A donor gives blood at a National Blood Service centre in London, March 16, 2004. Britain is to ban people who have had transfusions over the past 24 years from donating blood to reduce the risk of spreading the human form of mad cow disease. British Health Secretary John Reid announced the move three months after he reported what is throught to have been the world's first case of variant of Creutzfeldt-Jakob disease (vCJD) caused by transfusion. REUTERS/Toby Melville TM/JSG/RB/PW/