By Marilyn Perkins | Illustrations by Simbie Yau
The Hidden Virus Threatening Curacao's Sea Turtles
A strange virus is spreading tumors in sea turtles. Researchers are uncovering new clues as to why.
On Christmas Eve in 2022, Blue Bay Beach in Curaçao went dark. The resort where biology researcher Manuela Tripepi, PhD, was vacationing with her family had turned off all its lights for a special occasion: not the holiday, but sea turtle hatching season. Dr. Tripepi had seen volunteers preparing the beach for days in anticipation, and it looked like tonight would be the big night.
They had told her this was one of the last nests of the season to hatch. Dr. Tripepi watched as the tiny sea turtles emerged one by one from the nests their mothers had dug in the sand months before. The tiny hatchlings — only about 2 or 3 inches long — made their way to the ocean, orienting themselves by the light of the moon. If the resorts don’t turn off their lights, the turtles can’t find their way to the sea.
Sea turtles typically lay multiple nests per season, each with over 100 eggs. Only about 1 in 1,000 of these hatchlings will make it to adulthood, facing many threats along the way. In fact, as Dr. Tripepi talked to the volunteers watching over the hatchlings, she learned of a disease that was causing sea turtles in Curaçao and across the world to grow tumors at alarming rates, with no known cause.
“I made a promise that I would come back and help,” she says.
That promise led Dr. Tripepi on a years-long journey to study the disease-ravaged sea turtles in the Caribbean and beyond. She may be on her way to uncovering some answers about the disease’s origin, but conducting research nearly 2,000 miles away from home has posed its own challenges.
Problems in Paradise
Curaçao is known for its cerulean water, white sand beaches and marine wildlife. The island is home to three species of sea turtle: green, hawksbill and loggerhead. Tourists flock to Curaçao’s beaches for the guarantee of swimming with these creatures, but the turtles face major threats. According to the International Union for Conservation of Nature, each of these three species is endangered or critically endangered. Habitat destruction, climate change, fishing boats and pollution all jeopardize turtles in Curaçao. But a more mysterious threat has become apparent in recent years: a disease called fibropapillomatosis (FP).
A sea turtle on the ocean floor.
A tumor caused by the FP virus.
A green turtle hatchling.
FP is a virus in the herpes family that primarily affects green sea turtles. First documented in 1938 in Key West, Florida, it’s now been spotted worldwide. The condition causes tumors to sprout over sea turtles’ faces, flippers and the rest of their skin. The tumors themselves are benign, but they eventually grow so large that turtles can no longer see, eat, swim or reproduce, ultimately causing their death.
Ard Vreugdenhil, field director of Sea Turtle Conservation Curaçao (STCC), says that he first began to see turtles with FP in Curaçao about eight years ago. An outbreak among just a few turtles quickly snowballed, with more and more turtles around the island succumbing to the tumors.
“It was shocking to see how fast it was developing,” Vreugdenhil says. “In certain areas, we went from seeing no turtles with the disease to 100% being affected.”
Today, FP affects up to seven out of 10 sea turtles in Curaçao, though rates vary in different locations around the island.
FP is an ancient virus, and it likely evolved alongside sea turtles for millions of years. Like human herpes viruses, FP can lay dormant for years without causing any outward symptoms because the turtles’ immune system keeps the virus at bay. In fact, many turtles likely carry FP without ever developing tumors. The problem with FP, Dr. Tripepi says, is not just that more turtles are being infected, but rather that the virus is “activating” at rates never seen before.
So what makes FP activate in some sea turtles, but not others? The leading theory — and the one that Dr. Tripepi is investigating — is stress.
“Pollution, human activity and other disturbances may be causing stress to the turtles,” Dr. Tripepi says. “That stress may somehow dysregulate these animals’ bodies, which allows the virus to activate and cause these tumors to grow.”
In certain areas, we went from seeing no turtles with the disease to 100% being affected.
