Detection of Tickborne Relapsing Fever Spirochete, Austin, Texas, USA

Bissett, Jack; Ledet, Suzanne Calamari; Krishnavajhala, Aparna; Armstrong, Brittany A.; Klioueva, Anna; Sexton, Christopher; Replogle, Adam J.; Schriefer, Martin E.; López, Job E.

doi:10.3201/eid2411.172033

Cited by 22 publications

(36 citation statements)

References 24 publications

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“…Post Oak Savannah, Blackland Prairies, Cross Timbers, Edwards Plateau). Two additional case reports of five dogs (Piccione et al., ) and one human (Bissett et al., ) also coincide with our findings by indicating infections with B. turicatae centred in the same aforementioned ecoregions. The preliminary observation of geographical grouping, or clustering, of samples from case reports and surveillance sample sets may be explained by the ecology of its primary soft tick vector, Ornithodoros turicata , which has traditionally been associated with the cave system of central Texas, therefore corroborating the central cluster observed in this current study and prior case studies (Dworkin, Schwan, Anderson, & Borchardt, ).…”

Section: Discussionsupporting

confidence: 90%

Molecular prevalence and ecoregion distribution of select tick‐borne pathogens in Texas dogs

Modarelli

Tomeček

Piccione

et al. 2019

Transbound Emerg Dis

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Summary Tick‐borne diseases (TBD), caused by borrelial, rickettsial and babesial pathogens, are common across the United States and can cause severe clinical disease in susceptible hosts, such as domestic dogs. However, there are limited TBD molecular epidemiological reports for dogs in Texas, and none for the non‐Lyme borrelial pathogen responsible for causing tick‐borne relapsing fever (TBRF). Therefore, data to support the prevalence of TBRF in the canine population is inadequate. This study aimed to characterize the molecular prevalence of 11 causative agents responsible for three TBD groups within domestic dogs with an emphasis on pathogen distribution within Texas ecoregions. A total representative number of 1,171 whole‐blood samples were collected opportunistically from two Texas veterinary diagnostic laboratories. A layerplex real‐time PCR assay was utilized to screen the dog samples for all 11 pathogens simultaneously. The overall molecular infection prevalence of disease was 0.68% borrelial, 1.8% rickettsial and 0.43% babesial pathogens, for a TBD total of 2.73% across Texas. Higher molecular prevalence was observed when analysed by ecoregion distinction, including 5.78% rickettsial infections by Ehrlichia canis and Anaplasma platys in the Rolling Plains ecoregion, and an average of 1.1% Borrelia turicatae and 1.0% Babesia gibsoni across detected ecoregions. To our knowledge, our findings indicate the first molecular detection of A. platys in Texas, and the first report of coinfections with E. canis and A. platys in dogs of Texas. The zoonotic concerns associated with TBDs, in conjunction with dogs’ implication as an effective sentinel for human disease, highlight the importance of characterizing and monitoring regions associated with active infections in dogs. Surveillance data obtained from this study may aid public health agencies in updating maps depicting high‐risk areas of disease and developing preventative measures for the affected areas.

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Section: Discussionsupporting

confidence: 90%

Molecular prevalence and ecoregion distribution of select tick‐borne pathogens in Texas dogs

Modarelli

Tomeček

Piccione

et al. 2019

Transbound Emerg Dis

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“…turicatae may be emerging in these areas. In 2017 there was an outbreak of TBRF among conference attendees in Austin, Texas [ 34 ], which is located in Travis County. This outbreak was in a densely populated area of the city and B .…”

