Scientists have traced the origins of a killer frog fungus, which also affects toads and salamanders, to the Korean peninsula, where it likely emerged at the beginning of the 20th century.

The discovery, in addition to finally determining ground zero for the deadly disease, raises concerns on pet trade involving the amphibians.

The Origin Of The Chytrid Fungus

Over recent decades, frog, toad, and salamander populations have been attacked by the deadly chytridiomycosis disease, which is caused by the fungus named Batrachochytrium dendrobatidis. The amphibians have suffered through sudden and significant die-offs, prompting research to find the source of the killer fungus.

A team of scientists have now pinpointed East Asia, specifically the Korean peninsula, as the source of the chytrid fungus, after analyzing samples that were collected from both captive and wild amphibians. The group's findings were published in the Science journal.

The chytrid fungus is a disease so deadly to frogs, toads, and salamanders that it may lead a species to extinction. It comes in the form of a skin infection passed between the animals, causing chytridiomycosis that affects the ability of amphibians to regulate water and electrolytes. With their pores clogged, blood chemistry is affected and brains swell, resulting in heart failure for the infected animals.

The scientists determined that there were four main genetic lineages for the chytrid fungus. Three of the kinds are found all over the world, but the fourth kind is only found in native frogs living in Korea. All strains also shared genetic code with the one from the Korean peninsula, suggesting that the pathogen started there.

Furthermore, genetic analysis revealed that the disease's range greatly widened between 50 and 120 years ago, which coincides with the expansion of international trade.

Chytrid Fungus Research Highlights Pet Trade Issues

The chytrid fungus, which caused a destructive decline in the population of 200 frog species, including the Sierra Nevada yellow-legged frog, was determined by the researchers to be spreading through international pet trade.

The discovery that the killer frog fungus started in Korea provides additional arguments against pet trade, particularly on amphibians coming from East Asia. While there is a requirement by the U.S. Department of Agriculture for shipments of domesticated animals to receive certification as being disease-free, there is no such regulation for wildlife, wherein frogs, toads, and salamanders are categorized.

"Until the ongoing trade in infected amphibians is halted, we will continue to put our irreplaceable global amphibian biodiversity recklessly at risk," said Matthew Fisher from the Imperial College London, one of the scientists in the research team.

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