- A killer is on the loose.
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- As "mad cow" disease, it has taken more than
120 lives and devastated cattle farmers in England, elsewhere in Europe
and Japan.
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- Now as chronic wasting disease in deer and elk, it threatens
to cripple economies through the Rocky Mountain region - and possibly much
more.
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- How concerned should we be?
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- Recent research points to an unsettling possibility.
This family of diseases - called transmissible spongiform encephalopathies
(TSEs) - may be more sinister than even pessimistic scientists first envisioned.
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- The disease is now found in the wild in five states,
on the east side of the Mississippi River and the Western Slope of the
Rocky Mountains. It's found in captive animals in six states and two Canadian
provinces.
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- Once symptoms develop, each TSE is fatal, caused by a
mutant protein called a prion. Spongiform vividly describes the diseased
brain tissue: It is spongelike, filled with microscopic holes.
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- In laboratory tests, the National Institutes of Health
found that a TSE can rest undetected in one animal before attacking another
in a more virulent form.
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- There is no proof that chronic wasting disease can infect
humans, but there is evidence that it might be possible.
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- Test-tube experiments show that human proteins are as
susceptible to chronic wasting disease as to mad cow disease. Three young
venison eaters have come down with a TSE, but federal investigators were
unable to prove any linkage.
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- It is now clear that British authorities stumbled in
responding to the mad cow threat. Seeking to ease public fears and protect
economic interests, government officials said for 10 years that there was
no danger to humans from the disease that was attacking cattle.
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- Then people started dying. And the world witnessed grim,
almost medieval scenes of pyres of burning cattle in the English countryside.
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- During its decade of denial, Great Britain banned feeding
cattle a protein supplement called meat and bone meal (MBM), which was
determined to be at the root of mad cow disease.
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- Yet, during that same period, Great Britain exported
millions of tons of the same protein meal throughout the world. The full
impact of that mistake is still not known, but it's feared that mad cow
may break out in 10 to 15 additional countries.
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- How have we responded in America?
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- Without a sense of urgency.
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- The United States stalled for 10 years before banning
the feeding of MBM to cattle in this country. Then, after Britain and the
European Union halted all exports of MBM for public health concerns, the
United States saw a trade opportunity, becoming the world's leading exporter.
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- One result is that cattle in other countries that may
have eaten American meat and bone meal are being exported back to the United
States, as are meat products. Mexico, for example, only implemented a ban
on feeding MBM to cattle this year, and it exports 1 million cattle annually
to the United States. Even though there are questions about Mexico's enforcement
of the ban, to date no case of mad cow disease has been reported in either
country.
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- A study by a Harvard University-based group said that
the ban on feeding MBM to American cattle should insulate the United States
from a major mad cow outbreak. However, the General Accounting Office,
the congressional watchdog agency, has been sharply critical of the ban's
enforcement in the United States.
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- Scientists didn't know chronic wasting disease was a
TSE until Beth Williams, a young Colorado researcher, reached that conclusion
in 1977. The disease was first noticed almost 10 years earlier, but was
believed to be a digestive tract illness.
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- During the decade between the onset of the disease and
its classification as a TSE - and for at least a few years afterward -
some deer and elk were released from infected pens back into the wild and
were shipped between facilities.
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- It is not known whether these practices led to CWD in
wild deer and elk.
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- In a 1992 paper, Williams warned that the advent of elk
game ranching posed a significant threat for the spread of the disease.
Even so, during the decade of the '90s, Colorado permitted wholesale expansion
of elk ranches.
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- The game ranch risk is threefold. Regardless of which
way the disease might pass through the fence, free-ranging elk and deer
have nose-to-nose contact with captive animals. Animals escape from, or
break into, the ranches. Captive animals are transported in commerce around
the state, across state lines and to other countries.
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- Another critical question in the livestock-rich region
is whether CWD might cross the species barrier and infect cattle. The consequences
would be horrific. This has occurred under experimental conditions, but
there is no proof that it can happen outside a laboratory.
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- "This is an extraordinarily contagious disease,"
Dr. Paul Brown, former head of the federal Food and Drug Administration's
TSE committee, said last year of CWD.
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- "This is explosive." ___
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- Contact the Rocky Mountain News at http://www.rockymountainnews.com.
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- Note - This story/series ran in the Rocky Mountain News
on June 1. More information and full versions of these stories are available
online at http://cfapp.rockymountainnews.com/cwd/killer/
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- http://www.knoxstudio.com/shns/story.cfm?pk=CWD-INTRO-06-05-02=AN
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