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9 December 2002
Test everyone for CJD, says Nobel winner
Jonathan Leake, Science Editor, Sunday Times, 1st Decmeber 2002
A Nobel prize-winning scientist says the entire
British population should be tested for variant CJD, the human form
of mad cow disease, amid fears that the number of cases may be greater
than previously feared.
Professor Stan Prusiner, who discovered the cause
of BSE, said the impact of the epidemic could be bigger than so
far recognised. CJD has killed 117 people in Britain since 1995
and another 11 are known to be dying from the disease. Some experts
suggest the death toll could reach more than 100,000.
A million cattle infected with BSE entered
the British food chain so almost everyone in the country will have
been exposed to the infectious prion proteins that cause variant
CJD, said Prusiner. Every Briton should be tested so
that if they are developing the disease it can be spotted before
There is no cure for any form of CJD although
some therapies are undergoing early trials. Tests would help prevent
people who are incubating the disease from infecting others through
surgical instruments, blood donations or other procedures. Instruments
contaminated with CJD cannot be sterilised because the prions are
resistant to high temperatures and chemicals.
Prusiner, a professor at the University of California,
San Francisco, awarded the Nobel prize for medicine in 1997, was
in Britain to discuss research into the disease. He warned that
thousands of cows and sheep infected with BSE and related diseases
were still being sold for human consumption because they were being
killed before they developed symptoms. The government should
be testing every cow and sheep entering the food chain, he
said. Nobody should be being exposed to prions in any way.
Last week research by scientists at University
College London indicated that the number of CJD cases caused by
eating BSE-infected meat might be greater than previously thought.
Researchers found evidence that BSE, in addition to causing variant
CJD, may also be responsible for some cases of sporadic
CJD, a strain of the disease that tends to affect older people.
Since 1990, 588 cases of sporadic CJD have been reported in Britain.
Prusiners comments come as scientists at
the governments Veterinary Laboratories Agency are evaluating
five potential tests for prion disease. So far the only validated
tests need brain or spine tissue only available after death. At
least two of the new tests have been shown to work with blood, so
samples could be taken from living animals or people. Once the new
tests are validated, possibly next year, they would allow mass screenings
of livestock and people.
A national testing scheme could have political
consequences. Multi-million-pound compensation claims might be launched
by people told they are incubating the disease.