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Haynes E, Stanford K, Cox S, Vivirito K, Durante K, Wright A, Gramhofer M, Pohly A, Gartlan B, Fredrickson K, Allender MC. CONTROLLED CLINICAL TRIAL USING TERBINAFINE NEBULIZATION TO TREAT WILD LAKE ERIE WATERSNAKES ( NERODIA SIPEDON INSULARUM) WITH OPHIDIOMYCOSIS. J Zoo Wildl Med 2024; 54:746-756. [PMID: 38251998 DOI: 10.1638/2023-0050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2023] [Indexed: 01/23/2024] Open
Abstract
Ophidiomycosis (snake fungal disease) is an important infectious disease caused by the fungus Ophidiomyces ophidiicola. To mitigate the disease's impact on individual snakes, a controlled clinical trial was conducted using terbinafine nebulization to treat snakes with ophidiomycosis. Fifty-three wild-caught Lake Erie watersnakes (Nerodia sipedon insularum) with apparent ophidiomycosis (skin lesions present, qPCR positive for O. ophidiicola) were divided into treatment and control groups: treatment snakes were nebulized with a 2 mg/ml terbinafine solution for 30 min daily for 30 d; control snakes received nebulization with 0.9% saline or no nebulization. Weekly physical exams were conducted to assign disease severity scores based on the number, type, location, and size of lesions, and qPCR was repeated after each 30-d course of treatment. Persistently qPCR-positive snakes received multiple nebulization courses. Terbinafine nebulization showed mixed results as a treatment for ophidiomycosis: 29.2% of animals treated with terbinafine showed molecular resolution of external disease, based on antemortem swabbing, following 3-6 mon of daily nebulization; this was significantly more than with saline nebulization (5%), but molecular resolution also occurred in 11.1% of snakes that received no treatment. Terbinafine nebulization did not significantly decrease clinical disease, as measured by disease severity scores. Evaluating molecular response to treatment using fungal quantities, terbinafine nebulization significantly reduced fungal quantity after three or more courses of treatment. These results indicate that, although terbinafine nebulization is a promising treatment for ophidiomycosis, snakes may require multiple nebulization courses and disease may not always resolve completely, despite treatment. This treatment may be most useful in snakes from managed populations that can be treated for several months, rather than wild snakes who are not releasable after multiple months in captivity.
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Affiliation(s)
- Ellen Haynes
- Wildlife Epidemiology Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61802, USA,
| | - Kristin Stanford
- Franz Theodore Stone Laboratory, The Ohio State University, OH 43456, USA
| | - Sherry Cox
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996, USA
| | - Kathryn Vivirito
- Wildlife Epidemiology Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61802, USA
| | - Kennymac Durante
- Wildlife Epidemiology Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61802, USA
| | - Allison Wright
- Wildlife Epidemiology Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61802, USA
| | - Megan Gramhofer
- Wildlife Epidemiology Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61802, USA
| | - Andrea Pohly
- University of Illinois Veterinary Diagnostic Laboratory, Urbana, IL 61802, USA
| | - Brina Gartlan
- Wildlife Epidemiology Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61802, USA
| | - Kelcie Fredrickson
- Wildlife Epidemiology Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61802, USA
| | - Matthew C Allender
- Wildlife Epidemiology Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61802, USA
- Chicago Zoological Society, Brookfield Zoo, Brookfield, IL 60513, USA
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Haynes E, Lorch J, Allender MC. Development and application of a qPCR-based genotyping assay for Ophidiomyces ophidiicola to investigate the epidemiology of ophidiomycosis. PLoS One 2023; 18:e0289159. [PMID: 37535588 PMCID: PMC10399865 DOI: 10.1371/journal.pone.0289159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 07/12/2023] [Indexed: 08/05/2023] Open
Abstract
Ophidiomycosis (snake fungal disease) is an infectious disease caused by the fungus Ophidiomyces ophidiicola to which all snake species appear to be susceptible. Significant variation has been observed in clinical presentation, progression of disease, and response to treatment, which may be due to genetic variation in the causative agent. Recent phylogenetic analysis based on whole-genome sequencing identified that O. ophidiicola strains from the United States formed a clade distinct from European strains, and that multiple clonal lineages of the clade are present in the United States. The purpose of this study was to design a qPCR-based genotyping assay for O. ophidiicola, then apply that assay to swab-extracted DNA samples to investigate whether the multiple O. ophidiicola clades and clonal lineages in the United States have specific geographic, taxonomic, or temporal predilections. To this end, six full genome sequences of O. ophidiicola representing different clades and clonal lineages were aligned to identify genomic areas shared between subsets of the isolates. Eleven hydrolysis-based Taqman primer-probe sets were designed to amplify selected gene segments and produce unique amplification patterns for each isolate, each with a limit of detection of 10 or fewer copies of the target sequence and an amplification efficiency of 90-110%. The qPCR-based approach was validated using samples from strains known to belong to specific clades and applied to swab-extracted O. ophidiicola DNA samples from multiple snake species, states, and years. When compared to full-genome sequencing, the qPCR-based genotyping assay assigned 75% of samples to the same major clade (Cohen's kappa = 0.360, 95% Confidence Interval = 0.154-0.567) with 67-77% sensitivity and 88-100% specificity, depending on clade/clonal lineage. Swab-extracted O. ophidiicola DNA samples from across the United States were assigned to six different clonal lineages, including four of the six established lineages and two newly defined groups, which likely represent recombinant strains of O. ophidiicola. Using multinomial logistic regression modeling to predict clade based on snake taxonomic group, state of origin, and year of collection, state was the most significant predictor of clonal lineage. Furthermore, clonal lineage was not associated with disease severity in the most intensely sampled species, the Lake Erie watersnake (Nerodia sipedon insularum). Overall, this assay represents a rapid, cost-effective genotyping method for O. ophidiicola that can be used to better understand the epidemiology of ophidiomycosis.
