Washington

The US government is tightening its restrictions on blood donors in an effort to prevent the spread of the human form of mad cow disease. Variant Creutzfeldt–Jakob disease (vCJD) has killed about 100 people, mostly in Britain.

Advisers to the Food and Drug Administration (FDA) met on 28 June and recommended expanding an existing blood-donor ban to include people who have spent five years or more in Europe since 1980. They also recommended banning donors who lived in Britain for three months or more between 1980 and 1996. Current restrictions, put in place in 1999, ban donors who spent six months or more in Britain during that period.

The recommendations of the Transmissible Spongiform Encephalopathies Advisory Committee are only advisory, but the agency is expected to implement them.

In January, the advisory panel recommended that the agency ban blood donors who had spent 10 years in what it considered to be the high-risk countries of France, Portugal or Eire since 1980 (see Nature 409, 441; 2001). But the FDA, unsatisfied at the failure to address risks in the rest of Europe, asked the panel to reconsider the problem.

The FDA estimates that the new restrictions will reduce the number of blood donors by about 5%. Some officials opposed the new restrictions, arguing that they would reduce an already tight blood supply.

From September, the Red Cross plans to exclude donors who have spent six months or more in Europe since 1980. The FDA says that such a move would reduce total blood donors in the United States by up to 9%.

So far, there has been no epidemiological evidence that vCJD has been transmitted by blood, but animal models suggest that this may be possible. There is no validated test that allows the screening of blood donors.