Koch’s postulates: Confirming Nannizziopsis guarroi as the cause of yellow fungal disease in Pogona vitticeps

ABSTRACT

Nannizziopsis guarroi is an ascomycete fungus associated with a necrotizing dermatitis in captive green iguanas (Iguana iguana) and bearded dragons (Pogona vitticeps) across both Europe and North America. Clinical signs of the disease include swelling and lesion formation. Lesions develop from white raised bumps on the skin and progress into crusty, yellow, discolored scales, eventually becoming necrotic. The clinical signs are the basis of a colloquial name yellow fungal disease (YFD). However, until now, N. guarroi has not been confirmed as the primary agent of the disease in bearded dragons. In this experiment, we fulfill Koch’s postulates criteria of disease, demonstrating N. guarroi as the primary agent of YFD in bearded dragons.

KEYWORDS:

• Ascomycota
• Chrysosporium anamoroph of Nannizziopsis vriesii
• emerging infectious diseases
• pet trade
• wildlife

ACKNOWLEDGMENTS

We are exceedingly grateful to everyone at the Charmany Instructional Facility for their critical logistical support in caring for the animals. We thank the Pringle laboratory for their help in making this experiment possible. We also thank the Research Animal Resources Center staff for facilitating and providing the equipment necessary for humane euthanasia of the animals.

Additional information

Funding

We thank Mary Herman Rubinstein and the University of Wisconsin–Madison for financial support of the Pringle laboratory. S. Gentry was supported by a University of Wisconsin–Madison Advanced Opportunity Fellowship and Davis Research Award from the University of Wisconsin–Madison Department of Botany. The use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.