Chytridiomycosis is an often fatal infectious skin disease that seriously affects amphibians. The condition is caused by the chytrid fungus. Two types of this fungus has been responsible for huge die-offs in amphibian populations. Chytrid is one of the most devastating threats to amphibian populations.
Batrachochytrium salamandrivorans (Bs or Bsal)
The fungus Batrachochytrium salamandrivorans has been responsible for severe declines in salamander populations across Belgium and the Netherlands. The Fire Salamander (Salamandra salamandra), has been particularly impacted by Bsal. In some areas the population has declined so dramatically that it is now only 4 per cent of what it was in 2010. The mortality rate of Bsal is 96 percent. In fact Bsal has already extirpated fire salamander populations in northern Europe. (A. Martel et al., Proc. Natl. Acad. Sci. U.S.A. 110, 15325–15329 - 2013. A. Spitzen-van der Sluijs et al., Amphib.-reptil. 34, 233–239 - 2013).
Bsal has also been confirmed in Alpine Newts (Ichthyosaura alpestris) in Belgium where it has caused mortality in one population of alpine newts. The fungus has also been fatal to American salamanders in lab tests. The fungus is thought to be spread via the Pet Trade, and if it were to reach North America (the most salamander diverse continent in the world) it could decimate salamander populations! North America is a global hotspot for salamander biodiversity, accounting for about 50 percent of species worldwide. In particular, Mexico and the Appalachian Mountains are collectively home to more than 100 species of lungless salamanders. In North American forests, the biomass of salamanders can exceed the biomass of all other vertebrate species.
According to Recent introduction of a chytrid fungus endangers Western Palearctic salamanders, A. Martel et al. Science 346, 630 (2014), To assess the potential of B. salamandrivorans spread by captive amphibians, we tested 1765 skin samples from amphibians in pet shops in Europe, London Heathrow Airport, and an exporter in Hong Kong, and 570 samples from other captive amphibians for B. salamandrivorans. We found three positive samples from captive individuals of the Asian newt species Tylototriton vietnamensis, two of which were imported to Europe in 2010. Furthermore, our transmission experiments showed that B. salamandrivorans can effectively be transmitted across multiple urodelan (salamander) species (e.g., from Cynops pyrrhogaster to Salamandra salamandra) by direct contact, demonstrating the potential for pathogen spillover.
For more information on Bsal please see:
The National (USA) Bsal task force website : A Coordinated Response to a Devastating Amphibian Disease.
Batrachochytrium dendrobatidis (Bd)
The fungas Batrachochytrium dendrobatidis has been responsible for mass declines in amphibian populations. Devastatingly, Bd has been found on all of the continents where amphibians occur. It may be responsible for the greatest disease-caused loss of biodiversity in recorded history (Skerratt et al. 2007). Although, the fungus has impacted frogs more seriously, it does effect some salamander species. Furthermore, far less research has been conducted on salamanders, so Bd may affect them more then is currently thought. Bd has been implicated in the unexplained disappearances of Central American salamanders (Rovito et al. 2009). In addition, two neotropical salamander species (Pseudoeurycea leprosa and Bolitoglossa rufescens) were found to be quite susceptible to Bd infection in the laboratory (Cheng et al. 2011).
How You Can Help
The Bsal fungus is thought to have made its way from Asia via the importation of Asian Salamander (Newt) species. As such amphibian keepers are in a great position to help stop the spread of B. salamandrivorans via informed decision making, and therefore contribute to preservation of salamanders. Keepers can help by not buying Asian species and thus not supporting the sale and importation of Asian amphibians into North America. Several North American species, like the Axolotl and Tiger Salamander (genus Ambystoma) are commonly available in the pet trade. Furthermore these species turn up frequently on online classified sites, so the option to adopt salamanders that are in need of homes is a great option as well.
Currently several scientists, groups, and organizations, are seeking to implement a moratorium on imports of salamanders for the pet trade to help stop the spread of disease. Write your congress person to ask them to support the trade ban.
For people who currently are captive salamanders, be sure to make sure pets are in secure, escape proof enclosures. This will help prevent alien species from reaching non-native habitats. Never release unwanted pets/captives into the wild. Unwanted salamanders can be surrendered to rescues or exotic animal adoptions. For keepers who have species that are native to their region, these too should never be released after being in captivity as the risk of spreading disease to new locales is a very serious risk. Do not move, transport and release wild salamanders from one field site to another.
Guidelines for quarantine and hygiene have being developed to help ALL herpetoculturists (amphibian keepers) reduce and eliminate the risk of disease being spread. Click here
After providing care to any amphibians wash your hands with betadine germicide solution. Vigorously scrub hands for 20 seconds to ensure proper disinfecting. Make sure hands are completely (and well) rinsed before interacting with any other amphibians. Betadine is recommended due to its effectiveness.
Never throw old and discarded water, substrate, or anything else from enclosures out onto gardens or lawns. When cycling water from your newt tanks, make sure to dispose of this properly as to not degrade or contaminant the neighbouring environments. According to the Amphibian Survival Alliance (ASA), before you dispose of any waste water that might have come in contact with your pet salamanders/newts be sure you add a little bleach before you dispose of it. The best evidence points towards a ratio of about 1 part bleach to 10 parts water. Using this ratio should ensure any of the deadly Bsalfungus is killed before leaving your home. Remember – bleach is highly toxic to salamanders, never let your salamander come in to contact with bleach, only use it to disinfect waste water. Make sure any bleached equipment is thoroughly rinsed and dried before letting it come into contact with any live amphibian.
Those who work in the field, conduct field research, or partake in field herping are encouraged to take steps to try and prevent the spread of Bsal/Bd. Click here
for guidelines on how to stop the spread of disease when in the field.
The highest risk of chytrid spread is likely through anthropogenic-mediated transport of frogs and tadpoles, whether intentional or unintentional (Obendorf 2005). The two most common ways of spreading chytrid to new sites may be the use of amphibians as fishing bait and the collection and release of frogs and tadpoles as pets (Obendorf 2005). Amphibians should not be used as bait or released back into the wild once they have been taken into captivity. All newly acquired captive amphibians should be placed in quarantine initially. Again, note that cage water and soil substrates should also be regarded as contaminated and should not be dumped into the environment.
A study to collect skin swab samples in the field from salamanders in locations where Bsal has not been documented yet is currently underway. The swab samples will be sent to Ghent University in Belgium for analysis. The analysis will be performed by the scientists that originally discovered the fungus, Dr. An Martel and Dr. Frank Pasmans. The analysis will determine if a salamander was infected with the fungus or not. You can donate to this important study here