They are hunted, fed and photographed. They cause motorists to swerve and gardeners to curse.
Whatever your interest in or aversion to white-tailed deer, you may eventually see fewer of them sprinting across the road, eating your cabbage or magnified in your rifle scope. The reason: chronic wasting disease, a fatal, incurable affliction that continues to spread through four states in the Chesapeake Bay watershed.
Hunters and wildlife managers in the region can do little but slow the spread, hoping to head off the kind of scenario that has devastated deer populations in a few other states.
Though the number of deer found with CWD in Bay watershed states is relatively low so far — a total of 1,309 in Pennsylvania, Maryland, Virginia and West Virginia — the disease is expanding into new areas of each state. (New York found five CWD deer on a captive deer farm in 2005 but no infected deer have been found in the wild. CWD has not been found in Delaware.)
Pennsylvania, the state with the nation’s third-highest buck kill and second-highest number of deer hunters, has been particularly aggressive in thinning out deer populations to stop the spread in four affected areas in the state since CWD was first found there in 2012.
Yet, during hunting seasons last fall, the incidence of reported CWD rose in one disease management area to 14% of all deer shot, up from 8% the previous year. It was, said the Pennsylvania Game Commission’s top wildlife manager, “a punch in the stomach.”
“Unfortunately, the road you seem to be heading down right now will likely lead to a lot more of those punches in the stomach,” warned Bryan Richards, a wildlife biologist with the U.S. Geological Survey’s National Wildlife Health Center at a recent virtual forum about CWD in Pennsylvania.
In Virginia, where CWD was first detected in 2009, diseased deer have been reported in seven new counties over the last two years.
With no cure, or even a way to identify live infected deer, all wildlife managers can do to control the spread is dramatically reduce the size of deer herds. That’s because contact with another deer’s saliva, feces or urine appears to be the main path of transmission for the disease. Another method is to prevent deer from comingling, by prohibiting deer feeding and the use baits like deer licks or lures made of deer urine.
Herd reduction is being accomplished mainly by increasing bag limits for hunters in affected areas and occasionally using sharpshooters at night. But that approach is hampered by expense and the fact that not all hunters believe that the wholesale killing of deer is a solution.
“We’re approaching this realistically. I don’t think we can stop it from spreading,” said Brian Eyler, deer project leader for the Maryland Department of Natural Resources.
So far, no humans or livestock have gotten sick from eating or coming in contact with infected deer — unlike mad cow disease, to which CWD is related. But in one lab experiment, monkeys fed a diet of infected meat did contract the disease. As a precaution, national health officials advise against eating venison from a deer found with CWD. Some food banks no longer accept venison donations.
“It’s a game changer if it spreads to humans,” Eyler said.
“Based on what we know right now, CWD is among the greatest threats to the long-term health and stability of our deer herd,” was the sobering conclusion from a 2018 report by Gray Anderson, chief of Virginia’s Wildlife Resources Division. “CWD is essentially impossible to eradicate and very difficult to manage or contain.”
Passion for deer
The white-tailed deer is the most sought-after big game animal in North America. Deer hunting is a huge, traditional pastime and money maker in the Bay region.
Collectively, nearly 4 million hunters in Pennsylvania, Maryland, New York, Virginia and West Virginia took to the woods last fall and winter to hunt deer with guns, bows and arrows, muzzleloaders and crossbows. They shot 1.3 million deer that were turned into venison for year-round eating or donated to food banks.
In Pennsylvania, the tradition of deer hunting camps has spanned generations and, until the opening of gun season was changed two years ago to fall on a Saturday instead of a Monday, many school districts would close down for opening day.
Deer hunting pours billions of dollars into local economies. In Pennsylvania alone it has an annual economic impact of $1.5 billion, according to a 2016 study for the Theodore Roosevelt Conservation Partnership. That’s not counting money spent by residents who feed deer, or photographers and others who “shoot” deer only with cameras.
Fallout from CWD is expected to reduce the sale of hunting licenses and the number of people who advocate for hunting. That will in turn pinch state game agency budgets, hampering their ability to care for and manage wildlife in general.
CWD is thought to be caused by malformed or “folded” proteins in the animal’s brain, called prions, produced in the bodies of white-tailed deer and other cervids such as mule deer, moose, elk and reindeer/caribou. These aberrant proteins pass on the malformation to normal proteins, spreading the condition through the brain. The accumulating folded proteins riddle the brain tissue with tiny holes, rendering it spongelike and increasingly dysfunctional. As the brain impairment progresses, it causes health effects such as emaciation, but also significant behavioral changes — and invariably death.
