Fungal diseases are an emerging threat to wildlife, agriculture, and human health. In particular, the fungal disease chytridiomycosis, caused by the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), has had devastating effects on amphibian populations worldwide, resulting in drastic population declines and extinctions of numerous amphibian species. The recent emergence of a new pathogenic chytrid fungus, Batrachochytrium salamandrivorans (Bsal), has made the need for effective mitigation strategies against this class of diseases even more urgent.
A great deal of effort is currently being devoted to the development of strategies to protect amphibian populations threatened by chytridiomycosis. In this talk, we will summarize these efforts to date, and present the results of our modeling efforts aimed at evaluating which of the possible conservation methods have the greatest potential to prevent disease induced extinction of amphibian populations. The models include both deterministic and discrete stochastic formulations, and variants with differing assumptions about the within-host dynamics of the disease.
Results/Conclusions
A number of conservation methods have been developed, including various antifungal treatments, augmentation of the frogs’ own innate or adaptive defenses, and/or reduction of the zoospore density in the environment. Many of these strategies are expensive and labor intensive, and although they are effective for treating individuals in laboratory or captive rearing facilities, they can be difficult to implement in the field, and to date they have had only limited success at protecting amphibian populations from disease-induced extinction under field conditions.
The results of our models suggest that many of the proposed strategies are likely to be unsuccessful during the initial outbreak of chytridiomycosis in a population, and that an antifungal cleaning intervention has the greatest potential for an overall beneficial impact. The model also suggests that strategies aimed at permanently reducing the susceptibility of the amphibian host (such as application of probiotic bacteria) are more likely to be effective than strategies that reduce the survival of Bd zoospores in the environment. We found that stochastic dynamics play an important role in the population-level outcome of the amphibian/Bd interaction.