Bloodsucking Asian worms killing Florida snakes

Capable of growing longer than a giraffe, heavier than the average U.S. man, and as a thick as a telephone pole, the Burmese python ranks among the world’s largest snakes.

Imported from Southeast Asia and set loose in Florida’s southern swamps, the invasive serpent has no natural predators. While much has been said about how the Burmese python has decimated the Florida Everglades’ delicate ecosystem, what hasn’t is how — through a bloodsucking parasite — the serpent’s indirectly killing creatures as far north as Central Florida.

The target? Other snakes.

The worst part isn’t what’s known about the parasite, but what isn’t, said Stetson University biology professor Terence Farrell, who along with researchers from the University of Florida, Fairleigh Dickinson University and Stockton University in New Jersey, conducted a recent study on the invasive species.

“When an invasive species first shows up, no one knows what it’s going to do and that’s what we’re dealing with here,” Farrell said. “We’ve got something that has just appeared in Florida. It’s spreading rapidly. It’s impacting a bunch of different species, and at this point, nobody really understands how much damage it’s doing to local reptile populations. No one understands how far it will spread.”

It’s suspected that the pentastome parasite hitched a ride to Florida while embedded in Burmese pythons. Though pythons evolved to resist the parasite, native Florida snakes have not, leaving them exposed to its attacks, Farrell said.

Research from Auburn University showed that the parasites were found in road-killed pythons and several other native snakes in South Florida around 2012. However, no one suspected the parasite would make its way so far north, Farrell said.

In August, Farrell and team of students were studying a pygmy rattlesnake, but this one, appearing sickly and emaciated, was different. When the snake died, researchers discovered several worms had crawled out its mouth.

The findings troubled Farrell.

“That was our first realization that we had a strange new parasite invading our snakes,” Farrell said. “We’ve been studying these snakes for decades and were really surprised to see this.”

Based on his research, Farrell said the parasite has spread much further up the Florida peninsula than previously reported. While because of temperature constraints the Burmese python is limited to southern Florida, the parasite is not.

The worm appears to spreading very rapidly on its own, migrating at least 20 miles north each year, he said.

So far, Farrell has discovered 10 pygmy rattlesnakes that died from parasites in Volusia County, but he said it’s too early to know how often the parasite kills its host. Until more research is done, Farrell said he couldn't be sure how great the impact would be.

The three beasts — constrictor, bloodsucker, poison-fanged biter — all are entangled in a chain of events that pose a serious threat to Florida’s ecosystem. While as invasive species, both the parasite and python are bad for environment, Farrell said the parasite’s rapid advance makes it more concerning, especially for pygmy rattlesnakes, which only grow to about two feet and tend to harbor more and larger parasites than the Burmese python.

While a single parasite might not kill a pygmy, having multiple worms attached to its lungs certainly could, Farrell said. Worse, there’s already evidence, though still unpublished, that the pygmy population has declined.

However, given that the parasite has infected at least 10 other species, the total number of snakes afflicted in Florida reach into the millions, he said.

While a few snakes dying off wouldn’t be a problem, a major decline in snake population could “crash” the ecosystem, Stetson senior and aquatic and marine biology major Maddy Wheeler said.

This is because snakes are a critical component of the midpoint of the food web. While snakes eat frogs, lizards, rodents and smaller creatures, they also serve as food for alligators, birds and larger animals. Disrupting the balance could throw the food chain out of alignment, Wheeler said.

Researchers don’t know exactly how the parasite is spreading, but suspect it’s hitchhiking its way north through smaller food sources that snakes prey on, Farrell said.

When an animal eats the parasite’s eggs, the parasite develops into a larva and embeds itself in the animal’s digestive system. When a snake eats the animal, the parasite bores through the snake’s digestive system and hooks onto the lungs of the snake morphing into the adult bloodsucker, he said.

“They’re kind of like leeches that instead of being attached to the outside of an animal are attached to the inside of its lung,” he said.

Farrell said he isn’t sure how much the snakes suffer once infected.

“I can’t believe it’s pleasant to have a bloodsucking parasite in its lungs, but I don’t know to what degree it causes discomfort or pain,” he said.

Given the threat the parasite poses, the area of study needs to be greatly expanded, Farrell said.

“We know so little, but at this this point there’s no reason to suspect the spread will slow down and stop and this will just be Florida problem,” Farrell said. “We have no idea how far north and west it will spread in the United States.”