NYT, Feb 23, 1999 Weighing 'Mad Cow' Risks in American Deer and Elk

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NEW YORK TIMES, February 23, 1999

Weighing 'Mad Cow' Risks in American Deer and Elk

By SANDRA BLAKESLEE

As a 30-year-old deer hunter lies dying at his home near Salt Lake City,

consumer advocates and Government regulators are squabbling over a terrifying

question that cannot be answered to anyone's satisfaction: Is it possible to

contract a version of mad cow disease from eating deer or elk?

Mad cow disease appeared in British cattle in the mid-1980's and caused an

epidemic that left the brains of infected animals spongy and riddled with

gum-like strings. Eventually, the British Government ordered the

destruction of

more than four million animals.

At least 34 young people in Britain contracted a human form of the fatal

disease, possibly from eating infected beef or from coming into contact with

products made from sick cows.

Nothing similar has turned up in American beef, although experts believe

one in

a million cows will develop the disease spontaneously.

Animal feeding practices have been revised to reduce chances of transmission.

But a similar disease has been seen in sheep and mink, and people are now

worried about a version of mad cow disease endemic in deer and elk in parts of

Colorado and Wyoming, raising the possibility that hunters who eat infected

animals may similarly develop a human form of the deer and elk malady, called

chronic wasting disease.

The cow, elk, deer and human diseases belong to a family of disorders called

transmissible spongiform encephalopathies, or T.S.E. The human form,

Creutzfeldt-Jakob disease or C.J.D., occurs in three varieties. Most cases are

spontaneous with no known cause. About 10 percent of cases run in families,

linked to inherited gene defects.

The British cases are called new variant C.J.D.

In all three varieties, the disease agent is believed to be not a virus or

bacterium but a mysterious particle called a prion -- a kind of renegade

protein that transforms normal proteins into abnormal, indestructible

substances that create spongy holes in the brain.

Prion diseases have been found in 85 species, passing easily between some

animals and not others.

When a prion " jumps " species, new T.S.E. diseases are created that can be more

or less virulent for reasons no one can explain.

This is the question raised by the deer hunter's case: Does he have a new

variant of Creutzfeldt-Jakob disease contracted from deer and elk, and if so,

what does it look like?

Health and wildlife officials point out there is no proof that mad deer or elk

disease has " jumped " to humans. At the same time, consumer advocates point to

the dying hunter, Doug McEwen, whose illness is uncannily similar to that seen

in the young victims of mad cow.

According to his wife, Tracie, Mr. McEwen hunted in season, and often ate deer

and elk that he bagged. But he never hunted in Colorado or Wyoming, where

chronic wasting disease is found. So no one knows if he contracted his brain

disease from animals or spontaneously developed the illness destroying his

brain.

Moreover, Mr. McEwen was a frequent donor of blood plasma and his plasma was

pooled with many blood products and shipped to 21 countries. Blood safety

officials here and abroad at first quarantined the blood products but have

since let some of them be used.

In part because of the mad cow outbreak in Britain, the United States Food and

Drug Administration barred blood banks from accepting donations from people

with family members with C.J.D. But given that it is not known if blood or

plasma can transmit the disease, and the fact that almost all Americans with

the disease have the sporadic form, which tends not to involve the blood, the

Public Health Service and food and drug agency changed the nation's blood

policy in August.

Now only those people with familial or genetic versions of C.J.D. are

prohibited from donating blood, said Dr. Jay Epstein of the Center for

Biologics Evaluation and Research at the drug agency.

American public health officials say that chronic wasting disease in deer and

elk and Mr. McEwen's plasma donations pose no threat to people. Careful

epidemiological surveys have not shown any increase in the type of brain

disease afflicting Mr. McEwen and no indication that frequent users of blood

products, like hemophiliacs, have a higher incidence of any kind of C.J.D.,

said Dr. Lawrence Schonberger, an epidemiologist who coordinates surveillance

activities for Creutzfeldt-Jakob disease at the Centers for Disease Control

and

Prevention in Atlanta.

Many people are unconvinced. " The fact that we have a disease in elk and deer

at levels equivalent to mad cow disease at the height of the British epidemic

is truly alarming, " said Stauber, director of the Center for Media and

Democracy, a group that reports on government and industry public relations,

and the author of " Mad Cow U.S.A., " a book critical of American health

officials. In both cases, an estimated 6 percent of animals carry the

infection.

Mr. Stauber and others interested in the disease say they distrust Government

estimates, citing, among other things, published reports estimating that 6

to 8

percent of people who are told they have Alzheimer's disease may actually have

a form of C.J.D., said Dr. Pringle, a scientific consultant for the

Sperling Foundation, a charitable public health organization.

" Was nothing learned from the British experience? " asked Dr. Pringle, who

maintains an encyclopedic Web page on the subject (www.mad-cow.org). " Why are

we repeating the gamble they took? "

British officials for years adamantly denied the cow disease was any threat to

humans, he said.

Mr. McEwen, a territory manager of a groceries firm who lives in Kaysville,

Utah, first showed symptoms in June when he forgot how to spell his wife's

name

and could no longer do simple arithmetic. His condition worsened rapidly; by

the end of the summer he was forced to quit his job.

Neurologists carried out scores of tests, including brain scans and spinal

taps, to no avail, until Nov. 24, when they finally took a brain biopsy. The

next day, Mr. McEwen was given a diagnosis of C.J.D.

Creutzfeldt-Jakob disease strikes one in a million people over age 50, said

Dr.