Following the Turtles
As a researcher who studies how stress impacts organisms, Dr. Tripepi was uniquely positioned to study FP — but getting a study started in Curaçao wasn’t easy.
Curaçao is a small nation, with a population of only about 150,000 people. The country has limited scientific resources, meaning that most equipment needs to be bought elsewhere and flown onto the island. The majority of Curaçao’s conservation work is done by volunteer organizations, such as STCC. With 100 active volunteers but only one full-time paid staff member, STCC already juggles rescuing sea turtles injured by boats, protecting eggs during nesting season and educating the public.
But in the spring of 2023, Dr. Tripepi was able to secure an internal grant from Jefferson to return to Curaçao. The money was enough to cover 10 radio tracking devices, which she planned to use to map the sea turtles’ feeding grounds.
Dr. Tripepi (purple shirt) works with STCC volunteers to measure a sea turtle and take vitals.
A radio transmitter affixed to a turtle’s shell to track its movement.
Volunteers carrying a sea turtle.
Dr. Tripepi hoped if she could find where turtles with FP were eating, she might be able to find a nearby stressor that was causing the virus to activate. She worked with STCC to capture and affix the radio transmitters to turtles in Caracas Bay, a rocky beach on the southern coast of Curaçao. It was not an easy task. Dr. Tripepi paddled a kayak hundreds of meters out from shore, watching as the seafloor dropped off and the water turned from aquamarine to pitch black.
Vreugdenhil waited below the surface in scuba gear, scanning the dark water for turtles. Once he spotted one, he dove to retrieve it. The turtles were difficult to wrangle, weighing as much as 100 pounds. They were also angry.
“Twice, the turtle ripped the regulator out of my mouth, so I was without my oxygen source at a depth of 20 meters,” Vreugdenhil says.
With the help of another volunteer in the water, Vreugdenil hoisted each turtle into Dr. Tripepi’s kayak, leaving her to paddle against the wind as she attempted to calm the thrashing creature in her lap.
Back on shore, more volunteers waited to check the turtle for tumors, take pictures and affix the radio transmitter. Over the course of two weeks, Dr. Tripepi and the STCC volunteers were able to capture and affix radio devices to eight sea turtles in Caracas Bay. Five of them had tumors, making them prime candidates to track.
Once the sea turtles had been released, the team began searching for radio signals from the turtles’ feeding ground. They pinpointed a small inlet off the main beach where the turtles were feeding on seagrasses near a marina.
"Sentinels of Aquatic Pollution"
Green sea turtles are primarily herbivores, with a diet consisting mostly of seagrass and algae. Dr. Tripepi thought if she could find any pollutants in the seagrass the turtles were eating, it may provide clues as to why they were getting sick.
Dr. Tripepi, though, had to return to Philadelphia. So, Ingo van Veghel, a field assistant at STCC, set out to collect seagrass samples from the feeding grounds they’d identified earlier, as well as from other locations around the island. The samples were dehydrated and sent back to Philadelphia.
There, Dr. Tripepi’s colleague at Jefferson and analytical chemist Jeffrey Ashley, PhD, who studies how man-made chemicals travel through and accumulate within urban aquatic ecosystems, took them to his lab. Working with a team of undergraduate researchers — premedical studies majors Emily Valenzuela, Aliya Bilimoria, Giorgia Penesso and Isabella Vitales, and medical laboratory studies major Ellianna Ruggeri — he began looking for clues in the seagrass.
Seagrass, it turns out, is a powerful indicator of environmental conditions. It absorbs whatever pollutants are present in the water where it grows, making it a promising tool for monitoring marine contamination.
“We could use these seagrasses as stationary sentinels of aquatic pollution,” Dr. Ashley says.
