Since the mid 1990s, a type of virus known as a ranavirus has been taking a devastating toll on reptiles and amphibians, especially turtles, frogs, toads and salamanders, in more than 20 states across the U.S. Hundreds of thousands of these animals have died from the lethal virus and the disease continues to spread. Scientists are stepping up their efforts to better understand and combat the pathogen.
A few years ago, Scott Farnsworth, a graduate student at Towson University in Maryland, was sent to a wooded park in Maryland to relocate box turtles safely away from a new highway.
Farnsworth and his team tagged 100 turtles with radio transmitters. But then the reptiles started turning up dead. And not just turtles. They began seeing massive die-offs of toads, young frogs called tadpoles and salamanders. Lab analyses showed the culprit was the ranavirus, a class of viruses that mostly infect cold blooded animals.
“It’s pretty quick. We can go from seeing no outer signs,” he explained. “To having complete mortality for all of the ones in the pond within a few days.”
While amphibians die within hours of infection, box turtles can survive as long as a month. A lab test showed the animal died struggling to breathe. Ranavirus often infects amphibians during their egg and juvenile stages, leaving them unable to swim. But it affects only adult turtles. “It could send them on a glide path towards extinction,” said Farnsworth.