Experimental infection of ponies with Borrelia burgdorferi by exposure to Ixodid ticks

Knowledge and perception of equine ticks and tick-borne diseases of Pennsylvania horse owners and caretakers

There is limited data on current knowledge of Pennsylvania horse caretakers on tick-borne diseases (TBDs), tick identification, and tick management practices. This study aimed to determine tick knowledge, concern, and management among Pennsylvania equine caretakers using an online survey. Descriptive statistics and one-way ANOVA tests were used to analyze data. The survey received 894 responses (539 completed) from Pennsylvania equine owners and caretakers. The largest proportion of respondents cared for 3-5 horses (31 %), followed by 2 horses (27 %). Veterinarian-confirmed diagnosis rates of two TBDs, Lyme disease and anaplasmosis, were 38 % and 22 %, respectively. Most respondents (39 %) were moderately confident in recognizing Lyme disease, while most (44 %) were not confident at all in recognizing anaplasmosis. Most respondents (69 %) were either extremely or very concerned about their horses contracting any TBDs. Tick bite and TBD prevention methods used by equine caretakers included performing tick checks, using on-animal repellents, and conducting pasture/landscape management. Ten knowledge-based questions were asked, and the mean correct score was 3.97 ± 2.18 out of 10 possible points. There were significant positive associations between higher knowledge scores and previous veterinarian-confirmed equine Lyme disease diagnosis, higher concern level of TBDs, and higher frequency of tick checks. With increased equine TBD prevalence and high levels of horse owner concern about TBD, Extension educators should focus on teaching about TBDs and managing ticks on horses and farms.

Constructing an ELISA for Detection of Anti-Borrelia in Wildlife and Agricultural Animals

Zoonotic diseases have major impacts on human and animal health, as well as being ecologically significant. Lyme Borreliosis or Lyme disease, caused by infection by pathogenic members of the Borrelia genus, is among these zoonotic diseases. Serology is one of the most accessible means for indirect surveillance of pathogen presence by monitoring the presence, abundance, and type of immune response to the pathogen or pathogen-associated epitopes. Serological surveillance of wild animals is important as wild animals are the primary reservoirs of many zoonotic diseases. Similarly, serological surveillance of agricultural animals is important due to their economic importance, in addition to animal welfare concerns. However, serology in any non-model animal such as wildlife or agricultural animals is difficult because serology necessarily relies on blood samples from the animals being tested. While companion or laboratory animals are generally sufficiently accustomed to humans that blood samples can be obtained, obtaining blood samples from wild or agricultural animals is more challenging. This initial challenge is compounded by the absence of validated serological tools to evaluate antibody titres in the sera. In this chapter, we provide methods for constructing an ELISA for the detection of anti-Borrelia antibodies in non-model animals, using studies on horses and cows as a proof of principle. The methods focus on the problems specific to non-model animals including obtaining sera, options for determining positive and negative controls without the ability to perform controlled infections, and methods for test optimization and validation.

Seroprevalence of Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum Infections in German Horses

There are limited data on Lyme borreliosis (LB), a tick-borne disease caused by the Borrelia burgdorferi sensu lato complex, in horses. Seropositivity is not necessarily associated with clinical disease. Data on seropositivity against Borrelia burgdorferi and Anaplasma phagocytophilum in German horses are sparse. Therefore, serum samples from horses (n = 123) suspected of having Lyme borreliosis and clinically healthy horses (n = 113) from the same stables were tested for specific antibodies against Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum. The samples were screened for antibodies against Borrelia burgdorferi (ELISA and an IgG line immunoblot assay). Furthermore, the samples were examined for antibodies against B. burgdorferi and Anaplasma phagocytophilum with a validated rapid in-house test (SNAP^® 4Dx Plus^® ELISA). The clinical signs of suspect horses included lameness (n = 36), poor performance (n = 19), and apathy (n = 12). Twenty-three percent (n = 26) of suspect horses and 17% (n = 18) of clinically healthy horses were seropositive for having a Borrelia burgdorferi sensu lato infection (p = 0.371), showing that the detection of specific antibodies against B. burgdorferi alone is not sufficient for a diagnosis of equine LB. Anaplasma phagocytophilum seropositivity and seropositivity against both pathogens was 20%/6% in suspect horses and 16%/2% in the clinically healthy population, showing only minor differences (p = 0.108). Unspecific testing for antibodies against B. burgdorferi without clinical suspicion of Lyme borreliosis is not recommended since the clinical relevance of seropositivity against Borrelia burgdorferi sensu lato remains to be elucidated.

Tierärztliches Meinungsbild zur Equinen Lyme-Borreliose – Ergebnisse einer Fragebogenstudie

Ziel Erfassung des tierärztlichen Meinungsbildes zur Equinen Lyme-Borreliose

Material und Methoden Durch eine Befragung wurde untersucht, wie Pferdetierärzte die Bedeutung positiver serologischer Nachweise gegen Borrelia burgdorferi (Bb-AK) und einer klinisch manifesten Lyme-Borreliose (LB) einschätzten sowie letztere diagnostizieren und therapieren.

Ergebnisse Der Fragebogen wurde von 73 Tierärzten (TÄ) ausgefüllt. 48 % der TÄ erhoben nur sehr selten bis gar keine serologischen Bb-AK-Nachweise bei Pferden in ihrer Praxis, 47 % stellten gelegentlich Bb-AK fest und nur 5 % fanden häufig Bb-AK-Nachweise. 51 % der TÄ bestätigen, dass sie bereits klinisch-manifeste LB-Erkrankungen festgestellt hätten, während 43 % die Existenz dieser Erkrankung zwar nicht ausschlossen, aber selber keine Equine Lyme-Borreliose Fälle gesehen haben. 6 % der TÄ zweifeln die Existenz einer klinischen LB beim Pferd generell an.

Im Durchschnitt wurden 159-mal im Jahr weiterführende diagnostische Maßnahmen im Hinblick auf eine LB eingeleitet, und es wurden 1,4 ± 1,0 Fälle von equiner LB im Jahr diagnostiziert. Als Untersuchungsmethoden zur Abklärung von Borreliose-Verdachtsfällen verwendeten 68 % der TÄ den „indirekten Erregernachweis“, 27 % sowohl den direkten als auch den indirekten Erregernachweis und 5 % verwendeten ausschließlich den direkten Erregernachweis. Bei letzterem wurden am häufigsten Blut und Hautstanzen als Probenmaterial eingesandt.

Die Behandlung von Pferden mit auf eine Borrelioseerkrankung hinweisenden Laborergebnissen und als passend bewerteter, klinischer Symptomatik erfolgte durch 93 % der Tierärzte mit Antibiotika und 7 % mit Homöopathie. Am häufigsten wurde Doxycyclin (68 %) eingesetzt. Dabei erfolgte die antibiotische Behandlung über einen Zeitraum von 3 (31 %) bis 4 (63 %) Wochen.

