{{Short description|Species of fungus}} {{Use dmy dates|date=June 2024}} {{Speciesbox | image = Ophidiomyces ophiodiicola.jpg | image_caption = Hyphae | genus = Ophidiomyces | parent_authority = Sigler, Hambl. & Paré (2013) | species = ophidiicola | authority = (Guarro, Sutton, Wickes & Rajeev) Sigler, Hambleton & Paré (2013) | synonyms = ''Chrysosporium ophiodiicola'' <small>Guarro, Sutton, Wickes & Rajeev (2009)</small> }}
'''''Ophidiomyces ophidiicola''''' (formerly ''Ophidiomyces ophiodiicola'') is the cause of '''ophidiomycosis''' also known as '''snake fungal disease''' or '''SFD''' in some species of snakes.<ref name="Lorch et al., 2015" /> It is a keratinophilic fungus from the family Onygenaceae of the order Onygenales. ''O. ophidiicola'' is an emerging pathogen of captive and wild snakes in North America and Europe.<ref name="Rajeev et al., 2008" /> Clinical signs include skin swelling, crusts, and nodules of the skin. The mode of transmission is unknown, but is speculated to occur with direct contact between snakes or with the contaminated environment. Currently no treatment for ''O. ophidiicola'' is available. ''O. ophidiicola'' was identified by Sigler, Hambleton & Paré in 2013. ''O. ophidiicola'' is the only species in the genus '''''Ophidiomyces'''''. It was previously known as ''Chrysosporium ophiodiicola'' and is closely related to ''Chrysosporium'' anamorph ''Nannizziopsis vriesii'' (CANV).<ref name="Rajeev et al., 2008" />
==Taxonomy and naming== ''Ophidiomyces ophidiicola'' was first described as ''Chrysosporium ophiodiicola'' by Josef Guarro and colleagues in 2009 from infected snakes. Morphologically, the fungus resembled members of the genus ''Chrysosporium'', and was thought to be closely related to the reptile pathogen that had been referred to as the ''Chrysosporium'' anamorph ''Nannizziopsis vriesii'' (CANV). The genus ''Ophidiomyces'' was erected to accommodate this fungus in 2013 when DNA sequencing confirmed it to be a member of the family Onygenaceae but genetically distinct from members of the genus ''Chrysosporium''.<ref name="Rajeev et al., 2008" />
==Culture characteristics== [[File:O. ophiodiicola colony.jpg|thumb|Isolates from ''Nerodia clarkii'']]
Cultures of ''O. ophidiicola'' are powdery with whitish mycelium that becomes light yellowish with age. The cultures emit a pungent, skunk like odour. Optimal growth for ''O. ophidiicola'' occurs at a temperature of {{convert|25|C}}. Most isolates fail to grow at {{convert|35|C}}. ''O. ophidiicola'' is able to grow over pH range of 5–11 with optimal growth observed at pH of 9. ''O. ophidiicola'' is able tolerate matric induced water stress below −5 MPa. The fungus exhibits strong urease activity and produces robust growth on ammonium sulfate, sulfite and thiosulfate.<ref name="Allender et al., 2015" />
==Morphology== No sexual state has been identified in the fungus ''O. ophidiicola''. Vegetative hyphae of ''O. ophidiicola'' are narrow, branched and septate. Occasional racquet mycelia are observed. ''O. ophidiicola'' reproduces asexually by the production of conidia. The conidia are produces at the end of short stalks ranging from 2.5 to 7.5 μm in length and 1.5 to 2.5 μm in width. The conidia range from 3 to 12.5 μm long and 1.3 to 3.5 μm wide.<ref name="Sigler et al., 2013" /> and are released by rhexolytic dehiscence in which the walls of cell compartments adjacent to conidia erode, freeing the conidia from attached hyphae.<ref name="Sigler et al., 2013" /> The conidia are colourless to pale yellow and smooth-walled.<ref name="Allender et al., 2015" />
