevalence of four Ixodes-borne pathogens, Borrelia burgdorferisensu lato, Borrelia miyamotoi, Anaplasma phagocytophilum, and Babesia microti, across the continental United States.

IMPORTANCE In the 21st century, zoonotic pathogens continue to emerge, while previously discovered pathogens continue to have changes within their distribution and prevalence. Monitoring these pathogens is resource intensive, requiring both field and laboratory support; thus, data sets are often limited within their spatial and temporal extents. Citizen science collections provide a method to harness the general public to collect samples, enabling real-time monitoring of pathogen distribution and prevalence.

Seroprevalence of Antibodies against Tick-Borne Pathogens in Czech Patients with Suspected Post-Treatment Lyme Disease Syndrome

The hypothesized importance of coinfections in the pathogenesis of post-treatment Lyme disease syndrome (PTLDS) leads to the use of combined, ongoing antimicrobial treatment in many cases despite the absence of symptoms typical of the presence of infection with specific pathogens. Serum samples from 103 patients with suspected post-treatment Lyme disease syndrome were tested for the presence of antibodies to the major tick-borne pathogens Anaplasma phagocytophilum, Bartonella henselae/Bartonella quinatana, and Babesia microti. Although the presence of anti-Anaplasma antibodies was detected in 12.6% of the samples and anti-Bartonella antibodies in 9.7% of the samples, the presence of antibodies against both pathogens in the same samples or anti-Babesia antibodies in the selected group of patients could not be confirmed. However, we were able to detect autoantibodies, mostly antinuclear, in 11.6% of the patients studied. Our results are in good agreement with previously published studies showing the presence of a wide spectrum of autoantibodies in some patients with complicated forms of Lyme disease and post-treatment Lyme disease syndrome, but they do not reveal a significant influence of co-infections on the development of PTLDS in the studied group of patients.

Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Management of Tick-Borne Illness in the United States

The Wilderness Medical Society convened an expert panel to develop evidence-based guidelines for the prevention and management of tick-borne illness (TBI). Recommendations are graded based on quality of supporting evidence according to criteria put forth by the American College of Chest Physicians. The guidelines include a brief review of the clinical presentation, epidemiology, prevention, and management of TBI in the United States, with a primary focus on interventions that are appropriate for resource-limited settings. Strong recommendations are provided for the use of DEET, picaridin, and permethrin; tick checks; washing and drying clothing at high temperatures; mechanical tick removal within 36 h of attachment; single-dose doxycycline for high-risk Lyme disease exposures versus "watchful waiting;" evacuation from backcountry settings for symptomatic tick exposures; and TBI education programs. Weak recommendations are provided for the use of light-colored clothing; insect repellents other than DEET, picaridin, and permethrin; and showering after exposure to tick habitat. Weak recommendations are also provided against passive methods of tick removal, including the use of systemic and local treatments. There was insufficient evidence to support the use of long-sleeved clothing and the avoidance of tick habitat such as long grasses and leaf litter. Although there was sound evidence supporting Lyme disease vaccination, a grade was not offered as the vaccine is not currently available for use in the United States.

A brief history of OspA vaccines including their impact on diagnostic testing for Lyme disease

The only United States Food and Drug Administration approved vaccine preparation to prevent Lyme disease consisted of a single recombinant outer surface protein A (OspA), which was marketed for use from late 1998 until early 2002, with no vaccine currently available for humans for nearly 20 years. OspA vaccines generate an antibody-mediated, transmission blocking immunity, that prevents Borrelia burgdorferi from being transmitted during a tick bite. Although this OspA vaccine was safe and effective, it likely would have required booster doses to maintain immunity, and vaccination regularly caused false positive results on first-tier serologic testing for Lyme disease, when a whole cell-based enzyme immunoassay was used. Clinical trials are in progress to test a new multivalent OspA vaccine designed to prevent Lyme disease in both the United States and Europe.

Post-Treatment Lyme Disease Syndrome: Need for Diagnosis and Treatment

With the continued surge in Lyme disease cases, post-treatment Lyme disease syndrome (PTLDS) is becoming a more pressing health concern. The aim of this review is to identify comprehensive treatment strategies for PTLDS patients. Unfortunately, universal guidelines for diagnosing and treating PTLDS do not currently exist. Consequently, physicians cannot adequately address concerns of possible PTLDS patients. Patients are left suffering and searching for answers, and their activities of daily living and quality of life are adversely impacted. This review highlights that PTLDS clinical trials have focused mainly on treatment with antibiotics, yielding challenging results that lack consistency in inclusion criteria across trials. It will remain exceedingly difficult to extrapolate the outcomes of such studies if a standard for PTLDS diagnosis is not well-established. By focusing on treatment trials rather than establishing diagnostic criteria, research in this field ignores a critical step in investigating PTLDS. The first significant step is to create comprehensive guidelines for the diagnosis of PTLDS, which can generate uniformity and validate PTLDS treatment trials.

Zoonoses and global epidemics

PURPOSE OF REVIEW

The purpose of the review is to summarize recent advances in understanding the origins, drivers and clinical context of zoonotic disease epidemics and pandemics. In addition, we aimed to highlight the role of clinicians in identifying sentinel cases of zoonotic disease outbreaks.

