New hope of curing amphibian plague
Jeremy Hance, mongabay.com
November 28, 2008
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Amphibians worldwide are in trouble. One of the most endangered animal groups, amphibians are increasingly threatened by habitat loss, pollution, and climate change. However the largest threat is chytridiomycosis, a devastating disease caused by a parasitic chytrid fungus known as Batrachochytrium dendrobatidis, otherwise known as Bd.
Some hope for frogs and toads has been found at the Institute of Zoology in London. Scientists have discovered that tadpoles infected with Bd are cured by the fatal disease when submerged in an antifungal drug, itraconazole, for five minutes everyday day for a week.
“Even using extremely low doses, we showed that you can eliminate Bd from tadpoles,” Trent Garner told New Scientist. A month after treatment the tadpoles had developed none of the side effects connected to itraconazole, the most worrisome being liver damage.
Now that the team from the Institute of Zoology in London has evidence that itraconazole works, they are taking their cure into the field. Traveling to Mollorcan Island, Garner and his colleagues are planning to work with the Mallorcan midwife toad, so-called because after mating the male of this toad carries the eggs on its hindquarters until they are ready to hatch. The scientist’s plan is to provide the tadpoles with the same treatment as those in the lab.
The Mallorcan midwife toad is found only in a few pockets of limestone cliffs in northern Mallorca off the Eastern coast of Spain. Due to its evolutionary uniqueness and its threatened status, the toad is number 55 on EDGE’s list of the 100 most endangered and distinct amphibians. EDGE is a program through the Zoological Society of London.
Even while optimistic for the Mallorcan midwife toad and other amphibians, Garner stresses that the drug is not a cure-all. “The goal is mitigation, not elimination,” he told New Scientist. Even if implemented on a wide-scale, using itraconazole to protect frogs from chytridiomycosis would only be one strategy out of many. Currently, many endangered species of frog have been collected and kept in captivity to avoid the disease. Proposals have also been made for freezing sperm of endangered amphibians to use for assisted reproduction if needed.