Chronic Wasting Disease in Whitetail Deer
IN THE FALL OF 2004, a highway crew picked up the carcass of a road-killed buck near Slanesville, W.Va. The...
IN THE FALL OF 2004, a highway crew picked up the carcass of a road-killed buck near Slanesville, W.Va. The workers took the animal to a compost facility, where a wildlife manager arrived to pull tissue samples. He made an incision in the deer’s neck and popped out a lymph node the size of a cocktail olive. He then cut through its neck vertebrae and removed a slightly larger brain structure called the obex. After being fixed in formaldehyde, these samples were sent to the University of Georgia, where preliminary test results were positive for CWD, or chronic wasting disease. By fall 2005, the tissues had been forwarded to the USDA’s National Veterinary Services Lab in Ames, Iowa, which confirmed the diagnosis. It was the first positive case of CWD found in an east-central state.
Like mad cow disease in cattle, scrapie in sheep, and Creutzfeldt-Jakob disease in people, CWD is an incurable and fatal condition that afflicts whitetails, mule deer, elk, and moose. All are “transmissible spongiform encephalopathies,” which researchers believe are caused by mysterious, nonliving proteins known as prions. Prions accumulate in lymphatic and nerve tissues, riddling a victim’s brain with holes (the “sponge” in spongiform), and in the process causing a horrific death. CWD was first discovered in the 1960s in captive cervids in Colorado. In 1981, the first wild cases appeared in Rocky Mountain National Park. Over the next few decades, it spread through free-ranging deer and elk populations in Colorado and Wyoming, and eventually into adjacent states.
In 2002, the disease moved east of the Mississippi, with whitetails in Wisconsin, then Illinois, testing positive. For eastern state game managers, the jump to the Midwest was a nightmare realized: proof that the East’s much more densely populated herds were at risk. Wildlife managers stepped up their surveillance. In West Virginia, this included a cooperative agreement between the Division of Natural Resources and the highway department to sample road-killed deer. For the next three years, monitoring throughout the East was reassuring, with no new cases reported.
Then in April 2005, one emerged in Oneida County in central New York. The deer was a local game-farmed whitetail whose meat had been donated to a sportsmen’s charity feast. The test result came back only after some 350 people had consumed steak, chili, stew, and sausage from the diseased animal. Subsequent testing of a 15-mile area in Oneida County found that CWD had crossed into wild deer populations. New York’s experience left eastern DNR officers no longer wondering if but when the disease would strike their states.
In the case of West Virginia, it took less than six months to become the 14th state (along with two Canadian provinces and the nation of South Korea) to report CWD. Slanesville, perched as it is in the eastern panhandle of West Virginia, sits a mere 10 miles from the Virginia line and only a couple of dozen miles from Pennsylvania and Maryland–all of which support huge wild deer populations. “You probably couldn’t have picked an area that affects more states,” says Paul Johansen, assistant chief of the West Virginia DNR. “We got word of our positive reading late on a Friday afternoon, and one of the first things we did was pick up the phone and call our counterparts in neighboring states. They immediately offered their assistance–everything from staff to equipment to moral support.”
Among other strategies, wildlife authorities immediately established a containment zone, and a collection team of sharpshooters harvested 216 deer, four of which tested positive. To further lower deer populations, the DNR proposed an antlerless season, restricted the transport of carcasses outside the zone, and outlawed baiting and backyard feeding.
That fall, hunters took an additional 1,016 deer within the zone; all were negative. Alas, in the spring of 2006, a second collection team culled 85 more deer, four of which tested positive.
“So far our preliminary surveillance indicates the disease is still confined geographically,” says Johansen. “I think we have a chance of containing it in this area. I just hope it holds.”
Even if West Virginia succeeds at this–something no other affected states have managed to do–the costs are already soaring. “From a conservation standpoint,” says Brian Preston, a regional representative for the National Wildlife Federation, “it’s like trying to get the toothpaste back into the tube. Once CWD gets into the wild, you virtually can’t get it off the landscape. Management of it is a huge distraction of resources. Money for fisheries, quail, and every other game species gets diverted to deal with this nasty disease.”
Recent computer models now predict that the once unthinkable–local extinctions of deer populations due to CWD–are not only conceivable but increasingly likely within the next 20 to 50 years. For his part, Johansen tries not to dwell on the distant future, adding that he has enough to worry about in the short term. “Since we got our first case,” he says, “life has totally changed here at the WVDNR. I don’t like to think about worst-case scenarios, but I can tell you from our agency’s perspective, we’re running flat out right now. If CWD surfaces in another location, that’s going to really stretch us thin. I’m not sure I’ve got any more resources to throw at this thing.”
