- LONDON (AP) -- Scientists
have found evidence suggesting that the human form of mad cow disease might
be infecting a wider group of people than seen so far and that some may
develop a milder form of the illness.
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- Since variant Creutzfeldt-Jakob disease was first identified
in 1996, little has been learned about it. Until now, the fatal brain-wasting
disease was found only in people who have a certain genetic profile.
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- But research published this week in The Lancet medical
journal reported the infection in a person with a more common genetic makeup
and with no symptoms of the illness.
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- That means more people than previously believed could
be incubating the disease, thought to come from eating processed beef products
from cattle infected with mad cow disease, or bovine spongiform encephalopathy.
It also raises the possibility that some people may get only a mild infection,
as opposed to the fatal disease.
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- Scientists don't know how many people are infected with
the human form of mad cow disease. Projections vary wildly -- from just
10 more cases in the future to hundreds of thousands -- because so many
factors that play into the disease remain a mystery and because there have
been so few cases to study.
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- Experts don't know how long the incubation period is;
whether everybody is equally vulnerable; exactly how the disease spreads
and whether it can be easily passed on before symptoms develop. There is
no test to diagnose it, no treatment and no cure.
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- The latest finding means that forecasts need to be radically
revised because they were based on the assumption that the disease only
affects people with a particular genetic profile found in about 35 percent
of Caucasians, said James Ironside, director of Britain's national Creutzfeldt-Jakob
disease surveillance unit, which did the study.
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- In new research, an autopsy found the disease in a person
whose genetic signature is shared by about 50 percent of Caucasians.
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- Ironside said, "I think we have to go back and redo
all the calculations based on this case."
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- So far, 147 people in Britain, and another 10 elsewhere,
are known to have contracted the disease. Five are still alive.
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- The illness occurs when normal proteins found in the
brain, known as prions, change shape and prompt adjacent healthy prions
to do the same. When enough prions are altered, they deposit a plaque on
the brain and surround the mark with spongy holes, killing the victim.
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- The latest discovery was made during an autopsy of an
elderly person who died of an unrelated cause but who had received a blood
transfusion five years earlier from a donor who later died of the human
form of mad cow disease.
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- Strangely, the infection was found only in the spleen,
but not in the brain or other places the disease typically turns up. It
is unknown whether the disease might eventually have killed this person
after a longer incubation period or whether the infection was milder and
may have done no harm.
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- Dr. Kumanan Wilson, a blood safety expert at Toronto
General Hospital in Canada, said the finding is a vindication of policies
by some countries that have taken steps to protect against what was previously
a theoretical risk of spreading the disease through blood transfusions.
During the HIV epidemic, the blood supply wasn't protected until HIV began
spreading through transfusions.
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- "By acting in advance of complete certainty, policy
makers have potentially protected against vCJD emerging as a new large-scale
blood-borne epidemic," said Wilson, who was not connected with the
study.
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- Copyright 2004 by The Associated Press. All rights reserved.
This material may not be published, broadcast, rewritten or redistributed.
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