Mad Cows and Englishmen
By Lawrence Tim Goodnough, M.D.
The topic of the presentation by Dr. Patricia E. Hewitt of the National Blood Service, England, at the Transfusion Medicine Education Session yesterday and today, is "Variant Creutzfeldt-Jakob Disease (vCJD) and Blood
Transfusion: How Real is the Risk?”
The possibility that vCJD might present a risk to the blood supply has been a concern since its first description
related to ingestion of contaminated beef in 1996. A sheep animal model has previously demonstrated that
sheep infected via contaminated feed with bovine spongiform encephalopathy (BSE, or mad cow disease) is
transmissible to another (healthy) sheep via blood transfusion. To date, 29 of 151 cases of vCJD were reported to
have been blood donors prior to their development of vCJD. Of these, blood products from 19 donors have been
identified to have been transfused to a total of 51 identified recipients. In a report in December 2003, one of the
blood component recipients was identified to develop symptoms of vCJD more than six years after receiving a
transfusion of red cells. This blood had been donated more than three years before the donor developed symptoms
of v CJD. The linking of the case, through the Transfusion Medicine Epidemiologic Review (TMER), to a
case in the blood donor was the first evidence of vCJD transmitted through blood transfusion in humans.
Hewitt and her colleagues estimated that the probability that the recipient could have acquired vCJD from
the contaminated food chain, rather than from the contaminated blood unit, was less than a 1:40,000 chance.
A second patient has also been identified to have received a blood unit from a donor who developed vCJD;
this patient died of complications of cancer within months of the transfusion without pre-mortem manifestations
of vCJD. However, at autopsy, evidence of the abnormal prion characteristic to the disease was demonstrated
to be present in lymphoid appendiceal tissue. Based on this evidence, the case is being classified as
probable, but not definite, evidence of blood transmission of vCJD.
Dr. Hewitt highlighted the CJD surveillance and blood transfusion issues in the UK yesterday at 8:00 a.m.
and will also review the clinical epidemiology of vCJD today at 7:30 a.m. in the Transfusion Medicine Education
Session, sponsored jointly by the American Society of Hematology and the American Association of
Blood Banks.
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