Multimedia Reporting (Fred-Musser)

In the pristine tropical forest of El Valle, Panama, Joe Mendelson saw dozens of frogs bobbing in streams, lying on the ground—all dead. In death, the frogs looked much as they had in life, untouched by wounds, unmarked by predators.

They had succumbed to a pandemic; Batrachochytrium dendrobatidis, a little understood fungus, is still killing amphibians around the globe in waves. Scientists call it “chytrid” for short.

“The chytrid arrived and wiped out all the amphibians,” said Mendelson, a 1997 University of Kansas graduate and now herpetology curator at Zoo Atlanta. “It was horrible. I’ve had them die in my hand.”

According to a document presented at the 2005 Amphibian Conservation Summit in Washington, DC, at least 122 amphibian species have gone extinct since 1980. Nearly a third of the world’s amphibians, about 1,800, are threatened with extinction. Along with habitat loss, pesticides, climate change and other afflictions, many herpetologists suspect chytrid is contributing to a worldwide amphibian die-off.

Mendelson said that he had seen chytrid kill 80 percent of a region’s amphibians in a matter of months, and eliminate half its amphibian species. He said the pandemic—some compare it to amphibian AIDS—is currently raging in California, the Rocky Mountains, Mexico, all of Central America, the Andes mountains and eastern Australia.

According to Mendelson, the fungus spreads by frog-to-frog contact. Microscopic spores lodge in the amphibians’ skins. Also, when a frog enters the water, the spores can pop out, travel downstream and infect another host.

“It’s kind of ironic, because the spores look sort of like tadpoles,” Mendelson said.

Dave McLeod, a graduate teaching assistant in biology, said some infected frogs display certain symptoms that mark the chytrid infection. These symptoms include lethargy, a generally sick disposition and other odd behaviors.

“In an infected frog, if you flip it over, it’s unable to right itself,” McLeod said.

Mendelson said he had encountered frogs so sick they wouldn’t hop away when he approached them.

McLeod explained the killer fungus afflicts cells that produce keratin, a protein found in both frog and human skin.

The Wyoming toad, which lives in only one Wyoming county, has been endangered since 1984. The chytrid fungus was recently found among its few remaining wild and captive populations. Its survival is uncertain.
Photo: Suzanne L. Collins

“Because the frog uses its skin as a respiratory surface, the infection actually prevents the frog from being able to effectively use its skin to breathe,” McLeod said. “You end up seeing frogs in these mummified states, as they’re in the process of dying or have died, where the skin is completely covered with this fungal infection.”

When the disease gets really bad, Mendelson said pieces of skin begin to fall off.

Mendelson doesn’t know if chytrid is in Kansas. Nor does Joe Collins, a herpetologist with KU’s Kansas Biological Survey.

“Everyone wants answers,” Collins said. “We don’t have answers; there’s not enough money.”

But according to Collins, a failure to fund data-collecting research in Kansas doesn’t mean chytrid is not here. North American bullfrogs are common in Kansas and can carry the disease. Bullfrogs, however, remain mysteriously chytrid-resistant. Collins called the bullfrog “the cow of the amphibians.” It is commercially farmed for frog legs and shipped around the world. Bullfrog tadpoles also can carry chytrid.

“There are bullfrog tadpoles in every fish shipment in the United States,” Collins said.

According to Collins, Kansas farmers could unknowingly introduce the fungus into their own fishing ponds, and just one infected tadpole has the potential to infect the rest of the pond’s amphibian population.

Why should farmers, or others, care about chytrid? Collins said the pandemic could lead to a situation where frogs no longer sing to signal the start of spring, similar to the events described in Rachel Carson’s “Silent Spring.” Carson’s 1964 book tackled irresponsible pesticide use. Its first chapter describes a fictional town in heartland America whose springs lack not only birdsong, but also the voices of fish, bees and human children.

Meet Batrachochytrium dendrobatidis, the fungus responsible for chytridiomycosis, the chytrid disease. This image shows a cluster of chytrid fungi in the epidermis of an amphibian.
Photo: North-West University, South Africa

“We may be looking at the disappearance of amphibians,” Collins said.

Rafe Brown, assistant professor of ecology and evolutionary biology, fears that may happen in the Philippines.

“If the fungus gets introduced there,” Brown said, “literally hundreds of species could go extinct in a matter of years.”

Brown, who specializes in Asian amphibians and reptiles, said the Philippines had more diversity of life than anywhere else on the planet. However, parts of this biological hot-spot have already been devastated by deforestation. In response, Brown and other researchers are currently writing a grant to document vertebrate diversity, which includes amphibians, in the Philippines. The proposed team would also research ways to combat species extinction in the region.

In another diversity hot-spot, Thailand, McLeod, graduate teaching assistant, recently tested frogs for evidence of chytrid’s spread. McLeod said bullfrogs were imported to Thai farms and markets in the 80s. Those imports, along with a thriving Southeast Asian amphibian pet-trade, could easily ignite a Thai outbreak.

Even though McLeod did not find chytrid in Thailand, he said his research was just the first effort. “It’s the beginning of momentum, I hope.”

McLeod called Asia a huge blank spot on the map of chytrid research. His 123-frog survey was the first ever done concerning chytrid and the Asian continent. It does not prove chytrid is absent from Asia.

According to McLeod, since amphibians are extremely sensitive to changes in their environments, they make good environmental indicators. As their populations are declining worldwide, he said they could be our planet’s the canary in the coalmine.

“If they’re our early warning sign,” McLeod said, “how is this going to affect us next and can we prevent it?”

According to Mendelson, the chytrid disease in frogs is eerily similar to HIV, Ebola, and other diseases like SARS, diseases that the Centers for Disease Control and Prevention in Atlanta classifies as emerging infectious diseases.

Brown said scientists are finding that the fungus isn’t new, but is for some reason manifesting itself now.

According to Mendelson, the proposition that there could be a connection among everything from SARS to chytrid is the million-dollar question.

“We’d be stupid if we did not pay very close attention to this,” Mendelson said. “Something really terrifying is happening to the planet.”