Deadly Tumor Threatens Endangered Green Sea Turtle; Scientists Investigate the Development of New Viral Disease

In a new epidemiological study conducted on endangered juvenile green sea turtles in eastern Brazil, scientists discovered the factors that trigger the development of a tumor disease linked to a herpes virus. Researchers from the University of California, Davis, found how the distribution of the tumors from fibropapillomatosis (FP) can provide clues to understand the disease better.

What is Fibropapillomatosis?

Fibropapillomatosis is a tumor-causing disease that affects some sea turtles. In this condition, the skin all over the turtle's body, including the eyes and mouth, forms tumors that resemble cauliflower. The tumors can also grow in flippers, neck, and limbs. Although not invasive, the tumors can affect the animal's activities, such as swimming and feeding. These tumors can also develop in the internal organs of the animals.

All species of sea turtles are susceptible to this disease, but most cases with the highest severity are recorded in endangered juvenile green sea turtles. Some sea turtles only manifest mild forms of the disease, while others develop large or numerous tumors that can lead to blindness or interfere with vital body functions. In extreme cases, the tumors can cause debilitation and death.

The earliest cases of sea turtle FP were recorded in Florida in the late 1800s and first appeared in the scientific literature in 1938. It gained international attention in the 1980s when the disease was commonly reported in endangered populations of green sea turtles in the U.S. and other countries.

What Factors Trigger the Viral Disease?

Fibropapillomatosis is one of the diseases that has puzzled scientists for years, according to research senior author Marcela Uhart from One Health Institute at the UC Davis School of Veterinary Medicine. One of the reasons is that the site where the tumors show up is not as random as experts used to think.

To better understand the disease, UC Davis researchers collaborated with experts from various Brazilian institutions to study the ecology of FP in green turtles. They chose animal samples from Espírito Santo in eastern Brazil since this area has high cases of FP, with over 40% of the turtles manifesting the tumors.

The team discovered that the presence of metallurgical plants may have contributed to the high prevalence of FP in the area. The research findings also suggest that the combination of age, body condition, and environmental factors (temperature, salinity, proximity to metallurgical plants) play a crucial role in the likelihood of developing tumors.

The researchers also discovered three different patterns of FP. Tumors were found to concentrate either in the back flippers, front flippers, or other parts of the turtle's body. Environmental factors also influenced these FP patterns.

The information gathered from the research can be used to understand the emergence of the disease and how it can be controlled. As Uhart describes, sea turtles' health could worsen if the trends continue.