RECENT FINDINGS

The majority of emerging infectious disease events over recent decades, including the COVID-19 pandemic, have been caused by zoonotic viruses and bacteria. In particular, coronaviruses, haemorrhagic fever viruses, arboviruses and influenza A viruses have caused significant epidemics globally. There have been recent advances in understanding the origins and drivers of zoonotic epidemics, yet there are gaps in diagnostic capacity and clinical training about zoonoses.

SUMMARY

Identifying the origins of zoonotic pathogens, understanding factors influencing disease transmission and improving the diagnostic capacity of clinicians will be crucial to early detection and prevention of further epidemics of zoonoses.

Tick gut barriers impacting tick-microbe interactions and pathogen persistence

Ticks are regarded as one of the most ancient, unique, and highly evolved ectoparasites. They can parasitize diverse vertebrates and transmit a number of widespread infections. Once acquired from infected hosts, many tick-borne pathogens, like Borrelia burgdorferi, are confined within the tick gut lumen and are surrounded by discrete gut barriers. Such barriers include the peritrophic membrane (PM) and the dityrosine network (DTN), which are in close contact with resident microbiota and invading pathogens, influencing their survival within the vector. Herein, we review our current state of knowledge about tick-microbe interactions involving the PM and DTN structures. As a model, we will focus on Ixodes ticks, their microbiome, and the pathogen of Lyme disease. We will address the most salient findings on the structural and physiological roles of these Ixodes gut barriers on microbial interactions, with a comparison to analogous functions in other model vectors, such as mosquitoes. We will distill how this information could be leveraged towards a better understanding of the basic mechanisms of gut biology and tick-microbial interactions, which could contribute to potential therapeutic strategies in response to ticks and tick-borne infections.

Modelling Spatiotemporal Patterns of Lyme Disease Emergence in Québec

Lyme disease is a growing public health problem in Québec. Its emergence over the last decade is caused by environmental and anthropological factors that favour the survival of Ixodes scapularis, the vector of Lyme disease transmission. The objective of this study was to estimate the speed and direction of human Lyme disease emergence in Québec and to identify spatiotemporal risk patterns. A surface trend analysis was conducted to estimate the speed and direction of its emergence based upon the first detected case of Lyme disease in each municipality in Québec since 2004. A cluster analysis was also conducted to identify at-risk regions across space and time. These analyses were reproduced for the date of disease onset and date of notification for each case of Lyme disease. It was estimated that Lyme disease is spreading northward in Québec at a speed varying between 18 and 32 km/year according to the date of notification and the date of disease onset, respectively. A significantly high risk of disease was found in seven clusters identified in the south-west of Québec in the sociosanitary regions of Montérégie and Estrie. The results obtained in this study improve our understanding of the spatiotemporal patterns of Lyme disease in Québec, which can be used for proactive, targeted interventions by public and clinical health authorities.

Optimizing use of multi-antibody assays for Lyme disease diagnosis: A bioinformatic approach

Multiple different recombinant and peptide antigens are now available for serodiagnosis of Lyme disease (LD), but optimizing test utilization remains challenging. Since 1995 the Centers for Disease Control and Prevention (CDC) has recommended a 2-tiered serologic approach consisting of a first-tier whole-cell enzyme immunoassay (EIA) for polyvalent antibodies to Borrelia burgdorferi followed by confirmation of positive or equivocal results by IgG and IgM immunoblots [standard 2-tiered (STT) approach]. Newer modified 2-tiered (MTT) approaches employ a second-tier EIA to detect antibodies to B. burgdorferi rather than immunoblotting. We applied modern bioinformatic techniques to a large public database of recombinant and peptide antigen-based immunoassays to improve testing strategy. A retrospective CDC collection of 280 LD samples and 559 controls had been tested using the STT approach as well as kinetic-EIAs for VlsE1-IgG, C6-IgG, VlsE1-IgM, and pepC10-IgM antibodies. When used individually, the cutoff for each kinetic-EIA was set to generate 99% specificity. Utilizing logistic-likelihood regression analysis and receiver operating characteristic (ROC) techniques we determined that VlsE1-IgG, C6-IgG, and pepC10-IgM antibodies each contributed significant diagnostic information; a single-tier diagnostic score (DS) was generated for each sample using a weighted linear combination of antibody levels to these 3 antigens. DS performance was then compared to the STT and to MTT models employing different combinations of kinetic-EIAs. After setting the DS cutoff to match STT specificity (99%), the DS was 22.5% more sensitive than the STT for early-acute-phase disease (95% CI: 11.8% to 32.2%), 16.0% more sensitive for early-convalescent-phase disease (95% CI: 7.2% to 24.7%), and equivalent for detection of disseminated infection. The DS was also significantly more sensitive for early-acute-phase LD than MTT models whose specificity met or exceeded 99%. Prospective validation of this single-tier diagnostic score for Lyme disease will require larger studies using a broader range of potential cross-reacting conditions.

