- Thousands of people are to be tested
for CJD after scientists discovered evidence of the human form of cow disease
in people's tonsils.
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- The find means it may be possible in
the next three years to establish if a CJD time bomb is ticking within
Britain's population.
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- It also raises concerns about the rise
of infection from surgical equipment.
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- BBC News Health 1-15-99
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- New variant CJD is believed to be linked
to BSE in cows
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- Scientists have developed a test for
CJD which could show the extent of the disease in the population.
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- Until now it has only been possible to
diagnose cases of new variant CJD, the disease linked to BSE in cattle,
after death.
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- The test involves taking tissue from
the tonsils and can be conducted on living people.
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- The findings could eventually mean scientists
will be able to develop a test which could diagnose people with nvCJD as
soon as they are infected.
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- Research can now be done on material
from tonsillectomies to estimate the extent of nvCJD - which has a long
incubation period - in the general population.
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- But the findings also raise concern about
infection caused by the rogue proteins that spread the disease and cannot
be cleaned from surgical instruments no matter how thoroughly they are
sterilised.
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- Writing in The Lancet, the scientists
led by Professor John Collinge at the Imperial College School of Medicine
at St Mary's Hospital in London, say they tested tonsil tissue from 20
patients in the late stages of suspected prion disease.
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- An abnormal form of the protease-resistant
prion protein is thought to cause the breakdown of brain cells associated
with nvCJD.
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- Prions reproduce in the tissues of the
immune system, including the tonsils.
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- Because of the theoretical possibility
that the disease could be spread by surgery to the infected organs Professor
Collinge recommends that for such operations only disposable surgical instruments
be used.
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- The infection can withstand high temperatures
which make the usual sterilisation procedures ineffective.
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- Dr Stephen Dealer, from the BSE Research
Campaign, said the findings would help to assess the risk from surgical
instruments.
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- "This is one of the reasons why
John Collinge's test may be so wonderful. It will give use some insight
into just how big that risk is. This is a very important finding,"
he told BBC Radio 5 Live.
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- Thirty-three cases of nvCJD in the UK
and one case in France have been confirmed since 1996.
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- The researchers also tested tonsil, spleen
and lymph node tissues from patients who had died of the disease.
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- They found that all immune system tissue
obtained from dead patients whose CJD had been confirmed by brain biopsies
contained the rogue prion.
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- Different progression
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- Tonsil biopsies of living patients found
the tissue was positive for the prion in the three cases which were confirmed
on death to have the disease.
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- The research also showed that nvCJD has
a different progression from normal CJD and may spend longer in the immune
system.
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- This suggests it could present greater
dangers of infecting people through blood tranfusions, organ transplants
and tissue-sharing.
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- They believe the difference in progression
may be due to the suspected root of exposure - through eating BSE-infected
meat.
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- This could suggest that the people who
have developed nvCJD have immune systems which are particularly susceptible
to nvCJD.
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- The scientists believe they may eventually
be able to develop a test which is sensitive enough to detect prion infection
at an early stage of infection.
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- Definite diagnosis
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- Professor Collinge, whose research is
funded by the Wellcome Trust and the Medical Research Council, said: "This
new test has already proven very helpful in the diagnosis of new variant
CJD.
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- "While, unfortunately, we have at
present no means to treat this dreadful disease, we can at least now provide
a definite diagnosis at an earlier stage."
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- He said research needed to continue to
identify whether it would be possible to detect the disease through a simple
blood test.
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- Excite UK Channels News New CJD Fears
After Test Finds Disease In Tonsils 1-15-99
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- Scientists have discovered evidence of
CJD, the human form of mad cow disease, in people's tonsils.
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- The find means it may be possible in
the next three years to establish if a CJD time bomb is ticking within
Britain's population.
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- But it also raises renewed concerns about
the risk of infection from surgical equipment in hospitals, the expert
behind the discovery said.
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- Scientists plan to screen thousands of
people using the new test. A significant positive result would provide
early warning of a major epidemic to come and allow time for action aimed
at averting the disaster.
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- Professor John Collinge, from St Mary's
Hospital, London, said: "If we were to screen several thousand tonsils
and found that several were positive that would be a real cause for concern."
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- The concern about infection raised by
the new findings centres on rogue prion proteins that spread the disease
and cannot be cleaned from surgical instruments no matter how thoroughly
they are sterilised.
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- In future therefore it may be necessary
to introduce disposable instruments for certain procedures. A special committee
of experts advising the Government is already looking at this issue.
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- Animal studies have shown that spongiform
encephalopathy diseases, which include different forms of CJD, BSE in cattle
and the sheep infection scrapie, tend to reside in the lymph system before
attacking the brain. Tonsils are linked to the lymph system.
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- The new research by Professor Collinge's
team showed this also appeared to be the way new variant CJD behaved in
humans.
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- But only the new variant form of CJD,
which is effectively mad cow disease transferred to humans through infected
beef, was detected in tonsils. The "classical" form of CJD, which
appears for no known reason in one person in a million, was not seen in
the tissue samples.
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