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

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.

Vitreoretinal lymphoma: a diagnostic challenge

A 66-year-old man with posterior uveitis and recurrent cystic macular edema related to possible previously treated Lyme disease is presented. Due to the recurrence of macular edema despite systemic and local corticosteroid treatment with intravitreal dexamethasone, biological treatment with Adalimumab was established. During follow-up, the patient developed bilateral subretinal lesions compatible with Vitreoretinal Lymphoma (VRL), so vitrectomy was performed, confirming the diagnosis of large B-cell lymphoma. Treatment with systemic chemotherapy with BRAM-Carmustine, Metrotexate, Ara C, and Rituximab was started with a good answer. Two years later, the patient remains without ocular or systemic recurrences. Vitreoretinal Lymphoma is a rare type of primary central nervous system lymphoma. The diagnosis is frequently delayed due to the nonspecific symptoms, which mimic chronic posterior uveitis, hence the importance with a diagnostic suspicion.

Molecular detection of Spirochetes and Borrelia burgdorferi in stray dogs of Nineveh province, Iraq

Background

Borrelia burgdorferi is a Gram-negative bacterium that causes Lyme disease or borreliosis in domestic and wild animals, including dogs, with the possible transmission to humans.

Aim

This study was conducted to investigate the infection rate of Spirochetes and B. burgdorferi in stray dogs in Nineveh province, Iraq.

Methods

During the period from May to October (2022), a total of 55 stray dogs were selected randomly from different areas in Nineveh province, Iraq. Blood samples were collected from cephalic venous and tested molecularly using the conventional polymerase chain reaction technique.

Results

The present study revealed that the total infection rates of Spirochetes and B. burgdorferi were 41.82% and 27.27%, respectively. Concerning age, values of infection rate, odds ratio, and relative risk of B. burgdorferi were increased significantly in dogs aged ? 4 months (42.86%, 3.505%, and 2.438%, respectively), while decreased in dogs of ? 1-3 (12.5%, 0.337% and 0.42%, respectively) and ? 3 (13.33%, 0.32% and 0.409%) years old when compared to dogs aged 5-12 months (27.27%, 1% and 1%, respectively). While concerning dogs sex, a significantly higher infection rate, odds ratio, and relative risk of B. burgdorferi were shown in females (32.56%, 5.495% and 6.792%, respectively) compared to males (8.33%, 0.182% and 0.147%, respectively).

Conclusion

To the best of our knowledge, this represents the first Iraqi study on the prevalence of spirochetes, in particular B. burgdorferi, in stray dogs in Nineveh province (Iraq). However, additional studies of B. burgdorferi infection in other animals as well as vectors such as ticks in different geographic areas, appear necessary to detect variation in the distribution patterns of infection. In addition, owners and veterinarians should be aware of zoonotic diseases transmitted from wild and domestic animals, in particular those with tick-bite histories.

Antibodies against Borrelia burgdorferi Sensu Lato in Clinically Healthy and Sick Horses: First Report from the Czech Republic

Lyme disease, caused by some strains of bacterial spirochetes Borrelia burgdorferi sensu lato (Bbsl), affects humans but also domestic animals including horses. The primary pathogens in horses in Europe are B. afzelii, B. garinii and B. burgdorferi sensu stricto. To our knowledge, there are no data available on the seropositivity of B. burgdorferi s.l. in horses from the Czech Republic. In this country, horses are mainly used for sport, breeding, and recreational riding in areas where vectors of B. burgdorferi s.l. are present, which is why they are frequently at risk of infection. The aim of the study was to detect anti-borrelia IgM and IgG antibodies in clinically healthy and sick horses from the Czech Republic and to evaluate the risk factors of infection. In total, sera of 262 horses (247 clinically healthy horses and 15 horses hospitalized due to symptoms of encephalitis/meningoencephalitis) were examined by an indirect sandwich enzyme-linked immunosorbent assay. Positivity of B. burgdorferi was 27% (66/247) in clinically healthy horses (21% IgM, 7% IgG and 3% IgM + IgG antibodies) and 20% (3/15) in horses with clinical signs (20% IgM, 7% IgG and 7% IgM + IgG). In the clinically healthy horses, positivity statistically differed (p ≤ 0.05) only in Pony and Warmblood breeds, being the most affected at 32% and 30%, respectively, while other characteristics (sex, age, usage and localities) had no effect on positivity. This is the first survey of antibodies to B. burgdorferi s.l. in Czech horses showing that horses are exposed to ticks infected with B. burgdorferi s.l. This should be taken into account when making differential diagnoses in patients with non-specific symptoms to start with adequate therapy.

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.

Isolation and multilocus sequence typing of Borrelia burgdorferi from Ixodes scapularis collected from dogs in Ontario, Canada

OBJECTIVE

To identify the multilocus sequence typing (MLST) sequence types of Borrelia burgdorferi from Ixodes scapularis in Ontario, Canada.

RESULTS

One hundred and eighty-five I. scapularis ticks were submitted from 134 dogs via participating clinics from April 1, 2019, to March 31, 2020. Seventeen MLST sequence types of B. burgdorferi were detected from fifty-eight cultured isolates from 21 ticks. The most common MLST sequence types were 12 and 16. Mixed infections of two MLST sequence types were detected in four ticks. Three sequence types (48, 317, 639) were new detections in Ontario.