Efficacy of low-dose fipronil bait against blacklegged tick (Ixodes scapularis) larvae feeding on white-footed mice (Peromyscus leucopus) under simulated field conditions

BACKGROUND

Lyme disease, caused primarily by Borrelia burgdorferi sensu stricto, is the most prevalent vector-borne disease in the United States. Treatment of rodent pathogen reservoirs with an oral acaricide may suppress the production of infected host-seeking ticks posing a risk for human infection. A previous study showed that an oral fipronil bait effectively controlled larval Ixodes scapularis ticks on white-footed mice (Peromyscus leucopus) up to 15 days post-bait exposure. The present study expands upon this finding by exposing group-housed white-footed mice to fipronil bait under simulated field conditions prior to tick infestation.

METHODS

Mice (n = 80) were housed in groups of 10 within large enclosures and offered a choice between fipronil bait within a commercial bait station and an alternative diet. The mice were assigned to two treatment groups and two control groups to undergo bait exposure durations of either 24 h (reduced) or 168 h (extended). Groups were further differentiated by the time point post-bait exposure when larval ticks were applied to mice within feeding capsules (reduced day 1, day 15; extended day 21, day 35). For 4 days post-tick introduction, attached larvae were observed by microscopy and replete larvae were recovered. Replete larvae were monitored for molting success. Plasma was collected from all treatment group mice to obtain fipronil plasma concentrations (CP).

RESULTS

The fipronil bait (0.005% fipronil) was palatable and controlled larval ticks on white-footed mice when presented under simulated field conditions. Efficacy in preventing attached larvae from feeding to repletion was 100% (day 1), 89.0% (day 15), 85.8% (day 21), and 75.2% (day 35). When also considering molting success, the fipronil bait prevented 100% (day 1), 91.1% (day 15), 91.7% (day 21), and 82.5% (day 35) of larvae attaching to mice from molting. The mean CP per mouse was 191.5 ng/ml (day 1), 29.4 ng/ml (day 15), 10.6 ng/ml (day 21), and 1.0 ng/ml (day 35).

CONCLUSIONS

The results suggest that fipronil bait will be consumed by white-footed mice in the presence of an alternative diet, and effectively control larval ticks on treated mice. A field trial is needed to confirm the results of this study. Low-dose fipronil bait may provide a cost-effective means of controlling blacklegged ticks to be integrated into tick management programs.

Tickborne Illnesses

Over the past two decades, tickborne diseases have demonstrated a steady rise in the United States, with several novel tickborne pathogens discovered. Tickborne illnesses vary by geography and seasonality secondary to the associated tick vector. Interestingly, the geographic range of these tick vectors are also expanding with many more counties reporting cases than the previous 20 years. The clinical presentation of tickborne infections can range from mild to fatal, thus early identification and empiric treatment is of utmost importance. This article reviews the most common tick-borne infections in the US, including epidemiology, clinical presentation, diagnosis, treatment, and prevention. [Pediatr Ann. 2021;50(9):e350-e355.].

A simple method to detect Borrelia burgdorferi sensu lato proteins in different sub-cellular compartments by immunofluorescence

Spirochaetes constitute a unique phylum of bacteria, many of which cause severe clinical diseases. Borrelia burgdorferi sensu lato (B. burgdorferi s.l.)-the primary agent of Lyme borreliosis (LB)-is a quintessential member of this poorly understood phylum and the leading cause of tick-borne illness throughout most of the northern hemisphere. Despite its importance in human health, we lack a fundamental understanding of how B. burgdorferi s.l. is able to accomplish basic physiological tasks, such as DNA replication/segregation, and cell elongation or division. Recent advances in molecular tools to probe these essential cellular processes are great strides forward but require genetic manipulation. The latter is important since not all agents of LB are genetically tractable. Here, we describe a single method that is capable of fluorescently labeling B. burgdorferi s.l. proteins in different sub-cellular compartments. A comparative analysis of six different methods indicates that our optimized procedure outperforms all others and is the first to localize a cytoplasmic protein in B. burgdorferi s.l. by immunofluorescence. We contend that this strategy could be easily adapted to study the localization of any protein, in many Borrelia genospecies, information that will yield functional insights into the complex biology of this fascinating group of bacteria. In addition, it may provide new avenues of research in both in situ studies and in Lyme diagnostics.

Recent Progress in Lyme Disease and Remaining Challenges

Lyme disease (also known as Lyme borreliosis) is the most common vector-borne disease in the United States with an estimated 476,000 cases per year. While historically, the long-term impact of Lyme disease on patients has been controversial, mounting evidence supports the idea that a substantial number of patients experience persistent symptoms following treatment. The research community has largely lacked the necessary funding to properly advance the scientific and clinical understanding of the disease, or to develop and evaluate innovative approaches for prevention, diagnosis, and treatment. Given the many outstanding questions raised into the diagnosis, clinical presentation and treatment of Lyme disease, and the underlying molecular mechanisms that trigger persistent disease, there is an urgent need for more support. This review article summarizes progress over the past 5 years in our understanding of Lyme and tick-borne diseases in the United States and highlights remaining challenges.

