A Mysterious Snake Disease Is Spreading as the Planet Warms
A possible new treatment has been found for the fungal condition — but wild snakes need healthier habitats, not individual treatment.
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.
(Video courtesy of Michael Allender)
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.
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.
Lorch explained that snakes, as cold-blooded creatures, "are very sensitive to changes in temperature. Their immune systems generally function best at a particular temperature, and they need to find an area in their habitat where the temperatures are suitable for fighting an infection."
In locations where the reptiles can't find these optimal conditions, they are more at risk of infection, he said, adding that habitat fragmentation and degradation also limit their ability to access ideal microclimates.
If snakes continue to die out, rodents they eats could increase in number, heightening our chances for contracting rodent-harbored diseases that can be transmitted to us.
There is yet another related ominous threat to our species, and to other animals.
"Since the emergence of snake fungal disease may be linked to climate change, there are concerns that what we are seeing is just the tip of the iceberg," Lorch said. "As the climate continues to change, the disease may become more of a problem."