In his initial tests, Dr. Ashley focused his analysis on heavy metals, particularly those that could come from a nearby shooting range on the island. The data revealed elevated levels of lead and copper in the seagrass from Caracas Bay, the same area where most of the turtles with FP were found. Still, the findings raise more questions than they answer. If heavy metals are playing a role in FP, researchers will need to detect elevated metal levels in the turtles themselves — and determine whether those levels correlate with tumor growth. It also remains unclear how, exactly, such pollutants might trigger the virus to activate.
“It could mean that exposure to these chemicals reduces feeding behavior, sexual behavior, migration behavior — all potential stressors,” says Dr. Ashley. “Or these trace metals could be knocking out an important biochemical mechanism in the turtle’s ability to fend off the virus.”
Because the link to heavy metals remains tenuous, Dr. Tripepi plans to expand the search for other sources of stress affecting turtles around the island. A number of pollutants are still on her radar: municipal water treatment is limited, so cesspools of raw sewage leach into the nearby ocean. A legacy of oil refining may have left behind contaminants in soil and water, and boat activity introduces pollutants as well. But many of these chemicals are hard to test for — and often don’t survive the dehydration and shipping process needed to bring samples back to Jefferson, meaning the road ahead will be difficult. “The search continues,” says Dr. Tripepi.
It could mean that exposure to these chemicals reduces feeding behavior, migration behavior — all potential stressors.
Coming Full Circle
As Dr. Ashley’s lab analyzed the samples, Dr. Tripepi returned to Curaçao in December 2024. She wanted to catch the turtles they had previously tagged and see if their tumors had worsened — or, perhaps, healed.
Unfortunately, the glue binding the radio transmitters they’d affixed the year prior had already broken down, leaving the transmitters at the bottom of the ocean and the turtles nowhere to be found. Dr. Tripepi hoped they may be able to find them again, but the odds were slim. It was clear she needed a more reliable way to track the turtles.
Fortunately, she was able to secure a second Jefferson grant to acquire higher-tech microchip Bluetooth devices known as PIT tags. Unlike the bulky radio transmitters, the PIT tags are easier to read and cause less stress to the animals. Moreover, the grant allowed her to expand her research operations — at the end of 2025, she returned to Curaçao, this time with Dr. Ashley and seven Jefferson students in tow.
Photographs taken by John R. Gooding.
Over the course of the week, the researchers, students and STCC volunteers captured 35 sea turtles and implanted the PIT tags. The technology will allow researchers to more accurately estimate the total turtle population around the island, determine what proportion is affected by FP, and track how tumors progress over time.
The team also collected 22 DNA samples to analyze the turtles’ microbiome — the community of bacteria and fungi that live on and within all organisms. In humans, changes to the microbiome have been linked to immune dysfunction and disease. Dr. Tripepi hopes similar patterns may help explain why FP activates in some turtles but not others.
For Dr. Tripepi, the trip was a culmination of everything she’d been working on since she first visited Curaçao. During the visit, she and her students witnessed sea turtle hatchlings emerge from their nests — the same population she had first seen nesting on the island three years earlier. Seeing the turtles return, this time alongside students, felt like coming full circle.
Drs. Manuela Tripepi and Jeffrey Ashley with Jefferson students Joseph Hough, Ellianna Ruggeri, Emily Valenzuela, Isabella Vitales, Sarah Balkiewicz, Spencer Talbot and Aliya Bilimoria.
And after all these years, her research is gaining traction. She recently published the first formal scientific report documenting FP in Curaçao in the European Zoological Journal, helping put the island on the scientific map. During the 2025 trip, she and her students were received by the governor of Curaçao, a sign that government attention to the disease may finally be growing.
Meanwhile, Sea Turtle Conservation Curaçao is building its own physical center and research infrastructure, including an AI-assisted photo database to identify individual turtles.
“My dream would be to create a small research space we can keep coming back to,” Dr. Tripepi says. “When I’m down there and I think about all of these volunteers, that’s what brings me hope.”
“I miss it,” she adds. “I’m already thinking, when can I go back to help?”