Identity and density of parasite exposures alter the outcome of co-infections: Implications for management

1) Although research has focused on density-dependent responses of hosts to single-parasite infections, hosts are exposed to numerous parasites simultaneously under natural conditions and if these exposures lead to infections, they can threaten host populations and ecosystem stability. Moreover, spatiotemporal variation in abundance of co-occurring parasites might influence host infection intensity. If interactions are consistent between different co-infecting parasites, then these patterns could give managers another tool to control disease spread and even predict problematic disease emergences. 2) We investigated how parasite density and identity alter within-host co-infection dynamics. To test this, we simultaneously exposed Cuban treefrogs (Osteopilus septentrionalis) as a model amphibian species to all pairwise combinations of three problematic parasites that commonly co-infect amphibians: the fungus Batrachochytrium dendrobatidis (Bd), the nematode Aplectana hamatospicula, and Ran...