Hansen, a scientist who closely follows the issue for Consumer's

Union.

The disease strikes fewer than one in a billion people worldwide at Mr.

McEwen's age, 30. Moreover, in Mr. McEwen's case, the disease has moved with

astounding rapidity, leaving him near death, unable to recognize his two young

daughters or his wife.

Alarmed by Mr. McEwen's age and the speed of his illness, state health

officials sent a brain tissue sample to Dr. Pierluigi Gambetti, an expert on

prion diseases at Case Western Reserve University in Cleveland. Dr. Gambetti

ruled out most known causes of C.J.D. Mr. McEwen never received transplanted

tissues that might have been infected with abnormal prions.

His disease was not inherited and it definitely did not come from cattle.

The diagnosis: sporadic C.J.D., meaning no known cause.

Cases like that are rare but not unknown, Dr. Gambetti said.

But Dr. Pringle and others do not accept this diagnosis as final.

They point out that no one knows what chronic wasting disease would look like

in a human, and tests to determine the nature of such a disease have not been

done.

All mammals have prion proteins whose structures vary by just a few building

blocks called amino acids, Dr. Pringle said.

The difference between a cow and a human prion might be eight of these

building

blocks out of hundreds.

But when the abnormal cow prion co-opts the normal human prion, a new abnormal

human prion -- and a new disease -- is formed.

It looks exactly like a C.J.D.-related human prion but it can be more

insidious. If the new variety of human prion is injected into a cat, yet

another disease can be created. It may be more infectious or less

infectious in

the cat.

Such experiments in which the infectious prion of one species is " passaged "

into another species is a standard test for sorting out various T.S.E.'s.

" There are many imponderables in these experiments, " said Dr. Byron Caughey, a

prion expert at the National Institute of Health Rocky Mountain Laboratory in

Hamilton, Mont.

" One prion is an infectious unit large enough to give you the disease. But it

can be terribly inefficient going across species.

A person could take in a billion infectious units from a deer or elk and never

get sick in his lifetime, " he said.

Dr. Schonberger said that there were no plans to carry out interspecies tests

on Mr. McEwen's brain tissue because it is clear that he has a natural human

form of the disease and because there is no increase of C.J.D. where deer and

elk hunting occurs.

According to wildlife officials, chronic wasting disease affects about 5

percent of the deer and 1 percent of the elk found in a small area in

northeastern Colorado and southern Wyoming.

Sick animals drool excessively, stagger around and lose weight before dying.

Hunters in several states are required to turn in deer and elk heads so that

the brain tissue can be tested. So far, the disease in the wild has not spread

beyond Colorado and Wyoming.

Game farms are another story. The disease is found in captive deer and elk

herds in three states -- South Dakota, Nebraska and Oklahoma -- and in the

Canadian province of Saskatchewan, said Dr. Beth , the nation's

leading

expert on chronic wasting disease, at the University of Wyoming in Laramie.

The disease was reported in the mid-1960's at the Wildlife Research Station in

Fort , Colo., where it eventually wiped out 90 percent of the animals.

But before people knew what was happening, many infected animals were sold to

game farms or zoos elsewhere for breeding, thus spreading the infection.

Ranchers made large profits selling antlers to Asia, where they are used in

making herbal remedies and aphrodisiacs.

The disease was first observed in the wild in 1981, Dr. said. No one

knows how it spreads. The infectious prion may be shed in saliva, feces or

placenta and if wild animals come across downed fences, they might step on

contaminated ground. There is new evidence that the prion may be concentrated

in inflamed skin cells, suggesting that the disease could be spread by

scratching posts or trees in the wild.

But Dr. Mike , a veterinarian with the Colorado Department of Wildlife

who is familiar with the problem, said thousands of people had consumed deer

and elk meat and field dressed hundreds of infected animals in the Fort

area over the last 25 years. " We make no secret of where the disease occurs, "

and leave it up to hunters to decide the risks for themselves, he said,

although hunters are advised to wear gloves when cutting up animals and to

avoid brain and spinal cord tissue.

But a deeper reason to worry is the diabolical nature of the infectious prion

particle. It seemingly cannot be destroyed.

When medical instruments contaminated with prions are boiled at high

temperatures for 30 minutes, the prions remain infectious -- and have passed

the infection from person to person.

When infected materials are incinerated, the ash contains prions, which remain

infectious.

This problem is highly relevant to Mrs. McEwen, who has learned that a local

funeral home will not embalm her husband if an autopsy, exposing brain tissue,

is performed. Several prion laboratories want her to donate her husband's

brain

to them exclusively, said Mel Steiger, also from Salt Lake City, whose wife

died last spring from C.J.D. and who is now helping Mrs. McEwen. " She has not

decided what to do, " he said.

Meanwhile, Federal officials are in a regulatory bind, weighing risks and

benefits.

The risks of spreading C.J.D. contracted from deer and elk seem minuscule

compared with threatening jobs (Colorado's Department of Wildlife gets half

its

income from selling deer and elk tags), frightening hunters needlessly and

shaking confidence in the nation's blood supply.

Dr. Schonberger is confident that the best decisions have been made on the

available evidence.

" If something happens down the road people will come and chop our heads off, "

he said. " But I don't think that's going to happen. "

Related Sites

These sites are not part of The New York Times on the Web, and The Times

has no

control over their content or availability.

· · The Official Mad Cow Disease Home Page.

· · CJD Voice Further information about Creutzfeldt-Jakob

Disease.