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Elliott R Jacobson - One of the best experts on this subject based on the ideXlab platform.
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serologic and molecular evidence for testudinid herpesvirus 2 infection in wild agassiz s desert Tortoises gopherus agassizii
Journal of Wildlife Diseases, 2012Co-Authors: Elliott R Jacobson, Kristin H Berry, James F. X. Wellehan, April L. Childress, Francesco C. Origgi, Josephine Braun, Mark D Schrenzel, Julie Yee, Bruce A RideoutAbstract:Following field observations of wild Agassiz's desert Tortoises (Gopherus agassizii) with oral lesions similar to those seen in captive Tortoises with herpesvirus infection, we measured the prevalence of antibodies to Testudinid herpesvirus (TeHV) 3 in wild populations of desert Tortoises in California. The survey revealed 30.9% antibody prevalence. In 2009 and 2010, two wild adult male desert Tortoises, with gross lesions consistent with trauma and puncture wounds, respectively, were necropsied. Tortoise 1 was from the central Mojave Desert and tortoise 2 was from the northeastern Mojave Desert. We extracted DNA from the tongue of tortoise 1 and from the tongue and nasal mucosa of tortoise 2. Sequencing of polymerase chain reaction products of the herpesviral DNA-dependent DNA polymerase gene and the UL39 gene respectively showed 100% nucleotide identity with TeHV2, which was previously detected in an ill captive desert tortoise in California. Although several cases of herpesvirus infection have been described in captive desert Tortoises, our findings represent the first conclusive molecular evidence of TeHV2 infection in wild desert Tortoises. The serologic findings support cross-reactivity between TeHV2 and TeHV3. Further studies to determine the ecology, prevalence, and clinical significance of this virus in tortoise populations are needed.
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Intranuclear coccidiosis in Tortoises: nine cases.
Veterinary Pathology, 2006Co-Authors: Michael M. Garner, James F. X. Wellehan, April L. Childress, Chris H. Gardiner, April J. Johnson, T. Mcnamara, M. Linn, Scott P. Terrell, Elliott R JacobsonAbstract:Chelonian intranuclear coccidiosis has been reported once, in two radiated Tortoises (Geochelone radiata), and is apparently rare. We describe intranuclear coccidiosis diagnosed histologically in two radiated Tortoises, three Travancore Tortoises (Indotestudo forstenii), two leopard Tortoises (Geochelone pardalis), one bowsprit tortoise (Chersina angulata), and one impressed tortoise (Manouria impressa). Infection was systemic and involved alimentary, urogenital, respiratory, lymphoid, endocrine, and integumentary systems. Trophozoites, meronts, merozoites, macrogametocytes, microgametocytes, and nonsporulated oocysts were seen histologically or by electron microscopy. Intracytoplasmic and extracellular stages of parasite development also were identified histologically. Sequencing of a coccidial 18S rRNA consensus polymerase chain reaction (PCR) product revealed a novel sequence that provided phylogenetic information and may be useful for further diagnostic test design. Intranuclear coccidiosis was associated with variable degrees of inflammation in all cases, was considered the cause of death in six Tortoises, and was a substantial contributing factor to the cause of death in two Tortoises.
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Experimental transmission of a herpesvirus in Greek Tortoises (Testudo graeca).
Veterinary Pathology, 2004Co-Authors: Francesco C. Origgi, Paul A. Klein, Carlos H. Romero, David C. Bloom, Jack M. Gaskin, Sylvia J. Tucker, Elliott R JacobsonAbstract:An experimental transmission study aimed at fulfilling Koch's postulates for a herpesvirus-as- sociated stomatitis-rhinitis in Mediterranean Tortoises is presented. Clinical, pathologic, serologic, and molecular studies were performed linking tortoise herpesvirus with the pathogenesis of stomatitis-rhinitis. Four adult Greek Tortoises received either intranasally or intramuscularly two tortoise herpesvirus isolates by primary experimental infection and secondary challenge 11 months later. After the primary experimental infection and the secondary challenge, clinical signs of illness developed, which included conjunctivitis, diphtheritic oral plaques, and oral discharge. At 4 weeks after the secondary challenge, all Tortoises were humanely euthanatized and evaluated. Although neutralizing antibodies developed after the primary experimental infection, they apparently did not prevent the later development of recurrent clinical signs. Polymerase chain reaction (PCR) and reverse tran- scription-PCR analyses allowed sensitive characterization of the systemic distribution