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Estimating disease-associated mortality and transmission processes is difficult in free-ranging wildlife but important for understanding disease impacts and dynamics and for informing management decisions. In a capture–mark–recapture study, we used a PCR-based diagnostic test in combination with multistate models to provide the first estimates of disease-associated mortality and detection, infection, and recovery rates for frogs endemically infected with the chytrid fungus Batrachochytrium dendrobatidis (Bd), which causes the pandemic amphibian disease chytridiomycosis. We found that endemic chytridiomycosis was associated with a substantial reduction (approximately 38%) in apparent monthly survival of the threat- ened rainforest treefrog Litoria pearsoniana despite a long period of coexistence (approximately 30 years); detection rate was not influenced by disease status; improved recovery and reduced infection rates corre- lated with decreased prevalence, which occurred when temperatures increased; and incorporating changes in individuals’ infection status through time with multistate models increased effect size and support (98.6% vs. 71% of total support) for the presence of disease-associated mortality when compared with a Cormack– Jolly–Seber model in which infection status was restricted to the time of first capture. Our results indicate that amphibian populations can face significant ongoing pressure from chytridiomycosis long after epidemics associated with initial Bd invasions subside, an important consideration for the long-term conservation of many amphibian species worldwide. Our findings also improve confidence in estimates of disease prevalence in wild amphibians and provide a general framework for estimating parameters in epidemiological models for chytridiomycosis, an important step toward better understanding and management of this disease.

Item Type:	Refereed Article
Keywords:	amphibian declines, Batrachochytrium dendrobatidis, chytridiomycosis, endemic, epidemiology, mark–recapture, survival, transmission
Research Division:	Biological Sciences
Research Group:	Evolutionary Biology
Research Field:	Animal Systematics and Taxonomy
Objective Division:	Environment
Objective Group:	Control of Pests, Diseases and Exotic Species
Objective Field:	Control of Pests, Diseases and Exotic Species in Fresh, Ground and Surface Water Environments
Author:	McCallum, HI (Professor Hamish McCallum)
ID Code:	59902
Year Published:	2009
Web of Science® Times Cited:	97
Deposited By:	Zoology
Deposited On:	2009-12-21
Last Modified:	2010-04-27
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