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Brannelly LA, Sharma P, Ballesteros S, Wendt AS. Voriconazole successfully treats chytridiomycosis in frogs. DISEASES OF AQUATIC ORGANISMS 2024; 159:1-7. [PMID: 38989788 DOI: 10.3354/dao03795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/12/2024]
Abstract
Chytridiomycosis is a devastating disease and is a key cause of amphibian population declines around the world. Despite active research on this amphibian disease system for over 2 decades, we still do not have treatment methods that are safe and that can be broadly used across species. Here, we show evidence that voriconazole is a successful method of treatment for 1 species of amphibian in captivity and that this treatment could offer benefits over other treatment options like heat or itraconazole, which are not able to be used for all species and life stages. We conducted 2 treatments of chytridiomycosis using voriconazole. The treatment was effective and resulted in 100% pathogen clearance, and mortality ceased. Additionally, treating frogs with voriconazole requires less handling than treatment methods like itraconazole and requires no specialized equipment, like heat treatment. We highlight that clinical treatment trials should be conducted to identify an optimum dosage and treatment time and that trials should test whether this treatment is safe and effective for tadpoles and other species.
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Affiliation(s)
- Laura A Brannelly
- Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Preeti Sharma
- Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Werribee, Victoria 3030, Australia
- Centre for Planetary Health and Food Security, School of Environment and Science, Griffith University, Southport, Queensland 4215, Australia
| | - Sofia Ballesteros
- Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Werribee, Victoria 3030, Australia
| | - Alexander S Wendt
- Melbourne Veterinary School, Faculty of Science, The University of Melbourne, Werribee, Victoria 3030, Australia
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Mayer T, Moskaluk AE, Kolby JE, Russell M, Schaffer P, Fagre AC. First recorded outbreak of Veronaea botryosa in North American amphibians: Clinicopathologic features of a rare cause of phaeohyphomycosis in captive White's tree frogs ( Litoria caerulea). Med Mycol Case Rep 2022; 38:13-17. [PMID: 36193194 PMCID: PMC9526012 DOI: 10.1016/j.mmcr.2022.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 09/09/2022] [Accepted: 09/10/2022] [Indexed: 12/02/2022] Open
Abstract
We describe fatal phaeohyphomycosis due to Veronaea botryosa in captive White’s tree frogs (Litoria caerulea), the first confirmed report in amphibians in North America. Over 15 months, six frogs developed ulcerative dermatitis on distal extremities/ventrum, which in one animal progressed to vasculitis and necrotizing osteomyelitis. All six frogs died. Clinicopathologic findings, diagnostic challenges, and control are discussed. Emerging fungi such as V. botryosa pose serious concerns for zoonosis and potential spread through the pet trade.
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Affiliation(s)
- Treana Mayer
- Colorado State University, College of Veterinary Medicine & Biomedical Science, Fort Collins, CO, USA
| | - Alexandra E Moskaluk
- Colorado State University, College of Veterinary Medicine & Biomedical Science, Fort Collins, CO, USA
| | - Jonathan E Kolby
- James Cook University, College of Public Health, Medical and Veterinary Sciences, Townsville, Australia
| | - Michael Russell
- Colorado State University, College of Veterinary Medicine & Biomedical Science, Fort Collins, CO, USA
| | - Paula Schaffer
- Colorado State University, College of Veterinary Medicine & Biomedical Science, Fort Collins, CO, USA
| | - Anna C Fagre
- Colorado State University, College of Veterinary Medicine & Biomedical Science, Fort Collins, CO, USA
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Davidson MJ, Bushell R, Ploeg R, Marenda M, Halliday C, Goodall D, Gilbert D, Kosch TA, Skerratt LF, Berger L. Embryo mortality in a captive-bred, Critically Endangered amphibian. DISEASES OF AQUATIC ORGANISMS 2022; 152:73-83. [PMID: 36453456 DOI: 10.3354/dao03706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The Critically Endangered southern corroboree frog Pseudophryne corroboree is dependent upon captive assurance colonies for its continued survival. Although the captive breeding programme for this species has largely been successful, embryonic mortality remains high (40-90% per year). This study aimed to investigate the causes of mortality in P. corroboree embryos in the captive collection at Melbourne Zoo. During the 2021 breeding season, we investigated 108 abnormal embryos to determine the impact of infections and anatomical deformities on survival and used culture and molecular methods to identify microbes. Overall, 100% of abnormal embryos had fungal infections, and of these, 41.6% also had anatomical deformities. The mortality rate in abnormal embryos was 89.8%; however, we detected no difference in survival in any of the 3 observed fungal growth patterns or between deformed and non-deformed embryos. Sanger sequencing of the ITS region identified fungal isolates belonging to the genus Ilyonectria, the first record in a vertebrate host, and another as a Plectosphaerella sp., which is the first record of infection in an embryo. Dominant bacteria identified were of the genera Herbaspirillum and Flavobacterium; however, their role in the mortality is unknown. Fungal infection and deformities have a significant impact on embryo survival in captive-bred P. corroboree. In a species which relies on captive breeding, identifying and reducing the impacts of embryonic mortality can inform conservation efforts and improve reintroduction outcomes.
