In - situ itraconazole treatment improves survival rate during an amphibian chytridiomycosis 1 epidemic

52 The emerging infectious disease, amphibian chytridiomycosis caused by the fungus 53 Batrachochytrium dendrobatidis (Bd), threatens hundreds of amphibian species globally. In the 54 absence of field-based mitigation methods, the Amphibian Conservation Action Plan advocates 55 captive assurance programmes to prevent extinction from this infectious disease. Unfortunately, 56 with the cooperation of the entire global zoo community, the International Union for the 57 Conservation of Nature Amphibian Ark estimates only 50 species could be saved. Clearly, if 58 catastrophic losses are to be averted, alternative mitigation techniques need to be developed. There 59 has been an absence of trialling laboratory proven interventions for chytridiomycosis in field 60 settings, which must change in order to allow informed management decisions for highly threatened 61 amphibian populations. We tested the in-situ treatment of individual mountain chicken frogs 62 (Leptodactylus fallax) using the antifungal drug, itraconazole. Multi-state mark recapture analysis 63 showed increased probability of survival and loss of Bd infection for treated frogs compared to 64 untreated animals. There was evidence of a prophylactic effect of treatment as, during the 65 treatment period, infection probability was lower for treated animals than untreated animals. Whilst 66 long term, post-treatment increase in survival was not observed, a deterministic population model 67 estimated antifungal treatment would extend time to extinction of the population from 49 to 124 68 weeks, an approximated 60% increase. In-situ treatment of individuals could, therefore, be a useful 69 short-term measure to augment other conservation actions for amphibian species threatened by 70 chytridiomycosis or to facilitate population survival during periods of high disease risk. 71 72