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- PARIS, (AFP) - The human
version of mad-cow disease can be spread by blood transfusion, according
to preliminary research published Friday.
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- These early findings place a question mark over the safety
of blood transfusions, as the agent can be transmitted even before a blood
donor shows any symptoms of the disease, the researchers suggest.
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- Variant Creutzfeldt-Jakob disease (vCJD) is caused by
the same agent as mad-cow disease, in which a mutant form of a protein
called a prion proliferates crazily, causing sponge-like holes to form
in the brain.
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- Eating beef contamined by bovine spongiform encephalopathy
(BSE), as mad-cow disease is called, is an identified path of catching
vCJD.
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- But until now, data has been unclear or contested as
to whether it can also be passed on in blood transfusions.
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- Reporting in Friday's issue of The Lancet, scientists
at the Institute for Animal Health in Edinburgh say they fed a breed of
British sheep a sample of brain from cattle infected with BSE.
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- Sheep were chosen as they harbour the infectious agent
in tissues other than the brain and spinal cord, as do humans.
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- Blood was taken from 19 infected sheep before any symptoms
were apparent, and was transfused into healthy sheep imported from New
Zealand.
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- After 610 days, one of the transfused sheep began to
show signs of the disease. All the others are healthy at present, although
most are at an earlier stage after transfusion than the affected sheep.
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- While acknowledging that their study still had several
years to run and so far only one animal had fallen sick, the scientists
said this early finding was "sufficiently important" to announce
right now.
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- "This report suggests that blood donated by vCJD-infected
human beings may represent a risk of spread of vCJD infection among the
population of the UK," they said.
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- It should now be possible to identify which cells are
infected and develop a diagnostic test for vCJD based on a blood sample,
they said.
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- That would also help to test the effectiveness of a two-year-old
British policy which seeks to eliminate the likeliest source of vCJD transmission
by stripping out white blood cells from blood donations.
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- As its name suggests, vCJD is a form of Creutzfeldt-Jakob
disease (CJD), for which there is no evidence of a risk of transmission
by blood transfusion. However, vCJD "has a different pathogenesis
(from CJD) and could represent different risks," the scientists caution.
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- Meanwhile, researchers from France's National Centre
of Scientific Research (CNRS) report Friday that vCJD may be promoted by
normal prions as well as abnormal ones.
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- Three types of non-mutant prions play a role in a complex
"cascade" of enzyme signals that govern brain-cell functions,
they say in work published in the US weekly Science.
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- This discovery could ultimately throw up possible treatments
for vCJD by designing drugs that block or alter the signalling process.
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- Britain is the seat of the BSE epidemic and the vCJD
crisis that has followed in its wake. As of August, the total number of
identified British cases with vCJD stood at 79.
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- People with vCJD suffer jerky movements, forgetfulness,
dementia and finally death. There is no cure or vaccine at present.
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- link
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- _____
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- Strongest Evidence Yet CJD/Mad Cow Spread By Blood Transfusions
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- http://news.bbc.co.uk/hi/english/health/newsid_925000/925151.stm
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