Proceedings of a consensus conference: the screening of blood donors for variant CJD1

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Abstract

Since the identification, in 1996, of the first case of variant Creutzfeldt-Jakob disease (vCJD) in humans various approaches have been implemented and/or proposed to prevent this disease from being transfusion transmitted. In addition, a variety of possible laboratory-based approaches have been developed and will continue to be developed for the vCJD screening of blood donors. Various issues related to the implementation of such vCJD testing is likely to assume greater importance as diagnostic tests for vCJD becomes available for the potential screening of blood donors. The purpose of this Consensus Conference was to bring together international experts in an effort to determine which principles should guide the introduction of such testing. These experts provided the scientific and biological background of bovine spongiform encephalopathy (BSE) and vCJD, an understanding of their current epidemiology, as well as the ethical and legal issues that would impact on the implementation of a screening test for preventing the transfusion transmission of vCJD. This contentious issue is of potential considerable importance to transfusion medicine personnel worldwide, as well as to future recipients of allogeneic blood components.

Section snippets

Background and epidemiology of BSE

Presented by Maura N. Ricketts, MD, MHSC, FRCP(C) World Health Organization Geneva, Switzerland

Since the identification of the first bovine spongiform encephalopathy (BSE) in the United Kingdom in 1986, there have been over 180,000 cases of BSE reported from the United Kingdom alone. Although the origin of the epidemic is uncertain, it is clear that this infection was propagated by the recycling of bovine feed. The number of BSE reports in the United Kingdom and Europe by year is detailed in

Background and epidemiology of vCJD

Presented by Richard Knight, MD National CJD Surveillance Unit, Edinburgh, United Kingdom

TSEs have been described in both humans and in animals (Table 1). CJD occurs in 4 forms: sporadic, genetic, iatrogenic, and variant. vCJD was first described in humans in 1996 and is thought to be caused by the same agent responsible for BSE in cattle.

vCJD in transfusion

Presented by Chris Prowse, MD, Research Director, Scottish National Blood Transfusion Service, Edinburgh, United Kingdom

The main concern in the field of transfusion medicine, in relation to vCJD, is whether blood donations from vCJD-infected individuals are infectious.

Sensitivity, specificity, and predictive value of screening tests

Presented by Eleftherios C. Vamvakas, MD, PhD, Canadian Blood Services, Ottawa, Ontario, Canada

Laboratory tests used to screen blood donors for the presence of transfusion-transmitted infection detect the presence of a trait ordinarily associated with the infection in a population of donors with—or without—that trait. Presence of the trait is interpreted as presence of infection and thus the ability (on the part of the donor) to transmit infection. Absence of the trait is interpreted as absence

BSE and vCJD screening tests

David Anstee, MD Bristol Institute for Transfusion Sciences, Bristol, United Kingdom

The infective agent of BSE and vCJD is thought to be an abnormal form of prion protein, PRPSc. PRPSc is the most obvious target for a diagnostic test for BSE and vCJD. Its conformation differs from the normal form of prion protein, PRPc, with beta sheet regions replacing alpha helical regions. The production of specific antibodies that would detect these conformational differences has proved to be difficult. The

Legal aspects of a vCJD testing and notification program

Presented by Kathleen Sazama, MD, Anderson Cancer Center, Houston, TX, USA

Implementation of a test for vCJD would raise a number of legal issues with respect to the test procedure itself, notification of blood donors found to be test positive (or false positive), and follow-up of recipients of previous blood components donated by those individuals. One might anticipate legal action based on the adequacy of informed consent for donation (donor) or for transfusion (patient/recipient), failure of

Donor perceptions and ethical aspects of an eventual testing and notification program

Presented by Patricia Hewitt, MD, National Blood Service (England), London, United Kingdom

In the United Kingdom, the National Blood Service (NBS) (England) expects that there will be pressure to screen the blood supply for vCJD when a screening test becomes available. Screening tests may appear before a confirmatory test becomes available and before the meaning of a positive or negative test result has been determined. To explore how donors are likely to respond to the introduction of a vCJD

Open discussion

Lead by Gilles Delage, MD, Héma-Québec, Montreal, Québec, Canada

Acknowledgements

The authors of these Proceedings would like to thank the international group of expert presenters to this Consensus Conference for both their excellent presentations and for their cooperation in reviewing the summaries of their presentations for accuracy. We would like to also acknowledge the important contributions of Lisa Markus and her colleagues of Malachite Management (Vancouver, BC, Canada) for their exquisite attention to the organizational details of this Consensus Conference, the

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    This Consensus Conference took place at the Ritz Carlton Hotel in Montreal, Quebec, on March 26–28, 2003, and was chaired by Dr. Gilles Delage of Héma Québec.

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