Cutaneous chytridiomycosis in poison dart frogs (Dendrobates spp.) and White's tree frogs (Litoria caerulea).
Between September 1996 and October 1997, the sporadic deaths of 24 juvenile blue poison dart frogs (Dendrobates azureus), 4 juvenile green-and-black poison dart frogs (D. auratus) and 3 aged adult White's tree frogs (Litoria caerulea) at the National Zoological Park in Washington, DC, USA, were associated with cutaneous chytrid infections. Histological lesions in the skin were similar in all frogs and were most prominent in the ventral abdomen, pelvis and legs. There was mild to moderate epidermal hyperplasia with moderate to marked orthokeratotic hyperkeratosis. Large numbers of eukaryotic organisms were observed within the thickened stratum corneum of affected frogs. The morphology of living zoospores and several ultrastructural features placed the observed organism in the fungal phylum Chytridiomycota.