Proximity of CWD has Texas officials concerned

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June 20, 2002

Proximity of CWD case concerns wildlife officials

By SHANNON TOMPKINS, Houston Chronicle

Most professional wildlife biologists and animal health scientists believe it's only a matter of time before a Texas deer or an imported elk proves to be suffering from chronic wasting disease and the state is forced to address what in other states has become an environmental, social, political and economic nightmare.

It almost happened this week.

Laboratory tests on an obviously ill mule deer taken March 28 on the White Sands Missile Range in southern New Mexico came back positive for CWD.

That makes New Mexico the latest in the expanding list of states that have confirmed the fatal, untreatable neurological disease in their wild deer or elk herds.

New Mexico joins Colorado, Wyoming, Nebraska, South Dakota, Wisconsin and the Canadian province of Saskatchewan as states/provinces with documented cases of CWD in free-ranging herds.

CWD also has been documented in fenced or captive deer or elk in Montana, South Dakota, Oklahoma, Kansas and Nebraska.

With the exception of Colorado (where CWD was first identified in wild populations in the 1980s) and adjacent Wyoming, the other discoveries of CWD have occurred within the past five years.

The New Mexico mule deer is the closest confirmed CWD case to Texas.

How close?

Within 50 miles of the Texas border, sources said.

New Mexico officials immediately ordered the state's borders closed to importation of deer and elk and are devising a plan for further collection and testing of deer in the area where the infected mulie was taken.

In response to the threat of CWD-infected cervids being brought from other areas, Texas earlier has banned all importation of deer and elk. Approximately two dozen other states also prohibited importation of deer, elk or both.

But the discovery of the CWD-positive deer in the White Sands Missile Range threw the effectiveness of those prohibitions into doubt.

In almost all other cases of CWD, infected animals have been found in association with captive or "farmed" deer or elk -- either the CWD-infected animals were part of a fenced herd or the free-ranging animals were near a game farm.

New Mexico officials said no game farms or similar facilities are located near the sprawling White Sands range, a military tract of 2 million-plus acres in southern New Mexico.

While scientists admit there is much about CWD they don't understand, they have been working under the theory that the disease is transmitted by contact with an infected deer or elk.

"We don't know how CWD was transported to the White Sands area," Kerry Mower, wildlife disease specialist for the New Mexico Department of Game and Fish, said. "There are no game farms down there and it is far from the (CWD) endemic areas of Colorado and Wyoming.

"But this does illustrate how little we know about the spread of transmissible spongiform encephalopathies."

Chronic wasting disease is a form of TSE and affects the brain and brain stem of cervids such as deer and elk. Like its close relative bovine spongiform encephalopathy (commonly called Mad Cow Disease), the disease triggers deterioration of cells in the brain and brain stem leading to disorientation, weight loss, blindness, lack of control of bodily functions, and eventual death.

The New Mexico mule deer was "just skin covering a rack of bones," Mower said.

There is no treatment or cure for CWD or other TSEs.

Also, there is no live-animal test for the disease. Diagnosis requires examination of brain or brain stem tissue, so the animal must be dead.

Since the apparent spread of CWD over recent years, several states have implemented random sampling programs to check for CWD in their free-ranging deer or elk.

New Mexico has had such a program, using samples from hunter-taken deer and elk. Other states such as Iowa and New York are sampling road-killed deer.

It was a long-running sampling program involving hunter-taken deer that discovered CWD in Wisconsin's free-ranging deer herd. That discovery, the first confirmed cases of CWD east of the Mississippi River and the first in an incredibly dense deer herd, has created a fire storm in the state.

Wildlife officials, hoping to stem the spread of the disease, are pushing for the "depopulation" of all deer in a more than 300-square-mile area around where the infected deer were found. The killing of as many as 25,000 deer has begun, despite vocal opposition from some Wisconsin residents.

Although there is no evidence that contact with CWD-infected animals or tissue can cause the human form of TSE (Creutzfelt-Jakob Disease or variant CJD), there is no conclusive evidence it can't.

Fear of eating venison from CWD-infected deer is rippling through the state, triggering economic repercussions. Food banks have quit accepting donated venison, butchers and other deer processors say they will not handle deer, and a recent survey of Wisconsin's 600,000-plus deer hunters indicated 36 percent of them are considering not hunting deer during the coming season.

Texas holds about a half-million deer hunters, approximately 4 million free-ranging white-tailed deer, another 20,000 or so captive deer and an estimated 17,000 captive elk. Many of the captive deer and all of the captive elk have come from outside Texas.

No CWD-infected deer or elk have been documented in Texas. But testing for the disease has been nearly nonexistent.

Texas Parks and Wildlife Department and the Texas Animal Health Commission are working with the state's 450 or so deer breeders in hope of crafting a voluntary CWD testing program.

TPWD officials also are working to fashion a scientifically valid program for sampling hunter-taken deer for CWD testing.



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Shannon Tompkins covers the outdoors for the Chronicle. His column appears Thursdays, Fridays and Sundays.
 

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