Experimental infection of bats with Geomyces destructans causes white-nose syndrome

Bats with a nose for trouble Hibernating wild bat populations in eastern North America have suffered catastrophic decline in recent years as a result of white-nose syndrome (WNS). Colonization of the skin — on the eponymous nose — with the fungus Geomyces destructans has been linked to the disease, but other factors have been suggested as alternative causes. In a controlled experiment, it is now shown that G. destructans does infect bats, that it can be transmitted between animals and that infection causes WNS. This contrasts with recent reports that G. destructans is widespread among bats in Europe, where it seems to have no detrimental effects on carriers. White-nose syndrome (WNS) has caused recent catastrophic declines among multiple species of bats in eastern North America 1 , 2 . The disease’s name derives from a visually apparent white growth of the newly discovered fungus Geomyces destructans on the skin (including the muzzle) of hibernating bats 1 , 3 . Colonization of skin by this fungus is associated with characteristic cutaneous lesions that are the only consistent pathological finding related to WNS 4 . However, the role of G. destructans in WNS remains controversial because evidence to implicate the fungus as the primary cause of this disease is lacking. The debate is fuelled, in part, by the assumption that fungal infections in mammals are most commonly associated with immune system dysfunction 5 , 6 , 7 . Additionally, the recent discovery that G. destructans commonly colonizes the skin of bats of Europe, where no unusual bat mortality events have been reported 8 , 9 , 10 , has generated further speculation that the fungus is an opportunistic pathogen and that other unidentified factors are the primary cause of WNS 11 , 12 . Here we demonstrate that exposure of healthy little brown bats ( Myotis lucifugus ) to pure cultures of G. destructans causes WNS. Live G. destructans was subsequently cultured from diseased bats, successfully fulfilling established criteria for the determination of G. destructans as a primary pathogen 13 . We also confirmed that WNS can be transmitted from infected bats to healthy bats through direct contact. Our results provide the first direct evidence that G. destructans is the causal agent of WNS and that the recent emergence of WNS in North America may represent translocation of the fungus to a region with a naive population of animals 8 . Demonstration of causality is an instrumental step in elucidating the patho