Federal advisors said the U.S. should consider barring blood donations from people who lived in or visited Britain because of concerns about mad cow disease. The worry is that these people may have eaten meat or meat products infected with mad cow disease and could be at risk for getting and transmitting new variant Creutzfeldt-Jakob disease, or CJD, Food and Drug Administration advisors said. The FDA will now decide whether to direct blood banks to follow the panel's advice. No American cattle have had mad cow disease. The panelists said blood banks should survey donors to find out if they lived or spent up to a year in Britain or visited from 1980 to the present. After that data are gathered, a decision on whom to block from donating blood in the U.S. can be made, the panel said. Thirty-four people in Britain have come down with new variant CJD. Four donated blood at some point, said Jeremy Metters, deputy chief medical officer at the United Kingdom Department of Health.