The most deadly disease of all time & # 39; eliminates 90 species of frogs and toads



It is the plague of your worst science fiction nightmares, caused by a deadly pathogen that spreads not only through contact, but also in the water, literally swimming after new victims become infected.

The skin is eaten, which eventually causes heart failure and mbad deaths. Not only does it jump from one species to another, but among hundreds. And it has spread into the zoo equivalent of a global pandemic, thanks to humans.

Unfortunately, this is neither science fiction nor a dream. It is a very real disease called chytridiomycosis, caused by fungi. Batrachochytrium dendrobatidis Y B. salamandrivorans, It affects a wide range of amphibians, including frogs, toads, salamanders and newts.

This disease has caused more damage to more species than any other disease in the history of science.– Wendy Palen, Simon Fraser University

Scientists have just seen the "unprecedented lethality" that has caused worldwide in the last 50 years:

  • The complete extinction of 90 species, from the golden toad of Costa Rica to the torrential frog of Mount Glorious of Australia to the toad of Baxter in the state of Wyoming in the United States.

  • The dramatic decrease in the population in other 411 species, especially in Australia and Central and South America.

The international team of researchers, led by Ben Scheele and Claire Foster at the National University of Australia, published their results last week in the journal Science.

"We have records of pathogens since the time of the dinosaurs, and Undoubtedly, this is the deadliest disease that has hit the wildlife at all times. " Luis Felipe Toledo, a professor at the Biology Institute of the University of Campinas in Brazil and co-author of the study, said in a statement.

A yellow-legged mountain frog showing signs of severe chytridiomycosis, including an abnormal posture (left) and dead frogs after an outbreak of chytridiomycosis in Milestone Basin, California. (Jamie Voyles et al./PLoS ONE 7 (4): e35374 / licensed under CC BY)

Scientists had already linked the disease with declines and extinctions of amphibians worldwide, but the exact figures had been difficult to obtain due to the lack of data. The researchers compiled decades of unprecedented studies and research from experts around the world to arrive at what they consider a conservative estimate of the cost of the disease.

When Foster compiled the results of different researchers in different countries, he recalled in an email that "the overwhelming feeling was probably sadness."

Many of the species that were reported were taken to extinction due to the disease and that she had not heard before, so she searched for them on Google.

"So many amazing and beautiful species have been lost, "he wrote," and for many of us we almost do not know how they lived. "

Native to Central America, this red-eyed frog covered in moss (Duellmanohyla soralia) is one of hundreds of species negatively impacted by the chytrid fungus and is now in danger of extinction. (Jonathan E. Kolby / Amphibian Rescue and Conservation Center of Honduras)

The study found that the population decline caused by the disease peaked in the 1980s, at least a decade before the discovery of diseases in 1998. But only 12% of affected species show signs of recovery. Four out of 10 affected species continue to decline.

Pet trade blamed

Evidence suggests that the disease originated in Asia and was spread throughout the world by humans who imported and exported amphibians as pets.

Foster said governments and other agencies should begin to take biosecurity and illegal wildlife trade much more seriously to prevent the spread of disease.

Wendy Palen is a professor of biology at Simon Fraser University and conducts research on freshwater ecosystems, including amphibian populations. She co-authored a commentary published with the new article describing the mushroom as the "perfect recipe to take its hosts to extinction."

It is very transmissible through water, where it can reach many different types of amphibians. It has a wide variety of hosts and can infect some species without causing symptoms, allowing them to spread more widely.

This is an Australian corroboree frog in danger of extinction with chytridiomycosis, which attacks the animal's skin and eventually causes respiratory problems, cardiac arrest and death. (Image courtesy of Jamie Voyles, Alex Hyatt and Frank Fillipi)

Palen said the study confirmed that the disease was to blame for many declines and extinctions of amphibians worldwide, as many scientists in the field expected. "But it's also bigger than anyone has quantified before."

He added that its destructive effect on biodiversity has been much worse than that of other deadly wildlife diseases, such as the white nose syndrome in bats and avian malaria in birds.

"This disease has caused more damage to more species than any other disease in the history of science, "he said.

While none of the most affected species is in Canada, Palen said, the disease exists here and has caused problems for some of our amphibians.

"It's really global in scale," he said in an interview.

But he pointed out that it can still get worse, since it has not yet reached some parts of the world that are particularly rich in amphibian diversity, such as Papua New Guinea.

This is a microscope image of the fungus that causes chytridiomycosis. It can spread through the water and even swim in search of possible guests. (Christian Martin)

Your comment adds that Image of chytridiomycosis may Also being "a harbinger of other outbreaks of disease" as human beings "inadvertently spread pathogens around the world."

"That, I think, is a warning note, "he said. And in some way it demands that we think carefully about the policies related to the importation of amphibians especially alive. "

However, he pointed out that the disease is not the only or the greatest threat to amphibians worldwide.

"We know that climate change and habitat destruction and drainage of wetlands and changes in terrestrial ecosystems are causing an equal or greater number of amphibian declines," he added.

The disease is "Another nail in the coffin," he said. "And it forces us as a society and our communities to do something about it."


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