In Bezug auf eine mögliche Impfung der Pferde gegen Borreliose boten 39 % der Tierärzte diese Impfung nicht an, bei 20 % wurde sie noch nicht eingesetzt, aber auch nicht kategorisch abgelehnt und 41 % führten regelmäßig Borreliose-Impfungen durch.

Schlussfolgerung und klinische Relevanz Das Meinungsbild von praktizierenden Pferdetierärztinnen und Pferdetierärzten in Deutschland zur klinischen Relevanz der equinen LB ist sehr heterogen. Einheitliche Richtlinien hinsichtlich Diagnostik- und evtl. auch Therapieempfehlungen wären sinnvoll, um der Unsicherheit in der Tierärzteschaft entgegenzuwirken.

Molecular survey on the presence of arthropod-borne bacteria and protozoans in roe deer (Capreolus capreolus) and ticks from Central Italy

Environmental changes, due to climatic emergency and to anthropogenic activities severely impact on the epidemiology of vector borne diseases, mostly when transmitted by ticks. The data about the distribution of microorganisms responsible for them in roe deer (Capreolus capreolus) population living in Italy are scanty and completely lacking in Tuscany, so a molecular survey was carried out to estimate the prevalence of some zoonotic tick-borne pathogens in roe deer, and ticks removed from them, living in areas of Central Italy with high risk of arthropod exposure. Spleen samples from 72 roe deer were tested by PCR for Anaplasma phagocytophilum, Borrelia burgdorferi s.l., Francisella tularensis and piroplasms. Moreover, 345 ticks were removed from 65 roe deer, morphologically or molecularly identified and grouped into 162 pools that were submitted to PCR for detecting the same pathogens. Forty-six (63.88%) roe deer were positive for at least one investigated pathogen: 43 (59.72%) for A. phagocytophilum, 2 (2.78%) for Babesia capreoli, 1 (1.39%) for B. burgdorferi, and 1 (1.39%) for Babesia sp.. No animals were PCR positive for F. tularensis. All ticks were identified as Ixodes ricinus. Seventy-six (46.91%) tick pools showed DNA of one or more pathogens: 66 (40.74%) were positive for A. phagocytophilum, 22 (13.58%) for B. burgodorferi s.l., 6 (3.70%) for B. venatorum and 3 (1.85%) for B. capreoli. No pools were positive for F. tularensis. Two or three pathogens were detected in 23 (14.19%) pools.

A review of investigated risk factors for developing equine recurrent uveitis

Equine recurrent uveitis (ERU) is an ocular inflammatory disease that can be difficult to manage clinically. As such, it is the leading cause of bilateral blindness for horses. ERU is suspected to have a complex autoimmune etiology with both environmental and genetic risk factors contributing to onset and disease progression in some or all cases. Work in recent years has aimed at unraveling the primary triggers, such as infectious agents and inherited breed-specific risk factors, for disease onset, persistence, and progression. This review has aimed at encompassing those factors that have been associated, implicated, or substantiated as contributors to ERU, as well as identifying areas for which additional knowledge is needed to better understand risk for disease onset and progression. A greater understanding of the risk factors for ERU will enable earlier detection and better prognosis through prevention and new therapeutics.

Case Report: Nuchal Bursitis Associated With Borrelia burgdorferi Infection in a Horse

Cases of cranial nuchal bursitis associated with Borrelia burgdorferi infection have not been thoroughly described. Here, we describe the case of a 17-year-old mare that was presented for low head carriage, dull demeanor, and resistance to haltering. Imaging supported a diagnosis of nuchal bursitis, and bursoscopy with surgical debridement of the nuchal bursa was performed. B. burgdorferi was identified by molecular diagnostics in serial samples of the bursal fluid, with no other organisms identified. Serology revealed significant elevation in antibodies directed against OspA of B. burgdorferi, but not the typical infection markers, OspC and OspF. Intravenous ceftiofur was administered for 80 days, and the nuchal bursa was directly injected with ceftiofur. The mare recovered and was able to return to work with no recrudescence of clinical signs over the following year to date. Infection with B. burgdorferi should be considered as a differential in cases of septic nuchal bursitis.

Tick-borne zoonotic agents infecting horses from an urban area in Midwestern Brazil: epidemiological and hematological features

The emergence of tick-borne diseases has been reported as a serious problem in public health worldwide and many aspects of its epidemiology and effects on the health of its hosts are unclear. We aimed to perform an epidemiological study of tick-borne zoonotic Rickettsia, Borrelia, and Anaplasmataceae in horses from Midwestern Brazil. We also evaluated whether Borrelia spp. and Anaplasmataceae may be associated with hematological disorders in the sampled animals. Blood and serum samples as well as ticks were collected from 262 horses. Serum samples were used to perform serological tests, and hematological analyses were made using whole blood. Furthermore, DNA extracted from whole blood and ticks was used for molecular tests. Campo Grande is enzootic for tick-borne studied bacteria, since we found an overall exposure of 59.9% of the sampled horses, 28.7% of them presented co-exposure. Seropositivity rates of 20.6% for Borrelia spp., 25.6% for Rickettsia spp., and 31.6% for Anaplasmataceae were found in the sampled horses. Considering both molecular and serological tests for Borrelia spp., the infection rate was 48.0% (126/262). None of the tested horses showed molecular positivity for Anaplasma phagocytophilum. The horses sampled displayed 7.2% of parasitism by ixodid ticks in single and coinfestations. We did not find DNA of any studied bacteria in the sampled ticks. Positive horses for Borrelia spp. and Anaplasmataceae agents displayed leukopenia, monocytopenia, and lymphopenia. Together, our results suggest that horses may play a role as sentinel host for zoonotic bacteria and Borrelia spp. and Anaplasmataceae agents can impair the health of horses.

Zoonotic Tick-Borne Pathogens in Temperate and Cold Regions of Europe-A Review on the Prevalence in Domestic Animals

Ticks transmit a variety of pathogens affecting both human and animal health. In temperate and cold regions of Europe (Western, Central, Eastern, and Northern Europe), the most relevant zoonotic tick-borne pathogens are tick-borne encephalitis virus (TBEV), Borrelia spp. and Anaplasma phagocytophilum. More rarely, Rickettsia spp., Neoehrlichia mikurensis, and zoonotic Babesia spp. are identified as a cause of human disease. Domestic animals may also be clinically affected by these pathogens, and, furthermore, can be regarded as sentinel hosts for their occurrence in a certain area, or even play a role as reservoirs or amplifying hosts. For example, viraemic ruminants may transmit TBEV to humans via raw milk products. This review summarizes the role of domestic animals, including ruminants, horses, dogs, and cats, in the ecology of TBEV, Borrelia spp., A. phagocytophilum, Rickettsia spp., N. mikurensis, and zoonotic Babesia species. It gives an overview on the (sero-)prevalence of these infectious agents in domestic animals in temperate/cold regions of Europe, based on 148 individual prevalence studies. Meta-analyses of seroprevalence in asymptomatic animals estimated an overall seroprevalence of 2.7% for TBEV, 12.9% for Borrelia burgdorferi sensu lato (s.l.), 16.2% for A. phagocytophilum and 7.4% for Babesia divergens, with a high level of heterogeneity. Subgroup analyses with regard to animal species, diagnostic test, geographical region and decade of sampling were mostly non-significant, with the exception of significantly lower B. burgdorferi s.l. seroprevalences in dogs than in horses and cattle. More surveillance studies employing highly sensitive and specific test methods and including hitherto non-investigated regions are needed to determine if and how global changes in terms of climate, land use, agricultural practices and human behavior impact the frequency of zoonotic tick-borne pathogens in domestic animals.