Reptile Host Associations of Ixodes scapularis in Florida and Implications for Borrelia spp. Ecology

Host associations of the tick vector for Lyme Borreliosis, Ixodes scapularis, differ across its geographic range. In Florida, the primary competent mammalian host of Lyme disease is not present but instead has other small mammals and herpetofauna that I. scapularis can utilize. We investigated host–tick association for lizards, the abundance of ticks on lizards and the prevalence of Borrelia burgdorferi sensu lato (sl). To determine which lizard species I. scapularis associates with, we examined 11 native lizard species from historical herpetological specimens. We found that (294/5828) of the specimens had attached ticks. The most infested species were Plestiodon skinks (241/1228) and Ophisaurus glass lizards (25/572). These species were then targeted at six field sites across Florida and sampled from June to September 2020, using drift fence arrays, cover boards and fishing. We captured 125 lizards and collected 233 immature I. scapularis. DNA was extracted from ticks and lizard tissue samples, followed by PCR testing for Borrelia spp. Of the captured lizards, 69/125 were infested with immature I. scapularis. We did not detect Borrelia spp. from tick or lizard tissue samples. Overall, we found that lizards are commonly infested with I. scapularis. However, we did not detect Borrelia burgdorferi sl. These findings add to a growing body of evidence that lizards are poor reservoir species.

The value-ladenness of transparency in science: Lessons from Lyme disease

Both philosophers and scientists have recently promoted transparency as an important element of responsible scientific practice. Philosophers have placed particular emphasis on the ways that transparency can assist with efforts to manage value judgments in science responsibly. This paper examines a potential challenge to this approach, namely, that efforts to promote transparency can themselves be value-laden. This is particularly problematic when transparency incorporates second-order value judgments that are underwritten by the same values at stake in the desire for transparency about the first-order value judgments involved in scientific research. The paper uses a case study involving research on Lyme disease to illustrate this worry, but it responds by elucidating a range of scenarios in which transparency can still play an effective role in managing value judgments responsibly.

Comparison of Lyme Disease in the United States and Europe

Lyme disease, or Lyme borreliosis, is the most common tickborne disease in the United States and Europe. In both locations, Ixodes species ticks transmit the Borrelia burgdorferi sensu lato bacteria species responsible for causing the infection. The diversity of Borrelia species that cause human infection is greater in Europe; the 2 B. burgdorferi s.l. species collectively responsible for most infections in Europe, B. afzelii and B. garinii, are not found in the United States, where most infections are caused by B. burgdorferi sensu stricto. Strain differences seem to explain some of the variation in the clinical manifestations of Lyme disease, which are both minor and substantive, between the United States and Europe. Future studies should attempt to delineate the specific virulence factors of the different species of B. burgdorferi s.l. responsible for these variations in clinical features.

Risk of transfusion-transmitted Babesia microti in Canada

BACKGROUND

Babesia microti has gained a foothold in Canada as tick vectors become established in broader geographic areas. B. microti infection is associated with mild or no symptoms in healthy individuals but is transfusion-transmissible and can be fatal in immunocompromised individuals. This is the first estimate of clinically significant transfusion-transmitted babesiosis (TTB) risk in Canada.

STUDY DESIGN AND METHODS

The proportion of B. microti-antibody (AB)/nucleic acid amplification test (NAT)-positive whole blood donations was estimated at 5.5% of the proportion of the general population with reported Lyme Disease (also tick-borne) based on US data. Monte Carlo simulation estimated the number and proportion of infectious red cell units for three scenarios: base, localized incidence (risk in Manitoba only), and donor study informed (prevalence from donor data). The model simulated 1,029,800 donations repeated 100,000 times for each.

RESULTS

In the base scenario 0.5 (0.01, 1.75), B. microti-NAT-positive donations would be expected per year, with 0.08 (0, 0.38) recipients suffering clinically significant TTB (1 every 12.5 years). In the localized incidence scenario, there were 0.21(0, 0.7) B. microti-NAT-positive donations, with 0.04 (0, 0.14) recipient infections (about 1 every 25 years). In the donor study informed scenario, there were 4.6 (0.3, 15.8) B. microti-NAT-positive donations expected, and 0.81 (0.05, 3.14) clinically significant TTB cases per year.

DISCUSSION

The likelihood of clinically relevant TTB is low. Testing would have very little utility in Canada at this time. Ongoing pathogen surveillance in tick vectors is important as B. microti prevalence appears to be slowly increasing in Canada.

Resistance to Ticks and the Path to Anti-Tick and Transmission Blocking Vaccines

The medical and veterinary public health importance of ticks and tick-borne pathogens is increasing due to the expansion of the geographic ranges of both ticks and pathogens, increasing tick populations, growing incidence of tick-borne diseases, emerging tick transmitted pathogens, and continued challenges of achieving effective and sustained tick control. The past decades show an increasing interest in the immune-mediated control of tick infestations and pathogen transmission through the use of vaccines. Bovine tick resistance induced by repeated infestations was reported over a century ago. This review addresses the phenomena and immunological underpinning of resistance to tick infestation by livestock and laboratory animals; the scope of tick countermeasures to host immune defenses; and the impact of genomics, functional genomics, and proteomics on dissecting complex tick-host-pathogen interactions. From early studies utilizing tick tissue extracts to salivary gland derived molecules and components of physiologically important pathways in tick gut and other tissues, an increased understanding of these relationships, over time, impacted the evolution of anti-tick vaccine antigen selection. Novel antigens continue to emerge, including increased interest in the tick microbiome. Anti-tick and transmission blocking vaccines targeting pathogen reservoirs have the potential to disrupt enzootic cycles and reduce human, companion, domestic animal, and wildlife exposure to infected ticks.

