The introduction of novel pathogens to naïve host populations can cause catastrophic impacts and species extinctions. However, the mechanisms allowing hosts to persist with these same pathogens in disease-endemic regions are poorly known. We examined the global dynamics of white-nose syndrome (WNS) on bats and in the environment to determine how species and populations in endemic regions persist with this disease. WNS, a devastating disease of North American hibernating bats, was recently introduced to North America from Eurasia, where it has been present for millennia.
Results/Conclusions
In Eurasia, we found that infection dynamics during winter in species with the highest prevalences were similar to the first year of pathogen invasion in sites in North America (when bat mortality is low), with prevalence increasing from near zero to high levels (50-100%). These dynamics differed substantially from infection patterns during the decline-phase of WNS in North America, when most North American bats have sustained high infection prevalence (100%) over winter. Although P. destructans has been present in hibernacula in Europe and Asia for thousands of years, we found that P. destructans in the environment, which is the source for bat reinfection each winter, started at low levels at the beginning of winter, and decreased over the summer. In contrast, in North America, P. destructans increased in the environment with each year of WNS detection, reaching much higher levels than endemic regions with no decline between winters. The reduction in P. destructans each summer in endemic regions could explain the limited mortality in bat populations across Eurasia.