Models of B. dendrobatidis (Bd) infection altered by management. (A) Diagram of the Briggs et al.  model. The model follows the dynamics of the zoospores (Z) in a zoospore pool, and the sporangia (Si) on each frog i. Copied with permission from Proceedings of the National Academy of Sciences. (B) Examples of conservation strategies without an adaptive immune response: (a) frog remains untreated, (b) zoospore pool is eliminated on day 20, (c) constitutive defenses of the frog are increased on day 20, perhaps through the application of probiotic bacteria, and (d) both types of treatments are applied. Model details can be found in the appendix. (C) Examples of a treatment strategy if the frog has an effective adaptive immune response. (D) At the population level, reducing the density of frogs can slow the rate of increase of Bd in the zoospore pool, and give the frogs extra time to mount an effective immune response. In the untreated population of 100 frogs, the frogs' average fungal load (solid red line) increases rapidly to Smax, and the population goes extinct. In the treated population, the frog density is reduced to 10 frogs on day 30. The rates of increase of Bd both in the zoospore pool and on the frogs (dashed blue line = average S per frog) are decreased, and the frogs' immune response (dotted green line = average antibody level per frog) is able to suppress the infection before Smax is reached.
Woodhams et al. Frontiers in Zoology 2011 8:8 doi:10.1186/1742-9994-8-8