After the storm? UK blood safety and the risk of variant Creutzfeldt-Jakob Disease - Science and Technology Committee Contents


In the late 1990s, few diseases were as high profile, or as poorly understood, as variant Creutzfeldt-Jakob Disease (vCJD): the 'human form' of bovine spongiform encephalopathy (BSE). Invariably fatal and seemingly impossible to control, vCJD was an unusually enigmatic threat, leading prominent figures to warn of hundreds, even thousands of potential deaths, prompting widespread speculation that the handful of cases seen at the time were merely the tip of the iceberg.

Twenty years on, the feared epidemic has not materialised and vCJD has, to an extent, slipped from public consciousness. However, there remains much that we do not understand about vCJD and little to suggest that it should be dismissed as a threat.

While cases of vCJD are now rare, recent studies indicate that tens of thousands of people in the UK might be 'silent' carriers of the prions responsible for the disease and could perhaps transmit those prions to others. The most likely form of onward transmission is through blood transfusion. Cases of transfusion-transmitted vCJD are known to have occurred in the past, and, while it remains to be seen whether or not widespread transmission via the blood supply is probable, evidence suggests that it is possible. In the absence of a validated test capable of detecting the presence of prions in blood, we simply cannot know how significant a threat to public health vCJD might be.

The Government acknowledges this risk and claims that, like its predecessors, it has taken a precautionary stance in response. However, while administrations in the late 1990s assumed the worst and took steps to prevent it from happening, the Government recently appears to have adopted a more optimistic approach in which the low incidence of identified cases of vCJD is used as justification for inaction. This is particularly evident in the Government's less than enthusiastic response to emerging vCJD risk mitigation technologies such as prion filtration and the prototype vCJD blood assay recently developed by the MRC Prion Unit.

In this report we remind the Government that no evidence of harm is not the same as evidence of no harm. Cases of vCJD appear to be falling but, given the level of uncertainty regarding the potential for blood-borne transmission, precaution must remain the guiding principle in decision-making. Research intended to reduce this uncertainty should be pursued as a priority and, in the meantime, measures to reduce the risk of blood-borne transmission should be strengthened wherever possible.

The Government's casual attitude to vCJD transmission is not confined to blood transfusion: it is also evident in its response to the risk of surgical transmission. It is known that classical CJD can be transmitted via contaminated surgical instruments and there is reason to believe that vCJD may also be transmissible via this route; however, development of a commercial technology capable of eliminating this risk has ceased in the absence of Government support and as a result of the NHS's apparent lack of appetite for such technology. Without a technological solution, we cannot be confident that CJD is not being transmitted through surgery and we are disturbed by the Government's apparent lack of concern about this issue.

Failure to adequately mitigate these risks means that some people have inadvertently been exposed to CJD or vCJD and may be at increased risk of developing the disease. This inquiry has exposed deficiencies in the level of support provided to these individuals and the system of surveillance through which they are monitored; both of which, in many cases, have effectively been outsourced. We consider this arrangement to be unacceptable and urge the Government to take greater care of, and responsibility for, those who have been accidentally exposed to CJD or vCJD. We were also disappointed to find that so few 'at risk' individuals have been asked for their consent to participate in research and recommend that the Government takes immediate steps to remedy this situation.

At the conclusion of this inquiry we are unconvinced that the Government has done all that it potentially could do to ensure that the UK blood supply is, and continues to be, free of dangerous pathogens. We therefore conclude by recommending that the Government commission a full assessment of the key risks, known and unknown, that the UK blood supply currently faces and might face in the future, so that it can identify and fill relevant knowledge gaps and support the development of appropriate risk reduction measures and technologies.

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Prepared 24 July 2014