Scientists trace back origins of devastating crisis after studying human urine: 'It was shocking to watch the spread of the disease happen in real time'

Yahoo

21-04-2025

In the 20th century, a seemingly odd but effective pregnancy test helped advance modern medicine — and in the process, accidentally unleashed a global ecological disaster.
At the center of it all? A small aquatic amphibian with powerful legs and a surprising hormonal sensitivity. What started as a medical breakthrough turned into one of the most damaging wildlife pandemics ever recorded, with ripple effects that scientists are still grappling with today, as ZME Science detailed.
In the 1930s, British scientist Lancelot Hogben discovered that the African clawed frog could be used to detect pregnancy when injected with a woman's urine. The hormone-sensitive amphibian would begin producing eggs if the woman was pregnant, making the frog a reusable — and revolutionary — diagnostic tool.
And thus, the "Hogben test" came to be. Hospitals around the world began importing the species in massive numbers, and over tens of thousands of frogs were infused with human urine between the 1940s and the '60s, as reported in the National Center for Biotechnology Information.
Alongside this infusion, however, came an invisible hitchhiker: chytrid fungus, a highly infectious pathogen that the frogs carried without showing symptoms. As demand for the test waned in the 1960s and '70s as better and more sanitary options arose, many of the frogs were either euthanized or released into the wild, spreading the fungus to fragile ecosystems across the globe.
As the African clawed frogs were transported across the globe to be injected with human urine, they carried the pathogen without suffering its lethal effects, thereby becoming unwitting super-spreaders, introducing chytrid to ecosystems where native amphibians had no defenses.
Chytrid fungus invades a frog's skin — an organ essential for hydration and electrolyte balance, causing rapid, often fatal, cardiac arrest. Entire frog populations vanished in mere months. So far, the fungus has affected more than 700 species and driven at least 200 amphibian species to extinction.
This wasn't just bad news for the frogs.
Amphibians play a critical role in ecosystems as pest controllers and prey species. Their disappearance disrupts food chains, agriculture, and even water quality. Scientists call this one of the most devastating wildlife diseases in recorded history.
"It was shocking to watch the spread of the disease happen in real time 15 years ago," Jamie Voyles, assistant professor at the University of Nevada, told the BBC.
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Thankfully, hope is not lost. Conservationists are turning to captive breeding, habitat management, and even probiotic treatments to protect vulnerable species. Some frogs are starting to show signs of resistance, and researchers are exploring how to harness that for broader protection.
To help, people can support amphibian-friendly policies, avoid purchasing exotic pets, and donate to conservation groups like Amphibian Ark or the Wildlife Conservation Society. It is a cautionary tale — and a call to action — showing just how closely our choices are linked to the health of the natural world.
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