Seroexposure to Zoonotic Anaplasma and Borrelia in Dogs and Horses That Are in Contact with Vulnerable People in Italy

Equine and canine anaplasmosis and borreliosis are major tick-borne zoonotic diseases caused by Anaplasma phagocytophilum and various species of Borrelia (the most important being Borrelia burgdorferi s.l.), respectively. This study evaluated the seroexposure to Anaplasma and Borrelia in dogs and horses used in Animal-Assisted Interventions or living in contact with children, elderly people or immunocompromised persons. A total of 150 horses and 150 dogs living in Italy were equally divided into clinically healthy animals and animals with at least one clinical sign compatible with borreliosis and/or anaplasmosis (present at clinical examination or reported in the medical history). Serum samples were tested with ELISA and immunoblot for the presence of antibodies against A. phagocytophilum and B. burgdorferi s.l., and the association between seropositivity and possible risk factors was analyzed using multivariate and univariate tests. Overall, 13 dogs (8.7%) and 19 horses (12.7%) were positive for at least one of the two pathogens. In addition, 1 dog (0.7%) and 12 horses (8%) were positive for antibodies against A. phagocytophilum, while 12 dogs (8.0%) and 10 horses (6.7%) had antibodies against B. burgdorferi s.l. Tick infestation in the medical history of the dogs was significantly associated with seropositivity to at least one pathogen (p = 0.027; OR 7.398). These results indicate that, in Italy, ticks infected with A. phagocytophilum and/or B. burgdorferi circulate in places where horses and dogs are in contact with people at risk of developing severe diseases. Awareness should be increased, and adequate control plans need to be developed to protect human and animal health, especially where vulnerable, at-risk individuals are concerned.

Characterisation of faecal microbiota in horses medicated with oral doxycycline hyclate

BACKGROUND

Antimicrobial-associated diarrhoea is a common adverse effect of antimicrobial treatment in horses and has been reported following the administration of oral doxycycline. The administration of antimicrobials has also been associated with changes in the equine intestinal microbiota diversity yet has not been explored under doxycycline treatment.

OBJECTIVES

To describe the dynamics of the faecal microbial diversity following a 5-day oral administration of doxycycline in healthy horses with Streptococcus zooepidemicus infected tissue chambers.

STUDY DESIGN

Experimental prospective cohort study in a single horse group.

METHODS

Seven healthy adult horses with S. zooepidemicus infected tissue chambers received oral doxycycline at 10 mg/kg q 12 h for 5-days following the tissue chamber inoculation. Faeces were collected prior to the tissue chamber inoculation and until 28-days post inoculation. Faecal microbiota was characterised by high throughput sequencing of the V4 region of the 16S rRNA gene on the Illumina MiSeq sequencing platform. Bioinformatic analysis was performed with Mothur and statistical analysis were conducted on R Studio.

RESULTS

A significant decrease in alpha diversity, characterised by a decrease of richness and diversity, and a decrease in beta diversity, characterised by changes in relative abundance, occurred after initiation of and during the administration of doxycycline. A decrease in Verrucomicrobia and increase in Firmicutes:Bacteroidetes ratio occurred following the initiation of treatment, with a return to initial Firmicutes:Bacteroidetes ratio during the treatment. It took 23 days after discontinuing the treatment for the faecal microbiota to return close to the initial state.

MAIN LIMITATIONS

Lack of control population within the study.

CONCLUSIONS

Transitory intestinal dysbiosis occurs under oral administration of doxycycline in horses.

Spatial patterns of Borrelia burgdorferi, Borrelia miyamotoi and Anaplasma phagocytophilum detected in Ixodes spp. ticks from Canadian companion animals, 2019-2020

Increasing temperatures due to climate change have contributed to a northward range expansion of Ixodes scapularis ticks in Canada. These ticks harbour pathogens of public and animal health significance, including Borrelia burgdorferi and Anaplasma phagocytophilum, which cause Lyme disease and anaplasmosis, respectively, in humans, dogs and horses, and Borrelia miyamotoi, which causes a flu-like relapsing fever in humans. To address the risks associated with these vector-borne zoonotic diseases, continuous tick surveillance is advised. This study examined spatial patterns of B. burgdorferi, B. miyamotoi and A. phagocytophilum from ticks submitted through a national study on ticks of companion animals. From 1 April 2019 to 31 March 2020, we received a total of 1541 eligible submissions from 94 veterinary clinics across Canada. Individual and pooled samples of a maximum of either 5 I. scapularis, I. pacificus or I. angustus samples from the same animal and of the same life stage were screened using real-time PCR targeting genes 23S rRNA for Borrelia spp. and msp2 for A. phagocytophilum. Confirmatory testing was conducted on all 23S rRNA positive samples using a duplex assay for ospA and flaB to differentiate B. burgdorferi and B. miyamotoi, respectively. Prevalence estimates were highest (>20%) for B. burgdorferi in southwestern Manitoba, eastern Ontario, southwestern Quebec, New Brunswick and Nova Scotia. Estimates of B. miyamotoi and A. phagocytophilum were much lower (<5%), except for higher A. phagocytophilum (>5%) estimates for southern Manitoba, eastern Ontario and Prince Edward Island. Findings from this study, combined with other surveillance approaches, can be used to guide veterinary and public health approaches for ticks and tick-borne diseases.

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.

Prevalence of Anaplasma phagocytophilum and Borrelia burgdorferi infection in horses from Pennsylvania (2017-2019) using antibody and organism-based detection

OBJECTIVE

To determine the prevalence of Anaplasma phagocytophilum and Borrelia burgdorferi infections in Pennsylvania horses.

ANIMALS

271 horses.

PROCEDURES

A survey was conducted with PCR and serology to evaluate anaplasmosis and Lyme disease infections in horses from Pennsylvania that were suspected for tick-borne infection.

RESULTS

A phagocytophilum was detected in 19/271 (7.0%) Pennsylvania horses tested by the duplex PCR. B burgdorferi was not detected in any horse blood tested by PCR. Overall, 120/271 (44.3%) horses tested positive for presence of A phagocytophilum antibodies by at least the IDEXX SNAP 4Dx Plus lateral flow immunosorbent (SNAP) or indirect fluorescent antibody (IFA) assay, with 69 (25.5%) testing positive by both SNAP and IFA; 43 (15.9%) tested positive by IFA only, and 8 (3.0%) tested positive by SNAP only. Similarly, 209/271 (77.1%) horses tested positive for the presence of B burgdorferi antibodies by at least 1 test, with 139 (51.3%) testing positive by both SNAP and IFA; 45 (16.6%) tested positive by SNAP only, and 25 (9.2%) tested positive by IFA.