of the herpesvirus DNA sequences and their presence in the cranial nerves and brains of the infected Tortoises. Despite the failure to recover the herpesviruses used in the transmission study, the findings support the premise that tortoise herpes- virus is a primary pathogen of Greek Tortoises. A disease characterized by necrotizing stomatitis and rhinitis has been reported in several species of recently imported and captive Tortoises worldwide. This disease is particularly problematic in Greek (Tes- tudo graeca) and Hermann's (T. hermanni) Tortoises. Clinical signs range from mild conjunctivitis and clear nasal discharge to severe stomatitis and mucopurulent rhinitis. Signs of lower-respiratory tract and central nervous system (CNS) disease also have been seen. 7,22
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Enzyme-Linked Immunosorbent Assay for Detecting Herpesvirus Exposure in Mediterranean Tortoises (Spur-Thighed Tortoise [Testudo graeca] and Hermann's Tortoise [Testudo hermanni])
Journal of Clinical Microbiology, 2001Co-Authors: Francesco C. Origgi, Silvia Blahak, Paul A. Klein, Sylvia J. Tucker, K. Mathes, R. E. Marschang, Elliott R JacobsonAbstract:An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of antibodies to a herpesvirus associated with an upper respiratory tract disease in Mediterranean Tortoises [spur-thighed tortoise (Testudo graeca) and Hermann's tortoise (Testudo hermanni)]. This serodiagnostic test was validated through a hyperimmunization study. The mean of the A(405) readings of the plasma samples collected at time zero of the hyperimmunization study plus three times the standard deviation was used as the cutoff for seropositivity in Tortoises. ELISA results were compared to serum neutralization (SN) values for the same samples by using the McNemar test. The results obtained by SN and ELISA were not significantly different (P > 0.05). This new ELISA could be used as an important diagnostic tool for screening wild populations and private and zoo collections of Mediterranean Tortoises.
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upper respiratory tract disease in the gopher tortoise is caused by mycoplasma agassizii
Journal of Clinical Microbiology, 1999Co-Authors: Mary Bomberger Brown, Daniel R. Brown, Paul A. Klein, I. M. Schumacher, G S Mclaughlin, B C Crenshaw, Elliott R JacobsonAbstract:Upper respiratory tract disease (URTD) has been observed in a number of tortoise species, including the desert tortoise (Gopherus agassizii) and the gopher tortoise (Gopherus polyphemus). Clinical signs of URTD in gopher Tortoises are similar to those in desert Tortoises and include serous, mucoid, or purulent discharge from the nares, excessive tearing to purulent ocular discharge, conjunctivitis, and edema of the eyelids and ocular glands. The objectives of the present study were to determine if Mycoplasma agassizii was an etiologic agent of URTD in the gopher tortoise and to determine the clinical course of the experimental infection in a dose-response infection study. Tortoises were inoculated intranasally with 0.5 ml (0.25 ml/nostril) of either sterile SP4 broth (control group; n 5 10) or 10 8 color-changing units (CCU) (total dose) of M. agassizii 723 (experimental infection group; n 5 9). M. agassizii caused clinical signs compatible with those observed in Tortoises with natural infections. Clinical signs of URTD were evident in seven of nine experimentally infected Tortoises by 4 weeks postinfection (p.i.) and in eight of nine experimentally infected Tortoises by 8 weeks p.i. In the dose-response experiments, Tortoises were inoculated intranasally with a low (10 1 CCU; n 5 6), medium (10 3 CCU; n 5 6), or high (10 5 CCU; n 5 5) dose of M. agassizii 723 or with sterile SP4 broth (n 5 10). At all time points p.i. in both experiments, M. agassizii could be isolated from the nares of at least 50% of the Tortoises. All of the experimentally infected Tortoises seroconverted, and levels of antibody were statistically higher in infected animals than in control animals for all time points of >4 weeks p.i. (P < 0.0001). Control Tortoises in both experiments did not show clinical signs, did not seroconvert, and did not have detectable M. agassizii by either culture or PCR at any point in the study. Histological lesions were compatible with those observed in Tortoises with natural infections. The numbers of M. agassizii 723 did not influence the clinical expression of URTD or the antibody response, suggesting that the strain chosen for these studies was highly virulent. On the basis of the results of the transmission studies, we conclude that M. agassizii is an etiologic agent of URTD in the gopher tortoise.
Paul A. Klein - One of the best experts on this subject based on the ideXlab platform.
