A simple transmission experiment confirmed this as the etiologic agent. Simultaneously, a group at the National Zoo, Washington identified chytridiomycosis as the cause of death in captive amphibians 3 . The agent was subsequently cultured, described as Batrachochytrium dendrobatidis and Koch's postulates proven 4 . This individual died in a mass mortality event in a captive collection. No obvious gross lesions are visible and the animal showed no signs of emaciation.
Numerous vacuoles are visible within the keratinized cells of the epidermis.
We now know that chytridiomycosis has a wide host range including urodeles, aquatic amphibians such as Xenopus , terrestrial and semi-terrestrial frogs and toads 5,6 . The disease is present in North America, causing mass mortalities and population declines in a range of ranid and bufonid species, notably Rana yavapaiensis , R. chiricahuensis , Bufo boreas and B. canorus . Analysis of museum specimens suggests it was also involved in die-offs of some North American ranids and bufonids in the 1970s and 1980s 5 . Chytridiomycosis has recently been reported in South America, Europe, New Zealand and Western Australia, often associated with marked population declines. In Western Australia, a large retrospective survey suggests introduction of the disease from an eastern focus 6 .