Until recently the risk of developing CJD as a consequence of a blood transfusion was a theoretical concern. However, in December 2003 a patient died from vCJD after receiving a blood transfusion from a donor who subsequently also had vCJD. Since then, three further patients have been identified. One patient died of an unrelated condition, but a post mortem examination established that the abnormal form of the prion protein was present in their body. This suggested that the prion protein had been transmitted via the blood transfusion but had not yet caused a brain illness.

Although we hope ultimately that the numbers of individuals who develop vCJD from blood transfusions will be small, we still do not know how many people in the UK could be incubating vCJD from this route of infection. Our understanding of these matters will be improved when a screening test is developed so that abnormal prion protein can be detected in the blood of at risk individuals or used to screen blood before it is transfused into someone else. Until this happens only precautionary measures can be put in place in an attempt to reduce the risk of exposure.

When a person is diagnosed with CJD, their health history is examined to see if they have had surgery or donated blood in the past. The risk to public health is then determined and anyone who is identified to be at an increased risk of contracting CJD (for instance, through receiving a blood transfusion from that individual) is informed via their GP of the fact that they may have been exposed. As a consequence, a small but increasing number of people who are deemed to have an additional risk of developing vCJD are being identified. Despite the fact that these people have been exposed we still have little idea as to the exact extent of their actual risk making it difficult to give overall advice about what they should expect.

One major concern has been that vCJD caused by prion protein infection from blood might be different to the neurological illness vCJD caused by the infection as a result of eating BSE infected meat. There are examples in the studies of the different prion protein disease where changes in the "strain" of the prion protein occur when the protein has been passed from one person to the next. The recent study suggests that no change in the character of the prion protein occurs as it is passed from one human to the next via blood. These preliminary results are reassuring to some extent but we are still some way from understanding this very complex area.

Dr Angus Kennedy (Consultant Neurologist)
CJD Support Network