Getting Ahead of Bsal, a Deadly Salamander Fungus, Before It Reaches the United States

A deadly fungus that attacks amphibians' skin, Batrachochytrium salamandrivorans (Bsal), was discovered in 2014 during a die-off of European fire salamanders. It could make the already severe decline of the world's amphibians worse. Bsal is a close relative of Batrachochytrium dendrobatidis (Bd), which many scientists regard as the greatest disease threat to amphibian biodiversity: it infects a great many species and can, unusually, drive species and populations extinct.

Key facts

• Bsal began killing large numbers of European salamanders in 2014.
• It could be spread by the international pet trade; more than 28 million amphibians were imported into the United States in six years (2000–2005).
• The United States has the most diverse salamanders in the world, and some species are known to be susceptible.
• Amphibians are the most threatened group of animals in the world.

Bsal had not been detected in the United States when this fact sheet was written. If it arrives, it could threaten the country's salamanders, and its spread would likely lead to more amphibians being listed as threatened or endangered by states and the federal government, with economic consequences. Because resource management agencies are concerned, the U.S. Geological Survey has made Bsal and similar pathogens a research priority.

Acting before the crisis

An emerging infectious disease is a new disease that is quickly becoming more common or spreading to new areas. The response to such diseases has usually come after the fact, once an outbreak has reached crisis levels. White-nose syndrome is a recent example: it arrived and spread rapidly in the United States, killing bats in catastrophic numbers while agencies were still organising their response.

With Bsal, knowledge of the threat before it has been found in the country is unprecedented — a rare chance to plan and carry out a coordinated response before any serious biological or economic damage. The USGS provides the science to support the U.S. Fish and Wildlife Service and other Interior Department bureaus:

• A workshop in June 2015, led by the USGS, set out management actions and research needs, with international research institutions, zoos, resource agencies and states taking part.
• The Bsal Task Force, formed under USGS leadership, coordinates the national response. It includes the National Park Service, the Fish and Wildlife Service, the Forest Service, states, universities, zoos, nongovernmental organisations and the government of Canada.
• A risk analysis by the USGS National Wildlife Health Center mapped the parts of the country at highest risk of Bsal emerging.
• A listing: USGS science supported the Fish and Wildlife Service's interim rule under the Lacey Act listing 201 salamander species as "injurious."
• Monitoring: the USGS Amphibian Research and Monitoring Initiative (ARMI) is watching high-risk areas so any arrival can be met early.

Relative risk of Bsal being introduced, by county, with the sites where ARMI has sampled wild amphibians to detect and contain it. USGS.

Biological technicians sample a rough-skinned newt for Bsal at a pond near Portland, Oregon. Photograph by Brome McCreary, USGS.

Why amphibians matter

Amphibians are the most endangered animals on Earth: the International Union for Conservation of Nature estimates that 42.5 percent of the world's species are threatened to some degree. In the United States they live in forests and waters that support fishing, hunting, wildlife watching and recreation — and local businesses — worth billions of dollars to the economy.

Less conspicuous than birds and mammals, amphibians can easily be the most numerous animals in their ecosystems, and they do a great deal. They eat vast numbers of insects, which indirectly affects things such as the spread of human disease and the breakdown of leaves and wood on the forest floor — an effect on decomposition large enough to reach the global carbon cycle. They are also food for a wide range of other wildlife.

Corrected: the fact sheet calls it the "United Nations International Union for the Conservation of Nature"; the IUCN is an independent international union, not a United Nations body.

Sources

• Michael J. Adams, M. Camille Harris and Daniel A. Grear, Early Action to Address an Emerging Wildlife Disease, USGS Fact Sheet 2017–3013. https://doi.org/10.3133/fs20173013
• Bsal Task Force: http://www.salamanderfungus.org/
• USGS Amphibian Research and Monitoring Initiative: https://armi.usgs.gov/