CLINICAL RELEVANCE

Both A phagocytophilum and B burgdorferi are important tick-borne infections. The study provides prevalence data for both A phagocytophilum and B burgdorferi and compares test performance. For serologic detection, IFA detected antibodies to A phagocytophilum in a higher proportion (41.3%) of horses compared to SNAP (28.4%), while SNAP detected antibodies to B burgdorferi in a higher proportion (67.9%) of horses compared to IFA (60.5%). Both diseases showed a high seroprevalence in all areas surveyed.

Genomic hybrid capture assay to detect Borrelia burgdorferi: an application to diagnose neuroborreliosis in horses

Antemortem diagnosis of neuroborreliosis in horses has been hindered by both the low sensitivity of PCR testing for Borrelia burgdorferi in CSF and the low specificity of serum:CSF ELISA ratios used to determine intrathecal antibody production against the bacterium. PCR testing of the CSF of an adult horse with acute neurologic disease for the B. burgdorferi flagellin gene was negative. However, we enriched B. burgdorferi DNA through nucleic acid hybrid capture, followed by next-generation sequencing, and identified B. burgdorferi in the CSF of the horse, confirming a diagnosis of neuroborreliosis.

Pathologic Conditions of the Nervous System in Horses

The variety of neurologic diseases which affect horses makes pathologic examination of the nervous system a complex and lengthy process. An understanding of the common causes of neurologic disease, antemortem neurolocalization, and supplementation of the necropsy examination with ancillary testing will help to diagnose a large number of causes of neurologic disease. A general understanding of neuropathology and collaborative relationship with your local pathologists will aid in the definitive diagnosis of neurologic diseases.

Influence of ecological and climatic conditions on the spread of Borrelia burgdorferi in domestic dogs in Ukraine

Lyme-borreliosis is a zoonotic, infectious disease that has a complex chain of transmission of the pathogen Borrelia burgdorferi sensu lato and includes the relationship between ixodid ticks, vertebrate hosts, humans and companion animals in the environment. The article shows general trends in the prevalence of canine Lyme-borreliosis in Ukraine depending on environmental, climatic and physiographic factors. The results of a comparative cartographic analysis of the prevalence of Lyme borreliosis among domestic dogs in Ukraine are presented by systematizing, mathematical and statistical processing of the data obtained by surveying veterinarians engaged in clinical veterinary practice. The paper includes generalized data on the clinical manifestations, methods of diagnosis and treatment of Lyme borreliosis in dogs. We determined the dependence of the prevalence of Lyme borreliosis in dogs on the types of physical and geographical territories – natural zones of Ukraine. Each of the natural zones differs in types of relief, climatic conditions, soil types, composition of fauna and flora, which affect the epizootic chain of Lyme disease. There is a clear correlation between the incidence of Lyme borreliosis in dogs and the types of natural areas. The highest incidence of Lyme borreliosis in dogs was observed in the forest-steppe zone and the zone of broad-leaved forests. A sharp decrease in the incidence of dogs was recorded in areas of mixed forests, the Ukrainian Carpathians and in the South of Ukraine in the steppe zone. The study also confirmed that the prevalence of Lyme disease among domestic dogs was influenced by the climatic factors, in particular: gross moisture of territories, average annual air temperature and soil temperature. In Ukraine, veterinarians in the vast majority of cases use serological diagnostic methods: immunochromatographic analysis, immunoenzymatic assay, and western blot, which are insufficient, since the presence of antibodies to the Lyme borreliosis pathogen is only a confirmation of the animal's contact with the antigen and may not indicate the presence of the disease in the clinical form. The generalized data on the use of antimicrobial drugs in the treatment of Lyme borreliosis in dogs indicate the predominant use of tetracycline antibiotics and cephalosporins. The majority of veterinarians reported symptoms of Lyme arthritis, somewhat fewer reported Lyme nephritis, neuroborreliosis, Lyme carditis and in rare cases, veterinarians observed erythema at the site of tick bite. About half of the veterinarians in Ukraine observed an increase in the incidence of Lyme disease in dogs, indicating a probable deterioration of the epizootic and epidemiological situation regarding Lyme borreliosis, especially in areas with favourable conditions for the circulation of Lyme borreliosis pathogens in natural and urban ecotopes. The results substantiate the need for the further study of the circulation of Borrelia burgdorferi sensu lato and their ability to cause disease in humans and animals, as well as the need to implement the principles of the One Health concept for the control and management of Lyme borreliosis.

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.

Molecular characterization of some equine vector-borne diseases and associated arthropods in Egypt

Equine vector-borne diseases (EVBDs) are emerging and re-emerging diseases, and most of them are zoonotic. This study aimed to investigate EVBDs in equines and associated arthropods (ticks and flies) from Egypt using molecular analyses, in addition to a preliminary characterization of associated ticks and flies by the matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) and molecular techniques. In this study, 335 blood samples were obtained from equines that appeared to be in good health (320 horses and 15 donkeys) in Cairo and Beni Suef provinces, Egypt. From the same animals, 166 arthropods (105 sucking flies and 61 ticks) were collected. Ticks and flies were preliminary characterized by the MALDI-TOF and molecular tools. Quantitative PCR (qPCR) and standard PCR coupled with sequencing were performed on the DNA of equines, ticks, and flies to screen multiple pathogens. The MALDI-TOF and molecular characterization of arthropods revealed that louse fly (Hippobosca equina) and cattle tick (Rhipicephalus annulatus) infesting equines. Anaplasma platys-like (1.6%), Anaplasma marginale (1.6%), Candidatus Ehrlichia rustica (6.6%), a new Ehrlichia sp. (4.9%), and Borrelia theileri (3.3%) were identified in R. annulatus. Anaplasma sp. and Borrelia sp. DNAs were only detected in H. equina by qPCR. A. marginale, Anaplasma ovis, and Theileria ovis recorded the same low infection rate (0.6%) in donkeys, while horses were found to be infected with Theileria equi and a new Theileria sp. Africa with recorded prevalence rates of 1.2% and 2.7%, respectively. In conclusion, different pathogens were first detected such as A. platys-like, Candidatus E. rustica, and a new Ehrlichia sp. in R. annulatus; A. marginale, A. ovis, and T. ovis in donkeys; and a new Theileria sp. "Africa" in horses.