Ocular disease in horses with confirmed ocular or central nervous system Borrelia infection: Case series and review of literature

OBJECTIVE

To describe the clinical presentation, treatment, and clinical outcome of horses with ocular disease and evidence of systemic or ocular Lyme disease.

ANIMALS STUDIED

Five horses met the inclusion criteria of ocular disease with evidence of B burgdorferi present in ocular or CNS tissues.

PROCEDURE

The goal of this study was to describe the clinical presentation and progression of ocular disease when associated with ocular or CNS B burgdorferi infection in horses. A retrospective review of medical records was performed on horses admitted for ocular disease with evidence of B burgdorferi infection between 1998 and 2015. The diagnosis of B burgdorferi-associated uveitis was based on histopathologic lesions of lymphohistiocytic and suppurative uveitis/endophthalmitis and intralesional argyrophilic spirochetes in either ocular or CNS tissue consistent with Borrelia. Leptospiral uveitis was ruled out by PCR.

RESULTS

All five horses in the current study had intraocular inflammation at the time of presentation. Medical management with anti-inflammatories was successful in controlling uveitis in the two horses in which treatment of uveitis was attempted. Systemic treatment with oral tetracyclines was unsuccessful in a single case in which treatment of Borrelia was attempted. Four horses were euthanized due to progression of neurologic disease. The surviving horse had an enucleation performed and did not show systemic signs.

CONCLUSIONS

Infection with Borrelia burgdorferi should be considered in endemic areas as a differential for horses with ocular disease, in particular, uveitis. The prognosis for uveitis and neurologic disease associated with Lyme disease was poor in the current study.

Comparison of motif-based and whole-unique-sequence-based analyses of phage display library datasets generated by biopanning of anti-Borrelia burgdorferi immune sera

Detection of protection-associated epitopes via reverse vaccinology is the first step for development of subunit vaccines against microbial pathogens. Mapping subunit vaccine targets requires high throughput methods, which would allow delineation of epitopes recognized by protective antibodies on a large scale. Phage displayed random peptide library coupled to Next Generation Sequencing (PDRPL/NGS) is the universal platform that enables high-yield identification of peptides that mimic epitopes (mimotopes). Despite being unsurpassed as a tool for discovery of polyclonal serum mimotopes, the PDRPL/NGS is far inferior as a quantitative method of immune response. Difficult-to-control fluctuations in amounts of antibody-bound phages after rounds of selection and amplification diminish the quantitative capacity of the PDRPL/NGS. In an attempt to improve the accuracy of the PDRPL/NGS method, we compared the discriminating capacity of two approaches for PDRPL/NGS data analysis. The whole-unique-sequence-based analysis (WUSA) involved generation of 7-mer peptide profiles and comparison of the numbers of sequencing reads for unique peptide sequences between serum samples. The motif-based analysis (MA) included identification of 4-mer consensus motifs unifying unique 7-mer sequences and comparison of motifs between serum samples. The motif comparison was based not on the numbers of sequencing reads, but on the numbers of distinct 7-mers constituting the motifs. Our PDRPL/NGS datasets generated from biopanning of protective and non-protective anti-Borrelia burgdorferi sera of New Zealand rabbits were used to contrast the two approaches. As a result, the principle component analyses (PCA) showed that the discriminating powers of the WUSA and MA were similar. In contrast, the unsupervised hierarchical clustering obtained via the MA classified the preimmune, non-protective, and protective sera better than the WUSA-based clustering. Also, a total number of discriminating motifs was higher than that of discriminating 7-mers. In sum, our results indicate that MA approach improves the accuracy and quantitative capacity of the PDRPL/NGS method.

First description of Coxiella burnetii and Rickettsia spp. infection and molecular detection of piroplasma co-infecting horses in Xinjiang Uygur Autonomous Region, China

Q fever, spotted fever rickettsioses and equine piroplasmosis, are some of the most serious equine tick-borne diseases caused by Coxiella burnetii, Rickettsia spp., Babesia caballi and/or Theileria equi. This study surveyed and molecularly characterized these pathogens infecting horses in ten ranches from XUAR, China using molecular technology. Among 200 horse blood samples, 163 (81.5%) were infected with at least one of the pathogens. Rickettsia spp. was the most prevalent pathogen (n = 114, 57.0%), followed by C. burnetii (n = 79, 39.5%), T. equi (n = 79, 39.5%) and B. caballi (n = 49, 24.5%). Co-infections were observed in 61.3% of positive samples in this study. Statistically significant differences were observed between the sampling regions for C. burnetii, B. caballi and T. equi, and also in different age group for C. burnetii and T. equi. The genotype analysis indicated that C. burnetii htpB, Rickettsia spp. ompA, B. caballi rap-1, B. caballi 18S rRNA, T. equi EMA-1 and T. equi 18S rRNA gene sequences from horses in XUAR were variable. To the best of our knowledge, this study is the first report of C. burnetii and Rickettsia spp. infection and co-infected with piroplasma in horses in China. Overall, this study revealed the high infection rate of the pathogens in horses in XUAR, China. The current findings are expected to provide a basis for better tick-borne disease control in the region.

Delineating Surface Epitopes of Lyme Disease Pathogen Targeted by Highly Protective Antibodies of New Zealand White Rabbits

Lyme disease (LD), the most prevalent vector-borne illness in the United States and Europe, is caused by Borreliella burgdorferi No vaccine is available for humans. Dogmatically, B. burgdorferi can establish a persistent infection in the mammalian host (e.g., mice) due to a surface antigen, VlsE. This antigenically variable protein allows the spirochete to continually evade borreliacidal antibodies. However, our recent study has shown that the B. burgdorferi spirochete is effectively cleared by anti-B. burgdorferi antibodies of New Zealand White rabbits, despite the surface expression of VlsE. Besides homologous protection, the rabbit antibodies also cross-protect against heterologous B. burgdorferi spirochetes and significantly reduce the pathology of LD arthritis in persistently infected mice. Thus, this finding that NZW rabbits develop a unique repertoire of very potent antibodies targeting the protective surface epitopes, despite abundant VlsE, prompted us to identify the specificities of the protective rabbit antibodies and their respective targets. By applying subtractive reverse vaccinology, which involved the use of random peptide phage display libraries coupled with next-generation sequencing and our computational algorithms, repertoires of nonprotective (early) and protective (late) rabbit antibodies were identified and directly compared. Consequently, putative surface epitopes that are unique to the protective rabbit sera were mapped. Importantly, the relevance of newly identified protection-associated epitopes for their surface exposure has been strongly supported by prior empirical studies. This study is significant because it now allows us to systematically test the putative epitopes for their protective efficacy with an ultimate goal of selecting the most efficacious targets for development of a long-awaited LD vaccine.

