Data from: Skin sloughing rate increases with chytrid fungus infection load in a susceptible amphibian

1. Amphibian chytridiomycosis, caused by the fungal pathogen
Batrachochytrium dendrobatidis (Bd), is responsible for the greatest
disease-driven loss of vertebrate biodiversity in recorded history.
Understanding drivers of host susceptibility to this cutaneous disease is
hindered by gaps in our knowledge of the host–pathogen relationship. One
such overlooked aspect of susceptibility is variation in skin maintenance
processes, particularly skin turnover via routine sloughing. It has been
suggested that sloughing plays a role in immune defence, by removing
skin-associated microbes. Thus, skin sloughing may play an important role
in the pathogenesis of chytridiomycosis. 2. To determine the relationship
between skin sloughing and disease progression, we exposed adult
Australian green tree frogs (Litoria caerulea) to a local Bd strain and
monitored sloughing rates and individual infection loads on a naturalistic
cycling temperature regime (15–23 °C). 3. We determined sloughing rates in
real-time by using an array of infrared video cameras to film frog
behaviour and monitored infection load before and after sloughing by
swabbing and analysis with quantitative PCR. 4. We found that sloughing
rate increased with Bd infection load in infected frogs, but sloughing
itself did not affect Bd load on the ventral skin surface. Furthermore, Bd
infection did not affect the duration of characteristic sloughing
behaviour, and sloughing retained rhythmicity even at high infection
loads. 5. Although an increased sloughing rate might be considered
advantageous for Bd-infected animals, it does not appear to curb the
progression of disease and may actually contribute to the loss of
physiological homoeostasis seen in terminally ill frogs by further
inhibiting water and electrolyte transport across the skin. 6. By
measuring sloughing rates directly for the first time, our results shed
light on how Bd interacts with the physiological processes of the skin and
indicate that variation in skin sloughing frequency may play a role in the
observed inter- and intraspecific variation in susceptibility to disease.