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Affiliation(s)
- M J Davidson
- Faculty of Veterinary and Agricultural Science, University of Melbourne, Werribee, Victoria 3030, Australia
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SUCCESSFUL TREATMENT OF BATRACHOCHYTRIUM DENDROBATIDIS IN EASTERN HELLBENDERS (CRYPTOBRANCHUS ALLEGANIENSIS ALLEGANIENSIS) WITH TERBINAFINE. J Zoo Wildl Med 2022; 53:228-231. [DOI: 10.1638/2020-0146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/11/2021] [Indexed: 11/21/2022] Open
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EFFICACY OF SUBCUTANEOUS IMPLANTS TO PROVIDE CONTINUOUS PLASMA TERBINAFINE IN HELLBENDERS ( CRYPTOBRANCHUS ALLEGANIENSI) FOR FUTURE PROPHYLACTIC USE AGAINST CHYTRIDIOMYCOSIS. J Zoo Wildl Med 2021; 52:300-305. [PMID: 33827189 DOI: 10.1638/2020-0158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/12/2020] [Indexed: 11/21/2022] Open
Abstract
Batrachochytrium dendrobatidis (Bd) is an important fungal pathogen present in wild hellbender (Cryptobranchus alleganiensis) populations that appears to cause disease during novel exposure and acute stress. Hellbender repatriation efforts are ongoing to combat declining populations, but mortality by chytridiomycosis (disease from Bd) after release has been reported. The goal was to determine whether a safe antifungal agent could be administered and provide prolonged plasma concentrations without repeated handling. A subcutaneous implant impregnated with 24.5 mg of terbinafine was tested in three juvenile eastern hellbenders (C. a. alleganiensis) raised in human care, and plasma terbinafine concentrations were recorded from weekly to biweekly for 141 days. Plasma concentrations were variable, with peak plasma concentrations of 1,610, 112, and 66 ng/ml between 28 and 56 days postimplant. Although all hellbenders achieved plasma concentrations above the published minimum inhibitory concentration for terbinafine against Bd zoospores (63 ng/ml) at several time points, only one individual remained above this threshold for more than two consecutive time intervals. Results show the potential for these implants as a prophylaxis for chytridiomycosis in captive-to-wild hellbender releases. However, further investigation will be needed to determine the plasma concentrations required to achieve prophylaxis in vivo and implant reliability.
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The amphibian microbiome exhibits poor resilience following pathogen-induced disturbance. ISME JOURNAL 2021; 15:1628-1640. [PMID: 33564111 PMCID: PMC8163836 DOI: 10.1038/s41396-020-00875-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 11/24/2020] [Accepted: 12/07/2020] [Indexed: 12/29/2022]
Abstract
Infectious pathogens can disrupt the microbiome in addition to directly affecting the host. Impacts of disease may be dependent on the ability of the microbiome to recover from such disturbance, yet remarkably little is known about microbiome recovery after disease, particularly in nonhuman animals. We assessed the resilience of the amphibian skin microbial community after disturbance by the pathogen, Batrachochytrium dendrobatidis (Bd). Skin microbial communities of laboratory-reared mountain yellow-legged frogs were tracked through three experimental phases: prior to Bd infection, after Bd infection (disturbance), and after clearing Bd infection (recovery period). Bd infection disturbed microbiome composition and altered the relative abundances of several dominant bacterial taxa. After Bd infection, frogs were treated with an antifungal drug that cleared Bd infection, but this did not lead to recovery of microbiome composition (measured as Unifrac distance) or relative abundances of dominant bacterial groups. These results indicate that Bd infection can lead to an alternate stable state in the microbiome of sensitive amphibians, or that microbiome recovery is extremely slow—in either case resilience is low. Furthermore, antifungal treatment and clearance of Bd infection had the additional effect of reducing microbial community variability, which we hypothesize results from similarity across frogs in the taxa that colonize community vacancies resulting from the removal of Bd. Our results indicate that the skin microbiota of mountain yellow-legged frogs has low resilience following Bd-induced disturbance and is further altered by the process of clearing Bd infection, which may have implications for the conservation of this endangered amphibian.
