Chytrid: a Deadly Fungus Threatens Endangered Amphibians

Filed Under: Reptiles, Parasites

The chytrid fungus, whose scientific name is Batrachochytrium dendrobatidis (Bd), is decimating amphibian populations worldwide, especially in Central America and Australia. The fungus has contributed to the extinction of nine frog species native to Australia and almost 200 species worldwide. When B. dendrobatidis affects a community, up to a 50% morbidity rate is seen in the native amphibian population and 80% of the affected animals will die within a one year period (mortality rate). It is believed that the fungus was originally found in South Africa and has spread throughout the world by the transportation of amphibians for food and for the pet industry.

The fungus causes the skin of the infected amphibian to thicken, thereby interfering with the ability of the animal to absorb water and electrolytes. It is believed that the resulting electrolyte imbalance seen in frogs sends them into a fatal cardiac arrest. Electrolyte transport across the epidermis, or skin, of the frog results in depletion of potassium levels by up to 50% and plasma sodium by 20%, thereby disrupting the heart’s rhythm.

Symptoms of infection include difficulties in the balance of the infected frog (ataxia), problems in motor skills, convulsions, and paralysis.

The PCR test is the most reliable means of detecting chytrid infections in both wild and captive amphibians and is the only technique capable of accurately quantifying the number of B. dendrobatidis zoospores present on skin swabs. In the United States, PCR testing is available through Pisces Molecular in Boulder, Colorado at (303)546-9400.

Although there is as yet no cure for the chytrid fungus, researchers have found that giving affected amphibians drugs to restore electrolyte imbalances slightly prolongs the lives of animals infected by the fungus.

The chytrid is even a sporadic problem in world-wide zoo collections and with species reintroduction programs. The fungus is known to wipe out local populations-some of which are threatened already.

Steps which can be taken to prevent the introduction of the chytrid fungus include: testing of newly purchased animals, quarantine of new arrivals, practicing good hygiene when handling different animals (e.g. disposable gloves), and never mixing populations. Ideally, new animals should be PCR tested twice, 6 weeks apart. The fungus can be killed with a 1% bleach solution or by heating surfaces to 120°F for 30 minutes.

References:
http://www.abc.net.au/science/artilces/2009/10/23/2720384.htm

http://www.grizzlyrun.com/PetEDU/Amphibian_s_in_Trouble_-_the_chytrid_fu...

“Clue Found in ‘Phib Epidemic.” Pet Age. February 2010. P. 41.

Nolen, R. “New Guidelines Intended to Guard Amphibians against Deadly Fungus.” JAVMA Vol. 234, No. 8 news. P.1000.

Topics: endangered species, fungus

Symptoms: convulsions, impaired motor skills, loss of balance, paralysis

Similar entries

  • Is your mare having trouble with foaling? Think your foaling dates are almost a month off? Is your mare producing enough milk to care for her foal? Did you get what looks like a full term foal only to find it stillborn? This unfortunate situation may be a result of your pasture.

  • Want an unusual herp that is easy to keep? Try the axolotl. A native of Mexico, the axolotl is also known as the aquatic salamander, or the mole salamander. The axolotl is a neotenic amphibian whose scientific name is Ambystoma mexicanum. Neotinic amphibians are amphibians that do not undergo metamorphosis, under normal circumstances, from the larval to adult stages. The axolotl remains aquatic throughout its lifetime. This salamander never leaves the confines of water.

  • Think the current swine influenza scare is just a bit of media drama?  Don’t be too sure.  Pigs have the potential to serve as a genetic “mixing vessel” for influenza viruses carried by birds, pigs and humans.  Most viruses tend to be species specific but not those of the Influenza type A viruses.  These viruses can easily swap genetic code between traditional avian, pig and human infections.  It is feared that this mixing of genetic code may someday result in a flu pandemic to rival that of the 1918 Influenza epidemic.  

  • Think toads are harmless? Do you think it’s alright if your dog or cat decides on a frog-leg snack? If you live in a warmer part of the world you might just want to rethink your position. Especially large or colorful frogs may be hazardous to the health of your pets. In fact, toads were responsible for the 8th most common way pets were poisoned during 2007 in the United States.

  • Tall fescue (Festuca elatior or F. arundinace) is among the most common cool season pasture grasses grown in North America and in other countries having a temperate climate. Almost all of the pasture planted before 1980 is infected with Neotyphodium coenophialum, a microscopic fungus or endophyte. "Endophyte" describes the location of the fungal growth within the grass as endo=within and phyte=plant.