Mysterious Disease Spreads in Deer, Elk

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Wasting illness may travel via game farms.

by Brian McCombie

The first U.S. mad cow was diagnosed just last year, but for more than 30 years, deer in certain parts of this country are known to have been afflicted by a similar fatal neurological ailment called chronic wasting disease (CWD). Twenty years ago, the same illness was diagnosed in elk.

In the past nine years, possibly as a consequence of game farm practices, CWD in deer and elk has spread from two states to 10 more and two Canadian provinces. Hunters in certain areas now are being urged to have their deer and elk kills tested.

For 30 years, CWD in the wild was centered in portions of northeast Colorado and southeast Wyoming. Since 1997, it has turned up in the wild in Nebraska, South Dakota, Wisconsin, Illinois, New Mexico, Utah and Saskatchewan, too.

Game farms also have had the disease appear, and many suspect that animal sales between farms, as well as escapees, helped transport the disease.

From 1996 to 2002, CWD was discovered on game farms in Saskatchewan, Alberta, Colorado, Kansas, Minnesota, Montana, Nebraska, Oklahoma and South Dakota. Overall, there are about 12,000 deer and elk farms in the U.S. and Canada.

Several years ago, three young people — two hunters and one woman who ate venison hunted by her father — died of the human form of CWD, Creutzfeldt-Jakob Disease (pronounced Croytz-feld Yawkob), and scientists are wondering if humans could be infected by eating venison from sick deer or elk.

The jury's out on this all-important question, though research is ongoing. Dr. Patrick Bosque, a neurologist with the hospital Denver Health, has been studying CWD for many years. He says, "The most prudent assumption is that, at some low rate, if enough people consume enough chronic-wasting-disease meat, some people might get a chronic-wastinglike disease. But we really don't know for sure.'

First, mad sheep

Nearly 300 years ago, European herders noticed a new affliction among their sheep. Some of the animals suddenly would become disorientated and nervous, grind their teeth and bite at their legs and feet. Many displayed a maddening itch, rubbing themselves bloody against fence posts. Within six months, they would stop eating and die. Herders dubbed the disease "scrapie.'

Today, microscopic examination of scrapie-infected sheep brains reveals the calling card of this family of diseases: extremely tiny ruptures or holes in the brain cells. Imagine a normal, solid section of brain cells and, next to it, a scrapie-infected section that looks strangely swiss-cheesed. Both mad cow (bovine spongiform encephalopathy or BSE) and CWD have this similar abnormal brain-cell pathology.

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