==Ecology== Ecology of ''O. ophidiicola'' is not well known but it is believed that ''O. ophidiicola'' persists as an environmental saprobe in soil as well as in living hosts. ''O. ophidiicola'' is able to utilize multiple carbon and nitrogen sources, and tolerates a range of pH, naturally occurring sulfur compounds and low matric potential. These are mostly characteristics required to live in soil. Good growth on dead fish, insect, mushroom tissue and demineralized shrimp exoskeleton is observed. ''O. ophidiicola'' physiological characteristics indicate that it is capable of growing in numerous ecosystems. <ref name="Allender et al., 2015" />
==Clinical symptoms== The mode of transmission is unknown, but is speculated to occur with direct contact between individuals or with the contaminated environment. Different symptoms can be seen in different species of snakes. In pit viper species facial swelling, cloudy eyes, improperly shed skin, roughened scales, dermal or subcutaneous granuloma and destruction of venom glands can be seen.<ref name="Bunick et al., 2015" /> In massasaugas ''O. ophidiicola'' infection infect deep muscle tissue and bone. Also lesions can be observed on the skin of the entire body.<ref name="Allender et al., 2015" /> In colubrid species of snake fungal disease is reported to appear as pneumonia, ocular infection and subcutaneous nodules.<ref name="Allender et al., 2015" /> In garter snakes skin lesions are observed. The infection is reported to be systemic where it affects the lungs, liver and eyes.<ref name="Allender et al., 2015" />
==Pathogenicity in snakes== [[File:Lesions on Hoplocephalus bungaroides.jpg|thumb|Lesions on ''Hoplocephalus bungaroides'']] Infection begins in the outermost layer of the skin, the ''stratum corneum'', and progresses into the epidermis. Once the infection reaches epidermis, the snake's immune response becomes activated and immune cells are recruited at the site of infection, causing the epidermis to become necrotic and thickened after a few days.<ref name="Lorch et al., 2016" />
Lesions begin at the edge of individual scales and progress to adjacent scales. As lesions progress scales became rough and hyperpigmented. Lesions progressively become larger and more severe until the snake sheds its skin. Fluid-filled vesicles form between the new and old skin resulting in improper shedding of the skin: fragments of the old skin remain on the snake. Histological studies show skin lesions with areas of necrosis and granulocytic inflammation in the superficial to midepidermis. Mild chronic lymphoplasmacytic to lymphohistiocytic inflammation in the liver, lungs, heart, stomach and colon can be observed as well.<ref name="Lorch et al., 2015" />
The emergence of ophidiomycosis due to ''O. ophidiicola'' has caused great concern for the conservation of snake populations in the Eastern United States. Confirmed cases of ophidiomycosis have been reported in 23 states in USA though the disease is believed to be more widespread than has been documented.<ref name="Thompson et al., 2018" /> Multiple species of snakes that are affected including the northern water snake (''Nerodia sipedon''), eastern racer ''(Coluber constrictor''), rat snake (''Pantherophis obsoletus'' species complex), timber rattlesnake (''Crotalus horridus''), massasauga (''Sistrurus catenatus''), pygmy rattlesnake (''Sistrurus miliarius''), and milk snake (''Lampropeltis triangulum'').<ref name="USGS" /> It is reported that population of rattlesnake in New Hampshire reduced to 19 from 40 due to ophidiomycosis caused by ''O. ophidiicola''.<ref name="Allender et al., 2015" />
''Ophidiomyces ophidiicola'' has been successfully treated in captive settings using the antifungal drug terbinafine, which has shown to be effective via both nebulization or subcutaneous implant.<ref>Kane LP, Allender MC, Archer G, Leister K, Rzadkowska M, Boers K, Souza M, Cox S. Pharmacokinetics of nebulized and subcutaneously implanted terbinafine in cottonmouths (Agkistrodon piscivorus). J Vet Pharmacol Ther. 2017 Oct;40(5):575–579. doi: 10.1111/jvp.12406. Epub 2017 Apr 6. PMID 28382637.
