Mad Deer Disease Spreading Across the USA

As 'Mad' Deer Roam Freely, Scientists Worry Similarities Between Chronic
Wasting Disease and Mad Cow Boost Funding to Discover How the Former Spreads

By Marc Kaufman Washington Post Staff Writer Monday, February 9, 2004;
Page A12
http://www.washingtonpost.com/wp-dyn/articles/A23822-2004Feb8.html

Following the uproar triggered by the discovery of the first known case of
mad cow disease in the United States, researchers and regulators are
focusing new attention on a similar disease afflicting hundreds or
thousands of "mad" deer and elk that roam freely across large parts of
North America.

Scientists have found no instances in which the disease in these animals
has jumped the species barrier to people, cattle or other animals. But they
say that possibility is both real and worrisome.

The condition, known as chronic wasting disease, is also thought to be
caused by prions, the misfolded proteins found in mad cow disease, or
bovine spongiform encephalopathy (BSE). But the deer and elk version of the
disease spreads far more easily both in the wild and in captive herds.

A recently released study by the congressionally chartered Institute of
Medicine into mad cow and related neurological diseases presented the
threat in stark terms. In the preface, study chairman Richard Johnson of
the Johns Hopkins University School of Medicine said European researchers
who have lived through the mad cow crisis there are "astonished" by how
little attention has been paid to the similar and potentially equally
devastating chronic wasting disease epidemic in North America.

"They have told me, 'You may be sitting on a time-bomb,' " he wrote.

The relative lack of attention to chronic wasting disease is about to
change. At the end of this week, the Food and Drug Administration will hold
a two-day advisory hearing into the whole family of transmissible
spongiform encephalopathies (TSEs), including mad cow, chronic wasting and
variant Creutzfeldt-Jakob disease, the human version of mad cow disease --
with an emphasis on research into how the deadly agent is spread from
animal to animal, and from animals to humans. The amount of National
Institutes of Health and Department of Defense research money going to
study chronic wasting disease is also quickly rising, officials said.

"The investigation of chronic wasting disease has always been on the
periphery, but that will no longer continue," said Paul Brown, a TSE
specialist with the National Institutes of Health.

"There are so many important things we don't know about the disease, and
that's a serious problem given that it's so widespread," he said. "Wild
deer and elk are often around cattle, and we have to know whether their
chronic wasting disease can possibly be spread."

There are no firm estimates of how many animals have been infected by
chronic wasting disease, but most experts agree that the number is growing.
First detected almost 40 years ago in captive Colorado mule deer, the
disease has now been found in white-tailed deer and elk in all the states
bordering Colorado, as well as in Wisconsin, Illinois and several Canadian
provinces.

Thousands of animals in captive herds have been slaughtered when the
infection was found, and hunts have been organized to cull wild herds known
to include infected animals. Hunters were warned not to eat their catch.
The Agriculture Department, which has proposed a system for certifying
captive deer and elk herds as free of chronic wasting disease, says
infection rates in herds it has sampled ranged from 1 percent among wild
white-tailed deer in Wisconsin to 15 percent of wild mule deer in
northeastern Colorado.

Like mad cow disease, chronic wasting attacks the brain and central nervous
system and ultimately makes the animals grow scrawny and behave strangely.
Also like mad cow disease, it takes several years to incubate and is always
fatal. There are no definitive tests that can be used on live animals.

But unlike mad cow disease, which is known to spread only when cattle
consume feed containing tissue from infected animals, chronic wasting
spreads more easily from animal to animal, probably through saliva, urine,
hair or feces. Some animals have apparently gotten the disease without any
direct contact with others.

Although there is no known connection between chronic wasting disease and
Creutzfeldt-Jakob disease, researchers have been chastened by the British
experience with mad cow disease.

There, officials initially told the public that the mad cow epidemic that
was spreading through English cattle and dairy herds posed no threat to the
public. They later discovered that some who ate infected beef contracted
variant Creutzfeldt-Jakob disease, which has killed 140 people in the
United Kingdom.

Chronic wasting disease in wild animals was first diagnosed in 1977 by Beth
Williams, then a Colorado State University graduate student and now a
professor of veterinary sciences at the University of Wyoming. Williams is
considered a leader in the field and recently was awarded a $43 million,
multi-year grant from the Defense Department to study how TSEs are spread.
The department's National Prion Research Program has taken a lead in
funding TSE research out of concern that diseases such as mad cow could
pose a threat to the national food supply, and to food supplied to service
members abroad.

Williams said research into whether chronic wasting disease can jump to
other species has been somewhat reassuring. Sheep and cattle placed
alongside infected deer have not contracted the disease. In another
experiment, mush made from the brains of infected deer was fed to cattle to
see whether they would develop the disease. Six years later, Williams said,
they have not. Efforts to infect monkeys with chronic wasting disease have
not succeeded.

But researchers have found they can transmit chronic wasting disease to
cattle and to mice by injecting infected tissue into their brains. They are
also concerned that carnivores such as wolves and mountain lions could get
infected if they eat diseased wild deer and elk -- especially the brains
and central nervous system tissues.

The question of how TSEs spread took on additional importance in December
when British officials announced that a patient died of variant
Creutzfeldt-Jakob disease after getting a blood transfusion from another
patient who, unknown to doctors at the time, also had the disease. Although
officials said they could not rule out the possibility that both
individuals contracted it independently, they are treating the second
infection as probably related to the first. Researchers say they become
increasingly worried when a disease such as TSE is found to have another
way of spreading.

"The $64,000 question with TSEs is: How do they spread?" said Brown of NIH,
who also headed a TSE task force for the Food and Drug Administration. "We
have to be prepared for unexpected and unsettling discoveries, because
that's the history of our work with the disease."
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