Distribution and environmental persistence of the causative agent of white-nose syndrome, Geomyces destructans, in bat hibernacula of the eastern United States

Abstract

White-nose syndrome (WNS) is an emerging disease of hibernating bats caused by the recently described fungus Geomyces destructans. First isolated in 2008, the origins of this fungus in North America and its ability to persist in the environment remain undefined. To investigate the correlation between manifestation of WNS and distribution of G. destructans in the United States, we analyzed sediment samples collected from 55 bat hibernacula (caves and mines) both within and outside the known range of WNS using a newly developed real-time PCR assay. Geomyces destructans was detected in 17 of 21 sites within the known range of WNS at the time when the samples were collected; the fungus was not found in 28 sites beyond the known range of the disease at the time when environmental samples were collected. These data indicate that the distribution of G. destructans is correlated with disease in hibernating bats and support the hypothesis that the fungus is likely an exotic species in North America. Additionally, we examined whether G. destructans persists in infested bat hibernacula when bats are absent. Sediment samples were collected from 14 WNS-positive hibernacula, and the samples were screened for viable fungus by using a culture technique. Viable G. destructans was cultivated from 7 of the 14 sites sampled during late summer, when bats were no longer in hibernation, suggesting that the fungus can persist in the environment in the absence of bat hosts for long periods of time.

Fig 1

Map of the eastern United States showing the sampling locations described in Table 1. The left halves of the circles depict the disease status of individual bat hibernacula at the time when the samples were collected (red, diseased; blue, buffer; yellow, clean). The right halves of the circles represent the PCR results (red, G. destructans detected; yellow, G. destructans not detected). The solid white line marks the general geographic range of WNS (i.e., WNS zone) at the time of sample collection; the dotted white line marks the general geographic range of WNS during the following winter (i.e., buffer zone) (http://www.whitenosesyndrome.org/resources/map). Geomyces destructans was detected only in bat hibernacula that were situated within the known range of WNS as of the winter of 2008 to 2009. The PCR results for sites 20, 21, 22, and 23 represent only those for samples collected in the winter of 2008 to 2009 and not those collected in the winter of 2010 to 2011.