</ref> Such a strategy is impractical for many snake populations because it can be difficult to locate the majority of individuals within the population, is resource intensive, and fails to prevent reinfection.<ref name="Lorch et al., 2016" /> The National Wildlife Health Center along with other organizations and researchers are working together to develop management strategies to mitigate disease impact.<ref name="USGS" />
==References== {{Reflist|30em|refs=
<ref name="Allender et al., 2015">{{cite journal|last1=Allender|first1=Matthew C.|last2=Raudabaugh|first2=Daniel B.|last3=Gleason|first3=Frank H.|last4=Miller|first4=Andrew N.|title=The natural history, ecology, and epidemiology of ''Ophidiomyces ophiodiicola'' and its potential impact on free-ranging snake populations|journal=Fungal Ecology|date=October 2015|volume=17|pages=187–196|doi=10.1016/j.funeco.2015.05.003|bibcode=2015FunE...17..187A }}</ref>
<ref name="Bunick et al., 2015">{{cite journal|last1=Allender|first1=M. C.|last2=Bunick|first2=D.|last3=Dzhaman|first3=E.|last4=Burrus|first4=L.|last5=Maddox|first5=C.|title=Development and use of a real-time polymerase chain reaction assay for the detection of ''Ophidiomyces ophiodiicola'' in snakes|journal=Journal of Veterinary Diagnostic Investigation|date=16 March 2015|volume=27|issue=2|pages=217–220|doi=10.1177/1040638715573983|doi-access=free|pmid=25776546 }}</ref>
<ref name="Lorch et al., 2015"> : {{ Cite journal | issue = 9 | year = 2021 | last1 = Lopes | first1 = Patricia C. | last2 = French | first2 = Susannah S. | last3 = Woodhams | first3 = Douglas C. | last4 = Binning | first4 = Sandra A. | publisher = The Company of Biologists | journal = Journal of Experimental Biology | issn = 0022-0949 | volume = 224 | s2cid = 233719623 | doi = 10.1242/jeb.225847 | title = Sickness behaviors across vertebrate taxa: proximate and ultimate mechanisms | doi-access = free | pmid = 33942101 | bibcode = 2021JExpB.224B5847L }} : : This review is cited by Di Nicola ''et al.'', 2022, Aguilar ''et al.'', 2023 and others — {{ Cite journal | year = 2021 | volume = 8 | publisher = Frontiers Media SA | last1 = Davy | first1 = Christina M. | last2 = Shirose | first2 = Leonard | last3 = Campbell | first3 = Doug | last4 = Dillon | first4 = Rachel | last5 = McKenzie | first5 = Christina | last6 = Nemeth | first6 = Nicole | last7 = Braithwaite | first7 = Tony | last8 = Cai | first8 = Hugh | last9 = Degazio | first9 = Tarra | last10 = Dobbie | first10 = Tammy | last11 = Egan | first11 = Sean | last12 = Fotherby | first12 = Heather | last13 = Litzgus | first13 = Jacqueline D. | last14 = Manorome | first14 = Pilar | last15 = Marks | first15 = Steve | last16 = Paterson | first16 = James E. | last17 = Sigler | first17 = Lynne | last18 = Slavic | first18 = Durda | last19 = Slavik | first19 = Emily | last20 = Urquhart | first20 = John | last21 = Jardine | first21 = Claire | journal = Frontiers in Veterinary Science | issn = 2297-1769 | s2cid = 235249427 | pmc = 8200636 | pmid = 34136555 | doi = 10.3389/fvets.2021.665805 | title = Revisiting Ophidiomycosis (Snake Fungal Disease) After a Decade of Targeted Research | doi-access = free }} : : These reviews cite this research. : : {{ Cite journal | volume = 6 | issue = 6 | year = 2015 | publisher = American Society for Microbiology (ASM) | journal = mBio | issn = 2161-2129 | last1 = Lorch | first1 = Jeffrey M. | last2 = Lankton | first2 = Julia | last3 = Werner | first3 = Katrien | last4 = Falendysz | first4 = Elizabeth A. | last5 = McCurley | first5 = Kevin | last6 = Blehert | first6 = David S. | s2cid = 11404838 | doi = 10.1128/mbio.01534-15 | title = Experimental Infection of Snakes with ''Ophidiomyces ophiodiicola'' Causes Pathological Changes That Typify Snake Fungal Disease | pages = e01534-15 | doi-access = free | pmid = 26578676 | pmc = 4659463 }} </ref>
