Dec 2, 2016

A Mysterious Snake Disease Is Spreading as the Planet Warms

When Matthew Allender of the University of Illinois at Urbana-Champaign first saw snake fungal disease victims in 2010, he knew that he was witnessing a devastating illness. He told Seeker, "You could hardly even tell that they were snakes, since some were so disfigured."

The disease, caused by a fungus called Ophidiomyces ophiodiicola, can result in thickened skin, ulcers, blisters, emaciation and, in the majority of cases, death. It has infected over 20 species of wild snakes and has spread to snakes in at least 20 U.S. states, parts of Canada, and to captive snakes in many countries. Scientists say the spread of the disease is an ominous symptom of climate change.

There is some good news to report—the very recent discovery of a promising treatment—at least for captive snakes.

The treatment, which was announced at an American Association of Zoo Veterinarians meeting and will be outlined in a future paper, centers on a nebulizer. People with asthma use similar devices, which are readily available at everywhere from discount shops to "big-box" stores.

Here's how it works: A sick snake is placed in a fish tank-resembling chamber before an anti-fungal agent is pumped in via the nebulizer. The medicated "steam falls on the skin and the snake inhales it," Allender said.

While the process seems to clear up visible signs of the disease, treating wild snakes isn't terribly practical. The elusive nature of snakes, not to mention the need to capture and then diagnose wild-living victims of the disease, complicate implementing the cure. It holds promise for treating pet snakes and others in captivity, however, such as snakes at zoos.

Still, it remains unknown if snakes could still internally harbor the fungus and later pass it on to others of their own kind. (There are no known cases of it spreading to humans.)

Ideally the disease could be wiped out in the wild, but many mysteries still surround it, including how it might be connected to other fungal diseases, including those affecting humans.

"Over 80 percent of emerging diseases are fungal infections," Allender said. "A big question now is if they are all somehow linked."

He and his colleagues note that there are parallels between snake fungal disease and white-nose syndrome, an often-deadly infection affecting bats that is caused by the Pseudogymnoascus destructans fungus. Both pathogens seem to have spread quickly in recent years, and both can survive on most carbon and nitrogen sources found in soils, making them prevalent in the environment.

While it's largely believed that the white-nose pathogen was introduced into North America in more recent years, the presence of O. ophiodiicola in America has been known for some time. It was considered to be a relatively benign organism before one or more triggers likely led to it becoming a snake killer.

Northern water snake with fungal infection-caused deformity.
In a study published earlier this year, Allender and his colleagues evaluated how common disinfectants work against the fungus. Alcohol, bleach and certain other over-the-counter cleaners did a good job, but intriguingly, a common agricultural fungicide did not. He said further studies are needed to determine what role, if any, the fungicide's active ingredient—propiconazole—could play in the spread of snake fungal disease.

Jeffrey Lorch, a microbiologist with the U.S. Geological Survey National Wildlife Health Center, told Seeker that he does not believe there is a connection between these particular agricultural fungicides and the emergence of the disease "unless the fungicides are causing the immune system of snakes not to function properly."

Although the jury is still out on this matter, both he and Allender say climate change is contributing to the prevalence and severity of snake fungal disease.

Read more at Discovery News

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