Disease-Associated Multimolecular Signature in the Urine of Patients with Lyme Disease Detected Using Raman Spectroscopy and Chemometrics

A urine-based screening technique for Lyme disease (LD) was developed in this research. The screen is based on Raman spectroscopy, iterative smoothing-splines with root error adjustment (ISREA) spectral baselining, and chemometric analysis using Rametrix software. Raman spectra of urine from 30 patients with positive serologic tests (including the US Centers for Disease Control [CDC] two-tier standard) for LD were compared against subsets of our database of urine spectra from 235 healthy human volunteers, 362 end-stage kidney disease (ESKD) patients, and 17 patients with active or remissive bladder cancer (BCA). We found statistical differences (p < 0.001) between urine scans of healthy volunteers and LD-positive patients. We also found a unique LD molecular signature in urine involving 112 Raman shifts (31 major Raman shifts) with significant differences from urine of healthy individuals. We were able to distinguish the LD molecular signature as statistically different (p < 0.001) from the molecular signatures of ESKD and BCA. When comparing LD-positive patients against healthy volunteers, the Rametrix-based urine screen performed with 86.7% for overall accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), respectively. When considering patients with ESKD and BCA in the LD-negative group, these values were 88.7% (accuracy), 83.3% (sensitivity), 91.0% (specificity), 80.7% (PPV), and 92.4% (NPV). Additional advantages to the Raman-based urine screen include that it is rapid (minutes per analysis), is minimally invasive, requires no chemical labeling, uses a low-profile, off-the-shelf spectrometer, and is inexpensive relative to other available LD tests.

Community engaged tick surveillance and tickMAP as a public health tool to track the emergence of ticks and tick-borne diseases in New York

A community engaged passive surveillance program was utilized to acquire ticks and associated information throughout New York state. Ticks were speciated and screened for several tick-borne pathogens. Of these ticks, only I. scapularis was commonly infected with pathogens of human relevance, including B. burgdorferi, B. miyamotoi, A. phagocytophilum, B. microti, and Powassan virus. In addition, the geographic and temporal distribution of tick species and pathogens was determined. This enabled the construction of a powerful visual analytical mapping tool, tickMAP to track the emergence of ticks and tick-borne pathogens in real-time. The public can use this tool to identify hot-spots of disease emergence, clinicians for supportive evidence during differential diagnosis, and researchers to better understand factors influencing the emergence of ticks and tick-borne diseases in New York. Overall, we have created a community-engaged tick surveillance program and an interactive visual analytical tickMAP that other regions could emulate to provide real-time tracking and an early warning for the emergence of tick-borne diseases.

Molecular Identification of Selected Tick-Borne Protozoan and Bacterial Pathogens in Thoroughbred Racehorses in Cavite, Philippines

Tick-borne diseases (TBDs) considerably impair equine health and productivity. Moreover, TBDs, particularly equine piroplasmosis, impede international movement and trade of equids, which is a vital component of the global horse racing industry. In the Philippines, horse racing is a lucrative industry generating millions of USD annually. However, information on equine TBDs is scarce. This study intended to describe molecularly the equine tick-borne infections in a racehorse park in Cavite, Philippines and identify the risk factors associated with the infections. One hundred twenty-four (n = 124) thoroughbred racehorses were sampled and screened for selected tick-borne protozoan and bacterial pathogens using polymerase chain reaction (PCR) assays. Racehorses were positive for Babesia caballi (12.10%; 15/124), Theileria equi (0.81%; 1/124), Anaplasma phagocytophilum (10.48%; 13/124), Borrelia burgdorferi sensu lato (38.71%; 48/124), A. marginale (0.81%; 1/124), and Coxiella burnetii (0.81%; 1/124). Rickettsia was not detected in the samples. Gender was determined as a significant risk factor for B. caballi infection. Sequencing analysis revealed that seven partial 18S rRNA B. caballi isolates shared 98.63–100% identity with each other and were classified as genotype A. Meanwhile, the sequence obtained from the lone T. equi-positive sample was 99.77% identical to isolates from Spain, Switzerland, China, Saudi Arabia, and South Korea, and was confirmed as genotype E based on the 18S rRNA gene. Eight Anaplasma 16S rRNA partial sequences were highly identical to A. phagocytophilum and A. ovis. Partial sequences of Borrelia 5–23S rRNA were most closely related to B. japonica and other Borrelia sp. isolates from various countries. This study reports the first molecular detection of Borrelia and Anaplasma and the identification of B. caballi and T. equi genotypes in racehorses in the Philippines. Findings from this study shall be useful in crafting equine tick and TBD control and prevention programs in the country.

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.

Nonlinear Mixed-Effect Pharmacokinetic Modeling and Distribution of Doxycycline in Healthy Female Donkeys after Multiple Intragastric Dosing-Preliminary Investigation

Doxycycline (DXC) is a broad-spectrum antibacterial antimicrobial administered to horses for the treatment of bacterial infections which may also affect donkeys. Donkeys have a different metabolism than horses, leading to differences in the pharmacokinetics of drugs compared to horses. This study aimed to describe the population pharmacokinetics of DXC in donkeys. Five doses of DXC hyclate (10 mg/kg) were administered via a nasogastric tube, q12 h, to eight non-fasted, healthy, adult jennies. Serum, urine, synovial fluid and endometrium were collected for 72 h following the first administration. Doxycycline concentration was measured by competitive enzyme immunoassay. Serum concentrations versus time data were fitted simultaneously using the stochastic approximation expectation-maximization algorithm for nonlinear mixed effects. A one-compartment model with linear elimination and first-order absorption after intragastric administration, best described the available pharmacokinetic data. Final parameter estimates indicate that DXC has a high volume of distribution (108 L/kg) as well as high absorption (10.3 h^-1) in donkeys. However, results suggest that oral DXC at 10 mg/kg q12 h in donkeys would not result in a therapeutic concentration in serum, urine, synovial fluid or endometrium by comparison to the minimum inhibitory concentration of common equine pathogens. Further studies are recommended to identify appropriate dosage and dosing intervals of oral DXC in donkeys.

