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

Treatment

Prevention

Outcomes