Do zombie deer foretell a Texas hunting apocalypse? It might be decades before we know. Yet the rise of chronic wasting disease—colloquially known as “zombie deer disease” because it infects the brains of deer, essentially turning them into the walking dead—is so alarming that officials with the Texas Parks and Wildlife Department are testing deer roadkill across the state and tightening regulations on commercial deer breeders in an all-out attempt to slow the spread.
There’s no cure for chronic wasting disease, or CWD. The nervous-system condition is similar to mad cow disease in cattle and scrapie in sheep and goats—and it’s always fatal. Infected deer can quietly spread the disease for two years before symptoms even appear. While deer in the late stages of CWD often look emaciated and behave erratically, infections leave the animals so weakened and vulnerable to predators that they typically die before external symptoms manifest themselves, making the spread of the disease difficult to control.
“We’re talking about an insidious disease,” said Mitch Lockwood, TPWD’s big-game program director. “It’s slow. It’s not obvious. But it’s never dormant.”
Although wild deer also come down with CWD, Lockwood said the disease is transmitted more quickly through deer-breeding facilities, which keep the animals in relatively close confines and often move them across much greater distances than they would have traveled while roaming the landscape under natural conditions.
Folks who breed deer for hobby or profit (and who tend to have tall fences and deep pockets) are none too happy about the rising regulatory demands on their industry. Since TPWD’s emergency rules took effect in late June, more than 10 percent of the state’s nearly one thousand deer breeders have left the business, and another 10 percent are planning to do so, said John True, president of the Texas Deer Association, a nonprofit group that advocates for the deer-breeding industry.
Unlike a variant of mad cow disease, CWD can’t be transmitted to humans, which means it’s safe (so far) to eat the venison of an infected deer. Hunters, however, are required to bring their harvests to a TPWD check station within two days if the kills occurred in one of the seven CWD Zones, which are scattered across most of the state except for southeast Texas and the Rio Grande Valley. (The regular hunting season for whitetail deer in Texas runs through January 2 in the North Zone and January 16 in the South Zone.)
Chronic wasting disease is transmitted through bodily fluids, excrement, and carcasses, and is caused by a weird little protein called a prion, which triggers other proteins to fold abnormally in the central nervous system. The chain reaction of misfolding proteins slowly destroys the brains of whitetails, mule deer, and other members of the Cervidae family, such as elk and moose. Wildlife biologists don’t like the nickname “zombie deer disease,” with its B-movie connotations. “Their flesh doesn’t waste away, and they don’t start eating each other,” said Megan Radke, a TPWD press officer. “They slobber and stumble as opposed to being a zombie-type creature.” Left unchecked, the disease travels from deer to deer, reaching a tipping point when about 15 percent of a herd is infected. “That’s when it really begins to snowball,” Lockwood said.
Discovered in 1967 at a government research facility in Colorado, CWD has spread throughout half the United States and four Canadian provinces. It reached Texas in 2012, first in a free-ranging mule deer herd in the Hueco Mountains near El Paso, then at a South Texas breeding facility three years later. It was quickly discovered in several other breeding facilities. In the nine years since the illness arrived here, CWD has been detected in 270 animals; nearly three-fourths were whitetails in captive breeding facilities.
This spring, wildlife scientists found new cause for alarm. For the first time in northeast Texas, a whitetail deer tested positive for CWD at a breeding facility in Hunt County, about fifty miles northeast of Dallas. Another nine cases were traced to a breeding operation in Uvalde County, a hundred miles west of San Antonio. Upon further testing, a total of at least 30 infected deer were found at six facilities, 25 at the Uvalde operation alone.
Neither the Uvalde nor Hunt County farms had imported any deer in recent years—they were both considered “closed herds”—so the vector by which CWD spread there was a mystery. According to True, ranchers who bought infected animals from the Uvalde operation were forced to kill not only those deer but their entire herds—hundreds of captive does and bucks, culled as a precaution.
“When there’s CWD detected on your farm, it’s a total wipeout,” said True, the owner of Big Rack Ranch, a two-thousand-acre breeding operation about an hour east of Dallas. According to True, about 10,000 captive deer have been killed because CWD was found in their pens. Some, he said, were breeding bucks valued as high as $250,000.
The losses of all those prize whitetails ripple across the state’s rural economies, he added. From vet bills to feed costs, the association estimates that Texas deer breeders directly contribute $350 million in economic activity each year.
Deer breeders have often come up against regulators and conservationists who prefer to let whitetails roam naturally. True frames the tightening CWD regulations as a new front in that fight, arguing that his industry is being cast as a CWD scapegoat by critics within the Texas Parks and Wildlife Department and the broader conservation community who, he alleges, are using the disease as a pretense to destroy the practice of selectively breeding whitetail deer for massive antlers that fetch premium prices. “They’d love for all of us to be out of business,” he said. (Lockwood counters that the measures are necessary to protect the health of native deer and the hunting industry.)
This summer, the state’s deer breeders were scrambling as the hunting season approached. Under emergency orders from Parks and Wildlife, breeders were required to test every live deer before it could be moved out of its pen and onto a neighboring pasture or another property. About 12,000 bucks were tested at a cost of $300 per animal, True said, resulting in millions of dollars in lost profits across the industry. The weather was hot, and some deer died from the stress of being tranquilized, which True described as a necessary step before the deer can be tested. “It’s tough, and it’s expensive,” he said. Of those 12,000 bucks tested, only one had CWD, according to Lockwood of the TPWD. (The Texas Deer Association argues the infected deer would have been detected under previous testing requirements.)
Is CWD under control? The Texas Parks and Wildlife Commission doesn’t think so. In November, the commission further tightened regulations for deer breeders, as first reported by the Houston Chronicle, which has closely covered the CWD outbreak and ongoing response from TPWD. Breeding facilities are now required to test every deer that has reached an age of at least one year before it can be released or transported from its pen. In addition, every deer that dies in captivity must be tested for the disease, up from 80 percent of mortalities previously required to be tested. And the Trap, Transport, & Transplant Permit Program—an initiative that allows deer and other game animals to be captured on properties where they’re overcrowded and then relocated to different properties—has been temporarily suspended.
True said the new regulations are unnecessary. He wants to rescind the emergency orders and limit testing to every captive deer that dies at an age of one year or older. Lockwood, for his part, argues that widespread testing and culling of captive deer exposed to CWD are the prices Texans must pay to protect their mule deer and whitetails—which, as native species, are owned by the public, no matter whose pens they’re confined in. Not that either side will be able to claim vindication anytime soon.
“The sobering thought is it may be fifty years before we realize the consequences of our actions or inactions when dealing with this disease,” said Lockwood, arguing that the unchecked spread of CWD will be gradual and subtle, until it suddenly becomes catastrophic. “It’s often said this is not a disease for our lifetimes. This is a disease of our grandchildren’s lifetimes.”