Transmissible spongiform encephalopathy update and implications for blood safety.

At this time, the accumulated evidence does not support the implementation of measures targeted against the risk of transfusion transmission of sporadic, familial, or iatrogenic CJD. Evolving information about vCJD, however, suggests that policy makers need to consider implementing measures to protect against exposure to vCJD, if such measures themselves do not lead to decreased blood safety. Surveillance of human TSEs and investigation of the risk of transfusion transmission must continue in order to provide further refinements in blood safety policy.