Highlights
- Chronic wasting disease is a highly contagious and untreatable illness that kills deer and their close relatives. The disease has now been detected in a Florida deer for the first time.
- The state’s first confirmed case of chronic wasting disease has spurred regulatory changes designed to curb its spread.
- University of Florida scientists are working with Florida deer farmers as they navigate new regulations and make decisions about their operations.
In June, Florida confirmed its first known case of chronic wasting disease, a devastating and lethal illness that affects deer and their close relatives. A white-tailed deer killed on the road in Holmes County near the Alabama border tested positive for the highly contagious disease during routine surveillance by the Florida Fish and Wildlife Conservation Commission.
Chronic wasting disease is virtually impossible to eliminate once it is established. There is no treatment, and the disease inevitably ends in the infected animal’s death.
FWC regards chronic wasting disease as one of the state’s most serious wildlife diseases, with the potential to cause significant declines in Florida deer. The agency issued new rules for deer farmers and hunters in the Holmes County area to help curb the spread. More regulations could come as state-wide testing for the disease continues.
University of Florida disease experts are keeping deer farmers across the state informed of the shifting regulatory landscape and helping them think through their response plans.
“While we weren’t surprised by chronic wasting disease’s arrival in Florida, we were dismayed,” said Samantha Wisely, professor in the UF/IFAS Wildlife Ecology and Conservation Department and member of the Emerging Pathogens Institute. “This is going to change the nature of how we manage deer in Florida forever.”
Wisely directs the Cervidae Health Research Initiative, or CHeRI, a consortium of UF scientists and Extension specialists who work to protect the health of captive deer in Florida. CHeRI collaborates with deer farmers by sharing the latest scientific findings on deer diseases, nutrition and pest management; conducting research on deer farms; and providing free diagnostic testing of sick and dead captive deer.
Through CHeRI is not actively involved in chronic wasting disease research, “we have an important role to play in helping deer farmers in Florida navigate it,” Wisely said.
With chronic wasting disease, the body attacks itself
Unlike illnesses caused by viruses, bacteria or fungi, chronic wasting disease, or CWD, occurs when healthy proteins in deer, elk or moose become deformed. This transforms the proteins into infectious agents of disease known as prions. Prions trigger the same deformation in other proteins they encounter.
Enzymes are unable to break prions down, which gradually build up in plaques, particularly in the brain. Chronic wasting disease has a long incubation period – on average, infected animals do not show symptoms for 16 months. The disease eventually manifests itself in dramatic weight loss, trembling, staggering, listlessness and other neurologic symptoms.
“It’s really only in the very final stages of the disease that animals start to look sick, and then they decline quite rapidly,” Wisely said.
Prions can pass through direct contact between animals, such as touching nose to nose. Infected deer also shed prions in their bodily fluids, creating an environment in which other deer can easily become infected. Some research suggests shed prions can be taken up by plants and transmitted during foraging, Wisely said. Ticks can spread prions as well. The disease can also arise due to proteins spontaneously misfolding.
Wisely said part of the insidious nature of chronic wasting disease is the unusual persistence of prions, which can remain active in the soil for decades.
“In areas where a high number of deer become infected with CWD, it’s almost like a Superfund site,” she said.
There is no evidence that people can become infected with chronic wasting disease. As a cautionary measure, however, the Centers for Disease Control and Prevention recommends abstaining from eating meat from an infected deer or from untested deer in a CWD-positive area.
Chronic wasting disease, a kind of spongiform encephalitis, was first detected in Colorado in the 1960s. It is now found in 31 states, as well as parts of Canada, Norway and South Korea.
Chronic wasting disease could reshape Florida deer populations
While Wisely is not concerned chronic wasting disease will drive white-tailed deer extinct, the disease can change the structure of deer populations in places where it is prevalent, she said.
“We’re not going to see older animals in areas where there’s high incidence of CWD,” Wisely said. “That has big implications because it’s the large trophy-sized bucks that people want.”
That could signal trouble for Florida’s deer farmers: Raising and breeding deer for trophy hunting and venison is big business, bringing in $8 billion nationwide each year, according to a 2017 report by Texas A&M University. Florida’s deer farming industry is the fourth largest in the U.S.
In an effort to protect both captive and wild deer, CHeRI partners closely with Florida deer farmers to search for and study pathogens that impact deer. The organization also tests pest management techniques for the insects and ticks that transmit deer diseases. CHeRI’s work has led to the discovery of seven new viruses that infect Florida deer, Wisely said.
The consortium primarily focuses its research on epizootic hemorrhagic disease virus and bluetongue virus. These viruses have long affected Florida deer, but are emerging pathogens in other parts of the U.S. as warming temperatures allow the midges that spread these diseases to expand their range northwards.
Florida deer farmers see CHeRI as trusted source for chronic wasting disease
With the arrival of chronic wasting disease, Wisely’s goals are to help farmers navigate the new regulatory environment, stay abreast of evolving chronic wasting disease management in Florida and prepare for the possibility that the disease could appear in their area.
FWC’s response to chronic wasting disease has included quarantining deer farms in the Holmes County area for five years. Deer farmers in other parts of the state worry future rules could be stricter. Because there is no reliable chronic wasting disease test for live deer, some farmers are concerned agencies could require them to harvest their animals. Wisely said CHeRI can help moderate tense conversations.
“We’re working to make sure that when passions get high, people can still hear each other,” Wisely said. “There’s a huge human element to all wildlife diseases.”
Mike Mansfield of LaBelle, Fla., has been raising deer for more than 25 years and has collaborated with CHeRI for nearly a decade, allowing scientists to carry out entomological fieldwork on his property and necropsy several dead fawns. He said he trusts CHeRI and the information shared by its scientists.
“They’re doing real, on-the-ground studies,” Mansfield said. “Am I going to change my world because science comes along? Probably not. But I’m going to listen to them.”
CHeRI has also conducted research on the Levy County deer farm owned by Bill Leffler, vice president of the Southeast Trophy Deer Association, which co-hosted a recent seminar for deer farmers with CHeRI on deer nutrition, pest management and diseases, including chronic wasting disease.
Leffler said he believes CHeRI has a genuine interest in helping deer farmers preserve the lives of their animals and sees the organization as a vital conduit of scientific information on chronic wasting disease. “Facts can only be delivered effectively through proper communication,” he said. “I believe CHeRI does a great job.”
Written by: Natalie Van Hoose