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Emerging infectious diseases are one of the main suggested reasons for global amphibian decline. Fungal agents play a key role. Since its introduction, the Asian pathogen Batrachochytrium salamandrivorans has driven the European fire salamander, Salamandra salamandra, to the edge of extinction in the Netherlands and caused severe population declines in Belgium and Germany. We screened 1,526 amphibians (1,431 urodelans and 95 anurans) from 50 sites in a 1,500 km² large area in Germany, south of the next known infected populations. Furthermore, we conducted a presence-absence mapping of larval salamanders in 88 randomly selected creeks and creeks where salamanders had been reported in the past using a standardized removal sampling approach. Our results revealed an expanded distribution of the pathogen in Western Germany and we could detect seven infected urodelan populations including the southernmost locality of the fungus in its exotic range. Larval salamanders were found in 54 out of 63 creeks south, but only in seven out of 25 creeks north of a highway that divides the study area. Bsal infection could mainly be detected in newts (Ichthyosaura alpestris and Lissotriton helveticus) because many previously known European fire salamander populations most likely disappeared in the affected forest regions, however, silently and without observed mass mortalities. The only detectable salamander population north of the highway was found to be Bsal-infected at high prevalence in 2019, but not from 2016 to 2018, suggesting a recent infection event. Overall, prevalence at the individual (2.6%) and population level (14%) was very low. Moreover, modelling habitat suitability in seemingly unaffected areas suggests that most reproduction creeks and surrounding land habitats in the seemingly affected area are still suitable for S. salamandra, supporting our suspicion that the absence of the species is disease-related rather than habitat related. [ABSTRACT FROM AUTHOR]

The emerging infectious disease chytridiomycosis is one of the major factors triggering global amphibian declines. A recently discovered species of chytrid fungus, Batrachochytrium salamandrivorans (Bsal), likely originated in East Asia, has led to massive declines in populations of fire salamanders (Salamandra salamandra) after its apparent introduction to the Netherlands and Belgium. Here, we report the first detection of this pathogen in Germany where it caused mass mortality of fire salamanders in a captive collection. Salamanders from this collection showed an almost 100% prevalence of infection with Bsal. Supposed Bsal-induced mortality occurred in multiple Salamandra species (S. salamandra, S. algira, S. corsica, and S. infraimmaculata), while Bsal infection was confirmed in nine subspecies of S. salamandra and in S. algira. Our study indicates that this pathogen can potentially infect all fire salamander species and subspecies. If Bsal spreads from captive collections to wild populations, then a similar devastating effect associated with high mortality should be expected. [ABSTRACT FROM AUTHOR]