As far as we know, North American amphibian populations have not yet been exposed to this pathogen in the wild.
Threats of urbanization, habitat loss and environmental change are known to directly contribute to wild reptile and amphibian declines. In addition, reptiles and amphibians are suffering from an onslaught of emerging infectious fungal diseases. For example, snake fungal disease (SFD), sea turtle egg fusariosis, and amphibian chytridiomycosis are all linked to reptile and amphibian declines.
Batrachochytrium salamandrivorans (Bsal) is a recently discovered fungus shown to cause the infectious disease salamander chytridiomycosis, or salamander chytrid disease. Bsal is closely related to the pathogen known as Batrachochytrium dendrobatidis (Bd), which has been associated with global large-scale mortality and amphibian population declines.
Bsal appears to be native to Asia, where salamander populations are resistant. Infection in European salamanders, however, results in skin lesions, anorexia, lethargy and death. Infected individuals may not always show these symptoms. Some species, particularly those native to Asia, which have been exposed to the pathogen throughout evolutionary history, can become infected but will not show visible signs of the disease or experience mortality.
Current research suggests that Bsal can be transmitted via direct contact with an infected individual or via motile aquatic zoospores. Bsal can also persist in the environment in the absence of salamanders. While research in this area is still ongoing, it is also believed that Bsal may be able to tolerate a wide range of temperatures and survive in water or saturated terrestrial environments for some period of time. This means that the fungus can persist in materials used to house or transport pet salamanders, and salamanders can still be infected even if they’re not showing signs or symptoms.
What Salamanders Are At Risk?
As far as we know, North American amphibian populations have not yet been exposed to this pathogen in the wild. In Europe, however, exposure to Bsal has resulted in mass mortalities of fire salamanders (Salamandra salamandra). Population declines have been documented in Germany, Belgium and the Netherlands, as well as captive populations of related species.
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Preliminary research from the United States Geological Survey (USGS) National Wildlife Health Center suggests that most salamander species native to North America are highly susceptible to infection (read here). Lab trials document high levels of mortality in North American newt and fire salamander species. Lungless salamanders (Plethodontidae) also exhibited susceptibility and mortality when exposed to Bsal.
A major threat to wild populations is the accidental introduction or movement of individuals within and between localities. Responsible pet ownership, therefore, is more important than ever before. Pet and captive animals should not be released into the wild, as infected individuals can carry the disease with them to new areas, thereby putting other salamanders at risk.
Seven Ways You Can Help Prevent the Spread of Bsal
- Always adopt/purchase from a reputable source and discuss Bsal with your veterinarian.
- Check pet salamanders for skin problems (reddening and/or ulcers). If present, quarantine the animal and contact your local veterinarian.
- Do not release captive or wild-caught salamanders of any species into the wild.
- Treat wastewater used with captive animals (¼ cup bleach per quart of water) before disposal to kill any potential pathogens.
- People who participate in herping activities should sanitize their field equipment with a 10-percent bleach solution, and minimize handling of amphibians and reptiles to reduce spreading disease.
- Do not transport salamanders between field sites without following proper biosecurity protocols.
- Report occurrences of dead or dying salamanders to your state or provincial wildlife agency. Similarly, Contact the USGS National Wildlife Health Center at 608-270-2480.
What is Being Done to Prevent the Spread of Bsal?
In light of this emerging threat, the Pet Industry Joint Advisory Council (PIJAC) recommended a voluntary, temporary moratorium in 2015 on the importation of certain species into the U.S. , including the firebelly (Cynops orientalis) and paddletail (Pachytriton labiatus) newts, which were thought to be potential carriers of Bsal because they are native to Asia and presumably unaffected by infection. In addition, PIJAC encouraged all businesses and facilities involved in the salamander trade to develop extensive sanitation protocols as a further preventative measure.
A collaborative entity known as the the National Bsal Task Force was created to coordinate surveillance and communication efforts at the disease front. Its primary purpose is to collect and disseminate information regarding any new developments in research or response efforts related to Bsal. Furthermore, federal and state agencies, as well as universities and conservation entities throughout the United States, have initiated independent, large-scale monitoring efforts in response to this imminent threat.
These initial efforts are focused primarily on surveying locations near potential introduction sites (i.e., cities and shipping ports), as well as developing protocols and policies for commercial salamander markets. In addition to the voluntary moratorium issued by PIJAC in 2015, the U.S. Fish and Wildlife Service issued an interim rule, effective January 28, 2016, which listed 201 salamander species as injurious wildlife under the Lacey Act (read here). This rule prohibits the importation and interstate transport of species identified as potential carriers of Bsal at the time of the listing. Thus, many groups, including the commercial pet industry, government agencies, amphibian conservation groups, and university scientists are working to create awareness and prevent the emergence of salamander chytridiomycosis in North America.
For More Information
A wealth of resources has been collected and/or prepared by the National Bsal Task Force and can be found on several websites (including salamanderfungus.org and amphibiandisease.org). Additional resources on chytridiomycosis in frogs as well as salamanders can be found at the Amphibian Disease Portal (read here) and AmphibiaWeb (read here). Information on other emerging infectious diseases in wildlife can be found on the USGS National Wildlife Health Center website (read here).
All eyes are now turned toward North America. With approximately 50 percent of the world’s salamander species present there, the introduction of Bsal could lead to widespread mortality and subsequent loss of North America’s rich amphibian diversity. Thus, salamander enthusiasts, whether pet owners, herpetologists, or simply those who care about wildlife—all play critical roles in keeping our beloved U.S. native salamander populations safe in the wild.