The Long-term Spread
Although CWD has not yet panned out as a significant health concern for humans (a fact that seems to have engendered a sense of public complacency regarding the disease), it remains a staggering threat to cervids. The chief reason: Unlike other prion diseases, this form has proved remarkably easy to pass from one animal to the next. “This is perhaps the most unique feature of CWD–how readily it can be transmitted from deer to deer,” says veterinarian Edward A. Hoover, PhD, a professor at Colorado State University in Fort Collins.
Hoover is the lead author of a landmark CWD study published in the October 2006 issue of Science, a report that has further stoked anxiety levels in wildlife managers. He and his colleagues proved that the abnormal prions exist in both the saliva and blood of infected cervids. Though transmission via the latter is less likely in the wild, the former is inevitable given a wide range of deer behaviors, from licking scrapes and nose nuzzling to side-by-side grazing and grooming.
On game farms, where cervids are concentrated in high numbers, one contaminated animal can quickly infect 80 percent of the herd. In a few localized hot zones in Colorado and Wyoming, where the disease has been present for decades, prevalence rates of 30 to 50 percent have been reported in wild herds.
Cervids have no natural immunity to CWD, and there is no treatment. Most researchers believe animals are contagious long before they develop noticeable symptoms. These may take years to show, but eventually all victims succumb to a pattern of staggering, shaking, and excessive salivation, thirst, and urination. This “night of the living deer” stage leads to death.
Equally disturbing, the prions responsible don’t disappear along with their victim’s demise but rather leach intact into the environment. Recent studies have shown that prions are extraordinarily resistant to natural decay. Take the carcass of a deer felled by CWD, dump it in a fenced pasture, return in a couple of years and remove the now bare skeleton from the landscape, then reintroduce healthy deer. Many of these animals, researchers have found, will become infected.
“Prions bind tightly to soil particles,” says Bryan J. Richards, head of CWD research at the Department of the Interior’s National Wildlife Health Center in Madison, Wis. “For at least three years–the longest these paddock studies have been conducted in deer–prions in the soil continue to be infectious.” Though admittedly less efficient than direct deer-to-deer transmission, it is enough of a threat that wildlife officials must go to great lengths to safely dispose of CWD-positive carcasses.
In Wisconsin, for instance, any deer testing positive must, by law, be placed into a monstrous contraption called a tissue digester, which uses heat and chemicals to break down the prion protein. It’s expensive, but only one of multiple costs that have together rung up a $26 million tab for CWD management in Wisconsin since 2002. And it’s an important preventive measure.
“Conservation for future generations is one of the core missions of natural resource agencies,” says Richards. “Even at $26 million, are we doing enough to combat CWD? Years from now, do you want to go deer hunting in an area where every other deer is infected with a neurodegenerative disease? It will be up to future generations to judge our efforts.”
The High-Fence Factor
With no way to treat the disease, all wildlife managers can do to contain CWD is to curtail “accelerants” of the contagion. For cervids, the prime accelerants revolve around concentrating deer numbers beyond natural limits. The greater the overpopulation of a species, the greater the likelihood that disease will spread through its ranks.
Even in locales where wild deer have not exceeded the land’s carrying capacity, human behavior can dangerously increase local deer densities. Take baiting, for instance. Ethical or not, researchers believe the practice can serve as a powerful CWD accelerant. “What you get,” says Preston, “is an already high-density herd, all coming together to swap spit every night at the bait pile.”
Arguably the most controversial means of concentrating cervids occurs within the so-called captive-deer industry. In some cases, population densities of fenced-in deer, elk, and other “farmed” cervids extrapolate out to 10,000 animals per square mile. Some 8,000 such businesses exist in the multiple states that allow them. Fawns are born in pens, raised to adulthood, then sold for a variety of purposes, from “Velvet Viagra” (an aphrodisiac harvested from antlers that was exported to South Korea until a farmed elk tested positive for CWD) to meat sold to restaurants and supermarkets.
But by far the greatest revenue for most of these operators comes from the lucrative sale of trophy animal “targets”–big bucks for big bucks. Top-class whitetails can go for up to $12,000, and in Texas some “hunts” have been documented in the $40,000 range. The marketing slogan for one establishment nicely sums up the hunting “ethic” at many such places: “We supply the trophy–you supply the lie.”
There are some responsible, regulation-compliant proprietors in the captive-cervid industry, but officers like Wisconsin game warden Ron Preder have seen firsthand how farms that operate under the radar can contribute to the CWD problem. “We’ve been involved in this business long enough,” he says, “to know that not everybody plays by the rules.”
Take the curious case of Buckhorn Flats, a captive-cervid operation in Portage County, Wis., consisting of a 59-acre hunting preserve and a smaller breeding facility. On September 4, 2002, a hunter paid $4,000 to shoot a captive buck, which tested positive for CWD. When state authorities tried to trace its history to see what other captive herds might have been exposed, they were stymied by its lack of a state-mandated ear tag as well as inadequate record keeping by the preserve’s owner, Stanley Hall.