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Mycoplasmosis and upper respiratory tract disease of Tortoises: A review and update
Veterinary journal (London England : 1997), 2014Co-Authors: Mary B. Brown, Daniel R. Brown, Lori D. Wendland, Paul A. Klein, Mary M. Christopher, Kristin H BerryAbstract:Abstract Tortoise mycoplasmosis is one of the most extensively characterized infectious diseases of chelonians. A 1989 outbreak of upper respiratory tract disease (URTD) in free-ranging Agassiz's desert Tortoises ( Gopherus agassizii ) brought together an investigative team of researchers, diagnosticians, pathologists, immunologists and clinicians from multiple institutions and agencies. Electron microscopic studies of affected Tortoises revealed a microorganism in close association with the nasal mucosa that subsequently was identified as a new species, Mycoplasma agassizii . Over the next 24 years, a second causative agent, Mycoplasma testudineum , was discovered, the geographic distribution and host range of tortoise mycoplasmosis were expanded, diagnostic tests were developed and refined for antibody and pathogen detection, transmission studies confirmed the pathogenicity of the original M. agassizii isolate, clinical (and subclinical) disease and laboratory abnormalities were characterized, many extrinsic and predisposing factors were found to play a role in morbidity and mortality associated with mycoplasmal infection, and social behavior was implicated in disease transmission. The translation of scientific research into management decisions has sometimes led to undesirable outcomes, such as euthanasia of clinically healthy Tortoises. In this article, we review and assess current research on tortoise mycoplasmosis, arguably the most important chronic infectious disease of wild and captive North American and European Tortoises, and update the implications for management and conservation of Tortoises in the wild.
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Social behavior drives the dynamics of respiratory disease in threatened Tortoises.
Ecology, 2010Co-Authors: Lori D. Wendland, John B Wooding, C. Leann White, Dina L. Demcovitz, Ramon C. Littell, Joan Diemer Berish, Arpat Ozgul, Madan K. Oli, Paul A. Klein, Mary C. ChristmanAbstract:Since the early 1990s, morbidity and mortality in tortoise populations have been associated with a transmissible, mycoplasmal upper respiratory tract disease (URTD). Although the etiology, transmission, and diagnosis of URTD have been extensively studied, little is known about the dynamics of disease transmission in free-ranging tortoise populations. To understand the transmission dynamics of Mycoplasma agassizii, the primary etiological agent of URTD in wild tortoise populations, we studied 11 populations of free-ranging gopher Tortoises (Gopherus polyphemus; n = 1667 individuals) over five years and determined their exposure to the pathogen by serology, by clinical signs, and by detection of the pathogen in nasal lavages. Adults Tortoises (n = 759) were 11 times more likely to be seropositive than immature animals (n = 242) (odds ratio = 10.6, 95% CI = 5.7-20, P < 0.0001). Nasal discharge was observed in only 1.4% (4/296) of immature Tortoises as compared with 8.6% (120/1399) of adult Tortoises. Nasal lavages from all juvenile Tortoises (n = 283) were negative by PCR for mycoplasmal pathogens associated with URTD. We tested for spatial segregation among tortoise burrows by size class and found no consistent evidence of clustering of either juveniles or adults. We suggest that the social behavior of Tortoises plays a critical role in the spread of URTD in wild populations, with immature Tortoises having minimal interactions with adult Tortoises, thereby limiting their exposure to the pathogen. These findings may have broader implications for modeling horizontally transmitted diseases in other species with limited parental care and emphasize the importance of incorporating animal behavior parameters into disease transmission studies to better characterize the host-pathogen dynamics.
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Experimental transmission of a herpesvirus in Greek Tortoises (Testudo graeca).
Veterinary Pathology, 2004Co-Authors: Francesco C. Origgi, Paul A. Klein, Carlos H. Romero, David C. Bloom, Jack M. Gaskin, Sylvia J. Tucker, Elliott R JacobsonAbstract:An experimental transmission study aimed at fulfilling Koch's postulates for a herpesvirus-as- sociated stomatitis-rhinitis in Mediterranean Tortoises is presented. Clinical, pathologic, serologic, and molecular studies were performed linking tortoise herpesvirus with the pathogenesis of stomatitis-rhinitis. Four adult Greek Tortoises received either intranasally or intramuscularly two tortoise herpesvirus isolates by primary experimental infection and secondary challenge 11 months later. After the primary experimental infection and the secondary challenge, clinical signs of illness developed, which included conjunctivitis, diphtheritic oral plaques, and oral discharge. At 4 weeks after the secondary challenge, all Tortoises were