Our results suggest that subclinical costs of Bd infection can exert significant costs on an apparently resistant host amphibian, with potential threatening consequences on long term population viability.
Additionally, in Europe many species of potential paratenic hosts (fish, amphibians, and invertebrates) have been found to harbour infective larvae of the parasite [ 18, 19].
Ripple watched in amazement as the wolf's return to Yellowstone — an ecosystem where elk had had the browse of the place for 75 years — gave willow and other trees the chance to take hold along stream banks, cooling water temperatures for trout and encouraging the return of beaver, whose ponds host long-absent amphibians and songbirds.
This organism spends part of its life cycle as a motile zoospore, enabling it to propel itself through water and enter its amphibian host.
Batrachochytrium dendrobatidis (Bd) [11], [12] is a globally distributed fungal pathogen that infects a broad diversity of amphibian host species worldwide (lists of host species available at http://www.spatialepidemiology.net/bd/).net/bd/
Though Bd has often been considered a relatively superficial and non-lethal infection for larvae of most amphibian host species (but see [45]), it is clear that sub-lethal infection is sufficient to alter even basic behaviors such as schooling, thermoregulation [22], and foraging efficiency [20] in multiple species.
This finding emphasizes the importance of treatments that completely eliminate the fungus from the amphibian host.
Amphibian host mechanisms of disease resistance include a variety of behavioral, innate, and adaptive immune responses [ 12].
However, the ability of this fungus to survive in the environment in the absence of an amphibian host is unknown.
Their results, coupled with our findings, indicate there may be important coevolutionary dynamics between Bd cytotoxicity and amphibian host chitinase activity that warrant further investigation.
