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17 February 2003Clarification of the Possibility of Transmitting CJD in Man by Blood ProductsDr James Irvine(Filed 17/02/03)© Teviot Scientific Consultancy
There have been no proven cases of transmitting CJD via blood transfusions or from the use of blood products. Nevertheless there is a risk (however small) that this might happen (1). Pat Rickett’s letter in response to a piece I am quoted in Warmwell can be read in the Correspondence section (click here). He is quite right. Instead of the phrase used, which was:
It should have read:
Experimentally TSE's have been transmitted by blood transfusion in animal experiments (2). Iatrogenic (i.e. caused by medical intervention) CJD has occurred in man when tissues from a patient with CJD have been inadvertently used in the management of another patient (3, 4). Iatrogenic CJD has also occurred in humans treated with growth hormone, which in the early days was obtained from extracting the hormone from human pituitaries, one or more of which turned out to have come from subjects who had CJD (3, 4). Nowadays growth hormone is synthesised and carries no such risk. With this evidence it is understandable that there could be a risk that vCJD may possibly be transmissible by blood transfusion, if blood or blood products are obtained from a person who unknowingly is incubating vCJD. Likewise, there is a fear that vCJD may be transmissible by reusing surgical instruments that have been used in brain surgery (4). Prions are very difficult to remove from such instruments using most cleansing procedures. All sorts of elaborate and expensive Health & Safety measures are coming into effect with regard to land and livestock management, based on the risk of TSE agents (such as prions) getting into the water supply etc. (5). Although there may be other causes of vCJD apart from prions, prions are at least a contender for being one of the possible culprits. It would be unwise to ignore their possible role - hence the worry. Fortunately, to my knowledge there have been no proven cases of transmitting vCJD via blood transfusions or from the use of blood products. Major precautions are being taken to minimise that theoretical risk. The hazard is recognised, but the actual size of the risk of that hazard actually happening is unknown. The reason why I think that the research done by Gradipore and collaborators is important is that it will hopefully lead to a way of separating, concentrating and thereby studying prions from tissues (including blood) obtained by simple non-invasive procedures during normal life in both man and beast. If by such means it can be demonstrated that there are no pathogenic prions in a blood donation, or that they have all been effectively removed, this would greatly reduce the theoretical risk of transmitting CJD. It could lead to a great reduction in scaremongering (6) if we could get that reassurance. Development of the membrane technology being studied by the commercial company Gradipore (7), along with collaborators including the Scottish Blood Transfusion Service, should also hopefully throw some light on what prions are up to in the early preclinical stages of TSE's, both in animals and in humans. However, I understand that the research is still in an early stage of development with the preliminary results submitted for presentation at a Conference in April this year, and a paper being prepared for publication in a peer-reviewed scientific journal. The actual application of the technology to the human scene is a long way off - if it ever gets there - but it does sound promising. I should add that I have no vested interest in Gradipore, nor in the Scottish Blood Transfusion Service - apart from possibly being a patient needing a blood product at some time in the future.
References1. Editorial Comment (2002). Risk of vCJD from Blood Transfusion. Land-Care, 2002, click here to view). 2. Hunter, N., Foster, J., Chong, A., McCutcheon, S., Parnham, D., Eaton, S., MacKenzie, C. and Houston, F. (2002). Transmission of prion diseases by blood transfusion. J. Gen. Virol., Published ahead of print (16 July 2002) in JGV Direct as DOI 10.1099/vir.0.18580-0. (Download PDF). 3. The UK Creutzfeldt-Jakob Disease Surveillance Unit: www.cjd.ed.ac.uk 4. Has CJD been transmitted to 24 patients through the inappropriate use of surgical instruments? Land-Care, 2002, click here to view. 5. Regulation (EC) No 1774/2002 of the European Parliament and of the Council of 3 October 2002 laying down health rules concerning animal by-products not intended for human consumption. Download PDF (1.7MB). 6. Linklater, Magnus (2002). They
drive us Mad with False Fears about Mad Cows. The Times, 5th December,
2002. 7. Detection
of Prions: Developing Technology. Land-Care, 2003.
Further Reading Recommended by Land-Care
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Haywood, S. and Brown, D. R. (2003). Transmissible Spongiform Encephalopathies.
Veterinary Times, 33 (2): 8-10.