Blood scare unsettles UK

New vCJD scare rocks the UK
18:10 08 December 2006
Debora MacKenzie
New Scientist

A third person in the UK has caught variant CJD from another human, in
a blood transfusion. Many more people may be at risk of this human form
of BSE, experts warn.

Three of eight people tested so far in the UK are now confirmed to have
been infected with vCJD through blood transfusions, autopsies have
revealed. A total of 66 people in UK are known to have received
transfusions from blood donors who later went on to develop vCJD.

Of those, 34 later died from other causes. The remaining 24 people have
been informed that they may be at high risk of developing vCJD, but are
not reported to have been tested.

In each of the three cases, the victims received blood from someone who
went on to develop vCJD between 18 and 40 months after donating blood,
which shows that apparently healthy blood donors can pose a threat of
infection, at least in the late stages of incubation. Many carriers,
unaware of their infection, may have transmitted the mutant prion in
donated blood, experts say.

Definitive evidence
For that reason, it was "prudent" in 2004, once the first
transfusion-related case was discovered, for the UK to ban transfusion
recipients from later donating blood, say Kumanan Wilson and Maura
Ricketts of Toronto General Hospital and the Public Health Agency of
Canada. They penned a commentary on the case in the medical journal The
Lancet, which reported the third case this week (see vCJD death linked
to blood transfusion.

Animal experiments have shown it is possible to transmit the prion via
blood, but prions behave differently in different species, and these
three cases are the only definitive evidence that blood-borne
transmission can happen in people.

And for three of the eight people tested to be carrying the prion shows
that spread among humans, in blood, is much more efficient than spread
from cattle to humans via meat. Virtually the entire population of the
UK was exposed to infected meat in the late 1980s and early 1990s, but
relatively few cases of vCJD have resulted so far.

No treatment
There has been reluctance to test living people without vCJD symptoms
for vCJD infection, because of the ethical issues involved (see Should
people be tested for mad cow disease?).

The incubation period between infection and the manifestation of
disease is very long. There is no way to know if infection will result
in clinical disease within a person's lifetime, and no way to prevent
it or treat the disease.

In the most recent transfusion-related case, a 31-year-old man died
while receiving an experimental drug, quinacrine.

But John Collinge of University College London, UK, and colleagues, who
reported the clinical details of the most recent case, say people at
high risk of vCJD should be informed, so they can be enrolled in
clinical trials of drugs which are hoped to delay or prevent the onset
of the disease.

Journal reference: The Lancet (vol 368, p 2061)