Detection of Anaplasma Phagocytophilum in Horses With Suspected Tick-Borne Disease in Northeastern United States by Metagenomic Sequencing

Metagenomic sequencing of clinical diagnostic specimens has a potential for unbiased detection of infectious agents, diagnosis of polymicrobial infections and discovery of emerging pathogens. Herein, next generation sequencing (NGS)-based metagenomic approach was used to investigate the cause of illness in a subset of horses recruited for a tick-borne disease surveillance study during 2017–2019. Blood samples collected from 10 horses with suspected tick-borne infection and five apparently healthy horses were subjected to metagenomic analysis. Total genomic DNA extracted from the blood samples were enriched for microbial DNA and subjected to shotgun next generation sequencing using Nextera DNA Flex library preparation kit and V2 chemistry sequencing kit on the Illumina MiSeq sequencing platform. Overall, 0.4–0.6 million reads per sample were analyzed using Kraken metagenomic sequence classification program. The taxonomic classification of the reads indicated that bacterial genomes were overrepresented (0.5 to 1%) among the total microbial reads. Most of the bacterial reads (~91%) belonged to phyla Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, Cyanobacteria and Tenericutes in both groups. Importantly, 10–42.5% of Alphaproteobacterial reads in 5 of 10 animals with suspected tick-borne infection were identified as Anaplasma phagocytophilum. Of the 5 animals positive for A. phagocytophilum sequence reads, four animals tested A. phagocytophilum positive by PCR. Two animals with suspected tick-borne infection and A. phagocytophilum positive by PCR were found negative for any tick-borne microbial reads by metagenomic analysis. The present study demonstrates the usefulness of the NGS-based metagenomic analysis approach for the detection of blood-borne microbes.

Pharmacokinetics and pharmacodynamics of doxycycline in a Streptococcusequi subsp. zooepidemicus infection model in horses

The objectives of this study were to investigate the pharmacokinetics (PK), pharmacodynamics (PD), and the efficacy of oral administration of doxycycline (DXC) in horses with Streptococcus zooepidemicus tissue infections. Tissue chambers (TC) were implanted subcutaneously in the cervical region of 7 horses and inoculated with a single S. zooepidemicus isolate with a minimum inhibitory concentration (MIC) of 0.25 µg/ml, determined by agar dilution. Doxycycline hyclate (10 mg/kg, orally, q 12 h, for 5 days) mixed with poloxamer gel was started following inoculation. The TC fluid was sampled prior to and following inoculation for cytology analysis, quantitative culture, and DXC determination. Plasma DXC concentrations were measured over 48 h following the last dose of DXC administered. The mean plasma peak concentration (C_max ) of DXC was 0.32 µg/ml, and concentrations above the MIC were only reached in 3 TC samples. In plasma, mean T > MIC was 2.4 h, mean C_max /MIC was 1.30, and mean AUC_last /MIC was 11.63 h. These PK/PD indices did not reach the suggested targets for DXC treatments of infections, and the TC abscessed in all horses. This is the first study to evaluate the recommended dose of DXC in horse in an infection model.

Evaluation of 2 ELISAs to determine Borrelia burgdorferi seropositivity in horses over a 12-month period

The blacklegged tick (Ixodes scapularis), which transmits Borrelia burgdorferi, the causative agent of Lyme disease, has undergone rapid range expansion in Ontario. In horses, Lyme disease remains an enigmatic disease, with limited understanding of the pathogenesis and many issues pertaining to selection and interpretation of laboratory tests. We evaluated B. burgdorferi seropositivity in naturally exposed horses over a 12-mo period and compared paired samples with 2 common serologic tests. Serum samples were collected in 2017, ~1 y after initial testing, from a cohort of 22 horses that were seropositive in a 2016 seroprevalence study. Samples were tested using a C6 ELISA and a multiplex ELISA targeting outer surface proteins A, C, and F. 1 y after initial testing, 14 of 22 (64%) horses remained seropositive; 7 (32%) were positive on the multiplex ELISA, 2 (9%) on C6 ELISA, and 5 (23%) on both tests. Repeatability was 100% for the C6 ELISA, and 95% for the multiplex ELISA, with no significant difference between paired sample multiplex titer values. Our results indicate strong intra-test reliability, although further investigation is required to determine the clinical significance of serologic testing.

Role of Zoo-Housed Animals in the Ecology of Ticks and Tick-Borne Pathogens-A Review

Ticks are ubiquitous ectoparasites, feeding on representatives of all classes of terrestrial vertebrates and transmitting numerous pathogens of high human and veterinary medical importance. Exotic animals kept in zoological gardens, ranches, wildlife parks or farms may play an important role in the ecology of ticks and tick-borne pathogens (TBPs), as they may serve as hosts for local tick species. Moreover, they can develop diseases of varying severity after being infected by TBPs, and theoretically, can thus serve as reservoirs, thereby further propagating TBPs in local ecosystems. The definite role of these animals in the tick-host-pathogen network remains poorly investigated. This review provides a summary of the information currently available regarding ticks and TBPs in connection to captive local and exotic wildlife, with an emphasis on zoo-housed species.

