chytridiomycosis michael mcfadden unit supervisor herpetofauna division taronga zoo, sydney...
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Chytridiomycosis
Michael McFadden
Unit Supervisor
Herpetofauna Division
Taronga Zoo, Sydney
Materials produced by:
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Chytridiomycosis
• Caused by the pathogen Batrachochytrium dendrobatidis
• (Class Chytridiomycetes, Order Chytridiales)
• First report of chytrid in vertebrates
• Abundant and diverse group of fungi.
• Not described until 1998.
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Chytrid as a cause of mass declines and extinctions
• It is suspected that chytrid fungus has been responsible for the extinction of a great number of species in recent decades.
• It has been implicated in the extinction of 8 species in Australia and many, many more throughout Central America.
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How does it kills frogs?
• Interruption of osmoregulation?
• Release of toxins?
• A combination of these factors?
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The Chytrid life cycle
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Clinical Signs•Behavioural Change
•Neurological Signs
•Skin Lesions
•Death
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Infection with Chytrid
• Frogs susceptible to Chytrid fungus often die within 18-48 days after exposure.
• Tadpoles can carry the fungus in their kertanised mouthparts but will not die from it.
• Not all species are affected, some can live with no effects. These can act as reservoir hosts.
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Ideal Chytrid Environment
• Cooler temperatures –grows best between 17-25°C and dies at over 30°C.
• Must remain moist –
it is a waterborne
fungus.
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Diagnosis of Chytrid Fungus
• PCR- real time Taqman
• Enzyme Linked Immunosorbent Assay (ELISA)
• Microscopy – Histology
or examination of skin
scrapings
• Culture
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Treatment for Chytrid
• Many treatments have been tested with limited success.
• Itraconozole baths have had the best success to date.
• Heat treatment can be effective depending on the tolerance of the species.
• An antibiotic, chlorophenicol, is currently showing signs of success treating chytrid fungus and is undergoing further research.