humanely euthanatized and evaluated. Although neutralizing antibodies developed after the primary experimental infection, they apparently did not prevent the later development of recurrent clinical signs. Polymerase chain reaction (PCR) and reverse tran- scription-PCR analyses allowed sensitive characterization of the systemic distribution of the herpesvirus DNA sequences and their presence in the cranial nerves and brains of the infected Tortoises. Despite the failure to recover the herpesviruses used in the transmission study, the findings support the premise that tortoise herpes- virus is a primary pathogen of Greek Tortoises. A disease characterized by necrotizing stomatitis and rhinitis has been reported in several species of recently imported and captive Tortoises worldwide. This disease is particularly problematic in Greek (Tes- tudo graeca) and Hermann's (T. hermanni) Tortoises. Clinical signs range from mild conjunctivitis and clear nasal discharge to severe stomatitis and mucopurulent rhinitis. Signs of lower-respiratory tract and central nervous system (CNS) disease also have been seen. 7,22
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Enzyme-Linked Immunosorbent Assay for Detecting Herpesvirus Exposure in Mediterranean Tortoises (Spur-Thighed Tortoise [Testudo graeca] and Hermann's Tortoise [Testudo hermanni])
Journal of Clinical Microbiology, 2001Co-Authors: Francesco C. Origgi, Silvia Blahak, Paul A. Klein, Sylvia J. Tucker, K. Mathes, R. E. Marschang, Elliott R JacobsonAbstract:An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of antibodies to a herpesvirus associated with an upper respiratory tract disease in Mediterranean Tortoises [spur-thighed tortoise (Testudo graeca) and Hermann's tortoise (Testudo hermanni)]. This serodiagnostic test was validated through a hyperimmunization study. The mean of the A(405) readings of the plasma samples collected at time zero of the hyperimmunization study plus three times the standard deviation was used as the cutoff for seropositivity in Tortoises. ELISA results were compared to serum neutralization (SN) values for the same samples by using the McNemar test. The results obtained by SN and ELISA were not significantly different (P > 0.05). This new ELISA could be used as an important diagnostic tool for screening wild populations and private and zoo collections of Mediterranean Tortoises.
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upper respiratory tract disease in the gopher tortoise is caused by mycoplasma agassizii
Journal of Clinical Microbiology, 1999Co-Authors: Mary Bomberger Brown, Daniel R. Brown, Paul A. Klein, I. M. Schumacher, G S Mclaughlin, B C Crenshaw, Elliott R JacobsonAbstract:Upper respiratory tract disease (URTD) has been observed in a number of tortoise species, including the desert tortoise (Gopherus agassizii) and the gopher tortoise (Gopherus polyphemus). Clinical signs of URTD in gopher Tortoises are similar to those in desert Tortoises and include serous, mucoid, or purulent discharge from the nares, excessive tearing to purulent ocular discharge, conjunctivitis, and edema of the eyelids and ocular glands. The objectives of the present study were to determine if Mycoplasma agassizii was an etiologic agent of URTD in the gopher tortoise and to determine the clinical course of the experimental infection in a dose-response infection study. Tortoises were inoculated intranasally with 0.5 ml (0.25 ml/nostril) of either sterile SP4 broth (control group; n 5 10) or 10 8 color-changing units (CCU) (total dose) of M. agassizii 723 (experimental infection group; n 5 9). M. agassizii caused clinical signs compatible with those observed in Tortoises with natural infections. Clinical signs of URTD were evident in seven of nine experimentally infected Tortoises by 4 weeks postinfection (p.i.) and in eight of nine experimentally infected Tortoises by 8 weeks p.i. In the dose-response experiments, Tortoises were inoculated intranasally with a low (10 1 CCU; n 5 6), medium (10 3 CCU; n 5 6), or high (10 5 CCU; n 5 5) dose of M. agassizii 723 or with sterile SP4 broth (n 5 10). At all time points p.i. in both experiments, M. agassizii could be isolated from the nares of at least 50% of the Tortoises. All of the experimentally infected Tortoises seroconverted, and levels of antibody were statistically higher in infected animals than in control animals for all time points of >4 weeks p.i. (P < 0.0001). Control Tortoises in both experiments did not show clinical signs, did not seroconvert, and did not have detectable M. agassizii by either culture or PCR at any point in the study. Histological lesions were compatible with those observed in Tortoises with natural infections. The numbers of M. agassizii 723 did not influence the clinical expression of URTD or the antibody response, suggesting that the strain chosen for these studies was highly virulent. On the basis of the results of the transmission studies, we conclude that M. agassizii is an etiologic agent of URTD in the gopher tortoise.
Kristin H Berry - One of the best experts on this subject based on the ideXlab platform.