Hall, who did not respond to an interview request for this article, had a long history of trafficking captive deer. From 2000 to 2001 alone, he shipped at least 39 deer to seven other operations both across Wisconsin and out of state.
The state DNR involved 60 game wardens in tracing the trophy buck’s movement. Ultimately, Buckhorn Flats and a handful of other Wisconsin game farms were put under quarantine, and Hall was ordered to depopulate all his deer. He chose to appeal the ruling, as was his right, and the legal battle continued for the next three and a half years.
During this period, Wisconsin passed legislation requiring that all captive-cervid hunting preserves in the state needed a minimum of 80 acres. In the spring of 2005, the DNR notified Hall that his 59-acre facility no longer qualified and he had to stop hosting hunts as of that fall.
By December 2005, Hall and his lawyers came to an agreement with state and federal agriculture officials. Hall, who would receive indemnification payments from the state and federal government for each animal killed, told authorities he had around 80 does and yearlings in his breeding area, and 40 or so bucks in his hunting preserve.
On January 12, 2006, several days before the deer were to be put down, Hall notified the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) that someone had cut a hole in the preserve fence and baited the outside area. The DATCP closed the breech and alerted the DNR, which, concerned that dozens of exposed bucks had escaped into the wild, dispatched sharpshooters to the scene. They found none of the purported 40 bucks still inside the preserve–and no sign of them outside, either.
“We even sent a plane up to look for them,” says Preder. “One thing we didn’t find was a pile of deer running around on the landscape. So what happened to them?”
Whatever might have become of those valuable bucks, there were still the does and yearlings in Hall’s breeding pen. No hole had been cut in their fence. When the DATCP arrived for the scheduled cull several days later, they found three already dead and killed 76 more. When lab results came back, 60 of 79 deer tested positive.
According to their previously negotiated agreement, Hall was indemnified for his loss to the tune of $130,913, which worked out to a little over $1,700 per animal–a far cry from the $10,000 some hunters at Buckhorn Flats had said that they’d paid for trophy bucks.
Over a year after the mysterious hole in the fence appeared, the fate of the missing bucks is still uncertain. The local sheriff’s department and the DATCP initiated criminal investigations but thus far have come to no definitive conclusion.
Most everyone agrees that there was no mass escape into the woods. “These were pen-raised deer, dumber than a box of rocks,” says Preston. “It’s also one of the most heavily hunted areas in Wisconsin, and not one of them was seen during the rest of the season.”
The majority of those who’ve followed the case have a hypothesis. “The likeliest scenario is that these CWD-exposed bucks were sold and moved by horse trailer to other preserves,” says Preston, adding that a buck’s value as a trophy animal dwarfs even the most generous governmental buyout. “CWD is not being spread by law-abiding citizens–it’s being spread by these midnight cowboys who would sell their mother’s soul for a dollar.”
Indeed, when it comes to controlling the disease, the short-term financial interests of the few seem to trump the long-term conservation ethics of the many. Drastically culling herds within hot zones; outlawing baiting and backyard deer feeding nationwide; requiring high, double fences around all captive-cervid facilities; clamping down on the interstate transport of both live deer and harvested carcasses: All such tactics could make a real impact on the disease’s future course. But are any likely to become widely adopted?
Unfortunately, management strategies must be couched in “political and social realities, not biological ones,” says Preston. “That’s the world we live in. My commander in the National Guard always says, ‘The answer is money. Now what is your f—ing question?’ As long as there’s a market where somebody will pay $20,000 to shoot a piece of livestock in a pen, there will be bad things happening to wildlife.”
The Bureaucracy of Containment
The politics of deer management, both wild and captive, is a contentious and cumbersomely bureaucratic matter. If anything, the process seems designed to stall rather than foster constructive action. Were CWD to emerge as a threat to human health, federal authorities such as the Centers for Disease Control and Prevention could step in to direct a unified national strategy to combat it. But as far as we know, CWD doesn’t threaten us. It threatens a species that a disconcerting number of nonhunting suburbanites have come to view as rats with hooves.
Any regulatory powers not granted to the federal government by the U.S. Constitution typically default to state and local authorities. Many, though not all, of the laws involving deer and other cervids thus fall under a patchwork of balkanized purviews. Sometimes, as in the case of West Virginia and its neighbors, adjacent states do attempt to coordinate their efforts. Just as often, however, a hodgepodge of different and sometimes contradictory regulations switch abruptly at state lines.