Scientists say it is possible that prion-infected body fluids left behind by sick deer can remain viable on the ground or other surfaces for years, perhaps decades. There is no sign that deer are building up a resistance to the disease.
“Many hunters have never seen [an obviously] sick deer with CWD. It’s hard for them to fathom this clinical killer is out there. But [it is]. CWD is a death sentence for every deer that catches it,” said Richards of the USGS. The disease can take up to two years to kill an otherwise healthy deer. During that time, with associated brain impairment, the animal is much more likely to be hit by a car than a hunter’s bullet.
CWD was first detected in North America in a mule deer at a government research facility in Colorado in 1967. Since then, it has spread to 26 states.
First detections were found in West Virginia and New York in 2005, Virginia in 2009, Maryland in 2011, and Pennsylvania in 2012. Approximately 717 infected deer have been found in Pennsylvania, 403 in West Virginia, 109 in Virginia and 80 in Maryland.
Infected deer have been found in 24 counties in Pennsylvania, nine counties in Virginia, five in West Virginia and in two Western Maryland . Shenandoah National Park in Virginia has not recorded any CWD deer, but it expects to and plans to reduce herd sizes on its borders when that happens.
In both Pennsylvania and New York, the first cases of CWD were found in captive deer. In Pennsylvania especially, fenced private hunting preserves and deer farms to supply them are big business, with deer being bought and sold among facilities from various states. Thirty captive deer facilities in Pennsylvania have been found with CWD since 2012. Some would like to see this “stocking” practice banned, as has happened in Virginia and Maryland.
No method has yet been found to detect CWD in live deer. Instead, brain matter in hunter-killed and road-killed deer are tested, as is that of deer that die on captive deer farms.
In late 2019, Dr. Frank Bastian, a neuropathologist then at Louisiana State University, announced that he had discovered that CWD is not caused by prions at all, but rather by a previously unknown bacterium. He said if he had financial support, he could develop a vaccine for CWD and that mass killings of deer would no longer be necessary.
But wildlife agencies have not embraced that theory. In response to Bastian’s claim, the Association of Fish and Wildlife Agencies said it supports “the overwhelming scientific consensus that chronic wasting disease is caused by mutated proteins known as prions.”
Male deer are the most susceptible to getting CWD because they tend to travel the farthest and their social behavior brings them into contact with more deer. Killing male deer, therefore, is believed to be more effective in controlling transmission. The management goal of protecting bucks until they have bigger racks, as has been the case in Pennsylvania, will likely be abandoned in infected areas.
How bad could it get?Wisconsin was the first state east of the Mississippi to have CWD, beginning in 2002. Despite culling efforts, it is now in 32 of 72 counties and hunters that venture out in CWD hotspots have a nearly 50% chance of shooting an infected deer.
In Colorado and Wyoming, an estimated 40% or more of free-ranging cervids in certain hotspots contract the disease and die from it.
Help needed from hunters
Cooperation from hunters will be absolutely essential for CWD to be constrained, say game managers in the Bay states.
“The only hope for making things better is for hunters to help wildlife managers,” Richards said, but he added that the effort is undermined by misinformation and disinformation. “There are a lot of ulterior theories on the internet. Many believe there is no risk to deer or humans.”
And killing deer merely to eliminate them, not eat them, doesn’t sit well with many hunters either, he said. “Hunters are unlikely to kill more deer if you can’t eat them,” Richards said.
In Maryland, a ban on feeding and baiting deer was withdrawn in one disease management area “to keep hunters engaged,” Eyler noted.
But wildlife officials from the Bay states say that, so far, hunters are stepping up to the plate.
“We can be heroes to society,” said Kip Adams, a Pennsylvania resident and wildlife biologist with the National Deer Association.
Despite gloomy trends, Bay state game officials hold out hope that CWD can be minimized, if not eliminated.
“Is CWD the end of deer hunting? I’m going to say no,” Adams said. “We must be vigilant to minimize transmission [in] existing areas and to prevent introduction into new areas. But I think we can beat this.”
“The data don’t look promising right now,” Richards said, “but I would argue you can turn it around — but it will not be quick.”