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The review by Soldan and Barbara1 on the risks of infection transmission by blood transfusion is an interesting and comprehensive article. However, there is little reference of prion disease and in particular new variant Creutzfeldt-Jacob disease (nvCJD) and the recently recommended control measures for blood donated in the United Kingdom. The only mention is in the last paragraph where they state “whether prion disease can be transmitted by transfusion is currently uncertain.”
From 1995 to the end of March 1999, 40 cases of nvCJD had been reported in the United Kingdom,2 and it is currently not known how many people may be incubating it asymptomatically. A recent working party report3 considers that the distribution of infectivity of nvCJD may be different from that of other forms of CJD, as in the former there may be more involvement of lymphoreticular tissues, possibly involving circulating lymphocytes. Evidence of nvCJD has previously been found in human tonsillar tissue.4
In Britain donated blood supplies are to be treated to reduce the risk of patients being infected with nvCJD because of the theoretical risk that it could be transmitted by white blood cells.5 Plasma which is used to manufacture plasma products—for example, as used in haemophilia—is currently obtained outside Britain.5 Also from November 1999 all cellular blood products will undergo leucodepletion,6 a method which removes up to 95% of white blood cells.5
Hopefully, further research will resolve these uncertainties about the infectivity of blood products and allow an accurate determination of risk.
We agree with the author of this letter that more comment about nvCJD and the adoption of measures to try to control its possible transmission by blood donated in the United Kingdom is warranted. The situation with regard to nvCJD, as described by Dr Dawson, was evolving during and since the time we wrote our review, and we welcome its addition to the record in this manner.