Treatment of chytridiomycosis with reduced-dose itraconazole

Abstract

Effective treatment methods to eliminate infection with Batrachochytrium dendrobatidis (Bd) are required for development of sustainable captive survival assurance populations of amphibians and to reduce the risk of introducing Bd to new locations as part of amphibian trade or reintroduction programs. Treatment with itraconazole baths at 100 mg l-1 is commonly used in captive amphibians, but side effects are observed in some amphibian species and life stages. Naturally occurring outbreaks of chytridiomycosis in Wyoming toads Anaxyrus baxteri and White's tree frogs Litoria caerulea were treated with lower-dose itraconazole baths (e.g. 50 mg l-1 for White's tree frogs) and followed post-treatment with serial Taqman PCR testing to confirm elimination of Bd infection. Post-treatment PCR tests were consistently negative for the presence of Bd and treatment was deemed successful. Although this was not a controlled clinical trial, results suggest that lower doses of itraconazole may be effective for treatment of chytridiomycosis with resulting cost savings to amphibian conservation programs and a potential for a reduction in dose-related side effects from itraconazole treatment. Prospective clinical trials of alternative itraconazole treatment protocols are encouraged.