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, for example. 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==