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desert Tortoises gopherus agassizii are selective herbivores that track the flowering phenology of their preferred food plants
PLOS ONE, 2015Co-Authors: Bryan W Jennings, Kristin H BerryAbstract:Previous studies of desert tortoise foraging ecology in the western Mojave Desert suggest that these animals are selective herbivores, which alter their diet according to the temporal availability of preferred food plants. These studies, however, did not estimate availability of potential food plants by taking into account the spatial and temporal variability in ephemeral plant abundance that occurs within the spring season. In this study, we observed 18 free-ranging adult Tortoises take 35,388 bites during the spring foraging season. We also estimated the relative abundance of potential food plants by stratifying our sampling across different phenological periods of the 3-month long spring season and by different habitats and microhabitats. This methodology allowed us to conduct statistical tests comparing tortoise diet against plant abundance. Our results show that Tortoises choose food plants non-randomly throughout the foraging season, a finding that corroborates the hypothesis that desert Tortoises rely on key plants during different phenological periods of spring. Moreover, Tortoises only consumed plants in a succulent state until the last few weeks of spring, at which time most annuals and herbaceous perennials had dried and most Tortoises had ceased foraging. Many species of food plants—including several frequently eaten species—were not detected in our plant surveys, yet Tortoises located these rare plants in their home ranges. Over 50% of bites consumed were in the group of undetected species. Interestingly, Tortoises focused heavily on several leguminous species, which could be nutritious foods owing to their presumably high nitrogen contents. We suggest that herbaceous perennials, which were rare on our study area but represented ~30% of tortoise diet, may be important in sustaining tortoise populations during droughts when native annuals are absent. These findings highlight the vulnerability of desert Tortoises to climate change if such changes alter the availability of their preferred food plants.
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protection benefits desert tortoise gopherus agassizii abundance the influence of three management strategies on a threatened species
Herpetological Monographs, 2014Co-Authors: Kristin H Berry, Lisa M Lyren, Tracy Y BaileyAbstract:Abstract: We surveyed an area of ∼260 km2 in the western Mojave Desert to evaluate relationships between condition of Agassiz's Desert Tortoise populations (Gopherus agassizii) and habitat on lands that have experienced three different levels of management and protection. We established 240 1-ha plots using random sampling, with 80 plots on each of the three types of managed lands. We conducted surveys in spring 2011 and collected data on live Tortoises, shell-skeletal remains, other signs of Tortoises, perennial vegetation, predators, and evidence of human use. Throughout the study area and regardless of management area, tortoise abundance was positively associated with one of the more diverse associations of perennial vegetation. The management area with the longest history of protection, a fence, and legal exclusion of livestock and vehicles had significantly more live Tortoises and lower death rates than the other two areas. Tortoise presence and abundance in this protected area had no significant pos...
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Mycoplasmosis and upper respiratory tract disease of Tortoises: A review and update
Veterinary journal (London England : 1997), 2014Co-Authors: Mary B. Brown, Daniel R. Brown, Lori D. Wendland, Paul A. Klein, Mary M. Christopher, Kristin H BerryAbstract:Abstract Tortoise mycoplasmosis is one of the most extensively characterized infectious diseases of chelonians. A 1989 outbreak of upper respiratory tract disease (URTD) in free-ranging Agassiz's desert Tortoises ( Gopherus agassizii ) brought together an investigative team of researchers, diagnosticians, pathologists, immunologists and clinicians from multiple institutions and agencies. Electron microscopic studies of affected Tortoises revealed a microorganism in close association with the nasal mucosa that subsequently was identified as a new species, Mycoplasma agassizii . Over the next 24 years, a second causative agent, Mycoplasma testudineum , was discovered, the geographic distribution and host range of tortoise mycoplasmosis were expanded, diagnostic tests were developed and refined for antibody and pathogen detection, transmission studies confirmed the pathogenicity of the original M. agassizii isolate, clinical (and subclinical) disease and laboratory abnormalities were characterized, many extrinsic and predisposing factors were found to play a role in morbidity and mortality associated with mycoplasmal infection, and social behavior was implicated in disease transmission. The translation of scientific research into management decisions has sometimes led to undesirable outcomes, such as euthanasia of clinically healthy Tortoises. In this article, we review and assess current research on tortoise mycoplasmosis, arguably the most important chronic infectious disease of wild and captive North American and European Tortoises, and update the implications for management and conservation of Tortoises in the wild.
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multiple factors affect a population of agassiz s desert tortoise gopherus agassizii in the northwestern mojave desert
Herpetological Monographs, 2013Co-Authors: Kristin H Berry, William M Perry, Ashley A Coble, Timothy A ShieldsAbstract:Abstract: Numerous factors have contributed to declines in populations of the federally threatened Agassiz's Desert Tortoise (Gopherus agassizii) and continue to limit recovery. In 2010, we surveyed a low-density population on a military test facility in the northwestern Mojave Desert of California, USA, to evaluate population status and identify potential factors contributing to distribution and low densities. Estimated densities of live Tortoises ranged spatially from 1.2/km2 to 15.1/km2. Although only one death of a breeding-age tortoise was recorded for the 4-yr period prior to the survey, remains of 16 juvenile and immature Tortoises were found, and most showed signs of predation by Common Ravens (Corvus corax) and mammals. Predation may have limited recruitment of young Tortoises into the adult size classes. To evaluate the relative importance of different types of impacts to Tortoises, we developed predictive models for spatially explicit densities of tortoise sign and live Tortoises using topograp...