Comparative analysis of antibody responses to outer surface protein (Osp)A and OspC in dogs vaccinated with Lyme disease vaccines

Lyme disease (LD), the most common tick-borne disease of canines and humans in N. America, is caused by the spirochete Borreliella burgdorferi. Subunit and bacterin vaccines are available for the prevention of LD in dogs. LD bacterin vaccines, which are comprised of cell lysates of two strains of B. burgdorferi, contain over 1000 different proteins and cellular constituents. In contrast, subunit vaccines are defined in composition and consist of either outer surface protein (Osp)A or OspA and an OspC chimeritope. In this study, we comparatively assessed antibody responses to OspA and OspC induced by vaccination with all canine bacterin and subunit LD vaccines that are commercially available in North America. Dogs were administered a two-dose series of the vaccine to which they were assigned (3 weeks apart): Subunit-AC, Subunit-A, Bacterin-1, and Bacterin-2. Antibody titers to OspA and OspC were determined by ELISA and the ability of each vaccine to elicit antibodies that recognize diverse OspC proteins (referred to as OspC types) assessed by immunoblot. While all of the vaccines elicited similar OspA antibody responses, only Subunit-AC triggered a robust and broadly cross-reactive antibody response to divergent OspC proteins. The data presented within provide new information regarding vaccination-induced antibody responses to key tick and mammalian phase antigens by both subunit and bacterin LD canine vaccine formulations.

PlzA is a bifunctional c-di-GMP biosensor that promotes tick and mammalian host-adaptation of Borrelia burgdorferi

In this study, we examined the relationship between c-di-GMP and its only known effector protein, PlzA, in Borrelia burgdorferi during the arthropod and mammalian phases of the enzootic cycle. Using a B. burgdorferi strain expressing a plzA point mutant (plzA-R145D) unable to bind c-di-GMP, we confirmed that the protective function of PlzA in ticks is c-di-GMP-dependent. Unlike ΔplzA spirochetes, which are severely attenuated in mice, the plzA-R145D strain was fully infectious, firmly establishing that PlzA serves a c-di-GMP-independent function in mammals. Contrary to prior reports, loss of PlzA did not affect expression of RpoS or RpoS-dependent genes, which are essential for transmission, mammalian host-adaptation and murine infection. To ascertain the nature of PlzA's c-di-GMP-independent function(s), we employed infection models using (i) host-adapted mutant spirochetes for needle inoculation of immunocompetent mice and (ii) infection of scid mice with in vitro-grown organisms. Both approaches substantially restored ΔplzA infectivity, suggesting that PlzA enables B. burgdorferi to overcome an early bottleneck to infection. Furthermore, using a Borrelia strain expressing a heterologous, constitutively active diguanylate cyclase, we demonstrate that 'ectopic' production of c-di-GMP in mammals abrogates spirochete virulence and interferes with RpoS function at the post-translational level in a PlzA-dependent manner. Structural modeling and SAXS analysis of liganded- and unliganded-PlzA revealed marked conformational changes that underlie its biphasic functionality. This structural plasticity likely enables PlzA to serve as a c-di-GMP biosensor that in its respective liganded and unliganded states promote vector- and host-adaptation by the Lyme disease spirochete.

Experience and knowledge of Lyme disease: A scoping review of patient-provider communication

There has been limited research on patient-provider communication dynamics regarding Lyme disease (LD) diagnosis and treatment. Evidence suggests communication in the clinical encounter improves when both patient and healthcare provider (HCP) have concordant orientations (or beliefs) on discussed topics, resulting in higher patient satisfaction and care outcomes. The purpose of this scoping review was to characterize and summarize current research findings on patient and provider knowledge and experiences regarding LD - two factors that may influence the orientation of both patients and providers toward LD in the clinical setting. None of the articles included in the review specifically addressed patient-provider interaction and relationships as the main objective. However, the existing literature indicates notable HCP uncertainty regarding LD diagnosis, treatment, and applied practice patterns. Current research also describes limited knowledge of LD among patient populations and a high prevalence of negative perceptions of care received in mainstream healthcare settings among individuals with persistent symptoms. We identified a critical gap in research that seeks to understand the dynamic of patients and HCPs communicating on the topic of LD in the clinical setting. Future research may identify opportunities where the patient-provider communication dynamic can be improved.

Evidence-Based, Patient-Centered Treatment of Erythema Migrans in the United States

Lyme disease, often characterized as a readily treatable infection, can be a debilitating and expensive illness, especially when patients remain symptomatic following therapy for early disease. Identifying and promoting highly effective therapeutic interventions for US patients with erythema migrans (EM) rashes that return them to their pre-infection health status should be a priority. The recently released treatment recommendations by the Infectious Diseases Society of America/American Academy of Neurology/American College of Rheumatology (IDSA/AAN/ACR) for the treatment of US patients fall short of that goal. This paper reviews the US trial evidence regarding EM rashes, discusses the shortcomings of the IDSA/AAN/ACR recommendations in light of that evidence and offers evidence-based, patient-centered strategies for managing patients with erythema migrans lesions.

