- It began with what his father thought was another bout
with asthma.
-
- Steve Churchill - a tall, lanky English 18-year-old who
longed to join the Royal Air Force - had suffered attacks in the past and
his father, David, paid it little attention this time.
-
- Steve Churchill was to become the first human being to
die of a new disease that would soon panic the United Kingdom - variant
Creutzfeldt-Jakob Disease (vCJD), better known by its bovine relative,
mad cow disease.
-
- No one knew a thing about vCJD as Steve slowly descended
into the depths of the bizarre illness, leaving his family desperate, confused
and ultimately angry at the British government's inability to see it coming.
-
- The government's formal position, in fact, had been that
humans were safe from mad cow, that the disease could not break the "species
barrier." That is, it could not cross from one species, cows, to the
other, humans.
-
- Both mad cow and vCJD belong to a family of fatal maladies
called transmissible spongiform encephalopathies (TSEs), which also include
scrapie in sheep and chronic wasting disease in deer and elk.
-
- Steve Churchill had always been bright, but soon after
the asthma episode he began having troubles with his studies. On Aug. 26,
1994, the mechanically gifted pilot-in-training inexplicably crossed into
the approaching lane on a highway and collided with an army truck.
-
- Then came the depression. Symptoms worsened and Steve
developed elaborate hallucinations and began to lose short-term memory.
-
- On Feb. 13, 1995, doctors told the Churchills that Steve
had some sort of degenerative neurological disease, and for the first time
they heard a new term - CJD, short for Creutzfeldt-Jakob Disease.
-
- Steve Churchill died at 9:41 p.m., May 21, 1995. He had
just turned 19.
-
- It would not be until the next year that scientists shocked
the world with an announcement that Steve Churchill and nine other young
Britons had died from a disease officials had said for a decade could not
be transmitted from cows to humans.
-
- Even today, very little is known about what most scientists
say is the cause of the disease - a mutant protein called a prion.
-
- But scientists now know what was likely happening inside
Steve Churchill's brain both before and after his "asthma" attack
signaled the onset of his inevitable decline from first symptoms to death.
-
- Sometime before the summer of 1994, Steve had probably
eaten ground meat that contained brain or spinal tissue from a cow suffering
from mad cow disease - bovine spongiform encephalopathy, or BSE.
-
- This disease was first diagnosed in British cattle eight
years before Steve Churchill crossed the centerline and wrecked his mother's
car.
-
- By the time Steve's symptoms appeared, prions had built
up in his brain to the point where microscopic holes likely began forming
in neural tissue, according to scientists who have studied the disease.
-
- TSEs also naturally occur in about one in a million humans
a year, with the most common form called sporadic Creutzfeldt-Jakob Disease,
or simply CJD.
-
- There is no evidence that scrapie has ever infected a
human, and only in the cases of cannibalism in a New Guinea tribe and contaminated
surgical tissue or instruments has CJD spread from human to human.
-
- Those facts gave researchers a false sense of security,
at least as pertaining to mad cow. It simply wasn't believed that it could
cross the species barrier into humans.
-
- In 1967, deer held in a Colorado Division of Wildlife
pen in Fort Collins began dying after a period of strange behavior. Ten
years later, researcher Beth Williams took a slice of deer brain and looked
at it under a microscope.
-
- She noticed the spongiform change immediately, identifying
chronic wasting for the first time as a TSE disease.
-
- But in 1977 there were no loud calls of alarm about this
new TSE in wildlife. "It was mostly thought to be academic,"
said National Institutes of Health prion researcher Richard Race.
-
- Scientists believed that the TSE in deer and elk would
behave like scrapie, infecting only deer and elk and not jumping into other
species.
-
- But the alarms began sounding in 1986 when British cattle
suddenly started coming down with BSE.
-
- After an investigation, epidemiologists said the most
likely way cattle first were infected with the disease was when a sheep
with scrapie was slaughtered and sent to a rendering plant. Brain tissue,
some internal organs and bones were converted into meat and bone meal and
fed back to cattle.
-
- The theory of the cause of BSE set off sirens in the
scientific community.
-
- Many people in England began wondering: If the disease
could spread from sheep to cows, could it then continue from cattle to
humans?
-
- The answer they were told repeatedly was "no."
-
- But then, Steve Churchill and nine others began their
death march.
-
- At a tension-filled press conference on March 20, 1996,
red-faced British officials admitted that they had been mistaken. BSE had
spread to humans after all.
-
- Suddenly, interest in prions skyrocketed and many began
to cast a wary eye on the related illness first detected in Colorado -
chronic wasting disease.
-
- Could it also jump the species barrier? And what are
prions and why do they behave so badly?
-
- Naturally occurring in all mammals, the function of prion
proteins is little known. But it's after they mutate into rogue shapes
that scientists really get confused.
-
- The pioneer in prion research is a University of California-San
Francisco neurologist named Stanley Prusiner, an iconoclast who thought
so far outside the box that colleagues thought he was perhaps mad.
-
- Prusiner proposed that TSEs were caused by a protein
that managed to replicate itself without the use of genetic material like
DNA, the basic template for protein production.
-
- The notion was scoffed at and dismissed. Everyone knew
replication depended on chromosomes and genes, which are made of DNA. A
lowly rogue protein was hardly fit for this kind of endeavor.
-
- Self-replication was unheard of, said the critics. It
was impossible.
-
- That was in the early 1980s.
-
- The laughs had died down by 1997 when Prusiner went to
Stockholm, Sweden, to accept the Nobel Prize in medicine.
-
- The main evidence ruling out DNA's involvement in TSE
is the amazing toughness of the infectious prion.
-
- Separated out from other cell components, infectious
TSE-causing material can withstand temperatures to 1,100 degrees. Prions
are little disturbed by ultraviolet light. Most disinfectants leave it
unharmed.
