Batrachochytrium salamandrivorans

Distribution

Bsal appears to occupy a narrow climactic niche in its native range in East and Southeast Asia. In its introduced range in Europe, it was first detected in the Netherlands in 2012, where it wiped out a majority of the country's small fire salamander population. It has since naturally expanded into Belgium, western Germany, and possibly Luxembourg, although it was likely present in some of these regions well before the documented outbreaks; the oldest known record is from Germany in 2004. In Germany, it is primarily known from the states of North Rhine-Westphalia and Rhineland-Palatinate, with the core of its range being in the Eifel Mountains, where it has caused landscape-scale declines of fire salamanders. It was detected in the state of Hesse in 2024, on the border with North Rhine-Westphalia, where it was found to have caused a mass mortality of fire salamanders.

In addition to this contiguous range, several isolated outbreaks have been reported. One such outbreak is known from the Steigerwald in Bavaria, Germany, which was possibly introduced either by hitchhiking on shoes, animals, or machinery, although it is also possible that it had naturally expanded from northern Germany unnoticed. The southernmost outbreak was identified in Allgäu in 2020, which was possibly associated with an accidental introduction via aquatic plants for garden ponds; this outbreak caused a mass mortality event among alpine newts. Due to its proximity to the Alps, this outbreak poses a major risk to the alpine salamander and Lanza's alpine salamander if allowed to expand. Another outbreak was identified in a single site in Catalonia, Spain in 2018, which likely originated from released captive individuals. This outbreak caused mortality in fire salamanders and marbled newts, and posed a severe threat to the endemic salamanders of the Iberian Peninsula; the site was thus impounded to contain the outbreak and prevent any spillover. Several other reports of Bsal from other parts of Spain are thought to be false positives, as later surveys of these sites have found no presence of the disease.

Susceptible species

The most comprehensive Bsal species susceptibility performed to date has been by Martel et al 2014. Their experiments demonstrated Bsal susceptibility followed a phylogenetic trend with many Salamandridae species being lethally susceptible. Recent work has demonstrated that some lungless species, specifically those in the Spelerpini tribe might also be clinically susceptible to Bsal.

Threats to salamanders

Bsal is a serious threat to salamander species, while it has not yet been confirmed in North America, Bsal has had catastrophic effects on certain European salamander populations, believed to be the cause of a 96% decline in populations with in the Netherlands. More than a third of the worlds salamanders live in the United States, and 40% of those salamanders are already threatened. While regulations on the most likely avenue of introduction into North America, amphibian trade, are in place in both Canada and the United States, regulations are seriously lacking in Mexico. Furthermore, Bsal has the potential to infect an estimated 80 to 140 North American salamander species.

Tolerant

• Salamandrella keyserlingii
• Siren intermedia

Susceptible

• Cynops cyanurus
• Cynops pyrrhogaster
• Paramesotriton deloustali

Lethal

• Hydromantes strinatii
• Salamandrina perspicillata
• Salamandra salamandra
• Pleurodeles waltl
• Tylototriton wenxianensis
• Notophthalmus viridescens
• Taricha granulosa
• Euproctus platycephalus
• Lissotriton italicus
• Mesotriton alpestris
• Triturus cristatus
• Neurergus crocatus
• Eurycea wilderae
• Pseudotriton ruber

Information sources

More information on Bsal and other diseases impacting amphibian populations, including Batrachochytrium dendrobatidis and Ranavirus can be found at the Southeast Partners in Amphibian and Reptile Conservation disease task team web-page.