Yellow Fungus Disease in Bearded Dragons

Reptiles are increasingly common pets. Many of their diseases are related to housing and husbandry, but there is increasing recognition of a superficial fungal disease that can act as a primary pathogen. A 1.5-year-old bearded dragon was presented for focal swellings of 3 months’ duration. Skin biopsy specimens were submitted for histologic examination and culture. In addition, scales and squames were submitted for microbial culture. A Chrysosporium species was isolated from tissue, scales, and squames; fungal elements were found on histologic examination. Systemic antifungal therapy with ketoconazole (20 mg/kg) and topical chlorhexidine and terbinafine therapy was initiated. At a 1-month follow-up, lesions were regressing. Further molecular testing found the strain of Chrysosporium to be related to Nannizziopsis species.

COMMENTARY: Nannizziopsis has been found to be a primary pathogen in veiled chameleons. In bearded dragons, it is believed that the Chrysosporium anamorph of Nannizziopsis may be the etiologic agent of an emerging condition called yellow fungus disease. This infection is highly contagious among bearded dragons and can be a major cause of death in captive animals and breeding facilities. Rapid and accurate identification of the infectious agent is important to successful treatment. When specimens are being collected, tissue should be obtained for routine biopsy and tissues submitted for culture. Include scales and squames and be sure to inform the laboratory that this organism is suspect. Identification via in-house fungal cultures is not recommended because it can be difficult. Fungal diseases are probably underdiagnosed in reptiles because they can look so similar to bacterial skin diseases.—Karen A. Moriello, DVM, Diplomate ACVD

Dermatomycosis in a pet inland bearded dragon (Pogona vitticeps) caused by Chrysosporium species related to Nannizziopsis vriesii. Abarca ML, Martorell J, Castella G, et al. VET DERMATOL 20:295-299, 2009.