Section: Discussionmentioning

confidence: 99%

Seroprevalence for the tick-borne relapsing fever spirochete Borrelia turicatae among small and medium sized mammals of Texas

et al. 2018

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BackgroundIn low elevation arid regions throughout the southern United States, Borrelia turicatae is the principal agent of tick-borne relapsing fever. However, endemic foci and the vertebrate hosts involved in the ecology of B. turicatae remain undefined. Experimental infection studies suggest that small and medium sized mammals likely maintain B. turicatae in nature, while the tick vector is a long-lived reservoir.Methodology/principal findingsSerum samples from wild caught rodents, raccoons, and wild and domestic canids from 23 counties in Texas were screened for prior exposure to B. turicatae. Serological assays were performed using B. turicatae protein lysates and recombinant Borrelia immunogenic protein A (rBipA), a diagnostic protein that is unique to RF spirochetes and may be a species-specific antigen.Conclusions/significanceSerological responses to B. turicatae were detected from 24 coyotes, one gray fox, two raccoons, and one rodent from six counties in Texas. These studies indicate that wild canids and raccoons were exposed to B. turicatae and are likely involved in the pathogen’s ecology. Additionally, more work should focus on evaluating rodent exposure to B. turicatae and the role of these small mammals in the pathogen’s maintenance in nature.

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“…The primary species in the United States that transmit pathogens include Ornithodoros turicata, Ornithodoros hermsi, Ornithodoros parkeri, Ornithodoros talaje, and Ornithodoros coriaceus (Davis, 1939;Cooley and Kohls, 1944;Hess et al, 1987;Donaldson et al, 2016;Lopez et al, 2016;Sage et al, 2017). These species have been implicated in the transmission of tick-borne relapsing fever spirochetes (Lane et al, 1985;Dworkin et al, 2002;Nieto et al, 2012;Lopez et al, 2016;Christensen et al, 2017;Bissett et al, 2018). Moreover, O. turicata and O. coriaceus were experimentally shown to be competent vectors of African swine fever virus (ASFV) (Hess et al, 1987), an emerging pathogen in Europe and Asia.…”

Section: Introductionmentioning

confidence: 99%

Differential Expression of Putative Ornithodoros turicata Defensins Mediated by Tick Feeding

Armstrong

Kneubehl

Mitchell

et al. 2020

Front. Cell. Infect. Microbiol.

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Additional research on soft ticks in the family Argasidae is needed to bridge the knowledge gap relative to hard ticks of the family Ixodidae; especially, the molecular mechanisms of Ornithodoros biology. Ornithodoros species are vectors of human and animal pathogens that include tick-borne relapsing fever spirochetes and African swine fever virus. Soft tick vector-pathogen interactions involving components of the tick immune response are not understood. Ticks utilize a basic innate immune system consisting of recognition factors and cellular and humoral responses to produce antimicrobial peptides, like defensins. In the present study, we identified and characterized the first putative defensins of Ornithodoros turicata, an argasid tick found primarily in the southwestern United States and regions of Latin America. Four genes (otdA, otdB, otdC, and otdD) were identified through sequencing and their predicted amino acid sequences contained motifs characteristic of arthropod defensins. A phylogenetic analysis grouped these four genes with arthropod defensins, and computational structural analyses further supported the identification. Since pathogens transmitted by O. turicata colonize both the midgut and salivary glands, expression patterns of the putative defensins were determined in these tissues 1 week post engorgement and after molting. Defensin genes up-regulated in the tick midgut 1 week post blood feeding were otdA and otdC, while otdD was up-regulated in the midgut of post-molt ticks. Moreover, otdB and otdD were also up-regulated in the salivary glands of flat post-molt ticks, while otdC was up-regulated within 1 week post blood-feeding. This work is foundational toward additional studies to determine mechanisms of vector competence and pathogen transmission from O. turicata.

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Detection of Tickborne Relapsing Fever Spirochete, Austin, Texas, USA

Cited by 22 publications

References 24 publications

Molecular prevalence and ecoregion distribution of select tick‐borne pathogens in Texas dogs

Molecular prevalence and ecoregion distribution of select tick‐borne pathogens in Texas dogs

Seroprevalence for the tick-borne relapsing fever spirochete Borrelia turicatae among small and medium sized mammals of Texas

Differential Expression of Putative Ornithodoros turicata Defensins Mediated by Tick Feeding

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