Reducing environmentally mediated transmission to moderate impacts of an emerging wildlife disease.
Abstract
Emerging infectious diseases have caused population declines and biodiversity loss. The ability of pathogens to survive in the environment, independent of their host, can exacerbate disease impacts and increase the likelihood of species extinction. Control of pathogens with environmental stages remains a significant challenge for conservation and effective management strategies are urgently needed. We examined the effectiveness of managing environmental exposure to reduce the impacts of an emerging infectious disease of bats, white-nose syndrome (WNS). We used a chemical disinfectant, chlorine dioxide (ClO2), to experimentally reduce Pseudogymnoascus destructans, the fungal pathogen causing WNS, in the environment. We combined laboratory experiments with 3 years of field trials at four abandoned mines to determine whether ClO2 could effectively remove P. destructans from the environment, reduce host infection and limit population impacts. ClO2 was effective at killing P. destructans in vitro across multiple concentrations. In field settings, higher concentrations of ClO2 treatment were needed to sufficiently reduce viable P. destructans conidia in the environment. The reduction in the environmental reservoir at treatment sites resulted in lower fungal loads on bats compared to untreated control populations. Survival following treatment was also higher in little brown bats (Myotis lucifugus), and trended higher for tricolored bats (Perimyotis subflavus). Synthesis and applications. Our results highlight that targeted management of sources for environmental transmission can be an effective control strategy for wildlife disease. We found that successfully reducing pathogen in the environment decreased disease severity and increased survival, but required higher treatment exposure than was effective in laboratory experiments, and the effects varied among species. More broadly, our findings have implications for other emerging wildlife diseases with free-living pathogen stages by highlighting how the degree of environmental contamination can have cascading impacts on hosts, presenting an opportunity for intervention.