Fungal Disease in Snakes - Russell

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Transcript Fungal Disease in Snakes - Russell

Fungal Disease in Snakes
Julia Russell
November 2013
Introduction to Reptile Fungal Diseases
Snake Fungal Disease (SFD)
Fungi that Could Potentially Cause SFD
SFD Infection Symptoms
Effects of the Spread of SFD
Reptile Fungal Disease
• Reported in various kinds of captive reptiles
– Turtles, crocodilians, lizards, and snakes are all
• Mycotic pathogens associated with high humidity,
overcrowding, and debris accumulation
Reptile Fungal Disease
• Some of the more common fungal infections in
Trichosporon beigelii – Banded Rock Rattlesnakes
Geotrichium canidum – Carpet Python
Cladosporium species – Anaconda
Aspergillus species – Puff Adder
Chrysosporium anamorph Nanniziopsis vriesii (CANV) –
Massasauga Rattlesnake
– Ophidiomyces ophiodiicola (formerly Chrysosporium) –
Black Rat Snakes
– Several as of yet unclassified mycoses – Red Milk Snake,
Eastern Indigo Snake, Gopher Snake, Copperhead, as well
as other species
Snake Fungal Disease
• Outbreak of Fatal Mycotic Disease in Snakes in
the Southern United States
• This disease was given the name Snake Fungal
Disease (SFD) by the USGS
• The specific fungus causing this disease has
yet to be identified
– O. ophiodiicola is consistently associated
– CANV may also be associated
Snake Fungal Disease
• SFD noted in species common to the Eastern
United States including:
– Northern Watersnake
– Massasauga Rattlesnake
– Black Rat Snake
– Timber Rattlesnake
– Pygmy Rattlesnake
– Eastern Racer
– Milk Snake
Fungi That Could Potentially Cause SFD
• Chrysosporium anamorph Nanniziopsis vriesii
– Reproduces Sexually and Asexually
– Sexual Stage
• forms fruiting bodies consisting of ascocarps forming
– Does this on nutrient poor media at 30°C
– Asexual Stage
• Considered the typical form of Chrysosporium
• Consists of solitary conidia (aleuroconidia) and arthroconidia
Chrysosporium anamorph Nanniziopsis vriesii
• Arthroconidia
– 3.5-13µm long and 2-3.5µm wide
– Formed in chains by the fragmentation of hyphae
– Occasionally are separated by empty cells
• Known as alternate arthroconidia
• Aleuroconidia
– 4-6µm long and 2-3µm wide
– Produced on the sides of fertile hyphae or at the ends
of short stalks
• Arthroconidia predominated under certain
cultural conditions
Chrysosporium anamorph Nanniziopsis vriesii
All figures from (5)
Fungi That Could Potentially Cause SFD
• Ophidiomyces ophiodiicola (formerly
– Very similar to CANV
– Main Characteristics:
• Presence of numerous narrow to slightly clavate conidia
• Strong pungent odor in colonies
– Differences from CANV:
• Absence of asperulate fertile hyphae
• Globose to pyriform conidia are sometimes grouped in
• Presence of an odor in the colonies
Ophidiomyces ophiodiicola (formerly Chrysosporium)
SFD Infection Symptoms
• CANV and O. ophiodiicola not normally found
on healthy animals
• Fungal diseases in reptiles usually secondary
– Not the case with CANV and O. ophiodiicola
• Potentially caused by disruptions of the
normal defense mechanisms of the skin
– Wetter than usual conditions
– Stressful environment
– Change in pH
SFD Infection Symptoms
• SFD typically limited to head and ventral
• Head Region
– Subcutaneous swelling
– Lesions
– Cutaneous ulcers with granulomas
– Thick adherent crusts
• Contain numerous right angle branching hyphae with
terminal structures consisting of spores
SFD Infection Symptoms
Source (7)
Source (8)
Source (1)
Source (8)
SFD Infection Symptoms
• Ventral Region
– Edema of the ventral scales
– Formation of cutaneous vesicles
• Filled with clear to cloudy serous fluid
– Ruptured vesicles replaced by brown, caseous
– Underlying epidermis is dry and necrotic
– Lesions begin where ventral scales overlap and
continue to spread to over 50% of the snakes
ventral surface
SFD Infection Symptoms
Source (2)
Source (8)
SFD Infection Symptoms
• Fungal hyphae often extend deep into the
epidermis, but usually do not cross into
deeper tissue layers
• Fungal infection is usually not the immediate
cause of death
– Secondary bacterial infection
– Osmotic imbalance
Effects of the Spread of SFD
• High mortality rate of Timber Rattlesnakes in NH
in 2006 due to fungal infections
• Between 2008 and 2010 four Massasauga
Rattlesnakes found in IL with severe facial
swelling and disfiguration
• Other pressures that may be causing decline:
– Habitat fragmentation
– Inbreeding depression
– Climate change
• SFD is an emerging disease in Eastern and
Midwestern U.S.