New Zealand White Rabbits Effectively Clear Borrelia burgdorferi B31 despite the Bacterium's Functional vlsE Antigenic Variation System

Borrelia burgdorferi is a tick-borne bacterium responsible for approximately 300,000 annual cases of Lyme disease (LD) in the United States, with increasing incidences in other parts of the world. The debilitating nature of LD is mainly attributed to the ability of B. burgdorferi to persist in patients for many years despite strong anti-Borrelia antibody responses. Antimicrobial treatment of persistent infection is challenging. Similar to infection of humans, B. burgdorferi establishes long-term infection in various experimental animal models except for New Zealand White (NZW) rabbits, which clear the spirochete within 4 to 12 weeks. LD spirochetes have a highly evolved antigenic variation vls system, on the lp28-1 plasmid, where gene conversion results in surface expression of the antigenically variable VlsE protein. VlsE is required for B. burgdorferi to establish persistent infection by continually evading otherwise potent antibodies. Since the clearance of B. burgdorferi is mediated by humoral immunity in NZW rabbits, the previously reported results that LD spirochetes lose lp28-1 during rabbit infection could potentially explain the failure of B. burgdorferi to persist. However, the present study unequivocally disproves that previous finding by demonstrating that LD spirochetes retain the vls system. However, despite the vls system being fully functional, the spirochete fails to evade anti-Borrelia antibodies of NZW rabbits. In addition to being protective against homologous and heterologous challenges, the rabbit antibodies significantly ameliorate LD-induced arthritis in persistently infected mice. Overall, the current data indicate that NZW rabbits develop a protective antibody repertoire, whose specificities, once defined, will identify potential candidates for a much-anticipated LD vaccine.

Pericardial Disease, Myocardial Disease, and Great Vessel Abnormalities in Horses

Pericardial, myocardial, and great vessel diseases are relatively rare in horses. The clinical signs are often nonspecific and vague, or related to the underlying cause. Physical examination usually reveals tachycardia, fever, venous distension or jugular pulsation, a weak or bounding arterial pulse, ventral edema, and abnormal cardiac auscultation such as arrhythmia, murmur, or muffled heart sounds. The prognosis depends on the underlying cause and the disease progression, and ranges from full recovery to poor prognosis for survival. This article focuses on the etiology, diagnosis, prognosis, and treatment of pericarditis, pericardial mass lesions, myocarditis, cardiomyopathy, and great vessel aneurysm or rupture.

Borreliosis in Sport Horse Practice

Given the variable clinical signs attributed to Borrelia burgdorferi, including infectious arthritis, neurologic disease, and behavioral changes, B burgdorferi is an important differential for decreased performance in sport horses. The primary vectors (Ixodes tick species) are expanding their range and thus Borrelia species are located in a wider area, making exposure more likely. Due to regionally high seroprevalence and vague clinical signs, diagnosis of Lyme disease in the horse is believed overestimated. Antibiotics are first-line treatment of confirmed Lyme disease. A single positive serologic test, by itself, is not conformation of Lyme disease but is evidence of current or past infection.

Equine Granulocytic Anaplasmosis 28 years later

Equine granulocytic anaplasmosis (EGA) is an important tick borne disease of equines that is caused by Anaplasma phagocytophilum (A. phagocytophilum). The etiological agent has veterinary as well as public health importance because of its zoonotic nature. A. phagocytophilum causes an acute illness in equines with loss of appetite, lethargy, hemorrhages and lameness. Clinically, EGA is diagnosed upon examination of morulae within neutrophils especially granulocytes in the blood. The best diagnostic tool for the detection of EGA is Polymerase chain reaction (PCR). Previous studies suggested that EGA is a self-limiting disease and tetracycline therapy is considered as a best treatment regimen. There is no comprehensive summary on the occurrence and distribution of the infection at global level. Therefore, we intended to provide a comprehensive summary on the prevalence and epidemiology of EGA in different areas of the world. It includes mapping the global distribution of EGA in different areas of the world to identify the endemic regions which may be a source of potential disease outbreak. For this purpose, the published data from 1990 to 2018 on EGA was reviewed and collected by electronic literature search of five databases including Google, Google Scholar, Science Direct, PubMed and Web of Science.

Cerebrospinal fluid Lyme multiplex assay results are not diagnostic in horses with neuroborreliosis

BACKGROUND

The accuracy of the Lyme multiplex assay for the diagnosis of neuroborreliosis in horses is unknown.

HYPOTHESIS/OBJECTIVES

To describe Lyme multiplex results in horses with a postmortem diagnosis of neuroborreliosis. The hypothesis was that paired serum and cerebrospinal fluid (CSF) results and a CSF : serum ratio would allow differentiation of horses with neuroborreliosis from those with other neurologic diseases.

ANIMALS

Ninety horses that had neurologic examinations, serum and CSF Lyme multiplex analyses, and postmortem examination of the nervous system performed.

METHODS

Retrospective study. Data collected included signalment, ante- and postmortem diagnoses, and serum and CSF Lyme multiplex results. The CSF : serum ratio was calculated by dividing CSF median fluorescent intensity (MFI) by serum MFI for each result.

RESULTS

Ten horses had a final diagnosis of neuroborreliosis, 70 were diagnosed with other neurologic diseases, and 10 had no neurologic disease. Not all horses with neuroborreliosis had positive results: 4/10 had at least 1 positive serum result, 5/10 had at least 1 positive CSF result, and 3/10 had at least 1 CSF result 4-fold higher than the corresponding serum result. Results were similar for the 70 horses with other neurologic diseases: 53% had at least 1 positive serum result, 50% had at least 1 positive CSF result, and 16% had at least 1 CSF result 4-fold higher than the corresponding serum result.

CONCLUSIONS AND CLINICAL IMPORTANCE

Positive Lyme multiplex results were common in horses with neurologic diseases and did not adequately differentiate horses with neuroborreliosis from horses with other disorders.