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serologic and molecular evidence for testudinid herpesvirus 2 infection in wild agassiz s desert Tortoises gopherus agassizii
Journal of Wildlife Diseases, 2012Co-Authors: Elliott R Jacobson, Kristin H Berry, James F. X. Wellehan, April L. Childress, Francesco C. Origgi, Josephine Braun, Mark D Schrenzel, Julie Yee, Bruce A RideoutAbstract:Following field observations of wild Agassiz's desert Tortoises (Gopherus agassizii) with oral lesions similar to those seen in captive Tortoises with herpesvirus infection, we measured the prevalence of antibodies to Testudinid herpesvirus (TeHV) 3 in wild populations of desert Tortoises in California. The survey revealed 30.9% antibody prevalence. In 2009 and 2010, two wild adult male desert Tortoises, with gross lesions consistent with trauma and puncture wounds, respectively, were necropsied. Tortoise 1 was from the central Mojave Desert and tortoise 2 was from the northeastern Mojave Desert. We extracted DNA from the tongue of tortoise 1 and from the tongue and nasal mucosa of tortoise 2. Sequencing of polymerase chain reaction products of the herpesviral DNA-dependent DNA polymerase gene and the UL39 gene respectively showed 100% nucleotide identity with TeHV2, which was previously detected in an ill captive desert tortoise in California. Although several cases of herpesvirus infection have been described in captive desert Tortoises, our findings represent the first conclusive molecular evidence of TeHV2 infection in wild desert Tortoises. The serologic findings support cross-reactivity between TeHV2 and TeHV3. Further studies to determine the ecology, prevalence, and clinical significance of this virus in tortoise populations are needed.
K. W. Hunter - One of the best experts on this subject based on the ideXlab platform.
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quantitative pcr method for detection of mycoplasma spp dna in nasal lavage samples from the desert tortoise gopherus agassizii
Journal of Microbiological Methods, 2011Co-Authors: S. A. Dupre', C R Tracy, K. W. HunterAbstract:Abstract Mycoplasma agassizii and M. testudineum have been associated with upper respiratory tract disease (URTD) in the threatened desert tortoise ( Gopherus agassizii ). Because microbiological culture methods have proven difficult to employ in wild desert Tortoises, our goal was to develop a sensitive and specific qPCR method for detecting and quantifying mycoplasma DNA in nasal lavage fluid collected in the field. Primers for 16S ribosomal RNA gene sequences specific for M. agassizii and M. testudineum were designed, together with primers that recognize conserved sequences of both microorganisms. Standard curves generated with DNA extracted from known numbers of mycoplasma cells revealed a lower detection limit of approximately 5 fg. The qPCR method did not recognize normal flora DNA, and nasal lavage fluid contained no interfering substances. Nasal lavage samples collected from 20 captive desert Tortoises housed at the Desert Tortoise Conservation Center (Clark County, Nevada, USA) revealed the presence of M. agassizii DNA in 100% of the Tortoises. Concentrations ranged from a low of 6 pg ml − 1 to a high of 72,962 pg ml − 1 . Only one of the Tortoises was positive for M. testudineum . Interestingly, not all of the qPCR positive Tortoises showed evidence of seroconversion, suggesting that they were colonized but not infected. This new quantitative method will provide a critical tool for managing threatened populations of the desert tortoise.
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upper respiratory tract disease urtd as a threat to desert tortoise populations a reevaluation
Biological Conservation, 2009Co-Authors: Franziska C Sandmeier, S. A. Dupre', Richard C Tracy, K. W. HunterAbstract:The relationships between Mycoplasma agassizii, a causative agent of upper respiratory disease (URTD), and desert tortoise (Gopherus agassizii), generally illustrate the complexities of disease dynamics in wild vertebrate populations. In this review, we summarize current understanding of URTD in Mojave desert tortoise populations, we illustrate how inadequate knowledge of tortoise immune systems may obfuscate assessment of disease, and we suggest approaches to future management of URTD in desert tortoise populations. We challenge the view that M. agassizii causes consistent levels of morbidity and/or mortality across the Mojave desert. Instead, URTD may be described more accurately as a context-dependent disease. In addition, new evidence for relatively high levels of natural antibodies to M. agassizii in desert Tortoises suggests possible problems in conventional diagnostic tests of disease in Tortoises as well as a possible tortoise immune mechanism to protect against M. agassizii. Partly because of the problems in diagnostic testing, we recommend abandoning policies to euthanize Tortoises that test positive for an immune response to M. agassizii. Based on this review, we question management strategies aimed solely at reducing Mycoplasma spp. in desert tortoise populations, and advocate a more careful consideration of extrinsic factors as a cause of symptomatic disease.