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Affiliation(s)
- Ellen Haynes
- Wildlife Epidemiology Laboratory, Department of Veterinary Clinical Medicine, University of Illinois College of Veterinary Medicine, Urbana, Illinois, United States of America
- Current affiliation: Southeastern Cooperative Wildlife Disease Study, Department of Population Health, University of Georgia College of Veterinary Medicine, Athens, Georgia, United States of America
| | - Jeffrey Lorch
- U.S. Geological Survey, National Wildlife Health Center, Madison, Wisconsin, United States of America
| | - Matthew C Allender
- Wildlife Epidemiology Laboratory, Department of Veterinary Clinical Medicine, University of Illinois College of Veterinary Medicine, Urbana, Illinois, United States of America
- Chicago Zoological Society, Brookfield Zoo, Brookfield, Illinois, United States of America
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Lizarraga AJ, Hart L, Wright RM, Williams LR, Glavy JS. Incidents of snake fungal disease caused by the fungal pathogen Ophidiomyces ophidiicola in Texas. FRONTIERS IN FUNGAL BIOLOGY 2023; 4:1064939. [PMID: 37746129 PMCID: PMC10512329 DOI: 10.3389/ffunb.2023.1064939] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Accepted: 02/08/2023] [Indexed: 09/26/2023]
Abstract
The pathogen Ophidiomyces ophidiicola, widely known as the primary cause of snake fungal disease (SFD) has been detected in Texas's naïve snakes. Our team set out to characterize O. ophidiicola's spread in eastern Texas. From December 2018 until November 2021, we sampled and screened with ultraviolet (UV) light, 176 snakes across eastern Texas and detected 27. O. ophidiicola's positive snakes using qPCR and one snake in which SFD was confirmed via additional histological examination. Upon finding the ribbon snake with clear clinical display, we isolated and cultured what we believe to be the first culture from Texas. This cultured O. ophidiicola TX displays a ring halo formation when grown on a solid medium as well as cellular autofluorescence as expected. Imaging reveals individual cells within the septated hyphae branches contain a distinct nucleus separation from neighboring cells. Overall, we have found over 1/10 snakes that may be infected in East Texas, gives credence to the onset of SFD in Texas. These results add to the progress of the disease across the continental United States.
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Affiliation(s)
- Alan J. Lizarraga
- Biology Department, The University of Texas at Tyler, Tyler, TX, United States
| | - Lezley Hart
- Biology Department, The University of Texas at Tyler, Tyler, TX, United States
| | - R. Michele Wright
- Biology Department, The University of Texas at Tyler, Tyler, TX, United States
- The Department of Pharmaceutical Sciences, Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, TX, United States
| | - Lance R. Williams
- Biology Department, The University of Texas at Tyler, Tyler, TX, United States
| | - Joseph S. Glavy
- Biology Department, The University of Texas at Tyler, Tyler, TX, United States
- The Department of Pharmaceutical Sciences, Fisch College of Pharmacy, The University of Texas at Tyler, Tyler, TX, United States
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Ophidiomyces ophidiicola detection and infection: a global review on a potential threat to the world’s snake populations. EUR J WILDLIFE RES 2022. [DOI: 10.1007/s10344-022-01612-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
AbstractOphidiomyces ophidiicola (Oo) is one of the most relevant fungal pathogens for snakes. It is the etiological agent of ophidiomycosis, an emerging disease causing dysecdysis, skin abnormalities, crusting cutaneous lesions, and ulcerations. Despite this major tegumentary “tropism”, Oo infection can be systemic and it is capable of inducing visceral lesions. Moreover, ophidiomycosis may lead to abnormalities of reproductive physiology, hunting behavior, and thermoregulation, thus increasing the risks of sublethal effects and predation on affected snakes. Oo seems horizontally transmitted and can induce postnatal mortality. This article reviews published data on Oo detection and infection in all snake species in countries around the world and categorizes these data using new classification parameters. The presence of this fungus has been recorded in 11 states (considering the USA as a whole); however, in four states, the mycosis has only been reported in snakes held in captivity. Detection and/or infection of Oo has been ascertained in 62 snake species, divided into nine families. The taxa have been categorized with diagnostic criteria in order to report, for each species, the highest rank of categorization resulting from all cases. Therefore, 20 species have been included within the class “Ophidiomycosis and Oo shedder”, 11 within “Ophidiomycosis”, 16 in “Apparent ophidiomycosis”, and 15 within “Ophidiomyces ophidiicola present”. We also discuss the significance and limits of case classifications and Oo’s impact on wild populations, and we suggest methods for preliminary surveillance. Standardized methods, interdisciplinary studies, and cooperation between various research institutions may facilitate further Oo screening studies, elucidate the unclear aspects of the disease, and protect ophidiofauna from this emerging threat at the global level.
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