The first symptomatic case of vCJD associated with blood transfusion was identified in December 2003. This individual developed vCJD six and a half years after transfusion of red cells donated by an individual who developed symptoms of vCJD three and a half years after donation.

A second case of vCJD 'infection' was identified a few months later in a person who had received red cells from a donor who developed symptoms of vCJD 18 months after donation. This patient (the second case) died from causes unrelated to vCJD five years after transfusion. Post-mortem investigations found abnormal prion protein in the spleen and a cervical lymph node., However, prion protein was not found in the brain, and no pathological features of vCJD were found.

A third case developed symptoms of vCJD six years after receiving a transfusion of red blood cells, and died two years and eight months later. The donor of the blood involved developed vCJD about 20 months after donating it.

These three cases have been published as case reports and in the findings of the ongoing collaborative study between the National Blood Services, the National CJD Surveillance Unit, and the Office for National Statistics. This study aims to collect evidence about transmission of CJD or vCJD via the blood supply [2,3,4,5].

The new, fourth case is in a patient who developed symptoms of vCJD eight and a half years after receiving a transfusion of red blood cells from a donor who developed vCJD about 17 months after this blood was donated [1]. The donor to this case also donated the vCJD-implicated blood transfused to the third case. As for all other reported clinical vCJD cases that have been tested for genotype, this patient is a methionine homozygote at codon 129 of the prion protein gene. The patient is currently alive.

All four cases had received transfusions of non-leucodepleted red blood cells between 1996 and 1999. Since October 1999, leucocytes have been removed from all blood used for transfusion in the UK. The effect of leucodepletion on the reduction of the risk of transmission of vCJD from an infective donation is uncertain.

This fourth case of vCJD infection associated with blood transfusion further increases the level of concern about the risk of vCJD transmission between humans by blood transfusion, although much remains unknown. This reinforces the importance of the existing precautions that have been introduced to reduce the risk of transmission of vCJD infection by blood and blood products [6]. No cases of vCJD have been associated with fractionated plasma products. The small group of living recipients of vCJD-implicated blood transfusion in the UK have been informed of their potential exposure to vCJD by blood transfusion, asked to take certain precautions to reduce the risk of onward person-to-person transmission of vCJD during health care, and offered specialist neurological evaluation and advice.

This article has been adapted from reference 1