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Sunday, February 15, 2009

Scientists warn of first ever case of human mad cow disease from blood plasma

By Patrick Hennessy and Laura Donnelly

Cows - Scientists warn of first ever case of human mad cow disease from blood plasma
Scientists fear there could be a second wave of the human variant of mad cow disease, which was caused by cattle being fed the remains of other cattle in the 1980s Photo: EPA

The man was one of thousands of haemophiliacs who received blood plasma transfusions in the years before strict controls were brought in to eliminate the spread of variant Creutzfeldt-Jakob disease (vCJD).

Until now, scientists had maintained that the 4,000 people who may have received plasma from infected donors were at very low risk of developing the fatal brain disease. Warnings were issued to them as a "highly precautionary measure".

But the Health Protection Agency is expected to announce on Tuesday that an elderly man, who died from other causes, contracted vCJD from plasma.

Although vCJD has been transmitted by blood donations in the past, leading to three deaths, no cases of infection had ever been linked to plasma, which is used to clot blood. Scientists had believed the processing and dilution of the product before it is injected into patients significantly reduced the risks.

BSE expert Professor Hugh Pennington, Emeritus Professor of Bacteriology at Aberdeen University said the findings would have "significant implications" for thousands of people who had been given plasma before the dangers were suspected.

"This looks like pretty grim news for a group of people who have been through fire and water for so long; they have already had increased exposure to hepatitis B and HIV," he said.

Warnings were sent to 4,000 haemophiliacs, and patients suffering from other rare blood conditions in 2004 to warn them that they had had received transfusions from 200 batches of blood products at risk of contamination with vCJD. The plasma was collected from nine people who went on to develop the brain-wasting disease.

All 4,000 were advised not to give blood or donate organs and to warn doctors and dentists that they had been put at risk by the use of plasma.

To date, 164 people have died from vCJD in Britain, with most cases linked to eating meat infected with bovine spongiform encephalopathy.

Prof Pennington said details of the way the new link had been detected would be crucial in determining further investigations.

"There is a lot more we still need to know. The fact that this person is elderly, when most of the deaths from vCJD have been young people, and that they died from another cause, is another area for research," he said, suggesting that it might mean that the disease progressed more slowly in some people.

He said restrictions over blood donation, which mean anyone who has had a transfusion cannot donate, and that all plasma is now taken from stocks in the United States, meant the risks to those receiving blood or plasma now were "vanishingly low".

The brain-wasting disease vCJD was first detected in the mid 1990s. Most vCJD patients have been infected after eating BSE contaminated meat. The number of deaths peaked in 2000, when there were 28 deaths. That number has dropped to about five cases a year since 2005.

The epidemic of BSE in the 1980s and 1990s was caused by cattle being fed the remains of other cattle in the form of meat and bone meal, causing an infectious agent to spread.

More than 4 million cattle were slaughtered after almost 200,000 were infected with the fatal neurodegenerative disease.

Scientists recently warned that Britain could see a second wave of the vCJD, affecting as many as 300 people, after discovering that genetic differences can affect how long it takes a person to incubate the disease.

Original here

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