Pan-European distribution of white-nose syndrome fungus (Geomyces destructans) not associated with mass mortality

Abstract

Background: The dramatic mass mortalities amongst hibernating bats in Northeastern America caused by "white nose-syndrome" (WNS) continue to threaten populations of different bat species. The cold-loving fungus, Geomyces destructans, is the most likely causative agent leading to extensive destruction of the skin, particularly the wing membranes. Recent investigations in Europe confirmed the presence of the fungus G. destructans without associated mass mortality in hibernating bats in six countries but its distribution remains poorly known.

Methodology/principal findings: We collected data on the presence of bats with white fungal growth in 12 countries in Europe between 2003 and 2010 and conducted morphological and genetic analysis to confirm the identity of the fungus as Geomyces destructans. Our results demonstrate the presence of the fungus in eight countries spanning over 2000 km from West to East and provide compelling photographic evidence for its presence in another four countries including Romania, and Turkey. Furthermore, matching prevalence data of a hibernaculum monitored over two consecutive years with data from across Europe show that the temporal occurrence of the fungus, which first becomes visible around February, peaks in March but can still be seen in some torpid bats in May or June, is strikingly similar throughout Europe. Finally, we isolated and cultured G. destructans from a cave wall adjacent to a bat with fungal growth.

Conclusions/significance: G. destructans is widely found over large areas of the European continent without associated mass mortalities in bats, suggesting that the fungus is native to Europe. The characterisation of the temporal variation in G. destructans growth on bats provides reference data for studying the spatio-temporal dynamic of the fungus. Finally, the presence of G. destructans spores on cave walls suggests that hibernacula could act as passive vectors and/or reservoirs for G. destructans and therefore, might play an important role in the transmission process.

Figure 1. Distribution of confirmed and suspected records of G. destructans on hibernating bats in Europe.

Data are presented for genetically confirmed records of G. destructans in red (circles, this study; triangles, published records), photographic evidence in yellow, visual reports in green. Dead bats from Northern France which culture and genetic analysis did not reveal the presence of G. destructans are depicted as black dots. Countries abbreviated names are as follows: AUT: Austria, BEL: Belgium, CHE: Switzerland, CZE: Czech Republic, DEU: Germany, DNK: Denmark, EST: Estonia, FRA: France, HUN: Hungary, NLD: Netherlands, POL: Poland, ROM: Romania, SVK: Slovakia, TUR: Turkey, UKR: Ukraine.

Figure 2. Photographic evidence showing bats with confirmed or suspected growth of G. destructans.

Photographs of cases confirmed by genetic analysis, from (A) Estonia (M. brandtii, May 23^rd 2010, © L. Lutsar), (B) Poland (M. myotis, March 7^th 2010, © A. Wojtaszewski), (C) Germany (M. myotis, March 10^th 2010, © C. Jungmann), (D) France (M. myotis, March 4^th 2010, © Y. Le Bris), (E) Netherlands (M. daubentonii, March 9^th 2010, © T. Bosch), (F) Germany (M. myotis, March 23^rd 2010, © K. Passior) (G) Belgium (M. mystacinus, March 18^th 2010, © B. Mulkens), (H) Germany (M. mystacinus, March 23^rd 2010, © K. Passior) or bats with white-fungal growth suspected as G. destructans from (I) Denmark (M. dasycneme, March 14^th 2010, © B. Ohlendorf), (J) Austria (M. myotis, February 2^nd 2007, © O. Gebhardt), (K) Hungary (M. myotis, February 19^th 2010, © T. Görföl), (L) Belgium (M. myotis, March 7^th 2010, © F. Forget), (M) France (M. myotis, February 13^th 2010, © J. Vittier), (N) Ukraine (M. myotis, February 13^th 2010, © A.-T. Bashta), (O) France (M. escalerai/sp. A, June 25^th 2010, © F. Blanc), (P) Turkey (M. myotis/blythii, March 22^nd 2009, © M. Doker), and (Q) Romania (M. blythii, March 29^th 2008, © B. Szilárd).

Figure 3. Seasonal changes of the number of live bats reported with white fungal growth in Europe.

The number of bats with visible white fungal growth at an hibernaculum in Germany was monitored during the winter 2006/2007 (blue line) and the winter 2007/2008 (green line). The vertical red lines represent the number of Gd-suspect bats (or confirmed) observed across twelve European countries (n = 127) from 2003 until 2010. In the X-axis, the thick marks represent the start of each month.

Figure 4. Indirect evidence of bats grooming off G. destructans during hibernation.

Photographic evidence showing three different M. dasycneme individuals (A–B, C–D and E–F) observed at two different dates, first with visible fungal growth (A, C, E) and later without visible fungal growth (B, D, F). The bat in A–B changed its position within the hibernaculum whereas the other two (C–D and E–F) were captured when leaving the hibernaculum (© V. Korn).