Borrelia burgdorferi Infection and Lyme Disease in North American Horses: A Consensus Statement

Borrelia burgdorferi infection is common in horses living in Lyme endemic areas and the geographic range for exposure is increasing. Morbidity after B. burgdorferi infection in horses is unknown. Documented, naturally occurring syndromes attributed to B. burgdorferi infection in horses include neuroborreliosis, uveitis, and cutaneous pseudolymphoma. Although other clinical signs such as lameness and stiffness are reported in horses, these are often not well documented. Diagnosis of Lyme disease is based on exposure to B. burgdorferi, cytology or histopathology of infected fluid or tissue and antigen detection. Treatment of Lyme disease in horses is similar to treatment of humans or small animals but treatment success might not be the same because of species differences in antimicrobial bioavailability and duration of infection before initiation of treatment. There are no approved equine label Lyme vaccines but there is strong evidence that proper vaccination could prevent infection in horses.

Molecular survey on the occurrence of arthropod-borne pathogens in wild brown hares (Lepus europaeus) from Central Italy

Data about the spreading of arthropod-borne pathogens among hare populations are very scant, so the aim of the present preliminary study was to investigate, through molecular analysis, the occurrence of Anaplasma phagocytophilum, Bartonella sp., Borrelia burgdorferi sensu lato, Coxiella burnetii, Francisella tularensis, Leishmania spp. and piroplasms DNA in blood of 51 wild hares (Lepus europaeus) living in protected areas in Tuscany. All hares resulted negative for A. phagocytophilum, Bartonella sp., B. burgdorferi s.l., C. burnetii and F. tularensis. Five animals (9.8%) were positive for Leishmania and one hare (1.9%) tested positive for piroplasms. Sequencing of this sample showed a piroplasm similar to one Babesia isolate from the same animal species in Turkey. Therefore, to the best of our knowledge, this is the first molecular report of piroplasms occurring in wild hares from Italy, and the second worldwide. The examined hares appeared to be in good health status, corroborating the hypothesis of a chronic carrier state of some vector borne agents for this animal species.

Brazilian borreliosis with special emphasis on humans and horses

Borreliosis caused by Borrelia burgdorferi sensu lato is a cosmopolitan zoonosis studied worldwide; it is called Lyme disease in many countries of the Northern Hemisphere and Lyme-like or Baggio-Yoshinari Syndrome in Brazil. However, despite the increasing number of suspect cases, this disease is still neglected in Brazil by the medical and veterinary communities. Brazilian Lyme-like borreliosis likely involves capybaras as reservoirs and Amblyomma and Rhipicephalus ticks as vectors. Thus, domestic animals can serve as key carriers in pathogen dissemination. This zoonosis has been little studied in horses in Brazil. The first survey was performed in the state of Rio de Janeiro, and this Brazilian Borreliosis exhibits many differences from the disease widely described in the Northern Hemisphere. The etiological agent shows different morphological and genetic characteristics, the disease has a higher recurrence rate after treatment with antibiotics, and the pathogen stimulates intense symptoms such as a broader immune response in humans. Additionally, the Brazilian zoonosis is not transmitted by the Ixodes ricinus complex. With respect to clinical manifestations, Baggio-Yoshinari Syndrome has been reported to cause neurological, cardiac, ophthalmic, muscle, and joint alterations in humans. These symptoms can possibly occur in horses. Here, we present a current panel of studies involving the disease in humans and equines, particularly in Brazil.

Molecular survey on the presence of zoonotic arthropod-borne pathogens in wild red deer (Cervus elaphus)

To estimate the prevalence of some zoonotic tick-borne pathogens in red deer (Cervus elaphus) living in Italian areas with high risk of arthropod exposure, blood samples from 60 red deer were tested by PCR for A. phagocytophilum, Borrelia burgdorferi s.l., Coxiella burnetii, Francisella tularensis, and piroplasms. Thirty-four (56.67%) animals resulted positive for one or more pathogens. In particular, 24 (40%) red deer were positive for A. phagocytophilum, 16 (26.67%) for Babesia divergens, 6 (10%) for C. burnetii, 2 (3.33%) for B. burgdorferi s.l. No positive reaction was observed for F. tularensis. Thirteen (21.67%) animals resulted co-infected by two or three pathogens. Red deer is confirmed as competent reservoir of A. phagocytophilum and B. divergens, but not of B. burgdorferi. This is the first report of C. burnetii-positive red deer in central Italy. Hunters may be at risk of infection both through infected ticks and during the infected cervids carcasses dressing.

Retrospective Evaluation of Horses Diagnosed with Neuroborreliosis on Postmortem Examination: 16 Cases (2004-2015)

BACKGROUND

Equine neuroborreliosis (NB), Lyme disease, is difficult to diagnose and has limited description in the literature.

OBJECTIVE

Provide a detailed description of clinical signs, diagnostic, and pathologic findings of horses with NB.

ANIMALS

Sixteen horses with histologically confirmed NB.

METHODS

Retrospective review of medical records at the University of Pennsylvania and via an ACVIM listserv query with inclusion criteria requiring possible exposure to Borrelia burgdorferi and histologic findings consistent with previous reports of NB without evidence of other disease.

RESULTS

Sixteen horses were identified, 12 of which had additional evidence of NB. Clinical signs were variable including muscle atrophy or weight loss (12), cranial nerve deficits (11), ataxia (10), changes in behavior (9), dysphagia (7), fasciculations (6), neck stiffness (6), episodic respiratory distress (5), uveitis (5), fever (2), joint effusion (2), and cardiac arrhythmias (1). Serologic analysis was positive for B. burgdorferi infection in 6/13 cases tested. CSF abnormalities were present in 8/13 cases tested, including xanthochromia (4/13), increased total protein (5/13; median: 91 mg/dL, range: 25-219 mg/dL), and a neutrophilic (6/13) or lymphocytic (2/13) pleocytosis (median: 25 nucleated cells/μL, range: 0-922 nucleated cells/μL). PCR on CSF for B. burgdorferi was negative in the 7 cases that were tested.

CONCLUSION AND CLINICAL IMPORTANCE

Diagnosis of equine NB is challenging due to variable clinical presentation and lack of sensitive and specific diagnostic tests. Negative serology and normal CSF analysis do not exclude the diagnosis of NB.

Molecular survey on zoonotic tick-borne bacteria and chlamydiae in feral pigeons (Columba livia domestica)

OBJECTIVE

To determine the presence of zoonotic tick-borne bacteria in feral pigeons (Columba livia domestica) from urban areas.

METHODS

Spleen samples from 84 feral pigeons, found dead with traumatic injuries in urban areas, were examined by PCR to detect DNA of Anaplasma phagocytophilum, Bartonella spp., Borrelia burgdorferi sensu lato, Coxiella burnetii, Rickettsia spp., and Chlamydophila spp.

RESULTS

Twenty (23.8%) pigeons were infected by tick-borne agents, in particular 2 (2.38%) animals resulted positive for Bartonella spp., 5 (5.95%) for C. burnetii, 5 (5.95%) for Rickettsia spp., 13 (15.47%) for B. burgdorferi sensu lato. All birds scored negative for A. phagocytophilum. Moreover, 17 (20.23%) pigeons were positive for Chlamydophila spp. and among them 10 (11.9%) for Chlamydophila psittaci. Mixed infections by two or three agents were detected in 8 (9.52%) animals.

