SCARY stuff...
Evidence links ``mad cow'' disease to human illness
NEW YORK, Dec 20, 1999 (Reuters Health) -- For the first time,
scientists have established a direct link between the outbreak of
``mad-cow'' disease among cattle and cases of a new variation of a
similar disease in people.
Earlier in this decade, new variations of an infection called
Creutzfeldt-Jakob disease began to appear in Great Britain. The
incurable disease has symptoms including dementia, muscle spasms,
trembling and vision problems, usually rapidly progressing to
irreversible brain damage and death.
Creutzfeldt-Jakob disease is rare, but the new variety of the illness
surfaced in Britain about 5 years after the peak of an epidemic of mad
cow disease, a similar illness formally known as bovine spongiform
encephalopathy (BSE), according to one of the authors of the new study,
Dr. Stephen J. DeArmond, of the University of California, San Francisco.
Based on the coincidence, many experts suspected that the new variety of
Creutzfeldt-Jakob disease was passed on to people who ate meat taken
from cattle with mad cow disease, but there has been no direct
scientific proof, DeArmond told Reuters Health in an interview.
Now, DeArmond and his colleagues have shown that the disease could have
passed from cows to people. The researchers took proteins called prions
from cows with mad cow disease and from the brains of people who had
died with the new variety of Creutzfeldt-Jakob disease and placed them
in two groups of genetically altered mice.
The time between infection with the prions and the first symptoms was
identical in both sets of mice, according to DeArmond. In addition, the
human prions and the cow prions caused the same kind of damage to the
brains of the mice, he said. In contrast, when the researchers used
prions taken from sheep with a similar disease, the results were quite
different, he noted.
``Our findings provide the most compelling evidence to date that prions
from cattle with BSE have infected humans and caused fatal
neurodegeneration,'' the researchers write in the December 21st issue of
the Proceedings of the National Academy of Sciences.
``This is the first direct evidence that the mad cow disease was the
source of the prions that caused the new variant (of Creutzfeldt-Jakob
disease) in Great Britain,'' DeArmond said.
SOURCE: Proceedings of the National Academy of Sciences
1999;96:15137-15142.
Copyright © 1996-1999 Reuters Limited.
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Judith Richards, London, Ontario, Canada
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