-
- DNA could not easily survive any of the above. Prion
protein does.
-
- "Ten years ago the protein guys were the crazy guys,"
said NIH researcher Race from his laboratory in Hamilton, Mont. "Nobody
believed them. Now the pendulum has swung to the other side where the protein
guys are on top."
-
- Left unanswered is how this hearty little protein replicates,
and more important, how prions of one species can cause those of another
to malform.
-
- When a human gets vCJD by eating cows infected with BSE,
he doesn't inherit the BSE prion. Instead, the BSE prion induces a human
prion to change shape, and that newly shaped prion slowly induces other
human prion protein to misshape in a chain reaction that leads to disease
after five to 15 years.
-
- There is, however, at least one shield against the human
form of mad cow disease. So far, all 130 humans who have contracted the
disease have an amino acid sequence found in only 38 percent of the population.
-
- The majority of humans are apparently immune.
-
- Scientists are looking at CWD for similar patterns, asking
if any molecular patterns in livestock or human prion proteins might predispose
them to infection.
-
- Researchers are wary of CWD for other reasons, as well.
Deer and elk can be infected for several years before it can be detected
from their behavior.
-
- For the long incubation period, the infected brain would
even look healthy under the microscope, which was the standard test for
CWD for many years.
-
- Now a more sensitive chemical test is used that researchers
believe can detect the disease within six months of infection. A new experimental
test shows promise of detecting the disease after 42 days.
-
- CWD is also worrisome because it - unlike BSE - is infectious
in nature and spreads from animal to animal by deer and elk, perhaps even
by nose-to-nose contact.
-
- Paul Brown, former head of the U.S. Food and Drug Administration's
TSE Advisory Committee, has said he is most concerned about the disease
possibly crossing over into livestock, with crushing economic impact. There
is no proof in current studies that it can cross.
-
- Some of the most intriguing scientific research into
prion disease is taking place in Hamilton, Mont. - population 3,705.
-
- Hamilton's Rocky Mountain Laboratories, a part of the
National Institutes of Health, was in the TSE business even before Prusiner
developed his theory. Researchers there began examining scrapie in the
1950s and then picked up with BSE and now are concentrating resources on
chronic wasting disease.
-
- In a paper written nearly two years ago, the lab's Gregory
Raymond and other researchers gave ammunition to both sides of the issue
- to those who are alarmed by CWD and those who downgrade its possible
impact.
-
- Prions from CWD-infected animals were weak in converting
human prions into deadly misshapes, based on laboratory tests. In the test
tube, human prions were much more resistant than those naturally occurring
in elk and deer.
-
- Mike Miller, the top veterinarian for the Colorado Division
of Wildlife, takes the position that these results demonstrate a species
barrier and that there is no evidence that CWD is infective to humans.
-
- "There is no support that it is at all possible,"
he said in a recent interview.
-
- Michael Hansen, a scientist for Consumers Union, the
publisher of Consumer Reports, says there's no proof that it can't.
-
- Hansen's camp said Raymond's study found that the rate
at which CWD prions infected human prions in the test tube was almost identical
to the rate that BSE prions did so.
-
- And BSE can definitely spread to humans.
-
- Raymond's research in the NIH lab in Hamilton isn't the
only study there causing controversy and concern.
-
- Late last year, Richard Race and colleagues published
a paper in Virology that demonstrated how bizarre TSEs can be.
-
- Researchers took the brains of hamsters infected with
scrapie prions and injected the neural tissue into mice. The mice were
killed at various intervals and tested for the mutant prions. Every test
failed to find a continuing replication of prions. They didn't have any.
-
- To further research these apparently prion-free mice,
Race took brain matter from these healthy mice and injected it into other
healthy mice and hamsters.
-
- The newly infected mice and hamsters developed TSEs and
died.
-
- That means, Race said, that the mice from the first part
of the experiment were not prion-free after all.
-
- "That's the part that worries everybody," he
said. "It says there could be all types of asymptomatic carriers around
and we don't have an assay sensitive enough to pick it up."
-
- The possible implications?
-
- If, as in the test mice, the prions get more virulent
as they pass from one animal to the next, they might show up as full-blown
disease in someone who has - for example - received a blood transfusion
from the person originally infected.
-
- Other recent research by Prusiner and neurologist Patrick
Bosque is also raising alarms. They found that in lab mice infected with
a TSE, high levels of prions are detected in certain muscle groups.
-
- For years, the prions were thought to be confined mostly
to the brain and spinal cord. The research could mean that scientists must
look further. Prusiner has called for the testing of muscles in infected
deer, elk and cattle.
-
- Simply put, muscle is meat, the part consumed by humans.
-
- Says Race: "No one knows the full range of the human
implications."
-
- After Steve Churchill died in 1995, his family pressed
for an investigation, so rare it was for someone to die of normally occurring
CJD so young.
-
- "No one in authority would accept that Steve's death
was different to any other young person's death," his father later
complained. "We were voices in the wilderness."
-
- When the fateful announcement was made on March 20, 1996,
that Churchill had died of a variant form of CJD, the father didn't feel
so much vindicated as determined to press on.
-
- "We are not cranks," he said, "but just
grieving parents that need the truth behind the premature, untimely and
unnatural death of our son explained to us."
-
-
- On the Net: Bovine spongiform encephalopathy research
- http://www.bseinfo.org
-
- British Health Department - http://www.doh.gov.uk/cjd/cjd1.htm
-
- Contact Lou Kilzer of the Rocky Mountain News at kilzerl(at)rockymountainnews.com
http://www.knoxstudio.com/shns/story.cfm?pk=CWD-MADCOW-06-05-02
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