Lyme Neuroborreliosis: Mechanisms of B. burgdorferi Infection of the Nervous System

Lyme borreliosis is the most prevalent tick-borne disease in the United States, infecting ~476,000 people annually. Borrelia spp. spirochetal bacteria are the causative agents of Lyme disease in humans and are transmitted by Ixodes spp ticks. Clinical manifestations vary depending on which Borrelia genospecies infects the patient and may be a consequence of distinct organotropism between species. In the US, B. burgdorferi sensu stricto is the most commonly reported genospecies and infection can manifest as mild to severe symptoms. Different genotypes of B. burgdorferi sensu stricto may be responsible for causing varying degrees of clinical manifestations. While the majority of Lyme borreliae-infected patients fully recover with antibiotic treatment, approximately 15% of infected individuals experience long-term neurological and psychological symptoms that are unresponsive to antibiotics. Currently, long-term antibiotic treatment remains the only FDA-approved option for those suffering from these chronic effects. Here, we discuss the current knowledge pertaining to B. burgdorferi sensu stricto infection in the central nervous system (CNS), termed Lyme neuroborreliosis (LNB), within North America and specifically the United States. We explore the molecular mechanisms of spirochete entry into the brain and the role B. burgdorferi sensu stricto genotypes play in CNS infectivity. Understanding infectivity can provide therapeutic targets for LNB treatment and offer public health understanding of the B. burgdorferi sensu stricto genotypes that cause long-lasting symptoms.

High-resolution crystal structure of the Borreliella burgdorferi PlzA protein in complex with c-di-GMP: new insights into the interaction of c-di-GMP with the novel xPilZ domain

In the tick-borne pathogens, Borreliella burgdorferi and Borrelia hermsii, c-di-GMP is produced by a single diguanylate cyclase (Rrp1). In these pathogens, the Plz proteins (PlzA, B and C) are the only c-di-GMP receptors identified to date and PlzA is the sole c-di-GMP receptor found in all Borreliella isolates. Bioinformatic analyses suggest that PlzA has a unique PilZN3-PilZ architecture with the relatively uncommon xPilZ domain. Here, we present the crystal structure of PlzA in complex with c-di-GMP (1.6 Å resolution). This is the first structure of a xPilz domain in complex with c-di-GMP to be determined. PlzA has a two-domain structure, where each domain comprises topologically equivalent PilZ domains with minimal sequence identity but remarkable structural similarity. The c-di-GMP binding site is formed by the linker connecting the two domains. While the structure of apo PlzA could not be determined, previous fluorescence resonance energy transfer data suggest that apo and holo forms of the protein are structurally distinct. The information obtained from this study will facilitate ongoing efforts to identify the molecular mechanisms of PlzA-mediated regulation in ticks and mammals.

Pathogenesis of Borrelia burgdorferi and Babesia microti in TLR4-Competent and TLR4-dysfunctional C3H mice

Toll‐like receptors (TLRs) are a class of membrane‐spanning proteins of host cells. TLR2 and TLR4 are displayed on the surface of macrophages, neutrophils and dendritic cells and recognise structurally conserved microbial signatures defined as Pathogen associated molecular patterns (PAMPs). C3H mice are susceptible to tick‐borne pathogens; Lyme disease causing Borrelia burgdorferi that manifests arthritis and carditis and Apicomplexan protozoan, Babesia microti (Bm) that causes significant parasitemia associated with erythrocytopenia and haemoglobinuria. B. burgdorferi lacks typical TLR4 ligand lipopolysaccharides (LPS) and Bm TLR ligand(s) remain unknown. Only Borrelia lipoproteins that signal through TLR2 are established as PAMPs of these pathogens for TLR2/TLR4. Infection of C3H mice with each pathogen individually resulted in increase in the percentage of splenic B, T and FcR+ cells while their co‐infection significantly diminished levels of these cells and caused increased B. burgdorferi burden in the specific organs. The most pronounced inflammatory arthritis was observed in co‐infected C3H/HeJ mice. Parasitemia levels and kinetics of resolution of Bm in both mice strains were not significantly different. Transfected HEK293 cells showed pronounced signalling by B. burgdorferi through TLR2 and to some extent by TLR4 while Bm and infected erythrocytes did not show any response confirming our results in mice.

Quantitative multiplexed strategies for human Lyme disease serological testing

Lyme disease, which is primarily caused by infection with the bacterium Borrelia burgdorferi in the United States or other Borrelia species internationally, presents an ongoing challenge for diagnostics. Serological testing is the primary means of diagnosis but testing approaches differ widely, with varying degrees of sensitivity and specificity. Moreover, there is currently no reliable test to determine disease resolution following treatment. A distinct challenge in Lyme disease diagnostics is the variable patterns of human immune response to a plurality of antigens presented by Borrelia spp. during the infection. Thus, multiplexed testing approaches that capture these patterns and detect serological response against multiple antigens may be the key to prompt, accurate Lyme disease diagnosis. In this review, current state-of-the-art multiplexed diagnostic approaches are presented and compared with respect to their diagnostic accuracy and their potential for monitoring response to treatment.