Serological Evidence of Natural Exposure to Tick-Borne Pathogens in Horses, Romania

The purpose of this study was to investigate the seroprevalence of selected tick-borne-pathogens (TBPs) among Romanian horses. For this, a total of 223 animals originating from north, central, and southeast Romania, including horses from stud farms (n = 118) and working horses (n = 105), were tested using a commercial rapid ELISA-based test. Overall, 10.3% (95% confidence interval (CI): 6.7-15.1%) of the tested horses were seropositive for antibodies (Ab) against Anaplasma phagocytophilum. Additionally, 18.8% (95% CI: 13.9-24.6%) and 0.5% (95% CI: 0.01-2.5%) of horses were seropositive for Ab against Borrelia burgdorferi sensu lato and Ehrlichia spp., respectively. Among the tested horses, 3.1% were seroreactive to two or three pathogens. These findings show the natural exposure of Romanian horses to zoonotic tick-borne pathogens and emphasize the need for further studies to better understand the epidemiology of equine tick-borne diseases in Romania.

A cross-sectional study of hard ticks (acari: ixodidae) on horse farms to assess the risk factors associated with tick-borne diseases

Zoonotic diseases are significant public health issues. There is an urgent need to focus our efforts on the development of strategies that prevent and control potential arthropod vector-borne pathogens. Hard ticks transmit a variety of viral, bacterial and protozoan pathogens to their vertebrate hosts. This is becoming of more concern, as anthropogenic alterations of the environment may unleash the spread of tick-borne diseases throughout the world. Developing countries that are highly dependent on the livestock economy are a hot spot for tick-borne infectious diseases. In this work, through a cross-sectional approach that included a bibliographic survey, field collection and epidemiological questionnaire, we identified five tick species that were found to parasitize equines and transmit tick-borne pathogens. Our data revealed a gap in fundamental knowledge of ticks and tick-borne infectious diseases among equine breeders and owners. This article highlights the relevant risk factors that were found and the urgent actions that are needed to prevent the wide spread of hard ticks and their associated zoonotic diseases.

Single-cell resolution landscape of equine peripheral blood mononuclear cells reveals diverse cell types including T-bet+ B cells

BACKGROUND

Traditional laboratory model organisms represent a small fraction of the diversity of multicellular life, and findings in any given experimental model often do not translate to other species. Immunology research in non-traditional model organisms can be advantageous or even necessary, such as when studying host-pathogen interactions. However, such research presents multiple challenges, many stemming from an incomplete understanding of potentially species-specific immune cell types, frequencies, and phenotypes. Identifying and characterizing immune cells in such organisms is frequently limited by the availability of species-reactive immunophenotyping reagents for flow cytometry, and insufficient prior knowledge of cell type-defining markers.

RESULTS

Here, we demonstrate the utility of single-cell RNA sequencing (scRNA-Seq) to characterize immune cells for which traditional experimental tools are limited. Specifically, we used scRNA-Seq to comprehensively define the cellular diversity of equine peripheral blood mononuclear cells (PBMC) from healthy horses across different breeds, ages, and sexes. We identified 30 cell type clusters partitioned into five major populations: monocytes/dendritic cells, B cells, CD3+PRF1+ lymphocytes, CD3+PRF1- lymphocytes, and basophils. Comparative analyses revealed many cell populations analogous to human PBMC, including transcriptionally heterogeneous monocytes and distinct dendritic cell subsets (cDC1, cDC2, plasmacytoid DC). Remarkably, we found that a majority of the equine peripheral B cell compartment is comprised of T-bet+ B cells, an immune cell subpopulation typically associated with chronic infection and inflammation in human and mouse.

CONCLUSIONS

Taken together, our results demonstrate the potential of scRNA-Seq for cellular analyses in non-traditional model organisms and form the basis for an immune cell atlas of horse peripheral blood.

A Pilot Serosurvey for Selected Pathogens in Feral Donkeys (Equus asinus)

Simple Summary

This study aimed to assess the pathogen exposure status of recently captured feral donkeys from Death Valley National Park, California. Assays to detect the presence of antibodies to equine herpesvirus 1, equine influenza virus, West Nile virus, and Borrelia burgdorferi (the causative agent of Lyme disease) were performed on serum samples from these feral donkeys. The results indicate that this population is mostly naïve and likely susceptible to these common equid pathogens upon removal from the wild.

Abstract

Recent removal and relocation of feral donkeys from vast public lands to more concentrated holding pens, training facilities, and offsite adoption locations raises several health and welfare concerns. Very little is known regarding the common equid pathogens that are circulating within the feral donkey population in and around Death Valley National Park, California, USA. The aim of this study was to utilize serologic assays to assess previous exposure of these donkeys to equine herpesvirus 1 (EHV-1), equine influenza (EIV), West Nile virus (WNV), and Borrelia burgdorferi (the causative agent of Lyme disease). The results of this study indicate that this feral equid population is mostly naïve and likely susceptible to these common equid pathogens upon removal from the wild.

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.

Seroprevalence and evaluation of risk factors associated with seropositivity for Borrelia burgdorferi in Ontario horses

BACKGROUND

Recently, the blacklegged tick (Ixodes scapularis), which is the vector of Borrelia burgdorferi, has undergone a range expansion from the northeastern and mid-west United States to areas of southeastern Canada, including parts of Ontario. Understanding the seroprevalence of antibodies against B. burgdorferi in horses and risk factors for exposure is important for monitoring and preventing this emerging disease.

STUDY DESIGN

Cross-sectional study of 551 horses in southern, central, and eastern Ontario, Canada.

OBJECTIVES

To assess the seroprevalence of B. burgdorferi in horses in Ontario, Canada; to evaluate risk factors associated with seropositivity; and, to compare the performance of two diagnostic tests.

METHODS

Serum samples were obtained from clinically healthy horses in Ontario, Canada, along with completed questionnaires that were used for the risk factor analysis. Sera were tested with a Multiplex ELISA (Animal Health Diagnostic Center, Cornell University) and C6 ELISA (IDEXX SNAP^® 4Dx^® Plus test, IDEXX Laboratories).

RESULTS

The seroprevalence of B. burgdorferi on at least one test was 17% (91/551), though only 15 (16%) horses tested positive with both tests. A spatial cluster of cases was detected in Eastern Ontario. The odds of being seropositive for B. burgdorferi on the C6 ELISA were significantly increased when oak trees were present by pastures (OR = 7.3 (1.8-29.2), P = .005), while the odds were significantly decreased when regular tick checks were performed (OR = 0.1 (0.01-0.7), P = 0.02).

