A highly contagious and deadly fungal disease – considered the worst to affect wildlife in recorded history – is spreading, endangering amphibians across an entire continent.
The deadly disease, known as chytridiomycosis, is caused by a microscopic fungus called Batrachochytrium dendrobatidis (BD). Infection with this fungus has a devastating effect on frogs, toads and other amphibians.
The disease causes the skin of these animals to peel while leading to other symptoms like lethargy, weight loss and ultimately heart failure. The disease is highly contagious, transmitted by spores released by the fungus.
“The risks are significant,” said Vance Vredenburg, a professor in the biology department at San Francisco State University. Newsweek. “In fact, this disease is the worst in recorded history. It has infected over 1,000 species of amphibians and caused the decline of around 500 species – dozens have disappeared.”
Since the 1980s, the pathogen has spread and caused massive amphibian mortalities around the world. It continues to spread to this day.
A study published in the journal Frontiers of conservation science has now discovered that the fungal pathogen is spreading across the African continent, a region which scientists believe had escaped the worst of the disease.
But Vredenburg and his colleagues found that the disease has already established itself in Africa, and its spread over the past two decades appears to have been overlooked in the region. Researchers have found that it will likely become more widespread, and amphibian declines and extinctions may already be happening under the radar there.
“Since 2000, Bd has spread across Africa and may threaten species across the continent,” Vredenburg said.
Africa is home to about 16 percent of known living amphibian species, but there is no described Bd epizootic – a pathological event in an animal population similar to an epidemic in humans – in Africa, although the disease is known there.
The researchers said the lack of outbreak reporting was likely due to lower Bd sampling efforts in Africa compared to other continents rather than a true lack of events.
The authors of the Borders The study came to its conclusions after analyzing thousands of museum specimens collected from various locations in Africa between 1908 and 2013. They also tested skin swabs from live amphibians captured between 2011 and 2013, as well as scientific records from the period 1852-2017.
They found a pattern for the emergence of comics in Africa largely beginning around the turn of the century. From 1852 to 1999, they observed a low prevalence of Bd (about 3% overall) and a low geographic distribution on the continent.
But after 2000, they documented a steep rise in prevalence, rising to more than 21% during the 2010s. In some countries, for which more data were available, the rise was even higher, reaching more than 70% in Burundi, for example.
“We should be worried,” Vredenburg said. “This is the first fungal pathogen to cause this level of mortality in vertebrates. Although not a The last of us time for humanity, we should try to learn from it to better understand what factors led to a fungal pathogen having such a profound effect on hosts.”