The National Zoo’s Role in Chytrid Fungus Research
In the 1990s, a team of scientists at the Smithsonian’s National Zoo isolated—and in 1999 were able to describe—a new species of chytrid fungus, Batrachochytrium dendrobatidis. Their discovery confirmed suspicions within the amphibian conservation community that a disease could be responsible for causing amphibian deaths around the world. Chytridiomycosis, is the name of the disease caused by the Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis), which attacks keratin proteins in the skin. Symptoms of the disease include sloughing and discoloration of the skin, lethargic motions, and loss of appetite. Since frogs breathe through their skin, chytrid creates respiration problems. Zoo scientists also pioneered initial tests to cure the fungus in captive animals using Itraconazol, an anti-fungal medication. It can also be controlled in captivity by raising the temperature above 25°C which kills the heat-sensitive fungus.
Facts on Chytrid:
- This tongue-twisting name has a Greek etymology; Batracho = Frog, chytr = earthen pot (the shape of the fungal fruiting bodies), the species name is from the genus of poison dart frogs that it was discovered in Dentrobates. It is often simply called B.d. by scientists.
- The exact origin of chytrid fungus is unknown, but one theory is that it originated in Southern Africa and was distributed worldwide in the 1950s through the trade of the African clawed frog for pregnancy-testing and other amphibian trade.
- Chytrid fungus has been detected in many parts of the U.S., but some species are apparently resistant to the fungus and it is not always associated with amphibian declines. The most dramatic declines have been observed in mountainous parts of Central and South America and Australia where it is responsible for the disappearance and probable extinction of many species.
- Chytrid fungus is thought to be responsible for the extinction of the Panamanian golden frog (Atelopus zeteki) in the wild, but fortunately there are captive assurance colonies for this species at the National Zoo, several other zoos in the U.S. and breeding facilities in Panama. These animals will be used for reintroduction programs once scientists find out how to mitigate the disease threat.
- The fungus is thought to have driven two species of unique Australian gastric brooding frogs to extinction in the 1980s. These species raised their young in their stomachs and researchers were hopeful that these creatures might contain they key to preventing and treating human peptic ulcers which affect some 25 million people in the United States alone.
- An online map of chytrid outbreaks can be seen at this URL: http://www.spatialepidemiology.net/bd