April 1, 2002 The Washington Post by William SouderEvery year, in the cold hour before dawn on the Saturday before Thanksgiving, nearly 700,000 hunters slip quietly into the Wisconsin woods for the start of the firearms deer season, the main event of the state's several fall deer hunts. Deer season is a deeply rooted tradition here and also an essential wildlife management tool that keeps a proliferating deer herd in check.
But the future of deer hunting in Wisconsin became clouded in late February when startled state officials learned that three deer that had been shot not far from the capital in November had tested positive for chronic wasting disease, a fatal neurological infection closely related to "mad cow" disease. Further tests, reported on Friday, turned up two more cases of the disease in the same area. "My opinion right now is that the human health risk is low," said Julie Langenberg, a wildlife veterinarian with the Wisconsin Department of Natural Resources. "But I'm pretty concerned. Nobody knows enough about this disease to even ask all the right questions at this point."
Chronic wasting disease belongs to a family of disorders known as "transmissible spongiform encephalopathies," or TSEs, which cause catastrophic transformation of brain tissue, resulting in progressive loss of motor functions and death. Several forms of TSE infect humans, usually older people, and cause severe dementia, in addition to shaking, loss of balance and death.
Four million cattle were destroyed during an outbreak of mad cow disease in Great Britain in the 1980s. Anxious British health officials, who initially played down any human risk, are now grappling with an increase in human cases of TSE apparently from tainted beef.
Chronic wasting disease was first detected almost 40 years ago in captive, farm-reared deer in Colorado, although it was not recognized as a TSE until 1977. The disease spreads more aggressively among captive animals in close contact with one another.
It has now been found in both captive and wild populations of deer and elk in several western states. The Wisconsin outbreak in wild deer is the first time the disease has appeared east of the Mississippi River.
There is no evidence that chronic wasting disease infects humans. There is also no proof that it can't. The Centers for Disease Control and Prevention in Atlanta has found no increase and no clustering in the incidence of TSEs among people living in areas where chronic wasting disease has been reported.
Last year Ermias Belay, an epidemiologist with the CDC, led a study of three cases of TSE in which the victims were 30 years old or younger and regularly consumed deer and elk meat. Belay said the researchers examined brain tissue from more than 1,000 animals in the areas where the victims obtained their meat. No chronic wasting disease was found.
"This does not prove that you cannot get this disease from eating venison," Belay said. "That would be next to impossible to determine absolutely. But we believe the risk must be extremely low."
More than 400 deer from last fall's hunt in Wisconsin were tested for chronic wasting disease. The special hunt should be completed this week.
State officials are examining road-killed deer from the area and are testing an additional 500 deer that local landowners have begun shooting at the state's request. Test results from both the special hunt and the brainstem tissues of the first 80 animals should be completed this week.
Meanwhile, hunters are being cautioned not to eat venison from any deer that appeared sick at the time it was shot, and to avoid consuming organ meat -- especially brains, eyes, spinal cords, lymph nodes and spleens. [There's evidence that the deadly prions may also be found in muscle tissue (meat) as well--BSE coordinator]
Whether those precautions reduce a risk that is already assumed to be near zero is anybody's guess. Like other TSEs, chronic wasting disease has a long latency period.
Beth Williams, a veterinarian with the University of Wyoming, said the youngest deer that had been found with symptoms of the disease was about 16 months old. Deer shot during the hunting season in Wisconsin are typically between 1 and 2 years old. "You'd have to expect that the majority of infected animals taken by hunters would be asymptomatic," Williams said.
Doug Whitmore, 44, a motorcycle mechanic from Middleton, Wis., said his 2 1/2-year-old, eight-point buck had looked fat and healthy when he shot it near Mount Horeb last November. Whitmore said he would never intentionally consume any organ meat from a deer, but he added that he wouldn't know the spleen from any other part of a deer's innards. He also said he cut himself while gutting the deer in the field -- something most deer hunters do from time to time. Whitmore had been eating his venison until state officials informed him that his deer had tested positive for chronic wasting disease.
Whitmore said that he will get rid of what remains of the meat but that he will hunt again next fall. "From what I understand, this disease doesn't have any real connection to humans," he said. Even so, he's glad state officials are going to examine more deer. "Maybe I'll have to become just a trophy hunter and forgo the meat someday," he said.
Jim Kazmierczak, an epidemiologist in the Wisconsin health department, said state officials are advising hunters to take precautions because they want people to assess any small risk of infection for themselves. "The amount of risk I'm willing to assume is going to be different from the risk you're willing to take for yourself or your children," Kazmierczak said. "As a 50-year-old man, I'd feel comfortable eating Wisconsin venison. But it's an individual decision."
Will Hueston, an epidemiologist at the Center for Animal Health and Food Safety at the University of Minnesota, said it's unclear whether the disease is spreading or simply being discovered by more vigilant testing. "This is leading us into the kind of ambiguous situation you often find in public health," Hueston said. "How do you advise people when the risk of something appears low but isn't really known?"
Whether the stage is set in Wisconsin for a more intensified outbreak of chronic wasting disease may be the biggest unknown. Wisconsin's 1.5 million deer make the state look like one big game farm. "The fact is that the population density of wild deer in Wisconsin is pretty comparable to the densities in some of the larger captive deer operations out west," said Langenberg, the state wildlife veterinarian.
Langenberg has another pressing concern. Deer do extensive damage to crops and woodlands every year, and they cause shocking mayhem on roadways. Last year, there were nearly 46,000 car-deer collisions in Wisconsin -- a threat to human health far greater than anything expected from chronic wasting disease. Since 1990, 52 people have died in car-deer crashes in the state.
"If hunters suddenly become less interested in hunting deer because of chronic wasting disease, then we're going to have a major ecological problem on our hands," Langenberg said.