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Health: Creutzfeldt-Jakob Disease

Volume 698: debated on Monday 21 January 2008

My Lords, I beg leave to ask the Question standing in my name on the Order Paper. In so doing, I must declare an interest as having been a member of the Southwood working party, which was appointed in the early 1990s by the Government to advise on the implications for human health of the BSE epidemic.

The Question was as follows:

To ask Her Majesty’s Government whether they will promote, through the National Blood Service, clinical trials of the prion capture (P-CAPT) filter to assess the value of this device in the prevention of transfusion-induced variant Creutzfeldt-Jakob disease (vCJD).

My Lords, NHS Blood and Transplant has already initiated a number of studies to assess the efficacy of the P-CAPT filter in removing variant CJD infectivity from blood as well as the quality and clinical safety of blood once it has been filtered. These studies are ongoing. This approach is based on the advice that NHS Blood and Transplant received from the Spongiform Encephalopathy Advisory Committee and the Advisory Committee on the Safety of Blood, Tissues and Organs.

My Lords, I thank the Minister for that encouraging reply. Does he accept that three individuals have died as a consequence of variant CJD as a result of blood transfusion? The prion is not a bacterium; nor is it a virus. It is a small molecule of protein, which is infective, but which has a very long incubation period. I am glad to hear that these trials are being undertaken because this device has already received a European CE certificate and trials are under way in the Irish Blood Transfusion Service to try to prevent the death of any more individuals from infected blood.

My Lords, I am grateful for the advice of the noble Lord, who is a great expert in this field. The P-CAPT filter is an innovative product. However, I am sure that noble Lords will agree that the introduction of any new technology will be based on the efficacy and the safety of such technologies. We currently have three studies looking at the efficacy. We also have one safety study because the filter itself could create new antibodies that might harm the recipient patient. I also acknowledge the fact that Ireland has introduced the product in those cases where most of the recipients of blood are children.

My Lords, any medical intervention carries risks; we are fully aware of that. However, as it stands at the moment, we have applied every technology available to us in screening blood for conditions such as hepatitis B, hepatitis C and HIV. The difficulty in this situation is that we do not currently have a screening test for variant CJD. As we are all aware, it is carried not by blood but by prions—most of which are concentrated in lymphoreticular tissue.

My Lords, will the Minister comment on reported remarks by the chairman of SEAC to the effect that the prion is not the infectious agent but merely a sign of infection?

My Lords, I am grateful for the noble Countess’s intervention. I agree with the analysis that, while abnormal prion proteins are considered to be the infectious agent, the precise nature of infectivity may differ from that of the prion alone. That was highlighted in an editorial in Science in 2007 by one of my colleagues, Professor Collinge.

My Lords, the diagnostic technique of protein misfolding cyclic amplification is being used to test for variant CJD in brain tissue. Are there any plans to introduce that test for blood—could it be effective? Will he explain what it is?

My Lords, I will spare the House a tutorial in molecular biology. However, the test is valid in lymphoreticular tissue. The same test has been used in examining biopsies of, for example, tonsils. The noble Baroness will be aware of the study currently being undertaken to screen 100,000 tonsils. I am delighted to report that 45,000 have already been screened and there is no evidence of any infectivity.

My Lords, is the Minister aware that the device in question has a CE mark, which means that it has European regulatory approval and therefore can be used quite legally now? Given that the Government have already conducted studies into the prevalence of variant CJD and found the risk high enough to implement leucodepletion, which, as the Minister will know, is not by any means 100 per cent effective, why is it necessary to undertake further studies which will only delay the implementation of effective prion filtration?

My Lords, I am grateful for the noble Earl's intervention. CE marking does not necessarily mean that a product has been through effectiveness or efficacy studies. We are carrying out a study at the moment based on a recommendation of the Spongiform Encephalopathy Advisory Committee, which suggested that an identical study to the one carried out by the manufacturers should be independently carried out by the NHS.

My Lords, I understand that the number of new cases of variant CJD each year has now reduced to a trickle. However, Professor Collinge, whom the Minister mentioned a moment ago, has suggested that there may be future second and third waves of the disease. What is the Government’s attitude to that suggestion? If they accept Professor Collinge’s proposition, how will that affect their attitude towards risk management, including blood transfusion?

My Lords, we have had 166 infections for variant CJD, the peak of which was in 2000, when there were 28 cases. I am delighted to report that last year we had only one infection. The noble Lord referred to the genotype of these infections, most of which have been of the MM variety. There has been a recent scientific dispute about whether one case is of the VV variant. Scientists continue to disagree about whether that case is one of sporadic CJD or variant CJD. At the moment, as it stands, the registry in Edinburgh considers that the VV case is sporadic rather than variant CJD.