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western blot can distinguish natural and acquired antibodies to mycoplasma agassizii in the desert tortoise gopherus agassizii
Journal of Microbiological Methods, 2008Co-Authors: K. W. Hunter, S. A. Dupre', Franziska C Sandmeier, Tiffanny Sharp, Richard C TracyAbstract:Mycoplasma agassizi has been identified as a cause of upper respiratory tract disease (URTD) in the threatened Mojave population of the desert tortoise (Gopherus agassizii), and anti-M. agassizii antibodies have been found by ELISA in as many as 15% of these animals across their geographic range. Here we report that a cohort of 16 egg-reared desert Tortoises never exposed to M. agassizii had ELISA antibody titers to this organism that overlapped with titers obtained from some M. agassizii-infected Tortoises. These natural antibodies were predominantly of the IgM class. Western blots of plasma from these non-infected Tortoises produced a characteristic banding pattern against M. agassizii antigens. A group of 38 wild-caught desert Tortoises was tested by ELISA, and although some of these Tortoises had antibody titers significantly higher than the non-infected Tortoises, there was considerable overlap at the lower titer levels. However, Western blot analysis revealed distinct banding patterns that could readily distinguish between the non-infected Tortoises and Tortoises with acquired antibodies, regardless of ELISA antibody titers. We conclude that desert Tortoises have natural antibodies to M. agassizii that can compromise the determination of infection status by ELISA. However, the Western blot technique can distinguish between natural and acquired antibody patterns and can be used to confirm the diagnosis of M. agassizii infections in the desert tortoise.
Kenneth E Nussear - One of the best experts on this subject based on the ideXlab platform.
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desert tortoise use of burned habitat in the eastern mojave desert
Journal of Wildlife Management, 2015Co-Authors: Kristina K Drake, Andrew T. Modlin, Sara J Scolessciulla, Kenneth E Nussear, Lesley A. Defalco, Todd C. Esque, Philip A MedicaAbstract:Wildfires burned 24,254 ha of critical habitat designated for the recovery of the threatened Mojave desert tortoise (Gopherus agassizii) in southern Nevada during 2005. The proliferation of non-native annual grasses has increased wildfire frequency and extent in recent decades and continues to accelerate the conversion of tortoise habitat across the Mojave Desert. Immediate changes to vegetation are expected to reduce quality of critical habitat, yet whether Tortoises will use burned and recovering habitat differently from intact unburned habitat is unknown. We compared movement patterns, home-range size, behavior, microhabitat use, reproduction, and survival for adult desert Tortoises located in, and adjacent to, burned habitat to understand how Tortoises respond to recovering burned habitat. Approximately 45% of home ranges in the post-fire environment contained burned habitat, and numerous observations (n = 12,223) corroborated tortoise use of both habitat types (52% unburned, 48% burned). Tortoises moved progressively deeper into burned habitat during the first 5 years following the fire, frequently foraging in burned habitats that had abundant annual plants, and returning to adjacent unburned habitat for cover provided by intact perennial vegetation. However, by years 6 and 7, the live cover of the short-lived herbaceous perennial desert globemallow (Sphaeralcea ambigua) that typically re-colonizes burned areas declined, resulting in a contraction of tortoise movements from the burned areas. Health and egg production were similar between burned and unburned areas indicating that Tortoises were able to acquire necessary resources using both areas. This study documents that adult Mojave desert Tortoises continue to use habitat burned once by wildfire. Thus, continued management of this burned habitat may contribute toward the recovery of the species in the face of many sources of habitat loss. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.
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integrating gene transcription based biomarkers to understand desert tortoise and ecosystem health
Ecohealth, 2015Co-Authors: Lizabeth Bowen, Keith A Miles, Kristina K Drake, Shannon C Waters, Todd C. Esque, Kenneth E NussearAbstract:Tortoises are susceptible to a wide variety of environmental stressors, and the influence of human disturbances on health and survival of Tortoises is difficult to detect. As an addition to current diagnostic methods for desert Tortoises, we have developed the first leukocyte gene transcription biomarker panel for the desert tortoise (Gopherus agassizii), enhancing the ability to identify specific environmental conditions potentially linked to declining animal health. Blood leukocyte transcript profiles have the potential to identify physiologically stressed animals in lieu of clinical signs. For desert Tortoises, the gene transcript profile included a combination of immune or detoxification response genes with the potential to be modified by biological or physical injury and consequently provide information on the type and magnitude of stressors present in the animal’s habitat. Blood from 64 wild adult Tortoises at three sites in Clark County, NV, and San Bernardino, CA, and from 19 captive Tortoises in Clark County, NV, was collected and evaluated for genes indicative of physiological status. Statistical analysis using a priori groupings indicated significant differences among groups for several genes, while multidimensional scaling and cluster analyses of transcription C T values indicated strong differentiation of a large cluster and multiple outlying individual Tortoises or small clusters in multidimensional space. These analyses highlight the effectiveness of the gene panel at detecting environmental perturbations as well as providing guidance in determining the health of the desert tortoise.
