Batrachochytrium salamandrivorans (Bsal) Surveillance

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Scientists of the USGS National Wildlife Health Center (NWHC) in collaboration with partners have developed risk assessments for Batrachochytrium salamandrivorans (Bsal) in the United States and have begun sampling high-risk locations for the fungus.

Bsal has caused mass mortality events and severe population declines in European salamanders via introduction into wild populations from the pet trade. North America has the highest diversity of salamanders in the world and introduction of this pathogen could be devastating, not only to local populations but also to global salamander biodiversity.

 USGS scientists developed a county-specific Bsal risk assessment for the U.S. by analyzing characteristics of Bsal ecology, such as optimal temperatures for fungal growth, data on amphibian imports, pet trade establishments, and the regional diversity of salamander species. They found that if Bsal enters the country:

  • The total risk of Bsal to salamanders is highest throughout the eastern U.S., particularly the mid-Atlantic states of New York, Massachusetts, Rhode Island, Connecticut, New Jersey, Pennsylvania, Delaware and Maryland.

  • The Pacific coast and Appalachian Mountains are likely to have significant population declines due to high concentrations of diverse salamander species and mild climates that are well suited to Bsal growth.

Bsal Risk by County

This map shows the total relative risk of Bsal by U.S. county. Credit: USGS, Richgels et al. 2016.

The NWHC is working collaboratively with the USGS Amphibian Research and Monitoring Initiative (ARMI), to determine the presence of Bsal in North American salamander populations in targeted locations with high biodiversity and increased risk of exposure to the Bsal pathogen. The NWHC and ARMI are working to reach a 10,000 sample goal in these high-risk locations to determine if Bsal is already present (and previously undetected) in the United States during 2016. As of August 2016, Bsal has not been detected in 7,425 salamander and newt samples tested from 19 states in 20 species.

Samples are being collected by live capture and swabbing of salamander and newt species. Results are based on real-time PCR test for Bsal DNA at the NWHC (Blooi et al 2013). Sampling and diagnostic testing is ongoing and, once completed, the results will be incorporated with previous risk assessments (Richgels et al 2016; Yap et al 2015) to produce updated estimates of Bsal detection and absence in the U.S.


Scientist swabbing newt.

USGS scientist swabbing a Central Newt in Wisconsin to look for an invasive fungus, Batrachochytrium salamandrivorans (Bsal). (Public domain.)