Exotis ISSN 2398-2985

Reptiles

Fungal infections overview

Synonym(s): Mycosis, Mycoses, Mycotic infections

Contributor(s): Tariq Abou-Zahr, Bruce Maclean

Introduction

  • Cause: fungal agents (either primary contagious, or opportunistic ubiquitous/commensal organisms).
  • Signs: dermatological lesions, generalized illness, signs of systemic disease.
  • Diagnosis: fungal cultures, histopathology, molecular analysis/PCR.
  • Treatment: antifungals, treatment of secondary bacterial infections, analgesia, supportive care, correction of predisposing factors/husbandry deficiencies.
  • Prognosis: poor to good (depending on agent and stage of progression).

Pathogenesis

Etiology

Primary contagious fungal agents

  • Former CANV complex agents:
    • Nannizziopsis spp.
    • Paranannizziopsis spp.
    • Ophidiomyces spp.
    • Chamaeleomyces spp.

Opportunistic (ubiquitous) fungal agents

  • Aspergillosis spp.
  • Candida spp.
  • Fusarium spp.
  • Geotrichum spp.
  • Penicillium spp.
  • Trichophyton spp.
  • Cryptococcus spp.
  • Purpureocillium lilacinum.
  • Fusarium spp.
  • Beauveria bassiana.
  • Trichoderma spp.
  • Mucor spp.
  • Paecilomyces spp.

Predisposing factors

General

Contagious agents
  • Open collections.
  • Poor biosecurity.
  • Substandard quarantine practices.
Opportunistic agent infections
  • Overwhelming exposure.
  • Immune compromise.
  • Stress.
  • Substandard husbandry/environmental conditions.
  • Open skin lesions.

Specific

  • Skin damage.
  • Necrotic tissues secondary to cardiovascular/circulation issues.

Pathophysiology

  • Primary agents
  • Many of the opportunistic pathogens are commensals or environmental; pathogenicity requires damage to animal defenses (physical wound and/or immune compromise) to invade tissues.

Timecourse

  • Typically slow-developing lesions.

Epidemiology

  • Nannizziopsis guarroi ('yellow fungus disease'):
    • Is an obligate fungal pathogen.
    • It was first recognized in the early 2000’s.
    • It is unclear as to what may have caused recent affinity for reptilian hosts.
    • Climate change has been suggested as a potential contributing factor.
    • Historical infections may have occurred and may have been misidentified.
    • Most infections have been reported in the USA and Spain.
    • It remains unclear which factors lead to susceptibility.
  • Ophidiomyces ophidiicola (snake fungal disease (SFD) syndrome):
    • Has caused widespread morbidity and mortality in wild snakes, reported especially in North America.
    • Was incriminated in 2008 as cause of facial disfigurement in eastern massasaugas in Illinois.
    • Has been observed in timber rattlesnakes in New England and Massachusetts.
    • A wild black rat snake and several copperheads were subsequently confirmed to have O. ophidiicola infection in New Jersey.
    • It has since been identified in Europe and Australia.
    • Samples from wild snakes in the United Kingdom between 2010-2016 confirmed the presence of Ophidiomyces ophidiicola.
    • Much information is still to be learned about this fungus and its impact on free ranging wildlife, the epidemiology of O. ophidiicola in ecosystems remains poorly understood.
    • Free ranging snakes may clear the infection or remain chronically infected with variable clinical signs.
  • Chameleomyces granulomatis:
    • Was first reported more than four decades ago in 4 out of 50 jeweled chameleons imported to France from Madagascar.
    • Was recently identified as the cause of disseminated mycotic infection in veiled chameleons in a Danish zoo.
    • Has caused multiple mortalities in Jackson’s chameleons at a zoological collection in New Zealand.
    • The source of the fungus and its means of dissemination throughout a collection remain unknown.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Lind C M, McCoy C M & Farrell T M (2018) Tracking outcomes of snake fungal disease in free-ranging Pygmy rattlesnakes (Sistrurus miliarius). J Wildl Dis 54 (2), 352–356 PubMed.
  • Paré  JA & Sigler L (2016) An overview of reptile fungal pathogens in the genera Nannizziopsis, Paranannizziopsis and Ophidiomyces. J Herpetol Med Surg 26 (1-2), 46-53 VetMedResource.
  • Schmidt V (2015) Fungal infections in reptiles – an emerging problem. J Exotic Pet Med 24 (3), 267-275 VetMedResource.
  • Mitchell M A (2011) Zoonotic diseases associated with reptiles and amphibians: An update. Vet Clin North Am Exotic Anim Pract 14 (3), 439-456 PubMed.
  • Abarca M L, Castellá G, Martorell J & Cabañes F J (2010) Chrysosporium guarroi sp. nov. a new emerging pathogen of pet green iguanas (Iguana iguana). Med Mycol 48(2), 365-372 PubMed.
  • Van Waeyenberghe L, Baert K, Pasmans F et al (2010) Voriconazole, a safe alternative for treating infections caused by the Chrysosporium anamorph of Nannizziopsis vriesii in bearded dragons (Pogona vitticeps). Med Mycol 48 (6), 880-885 PubMed.

Other sources of information

  • Perry S M, Sander S J & Mitchel M A (2016) Integumentary System. In: Current Therapy in Exotic Pet Practice. Eds: Mitchell M A & Tully T N Jr. Elsevier Saunders, USA. pp 17-76.
  • Paré J A (2014) Update on Fungal Infections in Reptiles. In: Current Therapy in Reptile Medicine and Surgery. Eds: Mader D & Divers S J. Elsevier Saunders, USA. pp 53-56.
  • Pare J A, Sigler L, Rosenthal K L & Mader D R (2006) Microbiology: Fungal and Bacterial Diseases of Reptiles. In: Reptile Medicine and Surgery. Ed: Mader D R. Saunders Elsevier, USA. pp 217-226.

Organisation(s)

  • British Veterinary Zoological Society (BVZS). Website: www.bvzs.org.
  • Association of Reptilian and Amphibian Veterinarians (ARAV). Website: https://arav.org.


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