<ref name="Lorch et al., 2016">{{cite journal|last1=Lorch|first1=Jeffrey M.|last2=Knowles|first2=Susan|last3=Lankton|first3=Julia S.|last4=Michell|first4=Kathy|last5=Edwards|first5=Jaime L.|last6=Kapfer|first6=Joshua M.|last7=Staffen|first7=Richard A.|last8=Wild|first8=Erik R.|last9=Schmidt|first9=Katie Z.|last10=Ballmann|first10=Anne E.|last11=Blodgett|first11=Doug|last12=Farrell|first12=Terence M.|last13=Glorioso|first13=Brad M.|last14=Last|first14=Lisa A.|last15=Price|first15=Steven J.|last16=Schuler|first16=Krysten L.|last17=Smith|first17=Christopher E.|last18=Wellehan|first18=James F. X.|last19=Blehert|first19=David S.|title=Snake fungal disease: an emerging threat to wild snakes|journal=Philosophical Transactions of the Royal Society B: Biological Sciences|date=24 October 2016|volume=371|issue=1709|article-number=20150457|doi=10.1098/rstb.2015.0457|pmc=5095536|pmid=28080983}}</ref>
<ref name="Rajeev et al., 2008">{{cite journal|last1=Rajeev|first1=S.|last2=Sutton|first2=D. A.|last3=Wickes|first3=B. L.|last4=Miller|first4=D. L.|last5=Giri|first5=D.|last6=Van Meter|first6=M.|last7=Thompson|first7=E. H.|last8=Rinaldi|first8=M. G.|last9=Romanelli|first9=A. M.|last10=Cano|first10=J. F.|last11=Guarro|first11=J.|title=Isolation and Characterization of a New Fungal Species, ''Chrysosporium ophiodiicola'', from a Mycotic Granuloma of a Black Rat Snake (''Elaphe obsoleta obsoleta'')|journal=Journal of Clinical Microbiology|date=24 December 2008|volume=47|issue=4|pages=1264–1268|doi=10.1128/JCM.01751-08|pmc=2668353|pmid=19109465}}</ref>
<ref name="Sigler et al., 2013">{{cite journal|last1=Sigler|first1=L.|last2=Hambleton|first2=S.|last3=Pare|first3=J. A.|title=Molecular Characterization of Reptile Pathogens Currently Known as Members of the ''Chrysosporium'' Anamorph of ''Nannizziopsis vriesii'' Complex and Relationship with Some Human-Associated Isolates|journal=Journal of Clinical Microbiology|date=7 August 2013|volume=51|issue=10|pages=3338–3357|doi=10.1128/JCM.01465-13|pmc=3811641|pmid=23926168}}</ref>
<ref name="Thompson et al., 2018">{{cite web |last1=Thompson |first1=Noelle E. |last2=Lankau |first2=Emily W. |last3=Rogall |first3=Gail Moede |title=Snake Fungal Disease in North America: U.S. Geological Survey Updates |url=https://pubs.usgs.gov/fs/2017/3064/fs20173064.pdf |year=2018|website=USGS Publications |publisher=U.S. Department of the Interior & U.S. Geological Survey |access-date=23 April 2020}}</ref>
<ref name="USGS">{{cite web|title=Snake Fungal Disease|url=https://www.nwhc.usgs.gov/disease_information/other_diseases/snake_fungal_disease.jsp|website=National Wildlife Health Center|publisher=U.S. Geological Survey|archive-url=https://web.archive.org/web/20171224210626/https://www.nwhc.usgs.gov/disease_information/other_diseases/snake_fungal_disease.jsp|archive-date=24 December 2017|date=19 May 2016}}</ref>
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{{Taxonbar|from1=Q61928467|from2=Q28405719}}
Category:Onygenales Category:Eurotiomycetes genera