CONCLUSIONS

Feral pigeons living in urban and periurban areas are a hazard for the human health as source of several pathogens. The obtained results confirm pigeons as reservoirs of chlamydial agents and suggest that they may be involved in the epidemiology of zoonotic tick-borne infections too.

Molecular survey of tick-borne pathogens in Ixodid ticks collected from hunted wild animals in Tuscany, Italy

OBJECTIVE

To determine the prevalence of zoonotic tick-borne bacteria in feeding ticks removed from hunted wild animals.

METHODS

PCR was executed on DNA extracted from 77 tick pools to detect Anaplasma phagocytophilum, Bartonella spp., Borrelia burgdorferi sensu lato, Coxiella burnetii and Rickettsia spp.

RESULTS

A total of 432 ticks were collected: 30 (6.94%) Haemaphysalis punctata, 72 (16.7%) Dermacentor marginatus and 330 (76.38%) Ixodes ricinus. For each animal one or two pools of 3 ticks of the same species was constituted. Seventy-seven tick pools were examined by PCR: 58 (75.32%) resulted infected and among them 14 (18.18%) showed co-infections. In particular, 29 (37.66%) pools were positive for Bartonella spp., 23 (29.87%) for Anaplasma phagocytophilum, 16 (20.78%) for Rickettsia spp., and 5 (6.49%) for Borrelia burgdorferi s.l. All samples were negative for Coxiella burnetii.

CONCLUSIONS

The results demonstrate the presence of several zoonotic tick-borne pathogens in the studied area, and underline the risk of exposure to infections for hunters not only during the outdoor activity, but also when they manipulate hunted animals infested by infected ticks.

Antibodies to OspC, OspF and C6 antigens as indicators for infection with Borrelia burgdorferi in horses

REASONS FOR PERFORMING STUDY

Lyme disease is caused by Borrelia burgdorferi, which is transmitted by infected ticks (Ixodes spp.). Reports on Lyme disease in horses have increased in recent years. Nevertheless, the diagnosis of Lyme disease in horses is still challenging owing to its vague clinical presentation and the limitations of diagnostic tests.

OBJECTIVES

This study used a new serological Lyme multiplex assay to examine antibody responses to 3 antigens of B. burgdorferi, outer surface protein (Osp) C, OspF and C6, and to verify their use as markers for early and late infection stages in horses.

METHODS

Multiplex analysis of antibodies to OspC, OspF and C6 in equine patient sera (n = 191) was performed. A subset of the sera (n = 90) was also tested using a commercial C6-based Lyme test.

RESULTS

Antibodies to OspF and C6 highly correlate as reliable markers of infection with B. burgdorferi in horses. Antibodies to OspC, which have been confirmed as early infection markers in man and dogs, were only detected in some patient sera, suggesting that OspC antibodies are indicators of early infection in horses. Commercial C6 testing identified most infected horses but also resulted in false positive and false negative interpretations.

CONCLUSIONS

Serological multiplex testing is a rapid and quantitative diagnostic method to confirm infection with B. burgdorferi and to identify the stage of infection. In horses with risk of exposure and clinical signs, multiplex testing supports the diagnosis of Lyme disease.

POTENTIAL RELEVANCE

Antimicrobial treatment of B. burgdorferi is time sensitive. Treatment success decreases with time of persistent infection, while the risk of developing chronic disease increases. The ability to identify early infection with B. burgdorferi provides practitioners and clinicians with a tool to improve the diagnosis of equine Lyme disease and make treatment decisions.

Changes in Borrelia burgdorferi ELISA antibody over time in both antibiotic treated and untreated horses

Changes in ELISA serology are frequently used to determine antibiotic treatment success for Lyme disease in horses. This concept was based upon a previous report showing a marked decline in ELISA values in experimentally infected and antibiotic-treated ponies. Changes in Lyme serology following antibiotic treatment in naturally infected horses have not been reported. The objective of this study was to compare Borrelia ELISA antibody concentrations in naturally exposed horses both before and following antibiotic treatment for Lyme disease. A retrospective study was performed comparing oxytetracycline- or doxycyclinetreated (n = 68) and untreated (n = 183) horses from a single equine practice and their change in Borrelia ELISA values over a similar time period. Antibiotictreated horses had a decline in ELISA values in comparison to control horses (P ≤ 0.05) and untreated horses were twice as likely to have their ELISA values increase (OR = 0.5; 95% C.I. = 0.3-0.9) compared to treated horses. The magnitude of the decline in ELISA units following treatments was small compared to that previously reported in experimentally infected and treated ponies. Field-exposed horses with high Borrelia burgdorferi ELISA values who are treated with either oxytetracycline or doxycycline can be expected to have only a small decline in ELISA values following treatment. Persistently high ELISA titres following appropriate treatments for Lyme disease may not, without appropriate clinical signs, be a reason for more prolonged treatment.

Occurrence of Borrelia lusitaniae infection in horses

The aim of the study was to investigate Borrelia burgdorferi sensu lato (s.l.) infection in horses exposed to heavy tick infestations. Blood samples of 98 healthy horses from 5 stud farms were examined by SNAP(®) 4D× and PCR to detect antibodies against B. burgdorferi s.l. and Borrelia DNA, respectively. Ten samples (15.3%) were antibody positive and 5 samples (5.1%) were both antibody and PCR positive. Sequence analysis showed the highest homology with the B. lusitaniae genospecies. No differences were found between sexes and stud farms, while age was significantly related to seropositivity (p<0.05). Our data confirms the presence of B. lusitaniae infection in horses, previously not clearly demonstrated.

A case of Borrelia-associated cutaneous pseudolymphoma in a horse

This case report describes a 10-year-old horse that developed multiple dermal papules over the right masseter area following removal of a tick from the same site 3 months earlier. Histological examination of a biopsy from a papule was suggestive of either a T-cell-rich B-cell lymphoma or cutaneous lymphoid hyperplasia, a form of pseudolymphoma sometimes associated with a tick bite. Positive serological testing and PCR of the biopsy sample for Borrelia in conjunction with immunohistochemical testing of the skin biopsy, the clinical history and response to treatment with doxycycline strongly supported the diagnosis of Borrelia-associated cutaneous pseudolymphoma.