MAIN LIMITATIONS

Recruitment focused on known areas with blacklegged ticks as well as areas of higher horse density, which may have led to selection bias.

CONCLUSIONS

The expansion of blacklegged tick populations poses an ongoing risk for horses. Assessment of diagnostic testing options and risk factors is important for diagnosis and prevention, and with further investigation this information may be used to propose changes in management.

Modelling the probability and impact of false-positive serology for Borrelia burgdorferi sensu lato: A case study

Background

Serological screening tests for Lyme borreliosis have poor specificity, with potential for misdiagnosis and unnecessary antimicrobial treatment.

Objectives

To evaluate the impact of Lyme borreliosis seroprevalence and serologic test characteristics on the probability of obtaining a false‐positive result and impact on antimicrobial use.

Study design

Cross‐sectional serological survey and modelling.

Methods

Sera from 303 horses in southern Belgium were analysed by enzyme‐linked immunosorbent assay (ELISA). Apparent seroprevalence was derived from serological data and a Bayesian estimate of true seroprevalence was computed. These were a starting point to model the impact of test and population characteristics on the probability of obtaining false‐positive results and consequently unnecessary treatments and complications.

Results

Apparent and true seroprevalence were 22% (95% CI 18%‐27%) and 11% (credible interval with 95% probability 0.6%‐21%) respectively. We estimate that two‐thirds of positive samples are false positive in southern Belgium, with one in five of tested horses potentially misdiagnosed as infected. Around 5% of antimicrobial use in equine veterinary practice in Belgium may be attributable to treatment of a false‐positive result.

Main limitations

There was uncertainty regarding the ELISA's sensitivity and specificity.

Conclusions

This study highlights the importance of appreciating the poor diagnostic value of ELISA screening for Lyme borreliosis as demonstrated by this case study of seroprevalence in southern Belgium where we demonstrate that a nontrivial number of horses is estimated to receive unwarranted treatment due to poor appreciation of screening test characteristics by practitioners, contributing substantially to unnecessary use of antimicrobials.

Facial nerve paralysis in 64 equids: Clinical variables, diagnosis, and outcome

BACKGROUND

Facial nerve paralysis (FNP) in equids is not well described in the veterinary literature.

OBJECTIVE

To investigate the causes of FNP and associations among clinical variables, diagnosis, and outcome.

ANIMALS

Sixty-four equids presenting with FNP between July 2000 and April 2019. Cases of postanesthetic FNP were excluded.

METHODS

Medical records were retrospectively reviewed. Variables were evaluated for associations with outcomes (diagnosis and case outcome) using logistic regression.

RESULTS

The most common cause of FNP was trauma (n = 20). Additional diagnoses included central nervous system (CNS) disease (n = 16), idiopathic (n = 12, 4 of which had adequate diagnostic investigation and were considered "true" idiopathic, and 8 of which were considered "not investigated" idiopathic), temporohyoid osteoarthropathy (n = 10), otitis media-interna (n = 3), lymphoma (n = 1), iatrogenic as a consequence of infiltration of local anesthetic (n = 1), and clostridial myositis (n = 1). Follow-up was available for 55 (86%) cases. Twenty-nine (53%) equids had full resolution of FNP, 14 (25%) were euthanized, 6 (11%) partially improved, and 6 (11%) were unchanged or worse.

CONCLUSIONS AND CLINICAL IMPORTANCE

If FNP is the consequence of CNS disease, successful treatment of the primary disease likely leads to resolution of FNP. Most cases of FNP in equids are traumatic in origin. True idiopathic cases are uncommon.

Molecular Identification of Borrelia afzelii from Ticks Parasitizing Domestic and Wild Animals in South Korea

Lyme borreliosis is one of the most prevalent tick-borne infectious zoonotic diseases caused by spirochetes of the Borrelia burgdorferi sensu lato group. The present study assessed the risk factors and prevalence of Lyme borreliosis in ticks parasitizing domestic and wild animals. A total of 589 ticks (329 tick pools) collected from animals were identified as Haemaphysalis longicornis, (85.7%), H. flava (10.0%), and Ixodes nipponensis (4.3%) using morphological and molecular methods in South Korea. In this study, the 5S–23S gene sequences of B. afzelii (6/329, 1.8%) were detected in ticks taken from mammals, including ticks from horses (2/147 pools, 1.4%), wild boar (1/19 pools, 5.3%), native Korean goats (NKG, 2/34 pools, 5.9%), and Korean water deer (1/129 pools, 0.8%). Unfortunately, ospA, pyrG, and flagellin genes were not able to be amplified in the present study. To our knowledge, our results are the first inclusive data available for B. afzelii circulation in several tick species taken from NKG, horses, and wild boar in South Korea. We believe that the current findings extend our knowledge of the distribution and possible vector spectrum of Borrelia spp. We recommend continuous evaluation of the potential public health threat posed by Borrelia infected ticks.

Point-of-Care Diagnostics in Equine Practice

Point-of-care testing (POCT) refers to benchtop diagnostic modalities that have been translated into portable and easy-to-use formats suitable for patient-side use. Recent advances in diagnostic technology have allowed the development of a growing collection of POCT assays available to equine practitioners. Advantages include rapid results that reduce initial guesswork and promote diagnosis-targeted patient care, which may ultimately provide better clinical outcomes. Small handheld devices comprise most POCT technologies, providing qualitative or quantitative determination of an increasing range of analytes, including critical care analyzers and, more recently, hematology and immunology analyzers. This article discusses commercially available equine POCT.