Blocking Borrelia burgdorferi transmission from infected ticks to nonhuman primates with a human monoclonal antibody

Disrupting transmission of Borrelia burgdorferi sensu lato complex (B. burgdorferi) from infected ticks to humans is one strategy to prevent the significant morbidity from Lyme disease. We have previously shown that an anti-OspA human mAb, 2217, prevents transmission of B. burgdorferi from infected ticks in animal models. Maintenance of a protective plasma concentration of a human mAb for tick season presents a significant challenge for a preexposure prophylaxis strategy. Here, we describe the optimization of mAb 2217 by amino acid substitutions (2217LS: M428L and N434S) in the Fc domain. The LS mutation led to a 2-fold increase in half-life in cynomolgus monkeys. In a rhesus macaque model, 2217LS protected animals from tick transmission of spirochetes at a dose of 3 mg/kg. Crystallographic analysis of Fab in complex with OspA revealed that 2217 bound an epitope that was highly conserved among the B. burgdorferi, B. garinii, and B. afzelii species. Unlike most vaccines that may require boosters to achieve protection, our work supports the development of 2217LS as an effective preexposure prophylaxis in Lyme-endemic regions, with a single dose at the beginning of tick season offering immediate protection that remains for the duration of exposure risk.

Sexual Transmission of Lyme Borreliosis? The Question That Calls for an Answer

Transmission of the causative agents of numerous infectious diseases might be potentially conducted by various routes if this is supported by the genetics of the pathogen. Various transmission modes occur in related pathogens, reflecting a complex process that is specific for each particular host-pathogen system that relies on and is affected by pathogen and host genetics and ecology, ensuring the epidemiological spread of the pathogen. The recent dramatic rise in diagnosed cases of Lyme borreliosis might be due to several factors: the shifting of the distributional range of tick vectors caused by climate change; dispersal of infected ticks due to host animal migration; recent urbanization; an increasing overlap of humans' habitat with wildlife reservoirs and the environment of tick vectors of Borrelia; improvements in disease diagnosis; or establishment of adequate surveillance. The involvement of other bloodsucking arthropod vectors and/or other routes of transmission (human-to-human) of the causative agent of Lyme borreliosis, the spirochetes from the Borrelia burgdorferi sensu lato complex, has been speculated to be contributing to increased disease burden. It does not matter how controversial the idea of vector-free spirochete transmission might seem in the beginning. As long as evidence of sexual transmission of Borrelia burgdorferi both between vertebrate hosts and between tick vectors exists, this question must be addressed. In order to confirm or refute the existence of this phenomenon, which could have important implications for Lyme borreliosis epidemiology, the need of extensive research is obvious and required.

Monitoring the patterns of submission and presence of tick-borne pathogens in Ixodes scapularis collected from humans and companion animals in Ontario, Canada (2011-2017)

BACKGROUND

The universal nature of the human-companion animal relationship and their shared ticks and tick-borne pathogens offers an opportunity for improving public and veterinary health surveillance. With this in mind, we describe the spatiotemporal trends for blacklegged tick (Ixodes scapularis) submissions from humans and companion animals in Ontario, along with pathogen prevalence.

METHODS

We tested tick samples submitted through passive surveillance (2011-2017) from humans and companion animals for Borrelia burgdorferi, Borrelia miyamotoi, Anaplasma phagocytophilum and Babesia microti. We describe pathogen prevalence in ticks from humans and from companion animals and constructed univariable Poisson and negative binomial regression models to explore the spatiotemporal relationship between the rates of tick submissions by host type.

RESULTS

During the study, there were 17,230 blacklegged tick samples submitted from humans and 4375 from companion animals. Tick submission rates from companion animals were higher than expected in several public health units (PHUs) lacking established tick populations, potentially indicating newly emerging populations. Pathogen prevalence in ticks was higher in PHUs where established blacklegged tick populations exist. Borrelia burgdorferi prevalence was higher in ticks collected from humans (maximum likelihood estimate, MLE = 17.5%; 95% confidence interval, CI 16.97-18.09%) than from companion animals (9.9%, 95% CI 9.15-10.78%). There was no difference in pathogen prevalence in ticks by host type for the remaining pathogens, which were found in less than 1% of tested ticks. The most common co-infection B. burgdorferi + B. miyamotoi occurred in 0.11% of blacklegged ticks from humans and animals combined. Borrelia burgdorferi prevalence was higher in unengorged (21.9%, 95% CI 21.12-22.65%) than engorged ticks (10.0%, 95% CI 9.45-10.56%). There were no consistent and significant spatiotemporal relationships detected via regression models between the annual rates of submission of each host type.

CONCLUSIONS

While B. burgdorferi has been present in blacklegged ticks in Ontario for several decades, other tick-borne pathogens are also present at low prevalence. Blacklegged tick and pathogen surveillance data can be used to monitor risk in human and companion animal populations, and efforts are under consideration to unite surveillance efforts for the different target populations.