Development of a multiplex assay for the detection of antibodies to Borrelia burgdorferi in horses and its validation using Bayesian and conventional statistical methods

Lyme disease is a zoonotic, vector-borne disease and occurs in mammals including horses. The disease is induced by infection with spirochetes of the Borrelia burgdorferi sensu lato group. Infection of mammalian hosts requires transmission of spirochetes by infected ticks during tick bites. Lyme disease diagnosis is based on clinical signs, possible exposure to infected ticks, and antibody testing which is traditionally performed by ELISA and Western blotting (WB). This report describes the development and validation of a new fluorescent bead-based multiplex assay for the detection of antibodies to B. burgdorferi outer surface protein A (OspA), OspC and OspF antigens in horse serum. Testing of 562 equine sera was performed blindly and in parallel by using WB and the new multiplex assay. Because a true gold standard is missing for Lyme antibody testing, we performed and compared different statistical approaches to validate the new Lyme multiplex assay. One approach was to use WB results as a 'relative gold standard' in ROC-curve and likelihood-ratio analyses of the new test. Cut-off values and interpretation ranges of the multiplex assay were established by the analysis. The second statistical approach used a Bayesian model for the calculation of diagnostic sensitivities and specificities of the multiplex assay. The Bayesian analysis takes into consideration that no true gold standard exists for detecting antibodies to B. burgdorferi and estimated sensitivities and specificities of both tests that were compared. Therefore, the Bayesian analysis also resulted in an evaluation of diagnostic sensitivity and specificity of WB. Overall, the new assay was characterized by low background values and a wide dynamic quantification range for the detection of antibodies to OspA, OspC and OspF antigens of B. burgdorferi. The diagnostic sensitivity and specificity for the OspA bead-based assay were calculated as 49% and 85%, respectively, and by a standard ROC curve analysis only because the Bayesian model could not be run on this parameter. The Bayesian-derived diagnostic sensitivities of the OspC and OspF assays were 80% and 86%, respectively. For comparison, the Bayesian-derived estimates for WB resulted in sensitivities of 72% for OspC and 80% for OspF. The Bayesian diagnostic specificities of the multiplex assay were 79% and 69% for OspC and OspF, respectively. WB analysis had specificities of 92% for OspC and 77% for OspF. Although the analysis of a new assay in the absence of a true gold standard remains challenging, the approach used here can help to address this problem when new technologies and traditionally used test standards differ significantly in their analytical sensitivities, which consequently causes problems in the calculation of diagnostic sensitivity and sensitivity values for the new assay. In summary, the new multiplex assay for the detection of antibodies to B. burgdorferi OspA, OspC and OspF antigens in horse serum has improved analytical and diagnostic sensitivities compared to WB analysis. Multiplex analysis is a valuable quantitative tool that simultaneously detects antibodies indicative for natural infection with and/or vaccination against the Lyme pathogen.

Lyme Neuroborreliosis in 2 Horses

Lyme neuroborreliosis—characterized as chronic, necrosuppurative to nonsuppurative, perivascular to diffuse meningoradiculoneuritis—was diagnosed in 2 horses with progressive neurologic disease. In 1 horse, Borrelia burgdorferi sensu stricto was identified by polymerase chain reaction amplification of B burgdorferi sensu stricto–specific gene targets ( ospA, ospC, flaB, dbpA, arp). Highest spirochetal burdens were in tissues with inflammation, including spinal cord, muscle, and joint capsule. Sequence analysis of ospA, ospC, and flaB revealed 99.9% sequence identity to the respective genes in B burgdorferi strain 297, an isolate from a human case of neuroborreliosis. In both horses, spirochetes were visualized in affected tissues with Steiner silver impregnation and by immunohistochemistry, predominantly within the dense collagenous tissue of the dura mater and leptomeninges.

Seroprevalence of Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum in Danish horses

Background

Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum are able to infect horses. However, the extend to which Danish horses are infected and seroconvert due to these two bacteria is unknown. The aim of the present study was to evaluate the seroprevalence of B. burgdorferi sensu lato and A. phagocytophilum in Danish horses.

Methods

A total of 390 blood samples collected from all major regions of Denmark and with a geographical distribution corresponding to the density of the Danish horse population were analyzed. All samples were examined for the presence of antibodies against B. burgdorferi sensu lato and A. phagocytophilum by the use of the SNAP^®4DX ^® ELISA test.

Results

Overall, 29.0% of the horses were seropositive for B. burgdorferi sensu lato whereas 22.3% were seropositive for A. phagocytophilum.

Conclusions

Antibodies against B burgdorferi sensu lato and A. phagocytophilum are commonly found among Danish horses thus showing that Danish horses are frequently infected by these organisms.

Validation of an In-Clinic Enzyme-Linked Immunosorbent Assay Kit for Diagnosis of Borrelia Burgdorferi Infection in Horses

Confirmation of Borrelia burgdorferi infection in horses has required enzyme-linked immunosorbent assay (ELISA) or Western blot tests performed by reference laboratories. An in-clinic C6 ELISA SNAP kit has been marketed for dogs. This canine kit was evaluated for horses using serum from experimentally infected ponies. Serum samples originated from 2 previous studies. In the first study, 7 ponies were exposed to B. burgdorferi–infected ticks; 4 ponies served as uninfected controls. Serum samples were obtained bimonthly for 9 months. In the second study, 16 ponies were exposed to B. burgdorferi–infected ticks. After confirmation of infection by skin culture, polymerase chain reaction (PCR), and serology, the ponies were allocated to 4 groups that received tetracycline, doxycycline, ceftiofur, or no treatment. Serum samples were obtained monthly, both before and after antibiotic treatments, for 11 months. For the current study, selected samples ( n = 220) from both studies were tested with IDEXX SNAP Heartworm Ab/ Borrelia burgdorferi Ab/ Ehrlichia canis Ab Test Kits. Tested samples included samples taken before infection, from various times postinfection, and after antibiotic treatments. Results from confirmed positive or negative samples were used to determine sensitivity and specificity of the assay. Results indicate that the test kits have fair sensitivity (63%) and very high specificity (100%) for horses recently infected with B. burgdorferi. Validation of this test provides equine practitioners with an inexpensive, in-clinic method to confirm infection, although its moderate sensitivity may result in a moderate chance of a false negative test.

In vitro susceptibilities of Leptospira spp. and Borrelia burgdorferi isolates to amoxicillin, tilmicosin, and enrofloxacin

Antimicrobial susceptibility testing was conducted with 6 different spirochetal strains (4 strains of Leptospira spp. and 2 strains of Borrelia burgdorferi) against 3 antimicrobial agents, commonly used in equine and bovine practice. The ranges of MIC and MBC of amoxicillin against Leptospira spp. were 0.05 - 6.25 microgram/ml and 6.25 - 25.0 microgram/ml, respectively. And the ranges of minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of amoxicillin against B. burgdorferi were 0.05 - 0.39 microgram/ml and 0.20 - 0.78 microgram/ml, respectively. The ranges of MIC and MBC of enrofloxacin against Leptospira spp. were 0.05 - 0.39 microgram/ml and 0.05 - 0.39 microgram/ml, respectively. Two strains of B. burgdorferi were resistant to enrofloxacin at the highest concentration tested for MBC (>or=100 microgram/ml). Therefore, the potential role of tilmicosin in the treatment of leptospirosis and borreliosis should be further evaluated in animal models to understand whether the in vivo studies will confirm in vitro results. All spirochetal isolates were inhibited (MIC) and were killed (MBC) by tilmicosin at concentrations below the limit of testing (<or=0.01 microgram/ml).

