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article imageDeadly fungus found in over 30 species of snakes in US and Canada

By Karen Graham     Jun 12, 2017 in Science
Fungal diseases are an emerging threat to animals worldwide, including bats, frogs, and salamanders. Now, at least 30 snake species in North America are being hit with a deadly fungal infection and scientists want to know why.
The fungal disease in snakes is called Ophidiomyces ophiodiicola and was first identified in 2009 and put in the genus, Chrysosporium. However, in 2013, after DNA sequencing revealed the fungus to be a separate species, the genus Ophidiomyces was created to accommodate the new fungus.
Scientists examining rattlesnake specimens from 1880 to the present in Illinois have identified what appeared to be O. ophiodiicola, although the fungus didn't appear until the 2000s. Matt Allender at the University of Illinois in Urbana said he and his team of researchers looked at snake specimens in museums all across the state.
"We saw zero occurrences of the fungus from 1880 all the way through to 1999," says Allender. "The year 2000 is when we start to see its emergence in the area." The BBC is reporting that this suggests some sort of event occurred at the turn of the century that led to a relatively innocuous soil fungus turning into a deadly pathogen.
A northern water snake (Nerodia sipedon)  which was captured in 2009 from an island in western Lake ...
A northern water snake (Nerodia sipedon), which was captured in 2009 from an island in western Lake Erie, Ohio. The snake has crusty and thickened scales over raised blisters, a sign of snake fungal disease.
D. E. Green/USGS National Wildlife Health Center
The deadly fungal disease that is spreading
Some 30 snake species in 15 U.S. states and in Canada have been hit by the fungal infection, although rattlesnakes seem to have been hit hardest, particularly the endangered eastern massasauga, found in Illinois. It appears to start as a mild skin infection, and as the snake's immune system kicks in, within a few days the skin at the infection site begins to thicken and die-off.
This die-off creates a thick yellow crust that often breaks off, exposing raw flesh that allows the fungus to spread. When the infection reaches the head of the snake, it can interfere with the snake's eyes or sense of smell, leaving the animal unable to hunt and prone to death by starvation.
The mortality rate is as high as 90 percent, although scientists have discovered that a few snakes are able to recover, why this happens is another mystery about the disease. The disease also appears to affect the snake's behavior, causing them to lie in "conspicuous" places, making them more prone to attack by predators.
This eastern rat snake (Pantherophis alleghaniensis) has opaque eyes and hard  crusty scales on its ...
This eastern rat snake (Pantherophis alleghaniensis) has opaque eyes and hard, crusty scales on its snout, telltale signs of snake fungal disease.
D. E. Green/USGS National Wildlife Health Center
The disease is having a "domino effect" that puts humans at risk
Regardless of whether you like snakes or not, they are part of our ecosystem and play a major role in keeping rodent populations under control. This is relevant now because snakes hunt rodents, which spread ticks and parasites. So the absence of snakes can directly have an impact on human diseases.
"This is especially important now, with talk of this being one of the worst Lyme disease years that we’ve had in a long time," biologist Jonathan Kolby tells National Geographic. Kolby is also concerned that the captive reptile pet trade in the United States could be responsible for the spread of the disease globally.
The disease has shown up in Australia, Nigeria the UK and other countries. One theory suggests that the fungus is transferred on clothing, boots or field equipment used to handle snakes in the wild.
Timber Rattlesnake.
Timber Rattlesnake.
Massachusetts Division of Fisheries and Wildlife
Why O. ophiodiicola has become so deadly is clearly important. But there is an even more urgent question to answer: exactly how deadly is the fungus?
In 2010, Chris Reading at the Centre for Ecology & Hydrology in Wallingford, UK, and his team of researchers reported evidence of decidedly sharp snake population drops in the UK, France, Italy, Nigeria, and Australia.
"It is possible that environmental pressures on snakes, such as habitat loss or degradation, climate change, and prey availability, could all potentially impact on a snake's physiology," says Reading. "[That] might, therefore, result in a reduced ability to resist otherwise mild infections."
More about Snakes, Fungal disease, Ophidiomyces ophiodiicolaa, North America, Lyme disease
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