Physical Therapist Recognition and Referral of Individuals With Suspected Lyme Disease

The most commonly reported vector-borne and tick-borne disease in the United States is Lyme disease. Individuals with Lyme disease may present with a wide array of symptoms with resultant musculoskeletal, neurological, and cardiac manifestations that may cause them to seek physical therapist services. The symptoms may develop insidiously and with a variable presentation among individuals. Many persons with Lyme disease do not recall a tick bite or present with an erythema migrans rash, which is considered pathognomonic for the disease. Even if they do, they may fail to associate either with their symptoms, making the diagnosis elusive. It is important to diagnose individuals early in the disease process when antibiotic treatment is most likely to be successful. Physical therapists are in a unique position to recognize the possibility that individuals may have Lyme disease and refer them to another practitioner when appropriate. The purpose of this article is to (1) present an overview of the etiology, incidence, and clinical manifestations of Lyme disease, (2) review evaluation findings that should raise the index of suspicion for Lyme disease, (3) discuss the use of an empirically validated tool for differentiating those with Lyme disease from healthy individuals, (4) discuss the current state of diagnostic testing, and (5) review options for diagnosis and treatment available to individuals for whom referral is recommended.

The peptidoglycan-associated protein NapA plays an important role in the envelope integrity and in the pathogenesis of the lyme disease spirochete

The bacterial pathogen responsible for causing Lyme disease, Borrelia burgdorferi, is an atypical Gram-negative spirochete that is transmitted to humans via the bite of an infected Ixodes tick. In diderms, peptidoglycan (PG) is sandwiched between the inner and outer membrane of the cell envelope. In many other Gram-negative bacteria, PG is bound by protein(s), which provide both structural integrity and continuity between envelope layers. Here, we present evidence of a peptidoglycan-associated protein (PAP) in B. burgdorferi. Using an unbiased proteomics approach, we identified Neutrophil Attracting Protein A (NapA) as a PAP. Interestingly, NapA is a Dps homologue, which typically functions to bind and protect cellular DNA from damage during times of stress. While B. burgdorferi NapA is known to be involved in the oxidative stress response, it lacks the critical residues necessary for DNA binding. Biochemical and cellular studies demonstrate that NapA is localized to the B. burgdorferi periplasm and is indeed a PAP. Cryo-electron microscopy indicates that mutant bacteria, unable to produce NapA, have structural abnormalities. Defects in cell-wall integrity impact growth rate and cause the napA mutant to be more susceptible to osmotic and PG-specific stresses. NapA-linked PG is secreted in outer membrane vesicles and augments IL-17 production, relative to PG alone. Using microfluidics, we demonstrate that NapA acts as a molecular beacon-exacerbating the pathogenic properties of B. burgdorferi PG. These studies further our understanding of the B. burgdorferi cell envelope, provide critical information that underlies its pathogenesis, and highlight how a highly conserved bacterial protein can evolve mechanistically, while maintaining biological function.

Targeting Multicopy Prophage Genes for the Increased Detection of Borrelia burgdorferi Sensu Lato (s.l.), the Causative Agents of Lyme Disease, in Blood

The successful treatment of Lyme disease (LD) is contingent on accurate diagnosis. However, current laboratory detection assays lack sensitivity in the early stages of the disease. Because delayed diagnosis of LD incurs high healthcare costs and great suffering, new highly sensitive tests are in need. To overcome these challenges, we developed an internally controlled quantitative PCR (Ter-qPCR) that targets the multicopy terminase large subunit (terL) gene encoded by prophages that are only found in LD-causing bacteria. The terL protein helps phages pack their DNA. Strikingly, the detection limit of the Ter-qPCR was analytically estimated to be 22 copies and one bacterial cell in bacteria spiked blood. Furthermore, significant quantitative differences was observed in terms of the amount of terL detected in healthy individuals and patients with either early or late disease. Together, the data suggests that the prophage-targeting PCR has significant power to improve success detection for LD. After rigorous clinical validation, this new test could deliver a step-change in the detection of LD. Prophage encoded markers are prevalent in many other pathogenic bacteria rendering this approach highly applicable to bacterial identification in general.

The unusual cell wall of the Lyme disease spirochaete Borrelia burgdorferi is shaped by a tick sugar

Peptidoglycan-a mesh sac of glycans that are linked by peptides-is the main component of bacterial cell walls. Peptidoglycan provides structural strength, protects cells from osmotic pressure and contributes to shape. All bacterial glycans are repeating disaccharides of N-acetylglucosamine (GlcNAc) β-(1-4)-linked to N-acetylmuramic acid (MurNAc). Borrelia burgdorferi, the tick-borne Lyme disease pathogen, produces glycan chains in which MurNAc is occasionally replaced with an unknown sugar. Nuclear magnetic resonance, liquid chromatography-mass spectroscopy and genetic analyses show that B. burgdorferi produces glycans that contain GlcNAc-GlcNAc. This unusual disaccharide is chitobiose, a component of its chitinous tick vector. Mutant bacteria that are auxotrophic for chitobiose have altered morphology, reduced motility and cell envelope defects that probably result from producing peptidoglycan that is stiffer than that in wild-type bacteria. We propose that the peptidoglycan of B. burgdorferi probably evolved by adaptation to obligate parasitization of a tick vector, resulting in a biophysical cell-wall alteration to withstand the atypical torque associated with twisting motility.