Histopathological Studies of Experimental Lyme Disease in the Dog

Experimental borrelia infection was induced in 62 specific--pathogen-free beagle dogs by exposure to Ixodes scapularis ticks harbouring the spirochaete Borrelia burgdorferi. Clinical signs of Lyme disease occurred in 39/62 dogs, the remaining 23 being subclinically infected. Clinical signs consisted of one to six episodes of transitory lameness with joint swelling and pain, most commonly affecting the elbow or shoulder joints. The polymerase chain reaction and culture demonstrated that the dogs remained infected for up to 581 days. At necropsy, gross findings consisted of lymphadenopathy in the area of tick attachment. Microscopical changes consisted of effusive fibrinosuppurative inflammation or nonsuppurative inflammation, or both, affecting synovial membranes, joint capsules and associated tendon sheaths. Plasma cells dominated areas of chronic inflammation, with CD3(+) T cells being present in lesser numbers. Microscopical signs of arthritis were polyarticular and more widespread than indicated by clinical signs, and most of the subclinically affected animals also had synovitis. In areas of tick attachment to the skin, hyperkeratosis and a mixture of suppurative and nonsuppurative dermatitis were encountered. Lymphadenopathy in superficial lymph nodes resulted from follicular and parafollicular hyperplasia. In 14/62 dogs, lymphoplasmacytic periarteritis and perineuritis were noted, resembling lesions found in human Lyme disease and syphilis, in which an underlying microangiopathy has been proposed.

Antibiotic treatment of experimentally Borrelia burgdorferi-infected ponies

The objective of this study is to determine whether doxycycline, ceftiofur or tetracycline could be effectively used to treat equine Lyme disease. Ponies experimentally infected with Borrelia burgdorferi by tick exposure were treated with doxycycline, ceftiofur or tetracycline for 4 weeks (28 days). Doxycyline and ceftiofur treatment were inconsistent in eliminating persistent infection in this experimental model. However, tetracycline treatment seems to eliminate persistent infection. Although serum antibody levels to B. burgdorferi in all ponies declined gradually after antibiotic treatment, three out of four ponies treated with doxycline and two out of four ponies treated with ceftiofur, serum KELA titers were raised again 3 month after treatment was discontinued. Five months after antibiotic treatment, tissues aseptically collected at necropsy from ponies with increased antibody levels after antibiotic treatment also showed culture positive to B. burgdorferi in various post-mortem tissues. However, all four-tetracycline treatment ponies showed a negative antibody level and culture negative from post-mortem tissues. Untreated infected ponies maintained high KELA titers throughout the study and were tissue culture positive.

Lyme borreliosis in Europe and North America

Since the discovery of the Lyme disease spirochete in North America in 1982 and in Europe in 1983, a plethora of studies on this unique group of spirochetes that compriseBorrelia burgdorferisensu lato has been accumulated. In an attempt to compare and contrast Lyme borreliosis in Europe and North America we have reviewed the biology of the aetiologic agents, as well as the clinical aspects, diagnosis and treatment of this disease on both continents. Moreover, we have detailed the ecology of theIxodesticks that transmit this infection and the reservoir hosts that maintain the spirochete cycle in nature. Finally, we have examined the transmission dynamics of the spirochete on both continents, as well as the available prevention strategies. Although it has been over two decades since the discovery of the Lyme disease spirochete, Lyme borreliosis is an expanding public health problem that has defied our attempts to control it. By comparing the accumulated experience of investigators in North America and Europe, where the disease is most frequently reported, we hope to advance the cause of developing novel approaches to combat Lyme borreliosis.

Host-inducible immunogenic sphingomyelinase-like protein, Lk73.5, of Leptospira interrogans

Leptospira interrogans causes a variety of clinical syndromes in animals and humans. Although much information has accumulated on the importance of leptospiral lipopolysaccharide in protective antibody responses, relatively little is known about proteins that participate in immune responses. Identification of those proteins induced only in the host is particularly difficult. Using a novel double-antibody screen designed to identify clones in a gene library of L. interrogans serovar Pomona expressing host-inducible proteins, we have characterized a gene (lk75.3) encoding a sphingomyelinase-like preprotein of 648 amino acids with cytotoxic activity for equine pulmonary endothelial cells and weak hemolytic activity for equine and rabbit erythrocytes. lk73.5 was found as a single gene copy in all serovars of L. interrogans but not in other Leptospira spp. except L. inadai. The open reading frame (ORF) for Lk73.5 is followed by another partially homologous sequence containing an ORF (sph-like 2) for a 28.7-kDa peptide. Lk73.5 and Sph-like 2 share 95.1 and 97.7% amino acid identity with putative sphingomyelinases Sph2 and Sph1 (N terminus) from L. interrogans serovar Lai (S.-X. Ren, G. Fu, X.-G. Jiangk, R. Zeng, Y.-G. Miao, H. Xu, Y.-X. Zhang, H. Xiong, G. Lu, L.-F. Lu, H.-Q. Jiang, J. Jia, Y.-F. Tu, J.-X. Jiang, W.-Y. Gu, Y.-Q. Zhang, Z. Cai, H.-H. Sheng, H.-F. Yin, Y. Zhang, G.-F. Zhu, M. Wank, H.-L. Huangk, Z. Qian, S.-Y. Wang, Wei Ma, Z.-J. Yao, Y. Shen, B.-Q. Qiang, Q.-C. Xia, X.-K. Guo, A. Danchinq, I. S. Girons, R. L. Somerville, Y.-M. Wen, M.-H. Shik, Z. Chen, J.-G. Xuk, and G.-P. Zhao, Nature 422:88-893, 2003). Substantial homologies to sphingomyelinases from other leptospiras and other bacteria are also present. Lk73.5 was not detected in leptospiras cultured at 30 or 37 degrees C. The recombinant protein reacted strongly with sera from recently infected mares but not with sera from horses vaccinated with commercial pentavalent bacterin. The host-inducible immunogenic Lk73.5 should have value in distinguishing vaccine from infection immune response.

Lyme borreliosis

Despite more than 25 years' experience with Lyme borreliosis, much remains to be learned about this complex zoonosis. Practicing veterinarians, particularly those in the northeastern and upper midwestern states, where Lyme borreliosis is highly endemic, should be familiar with the ecologic features and typical clinical signs of Lyme borreliosis. Interpretation of signs and serologic test results should be made with consideration of the regional prevalence of Lyme borreliosis and the animal's opportunity for exposure to infected Ixodes spp. The availability of recently marketed topical acaracides is a valuable adjunctive measure in prevention of Lyme borreliosis. A maximally effective prevention strategy should include consideration of environmental modification, activity restrictions, routine examinations for ticks, prompt removal of attached ticks, and vaccination. Technologic advances, such as the C6 EIA and the Osp A recombinant vaccine, offer the promise of additional tools for the clinical management and prevention of this tick-borne zoonosis.