Breaking the Fall of FrogsSpotlight on Vet Medicine
March 5, 2009
Frogs in Quarantine
Lemur leaf frogs are aptly named: Their oversized, black-lined eyes give them the same startled look for which lemurs are famous. Add to that their long-limbed bodies and their nocturnal, rainforest-dwelling lifestyle, and the name seems particularly apt.
The similarities stop there, though. Lemur leaf frogs are amphibians that range throughout Central and South America, predominately in Costa Rica, Panama, and Colombia. During the day, they are a bright green and sleep clinging to the underside of leaves. When they wake up and start moving around at night, their backs turn dark green or vivid red, the better to camouflage themselves from predators, such as snakes and birds of prey.
Lemur leaf frogs face even scarier threats than hungry birds and snakes. Their population levels have dropped by more than 50 percent over the last two decades. The culprit is a fungus too small to be seen with the naked eye.
Fungus Among Us
Chytridiomycosis (pronounced "kih-TRID-ee-oh-my-KOH-sis) is a fungal skin infection that can be, and frequently is, fatal to frogs and other amphibians. Scientists believe it is responsible for the sharp decline in amphibian populations over the last 15 years. “Chytrid,” as scientists call it (pronounced "KIT-rid") affects each amphibian species differently, but in some frogs it can kill up to 90 percent of the population, and it has been found all over the world.
Scientists think chytrid originally came from South Africa. In the 1940s, people started exporting
African clawed frogs from South Africa. These frogs are popular lab animals, and for years, they were used in human pregnancy tests. Scientists suspect that, as these frogs traveled all over the world, chytrid—which is harmless to the African clawless frogs—went with it, with devastating effects to frog species who’d never encountered it before.
The fungus lives in the environment, particularly in cool, wet, habitats. It can climb into a frog’s body through even a very small cut in the skin. The fungus eats away at the frog’s skin, eroding it and letting in other pathogens from the environment. These pathogens give the frog body-wide infections, which eventually kill the frog. Scientists are still working to understand how the fungus is passed and how to prevent it spreading to any new species.
In 2009, the National Zoo, along with seven other institutions, formed the 
Panama Amphibian Rescue and Conservation Project aimed at saving amphibians from extinction as the result of chytrid.
New Frogs on the Block
In January, 16 lemur leaf frogs arrived at the Zoo from the National Aquarium in Baltimore. They will be part of a new exhibit on amphibian conservation in Amazonia.
Whenever any new animal comes to the Zoo, it stays in quarantine for at least 30 days. During this time, vets watch it very closely to make sure it’s not sick or bringing any pathogens into the Zoo’s community of animals. Because the risk of chytrid is so serious, this period is doubly important for the lemur leaf frogs.
The Veterinary Hospital has a special building set aside for newly arrived animals. When an animal is in quarantine, only animal health staff—veterinarians, veterinary technicians and hospital animal keepers—go near it, and then only for daily feeding, cleaning, and health assessments. Keepers and vets wear scrubs, gloves, and foot coverings when interacting with quarantined animals to try to avoid carrying any germs in or out.
While animals are in quarantine, keepers keep an eye out for any possible symptom of illness, though for amphibians vulnerable to chytrid, they watched the frogs even more closely. They inspected the frogs visually every day, to see how they were eating, defecating, and behaving. Unfortunately, though, visual inspections can’t spot everything.
Back Swabbing
Because some frogs can carry chytrid but not show any symptoms, the vets wanted to be doubly sure the frogs were healthy before they moved into their new exhibit in Amazonia, where they will share a building with other amphibian species. They needed some way to test the frogs and make sure they were chytrid-free.
The Zoo is lucky; as a Smithsonian institution, we have a highly sophisticated genetics lab equipped to handle exactly this type of challenge. The geneticists created a new test for chytrid that involves swabbing the underside of each frog with cotton swabs. Those samples went down to the genetics lab for testing. There, geneticists analyzed the samples, searching for any evidence of chytridiomycosis. The samples were negative, so the vets gave our frogs a clean bill of health.
The frogs, all 16 very healthy, have moved out of quarantine and are headed up to Amazonia. Visit them there when the new “Amphibian Alert” exhibit opens this spring!
Note to Media: If you would like more information about this project, or any of the Zoo's conservation and science programs, please contact the Zoo's Office of Public Affairs.