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McDonald CA, Longo AV, Lips KR, Zamudio KR. Incapacitating effects of fungal coinfection in a novel pathogen system. Mol Ecol 2020; 29:3173-3186. [PMID: 32310322 DOI: 10.1111/mec.15452] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 03/16/2020] [Accepted: 04/08/2020] [Indexed: 12/20/2022]
Abstract
As globalization lowers geographic barriers to movement, coinfection with novel and enzootic pathogens is increasingly likely. Novel and enzootic pathogens can interact synergistically or antagonistically, leading to increased or decreased disease severity. Here we examine host immune responses to coinfection with two closely related fungal pathogens: Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal). Both pathogens have had detrimental effects on amphibian populations, with Bd now largely enzootic, while Bsal is currently spreading and causing epizootics. Recent experimental work revealed that newts coinfected with Bd and Bsal had significantly higher mortality than those infected with either pathogen alone. Here we characterize host immunogenomic responses to chytrid coinfection relative to single infection. Across several classes of immune genes including pattern recognition receptors, cytokines, and MHC, coinfected host gene expression was weakly upregulated or comparable to that seen in single Bd infection, but significantly decreased when compared to Bsal infection. Combined with strong complement pathway downregulation and keratin upregulation, these results indicate that coinfection with Bd and Bsal compromises immune responses active against Bsal alone. As Bsal continues to invade naïve habitats where Bd is enzootic, coinfection will be increasingly common. If other Bd-susceptible species in the region have similar responses, interactions between the two pathogens could cause severe population and community-level declines.
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Affiliation(s)
- Cait A McDonald
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA
| | - Ana V Longo
- Department of Biology, University of Maryland, College Park, MD, USA
| | - Karen R Lips
- Department of Biology, University of Maryland, College Park, MD, USA
| | - Kelly R Zamudio
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA
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Del Valle JM, Eisthen HL. Treatment of Chytridiomycosis in Laboratory Axolotls ( Ambystoma mexicanum) and Rough-skinned Newts ( Taricha granulosa). Comp Med 2019; 69:204-211. [PMID: 31142399 DOI: 10.30802/aalas-cm-18-000090] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Chytridiomycosis is an infectious disease of amphibians caused by the fungal species Batrachochytrium dendrobatidis and B. salamandrivorans and has been implicated in the population decline of amphibian species worldwide. This case report describes a successful treatment protocol for chytridiomycosis in laboratory-maintained colonies of axolotls (Ambystoma mexicanum) and rough-skinned newts (Taricha granulosa). Over 12 mo, axolotls (n = 12) in a laboratory-reared colony developed multifocal erythematous dermatitis, mainly on the distal limbs and tails. Wild-caught newts handled by the same lab personnel were housed in an adjacent room and occasionally presented with abdominal distension and lethargy. Differentials included poor water quality, pathogen infection, parasitic infestation, and trauma. Antibiotic treatment of animals according to results of bacterial culture and sensitivity, combined with bleach disinfection of aquaria, did not resolve clinical signs. Skin swabs from clinically affected axolotls submitted for a newly available commercial screen were positive for B. dendrobatidis. Additional PCR and sequencing analysis revealed chytrid-positive animals among group-housed newts in 2 clinically unaffected aquaria and suspected PCR-positives for 2 affected newt aquaria and an additional axolotl. Axolotls with skin lesions (n = 2) and newts with abdominal distension and lethargy (n = 2) underwent experimental treatment with itraconazole submersion (0.002% to 0.0025%; 5 min daily for 10 d). This pilot treatment was well tolerated and led to clinical resolution. Subsequent itraconazole treatment of the entire colony led to regrowth of extremities and restoration of normal coloration among axolotls. During treatment, the facility was decontaminated, and additional biosecurity measures were developed. PCR results after the pilot treatment and subsequent full-colony treatments (at 1 wk, 1 mo, and 6 mo after treatment) were negative for the presence of B. dendrobatidis. Because chytridiomycosis is a reportable animal disease in our state, colonies officially remained quarantined until negative PCR results were obtained at least 6 mo after treatment.
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Affiliation(s)
| | - Heather L Eisthen
- Department of Integrative Biology, Michigan State University, East Lansing, Michigan,
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Longo AV, Fleischer RC, Lips KR. Double trouble: co-infections of chytrid fungi will severely impact widely distributed newts. Biol Invasions 2019. [DOI: 10.1007/s10530-019-01973-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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