Researchers at the Cornell Wildlife Health Lab are leading interagency efforts to prevent the spread of chronic wasting disease in New York and in the United States.
CWD is a transmissible spongiform encephalopathy, a rare neurodegenerative disease affecting free-ranging cervids, such as elk, deer and moose.
Transmissible spongiform encephalopathies are spread by prions, which cause abnormal folding of proteins in the brain. Abnormally folded proteins are unable to be broken down, resulting in plaques that cause brain cells to die and holes to form in the infected animal’s brain.
Deer infected with CWD may exhibit poor coordination; lowered head and ears; abnormal behaviors and excessive urination, thirst and drooling. At the end-stage of the disease, an infected deer will lose substantial weight, also known as wasting, and die. A deer may not show clinical signs for a year or more, but they can spread the disease before showing symptoms.
According to Prof. Krysten Schuler, public and ecosystem health, director of the Cornell Wildlife Health Lab, it remains unclear whether deer are infected through direct contact with an infected deer or through indirect contact with prions spread into the environment from an infected deer’s urine, feces or saliva.
“This is the only prion disease that occurs in free-ranging animals, and free-ranging animals are very difficult to study,” Schuler said.
Since CWD was first detected in wild deer in 1981, CWD has spread to 31 states. Once CWD is established in the environment, the disease can spread quickly and is difficult to contain. To date, New York State is the only state that has eradicated CWD, and surveillance on cervid populations is ongoing.
“You want people to look for the disease at a level that’s appropriate and where they’re most likely to find it because that earliest detection is when we have the best opportunity to do something about it,” Schuler said.
In 2012, NYS implemented a risk-weighted surveillance plan. The plan accounts for risk factors of CWD, including the number of deer, known presence of CWD and possible transmission routes. This surveillance plan has since been implemented in other states.
The Cornell Wildlife Health Lab leads the Surveillance Optimization Project for CWD, which allows wildlife agencies to share and compare surveillance data and to monitor CWD in several states.
“We started doing the surveillance optimization project to get states to work together on a bigger scale using the same methods,” Schuler said.
The project has formed a CWD data warehouse, which stores data for wildlife management agencies and researchers. The warehouse allows for NYS to monitor CWD in neighboring states to prevent re-introduction.
At the local level, New York hunters’ knowledge of CWD risk and NYS hunting regulations can prevent disease reentry. A recent interdisciplinary study conducted by Cornell researchers identified social-psychological factors that may influence CWD risk perception among NYS hunters.
Hunters were shown one of six Facebook messages or were shown no message as a control group. The messages were attributed to the Cornell Wildlife Health Lab, the New York State Department of Environmental Conservation or the National Deer Association. Messages were either certain or uncertain about CWD risks.
Past hunting behaviors, knowledge of other hunter’s behaviors, knowledge of CWD, environmental values and the perceived credibility of the post’s source influenced the perception of CWD risk among hunters.
The study found that hunters that had less knowledge of CWD, stronger environmental values and less knowledge of other hunters’ dangerous hunting practices were more likely to be influenced by the messages. Among hunters that did not initially view CWD as a threat, social media posts attributed to the Cornell Wildlife Health Lab were more effective at changing CWD risk perception in hunters than posts made by the NYSDEC and the NDA.
“I’m pleasantly surprised,” Schuler said. “We put a lot of effort into the website to make it as useful for the public as we can. So the fact that people recognize it as a credible source is really important.”
According to Schuler, hunters should adhere to best practices such as wearing gloves when touching an animal and washing hands and utensils after contact with meat. They are advised to not consume any meat from an animal that is infected with CWD, because cooking meat will not kill prions. Schuler emphasized that hunters should be aware of NYS hunting regulations as well as relevant local regulations when hunting out-of-state.
While CWD has yet to appear in humans, studies in animal models have suggested that CWD may have the potential to be transmitted to humans.
According to Schuler, CWD is in the same disease family as bovine spongiform encephalopathy, also known as mad cow disease, which has been known to infect humans. Other transmissible spongiform encephalopathies, such as scrapie in sheep and goats, are not transmissible to humans.
The Cornell Wildlife Health Lab advises that people should not refrain from hunting.
“What worries me more is what would happen if people think they can get it,” Schuler said. “Even though the risk may be very low, if the perception [of transmissibility] is there, then that could be really devastating for wildlife conservation.”
While CWD should be perceived as a risk, Schuler emphasizes that the disease is “not a doomsday scenario.” The lab continues to help hunters, wildlife management agencies and researchers prevent the spread of CWD.
Taylor Rijos can be reached at [email protected].