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Translocation as a conservation tool for Agassiz's desert Tortoises: survivorship, reproduction, and movements
Journal of Wildlife Management, 2012Co-Authors: Kenneth E Nussear, C R Tracy, Philip A Medica, D. S. Wilson, Ronald W. Marlow, Paul Stephen CornAbstract:We translocated 120 Agassiz's desert Tortoises to 5 sites in Nevada and Utah to evaluate the effects of translocation on tortoise survivorship, reproduction, and habitat use. Translocation sites included several elevations, and extended to sites with vegetation assemblages not typically associated with desert Tortoises in order to explore the possibility of moving animals to upper elevation areas. We measured survivorship, reproduction, and movements of translocated and resident animals at each site. Survivorship was not significantly different between translocated and resident animals within and among sites, and survivorship was greater overall during non-drought years. The number of eggs produced by Tortoises was similar for translocated and resident females, but differed among sites. Animals translocated to atypical habitat generally moved until they reached vegetation communities more typical of desert tortoise habitat. Even within typical tortoise habitat, Tortoises tended to move greater distances in the first year after translocation than did residents, but their movements in the second or third year after translocation were indistinguishable from those of resident Tortoises. Our data show that Tortoises translocated into typical Mojave desert scrub habitats perform well; however, the large first-year movements of translocated Tortoises have important management implications. Projects that employ translocations must consider how much area will be needed to contain translocated Tortoises and whether roads need fencing to prevent the loss of animals. 2012 The Wildlife Society.
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effects of subsidized predators resource variability and human population density on desert tortoise populations in the mojave desert usa
Endangered Species Research, 2010Co-Authors: Todd C. Esque, Andrew D. Walde, Kristin H Berry, Kristina K Drake, Roy C Averillmurray, Peter A Woodman, William I Boarman, Kenneth E Nussear, Philip A Medica, Jeremy S MackAbstract:Understanding predator-prey relationships can be pivotal in the conservation of spe- cies. For 2 decades, desert tortoise Gopherus agassizii populations have declined, yet quantitative evidence regarding the causes of declines is scarce. In 2005, Ft. Irwin National Training Center, California, USA, implemented a translocation project including 2 yr of baseline monitoring of desert Tortoises. Unusually high predation on Tortoises was observed after translocation occurred. We conducted a retrospective analysis of predation and found that translocation did not affect the proba- bility of predation: translocated, resident, and control Tortoises all had similar levels of predation. However, predation rates were higher near human population concentrations, at lower elevation sites, and for smaller Tortoises and females. Furthermore, high mortality rates were not limited to the National Training Center. In 2008, elevated mortality (as high as 43%) occurred throughout the listed range of the desert tortoise. Although no temporal prey base data are available for analysis from any of the study sites, we hypothesize that low population levels of typical coyote Canis latrans prey (i.e. jackrabbits Lepus californicus and other small animals) due to drought conditions influenced high predation rates in previous years. Predation may have been exacerbated in areas with high levels of subsidized predators. Many historical reports of increased predation, and our observation of a range- wide pattern, may indicate that high predation rates are more common than generally considered and may impact recovery of the desert tortoise throughout its range.
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can modeling improve estimation of desert tortoise population densities
Ecological Applications, 2007Co-Authors: Kenneth E Nussear, Richard C TracyAbstract:The federally listed desert tortoise (Gopherus agassizii) is currently monitored using distance sampling to estimate population densities. Distance sampling, as with many other techniques for estimating population density, assumes that it is possible to quantify the proportion of animals available to be counted in any census. Because desert Tortoises spend much of their life in burrows, and the proportion of Tortoises in burrows at any time can be extremely variable, this assumption is difficult to meet. This proportion of animals available to be counted is used as a correction factor (g0) in distance sampling and has been estimated from daily censuses of small populations of Tortoises (6-12 individuals). These censuses are costly and produce imprecise estimates of g0 due to small sample sizes. We used data on tortoise activity from a large (N = 1 50) experimental population to model activity as a function of the biophysical attributes of the environment, but these models did not improve the precision of estimates from the focal populations. Thus, to evaluate how much of the variance in tortoise activity is apparently not predictable, we assessed whether activity on any particular day can predict activity on subsequent days with essentially identical environmental conditions. Tortoise activity was only weakly correlated on consecutive days, indicating that behavior was not repeatable or consistent among days with similar physical environments.