Further complicating the odds of an effective overall strategy is the wrangling within different state agencies. Deer and other game, historically speaking, have largely been the responsibility of natural resource agencies whose mission it is to manage, conserve, and otherwise provide stewardship to wildlife. As more evidence has linked the captive-cervid industry to CWD’s spread, many game farmers balked at what they considered to be costly DNR regulations designed to protect free-ranging deer. In many states, they lobbied successfully to have their deer reclassified from “wildlife” to “livestock.” This meant that deer in pens would fall under the control of state agriculture departments, whose mission includes the promotion of alternative agriculture.
“As soon as captive-cervid operators started feeling pressure from wildlife agencies to have, for instance, taller fences around their property and mandatory ear tags,” explains Preston, “they went and hid behind the skirt of the ag department. They did this purely to protect themselves from regulations they didn’t like. Face it: Nobody is giving to pay $20,000 to shoot a deer with a 3-inch orange ear tag.”
When it comes to matters affecting multiple states, such as the interstate transport of deer, the federal government does play some role in cervid management. Similar philosophical differences–i.e., the stewardship of wildlife vs. agricultural commerce–are regularly debated before Congress. On one side is the U.S. Fish and Wildlife Service, part of the $16 billion Interior Department. This agency serves as a kind of national-level DNR with a mission of “Conserving the Nature of America.” On the other side is the Animal and Plant Health Inspection Service (APHIS), under the $96 billion Department of Agriculture. APHIS exists to “improve agricultural productivity and competitiveness and contribute to the national economy and the public health.” In terms of funding and influence, it hardly seems a fair match.
Dean Goeldner, a veterinarian and the APHIS program coordinator for CWD, acknowledges that his agency gets “the lion’s share of the federal budget for this disease.” The funds, he says, are targeted primarily at eliminating it from captive cervids but also at helping states address its spread in the wild.
Among other perks for the industry, APHIS shoulders the tab for laboratory testing of some 15,000 captive deer and elk per year. And it pays to depopulate affected captive herds, as well as to compensate operators for their loss. Goeldner denies that the industry has undue influence over his agency’s decisions. But not every interest group agrees.
Consider, for example, proposed regulations that APHIS began drafting in 2002 in the wake of the outbreak in Wisconsin. The idea was to create a nationwide “captive herd certification program” that would, among other provisions, spell out rules for the interstate movement of farmed deer, elk, and moose.
After consulting with various groups, from state wildlife authorities to deer farm lobbyists, APHIS published its final proposed rules last July–four years after the process started. These rules were slated to take effect on October 19. Almost immediately, however, there was an outcry. By early August, APHIS had received petitions from the Association of Fish and Wildlife Agencies, the National Assembly of State Animal Health Officials, and the U.S. Animal Health Association–demanding a review of what they believed was overly lenient treatment of the captive-cervid industry.
To entice game farmers into signing up for its voluntary herd certification program, APHIS proposed to allow them, after a period a surveillance, to move animals from state to state. Problem was, this was shorter than the incubation time necessary for CWD to become detectable.
Moreover, individual states could do nothing more to protect themselves from the unwanted important of captive cervids. The APHIS guidelines would supersede any more restrictive state legislation.
APHIS recently solicited public comments as part of its review process, which–depending on the outcome–may wind up in federal court as a states’ rights issue. “Some states do want stricter standards than what we’re proposing,” says Goeldner. “But our lawyers are telling us that there has to be one national set of standards. That’s part of why we pulled back and plan to work with the states to sort this out.”
Meanwhile, in areas like West Virginia, where the ordeal with CWD has just begun, the prospect of further import and contamination keeps DNR officials like Paul Johansen up at night. “I don’t think that CWD just arose spontaneously in our state,” he says. “It was either brought here in a truck in the form of a captive animal, or it came in on an infected carcass.” To be sure, as federal agencies, private industry, local authorities, and legions of attorneys debate, CWD prions continue to slip quietly through wire fences and across state lines.
CWD STATUS REPORT WHERE THE DISEASE IS TODAY
This chart lists testing results in the 11 states that report the disease in the wild. No national CWD monitoring system exists, so each state was contacted for statistics. Note: Sampling procedures vary among states, so these numbers do not represent a side-by-side assessment of prevalence.
|STATE||CERVIDS TESTED LAST YEAR||POSITIVES LAST YEAR|
|WEST VIRGINIA||1,900 (est.)||5|
CWD BY THE NUMBERS
Percentage of reporting states that indicate they have less than satisfactory funding to combat chronic wasting disease: 75
Amount the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) spent on CWD in 2005-06: $18,523,000
Amount the Wyoming Game and Fish Department spent on CWD management in fiscal 2006: $434,500
Amount the Wisconsin Department of Natural Resources spent on CWD management in fiscal 2006: $4.9 million
Total number of animals tested by all 50 states in 2002-03: 117,715
Number of same that tested positive: 592
Estimated number of wild cervids tested by the 11 states with CWD in free-ranging animals last year: At least 64,449
Estimated number of same that tested positive: At least 381