First, they slithered a deadly path through the Everglades, swallowing whole some of the most endangered wading birds and small mammals in Florida.
Now, Burmese pythons are killing — although indirectly — one of their own ilk, the pygmy rattler.
A new study, led by researchers at Stetson University, shows that parasitic worms spread by invasive Burmese pythons are killing native Florida pygmy snakes, News 6 partner Florida Today reported.
The researchers found the invasive worms in Central Florida, more than 100 miles away from where the Burmese pythons reside in the southern portion of the state. But that doesn't mean the pythons are there. The parasite is getting that far north by other means, hitching rides in reptiles and other host critters that Florida snakes eat, with risk of spreading far beyond the Sunshine State.
"At this point, they are moving very rapidly. They are certainly in Brevard County," said Terence Farrell, a biologist at Stetson University and lead author on the study. "It's conceivable they will spread throughout the whole United States."
These bloodsucking snake parasites are not thought to be a health risk to humans.
"There are relatives of this parasite that people have gotten by eating raw snakes," Farrell said, adding that the odds of anyone getting this specific invasive parasite are extremely low. "There isn't a human health concern at this time."
The parasite also doesn't tend to kill or harm Burmese python, which evolved natural defenses against it.
The study, published in the journal Herpetological Review, suggests that the so-called pentastome parasites or worms, likely killed three pygmy rattlesnakes at Lake Woodruff National Wildlife Refuge in DeLeon Springs in Volusia County.
In August, Farrell, along with Craig Lind, assistant professor of biology at Stockton University, found one pygmy rattlesnake they'd been studying dead. The parasitic worms were crawling out of its mouth.
"It's truly disgusting," Farrell said of seeing the parasite's effects on its victims.
When the researchers dissected the three pygmy rattlesnakes, they found the parasites in the lung and trachea of the snakes. One of the worms was as wide as the snake's trachea, and may have obstructed the snake's airway, the researchers said.
These bloodsucking parasites typically lodge in the lungs of reptiles that become infected after eating contaminated frogs and other prey.
Pygmy rattlesnakes, which grow only a few feet long, are venomous snakes native to the southeastern United States.
Other research has found major declines in pygmy rattlesnake populations in the Everglades over the past 15 years.
But the researchers suspect many more snakes may be dying from the parasites.
"It looks like more than a dozen (species of) native snakes are being infected by this parasite," Farrell said.
The study included researchers from Stetson, University of Florida, Fairleigh Dickinson University and Stockton University in New Jersey.
“The research tells us that there’s a whole new concern about invasive species and the diseases and parasites that they bring with them,” Farrell said. “This parasite isn’t just a Florida problem. We have no idea how much of the U.S. this parasite will spread and move into, which may cause it to become a nationwide problem in a few years.”
Beyond reptiles, fish, mammals, frogs and other amphibians also are known to host the worms. So the rattlesnakes could be getting the parasites from eating some of those hosts, the researchers said.
Farrell suspects anoles and other lizards that hitch rides on vehicles could be spreading the parasites from South Florida, via the interstate highways, camping equipment and hauling loads of firewood.
Farrell, who's studied pygmy rattlesnakes for decades, called the presence of the parasites "pretty alarming" and a first in pygmy rattlesnakes.
The Burmese python, one of the largest snakes on the planet, and a native of southeast Asia, has been spreading north from South Florida for more than 15 years. The colossal reptile has slithered a path of destruction, and now reigns as a supreme predator in the Florida Everglades.
The Stetson team collaborated with the College of Veterinary Medicine at the University of Florida, which conducted DNA testing to identify the pentastome parasites. The DNA testing found the worms in the pygmy rattlesnakes were consistent with the same parasite species from southeast Asia, normally found in Burmese pythons.
“The parasites that were found in the pygmy rattlesnakes were larger than the ones found in Burmese pythons,” Farrell said. “It’s a nasty situation because the pygmy rattlesnakes haven’t evolved or developed defenses against the parasite.”