Fatal mycotic dermatitis in captive brown tree snakes (Boiga irregularis)

Cutaneous fungal infections occurred in four captive brown tree snakes (Boi ga irregularis). The ventral scales were most commonly affected, and lesion s began as areas of erythema and edema with vesicle formation, followed by development of caseous brown plaques. Lesions usually started where Ventral scales overlapped and spread rapidly. All snakes died within 14 days after clinical signs were first noted. The deaths of three of the snakes were di rectly attributable to the cutaneous disease; the other snake died from ren al failure and visceral gout, most likely induced by gentamicin therapy. Hi stologically, lesions consisted of epidermal hyperplasia and hyperkeratosis , with foci of epidermal necrosis, intraepidermal vesicle formation, and su bacute inflammation of the underlying dermis. These lesions were associated with bacteria and numerous septate, branched fungal hyphae within the epid ermis and overlying serocelluar crusts. Hyphae that penetrated through the superficial surface of the epidermis often formed terminal arthroconidia. T he same species of fungus was isolated in pure culture from the skin of thr ee snakes, but fungal cultures were not performed on samples from the fourt h snake. The fungus has been identified as the Chrysosporium anamorph of Na nnizziopsis vriesii based on its formation of solitary dermatophytelike ale urioconidia and alternate and fission arthroconidia. The source of the fung us in this outbreak was not determined; however, the warm, moist conditions under which the snakes were housed likely predisposed them to opportunisti c cutaneous fungal infections.