Detection and Transstadial Passage of Babesia Species and Borrelia burgdorferi Sensu Lato in Ticks Collected from Avian and Mammalian Hosts in Canada

Lyme disease and human babesiosis are the most common tick-borne zoonoses in the Temperate Zone of North America. The number of infected patients has continued to rise globally, and these zoonoses pose a major healthcare threat. This tick-host-pathogen study was conducted to test for infectious microbes associated with Lyme disease and human babesiosis in Canada. Using the flagellin (flaB) gene, three members of the Borrelia burgdorferi sensu lato (Bbsl) complex were detected, namely a Borrelia lanei-like spirochete, Borrelia burgdorferi sensu stricto (Bbss), and a distinct strain that may represent a separate Bbsl genospecies. This novel Bbsl strain was detected in a mouse tick, Ixodes muris, collected from a House Wren, Troglodytes aedon, in Quebec during the southward fall migration. The presence of Bbsl in bird-feeding larvae of I. muris suggests reservoir competency in three passerines (i.e., Common Yellowthroat, House Wren, Magnolia Warbler). Based on the 18S ribosomal RNA (rRNA) gene, three Babesia species (i.e., Babesia divergens-like, Babesia microti, Babesia odocoilei) were detected in field-collected ticks. Not only was B. odocoilei found in songbird-derived ticks, this piroplasm was apparent in adult questing blacklegged ticks, Ixodes scapularis, in southern Canada. By allowing live, engorged ticks to molt, we confirm the transstadial passage of Bbsl in I. muris and B. odocoilei in I. scapularis. Bbss and Babesia microti were detected concurrently in a groundhog tick, Ixodes cookei, in Western Ontario. In Alberta, a winter tick, Dermacentor albipictus, which was collected from a moose, Alces alces, tested positive for Bbss. Notably, a B. divergens-like piroplasm was detected in a rabbit tick, Haemaphysalis leporispalustris, collected from an eastern cottontail in southern Manitoba; this Babesia species is a first-time discovery in Canada. This rabbit tick was also co-infected with Borrelia lanei-like spirochetes, which constitutes a first in Canada. Overall, five ticks were concurrently infected with Babesia and Bbsl pathogens and, after the molt, could potentially co-infect humans. Notably, we provide the first authentic report of I. scapularis ticks co-infected with Bbsl and B. odocoilei in Canada. The full extent of infectious microorganisms transmitted to humans by ticks is not fully elucidated, and clinicians need to be aware of the complexity of these tick-transmitted enzootic agents on human health. Diagnosis and treatment must be administered by those with accredited medical training in tick-borne zoonosis.

A Suspected Case of Rocky Mountain Spotted Fever in an Adult Horse in the Southeastern United States

A 20-year-old Paint gelding was evaluated for fever of unknown origin. History and clinical signs were consistent with potential tick-borne disease. Samples were collected and submitted for tick-borne disease panel, herpes virus, complete blood count, and serum biochemistry. Based on physical examination findings and vaccination history, the gelding was treated for suspected tick-borne disease with oxytetracycline (8 mg/kg intravenously BID) for 5 days, followed by doxycycline (10 mg/kg PO BID) for an additional 5 days. Although titers to Borrelia burgdorferi, Anaplasma phagocytophilum, and Neorickettsia risticii on Days 4 and 8 were negative, the Rickettsia rickettsii titer went from 1:1,600 on Day 4 to 1:800 on Day 8, 1:100 on Day 21, and was seronegative by Day 38. Although complete blood polymerase chain reaction for Rickettsia rickettsii was negative, the clinical and serologic features of this case are extremely consistent with clinical cases of Rocky Mountain Spotted Fever (RMSF) described in both dogs and humans. Therefore, we submit this case report to document suspected clinical infection of an adult horse in the southeastern United States with Rickettsia rickettsii, the causative agent of RMSF. Other relevant differentials (i.e., Rickettsia parkeri, Theileria equi, and Babesia caballi) are also discussed.

Analysis of the antigenic determinants of the OspC protein of the Lyme disease spirochetes: Evidence that the C10 motif is not immunodominant or required to elicit bactericidal antibody responses

As Ixodes ticks spread to new regions, the incidence of Lyme disease (LD) in companion animals and humans will increase. Preventive strategies for LD in canines center on vaccination and tick control (acaricides). Both subunit and bacterin based LD veterinary vaccines are available. Outer surface protein C (OspC), a potent immunogen and dominant early antigen, has been demonstrated to elicit protective antibody (Ab) responses. However, a single OspC protein elicits a relatively narrow range of protection. There are conflicting reports as to whether the immunodominant epitopes of OspC reside within variable or conserved domains. A detailed understanding of the antigenic determinants of OspC is essential for understanding immune responses to this essential virulence factor and vaccinogen. Here, we investigate the contribution of the conserved C-terminal C10 motif in OspC triggered Ab responses. Using a panel of diverse recombinant full length OspC proteins and their corresponding C10 deletion variants (OspCΔC10), we demonstrate that the C10 motif does not significantly contribute to immunization or infection induced Ab responses in rabbits, rats, canines, horses and non-human primates. Furthermore, the C10 motif is not required to trigger potent bactericidal Ab responses. This study provides insight into the antigenic structure of OspC. The results enhance our understanding of immune responses that develop during infection or upon vaccination and have implications for interpretation of LD diagnostic assays that employ OspC.

Neuroborreliosis in a horse with common variable immunodeficiency

Common variable immunodeficiency (CVID) is a rare condition in adult horses characterized by hypogammaglobulinemia and increased susceptibility to parasitic and bacterial infections, including recurrent respiratory diseases, septicemia, and meningitis. Lyme disease is often included as a differential diagnosis in CVID horses with signs of meningitis; however, the Borrelia burgdorferi organism has not been demonstrated previously within central nervous system tissues of CVID horses with neurologic disease, to our knowledge. We report herein a case of neuroborreliosis in a CVID horse, confirmed by combined immunologic testing, histopathology, real-time PCR assay, fluorescent in situ hybridization, and immunohistochemical staining. Implications of these findings include heightened monitoring of CVID horses for Lyme disease in endemic areas and appropriate therapy in the case of neurologic disease.

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.