• Exact fungal origin is uncertain
• Disease may be more prevalent than currently
• Will affect small isolated populations the
• Population impacts difficult to assess due to
the cryptic and solitary nature of snakes
(1) Allender M.C., Dreslik M., Wylie S., Phillips C., Wylie D.B., Maddox C., Delaney M.A., & Kinsel M.J. (2011, December).
Chrysosporium sp. Infection in Eastern Massasauga Rattlesnakes. Emerging Infectious Diseases, 17(12), 2383-2384.
(2) Bertelsen M.F., Crawshaw G.J., Sigler L., & Smith D.A. (2005, March). Fatal Cutaneous Mycosis in Tentacled Snakes
(Erpeton tentaculum) Caused by Chrysosporium Anamoph of Nannizziopsis vriesii. Journal of Zoo and Wildlife
Medicine, 36(1), 82-87.
(3) Clark R.W., Marchand M.N., Clifford B.J., Stechert R., & Stephens S. (2011) Decline of an isolated timber rattlesnake
(Cortalus horridus) population: Interaction between climate change, disease, and loss of genetic diversity.
Biological Conservation, 144(2011), 886-891.
(4) Jacobson E.R., Cheatwood J.L., & Maxwell L.K. (2000, April). Mycotic Diseases of Reptiles. Seminars in Avian and
Exotic Pet Medicine, 9(2), 94-101.
(5) Nichols D.K., Weyant R.S., Lamirande E.W., Sigler L., & Mason R.T. (1999). Fatal Mycotic Dermatitis in Captive Brown
Tree Snakes (Boiga irregularis). Journal of Zoo and Wildlife Medicine, 30(1), 111-118.
(6) Pare J.A., Sigler L., Rypien K.L., Gibas C.C. (2003). Survey for the Chrysosporium Anamorph of Nannizziopsis vriesii on
the Skin of Healthy Captive Squamate Reptiles and Notes on their Cutaneous Fungal Mycobiota. Journal of
Herpetological Medicine and Surgery, 13(4), 10-15.
(7) Rajeev S., Sutton D.A., Wickes B.L., Miller D.L., Giri D., Van Meter M., Thompson E.H., Rinaldi M.G., Romanelli A.M.,
Cano J.F., & Guarro J. (2009, April). Isolation and Cahracterization of a New Fungal Species Chrysosporium
ophiodiicola, from a Mycotic Granuloma of a Black Rat Snake (Elaphe obsoleta obsoleta). Journal of Clinical
Microbiology, 2009, 1264-1268.
(8) Sleeman J. (2013, May 2). Snake Fungal Disease in the United States. USGS National Wildlife Health Bulletin 201302. Retrieved from:
(9) Vissiennon T.H. Schuppel K.F., Ullrich E., & Kuijpers A.F.A. (1999). Case Report. A disseminated infection due to
Chrysosporium queenslandicum in a garter snake (Thamnophis). Mycosis, 42, 107-110.