"Mad cow" disease may not have come to the U.S., but "mad deer" - a similar brain-destroying condition- has been identified in herds of deer and elk in several Western states and one Canadian province. Scientific advisers to the Food and Drug Administration are meeting today in Bethesda, Md., to consider whether the disease poses risks to human health.
So far, there is no evidence that humans can acquire the condition, known as chronic wasting disease, or CWD. But the advisory panel is expected to issue by the end of today an opinion as to whether people are at risk if they eat venison or take nutritional supplements made from antlers. The FDA also has asked its experts whether hunters and others exposed to deer and elk products should be prevented from donating blood.
CWD, first identified in the 1960s, has affected wild animals in northeast Colorado, southeast Wyoming and Nebraska, according to Mike Miller, a veterinarian with the Colorado State Division of Wildlife. Since 1997, the condition also has been found on 13 U.S. commercial elk farms in five Western states - Colorado, Montana, South Dakota, Nebraska and Oklahoma - and on elk ranches in Saskatchewan. Elk are raised for their meat and antlers, which are worth about $50 a pound.
In Colorado and Wyoming, state wildlife officials are closely tracking the disease in wild animals. Hunters there are being asked to send in the heads of their kills for analysis by state labs. Although there is no way to test for the disease in live animals, it leaves a telltale spongelike decay in the brain. In Colorado, where CWD rates among wild deer range as high as 15%, authorities have opened a special hunting season this month and next in an attempt to cull the number of wild deer by half, an effort that may take three years to accomplish.
CWD and mad cow disease, also known as bovine spongiform encephalopathy, or BSE, are related illnesses. Both are thought to be caused by a similar-acting infectious agent: a rogue protein that causes brain damage and death. Basic symptoms of CWD are weight loss, lethargy and excessive salvation. Its spread among wild deer and elk has been slow, taking decades to reach its current extent. But among domesticated elk, the disease may spread unpredictably since these animals are often transported beyond their natural range.
Cattle ranchers in areas with infected deer and elk express concern that the disease could spread to their herds. But Beth Williams, a University of Wyoming veterinarian leading efforts to track the disease, says there is no evidence to support such fears. In continuing experiments run by her lab, cows kept in pens with infected elk, and cows fed diseased brain tissue didn't get sick. Only when infected tissue was directly injected into their brains did cattle catch the disease. Scientists say it's still not clear how CWD is passed between animals, although experiments on penned deer and elk show that it is contagious.
Some experts say there also is no evidence that CWD poses a threat to people. "I would think there would be virtually no way history could repeat itself," says Dr. Miller, the Colorado wildlife veterinarian, referring to the way mad cow disease jumped the species barrier between cattle and human.
Yet others fear that, with the potential harm to people still poorly understood, too many risks are being taken. Byron Caughey, for one, a researcher at the National Institutes of Health's Rocky Mountain Laboratory, in Hamilton, Mont., questions the way states have permitted - even encouraged- deer and elk hunting to continue in areas where the disease is present. The implication that it is safe for hunters to be exposed to infectious spinal-cord material when they cut off the animals' head, he says, is "a decision that isn't based on hard fact, it's based on speculation. We don't know what the real risks are."
Also to be discussed at today's FDA meeting are the cases of three people in the U.S. who died at young ages from Creutzfeldt-Jakob disease. The disease, which occurs naturally in about one in a million people, typically strikes late in life. An unusually early onset has been one of the hallmarks of the "new variant" Creutzfeldt-Jakob disease cases in Britain that are believed to be the human version of mad cow disease. The three had all eaten venison, and two were hunters. Ermias Belay, an epidemiologist at the Center for Disease Control and Prevention in Atlanta who has studied the cases, says there is no evidence they were connected to CWD. "This does not mean CWD will not cause human illnesses ever," he says. "We need to continue to monitor the situation."
Some fear that, in addiction to venison eaters, people who take dietary supplements containing ground elk antler may be at risk. Lloyd Riddle, president of supplement maker Natraflex Brands in Castle Rock, Colo., defends his company's safety record, saying only antlers "from verified CWD-free herds" are used. Natraflex distributes its pills to 4,300 General Nutrition Centers stores and other outlets across the U.S. The product is thought by some to help treat arthritis and promote bone strength. Americans consumed between five and 10 tons of deer antlers last year, says Mr. Riddle, who estimates about 90% of U.S. production was exported to Asia, where antlers are a staple of traditional medicine.
Mr. Riddle and other people knowledgeable about the industry say elk farmers have been active in dealing with the CWD outbreak, working with the U.S. Department of Agriculture and others to test about 2,500 animals so far. Of the 13 infected herds on record, all but four have been voluntarily liquidated, and the others are being monitored. The North American Elk Breeders Association, a Platte City, Mo., industry group, is pressing for federal aid to help wipe out the disease and also to indemnify farmers against the loss of their animals. Currently, most measures are voluntary.
Indeed, there are those who think the dangers of CWD have been exaggerated. Tom Thorne, a veterinarian with the Wyoming Game and Fish Department says he still hunts and eats venison from an area where the disease is present. "I just haven't seen enough evidence to worry me." he says. "I am concerned about unjustified restrictions that are to broad or sweeping."