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FDA mulls blood risk of Canadian mad cow

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WASHINGTON, Jul 21, 2003 (United Press International via COMTEX) -- A recent report of a Canadian case of mad cow disease has prompted the Food and Drug Administration to ask U.S. blood banks to assess how many donors they would lose if the agency banned people who had spent a substantial amount of time in Canada from donating blood.

The concern is variant Creutzfeldt-Jakob disease, a fatal brain illness humans can acquire from eating beef infected with mad cow disease, could be unwittingly transmitted via blood transfusions. The potential for this to occur in the United States was raised in late May when Canadian authorities reported a cow in the province of Alberta had tested positive for mad cow disease.

Dr. Jay Epstein, director of the FDA's office of blood research and review, speaking at a meeting of the agency's transmissible spongiform encephalopathies advisory committee, said the agency had requested blood banks conduct residential travel surveys to estimate the number of donors that would be lost if restrictions were imposed on people who had lived or spent time in Canada. Several blood organizations have signaled their support for this, he noted.

"This discussion actually started...when the Canadian cow was discovered (May 20)," Dr. Louis Katz, president of America's Blood Centers, a network of blood banks located in 46 U.S. states and Quebec, Canada, told United Press International.

Since then, "people at FDA and people at blood centers have been discussing what information we want and how best to collect it," he said.

One concern is a Canadian ban could drastically limit the number of people who could donate, as "a substantial number of people," particularly in the northern and mid-western states, have spent a substantial amount of time in Canada, Katz said. He noted they do not yet have a good estimate of the number of donors a Canadian ban would affect.

Epstein, speaking via FDA spokeswoman Lenore Gelb, emphasized the agency is not currently considering putting a Canadian restriction in place.

"Our current thinking is the available data do not support a change in policy at this time," he said. The FDA wants to have the data on the impact of such a ban "just in case."

If anyone were infected with vCJD by Canadian beef, it could be years before cases are detected as people can carry the illness for 10 years or more before symptoms develop.

If the agency thought it was prudent to restrict people who had spent a lengthy amount of time in Canada from donating blood, they first would put the question to one of their advisory committees, Gelb said.

No case of CJD has ever been conclusively linked to a blood transfusion but studies in animals have shown it is theoretically possible to transmit the disease via blood, according to the World Health Organization. For that reason, the FDA has banned people who spent three months or more in the United Kingdom or five years or more in Europe from donating blood in the United States. Beginning in the mid-1990s, more than 100 people in the United Kingdom and several individuals in various European countries contracted vCJD after eating beef tainted with mad cow disease.

All of those infected with vCJD eventually die from the brain-wasting disease as there is no treatment.

"Until more scientific information about blood safety is available or a test is found to diagnose people who may carry vCJD, the main way to lower the theoretical risk of vCJD in blood is through deferral of donors who might have eaten contaminated beef products," the FDA said in a statement posted on its Web site.

The agency estimated deferring the U.K. and European donors reduces the risk by 90 percent, while not unduly limiting the blood supply.

So far, blood banks have not begun issuing a survey, Katz said. It would be fairly easy to collect information on how much time donors have spent in Canada, but the blood banks are considering whether it would be appropriate to collect similar information for other countries so they do not have to repeat the survey every time a country reports its first case of mad cow disease.

If the FDA decides to impose restrictions on donors who have spent time in Canada, Katz said he would expect it to be in accord with European restrictions and require that people had spent a considerable amount of time there, such as five years, due to the low-risk of a single case of mad cow disease.

In the meantime, Katz said the blood supply is safe with regard to vCJD. "The precautionary measures we've taken in the U.S. are adequate," he said.

Other deadly risks of blood transfusions, such as being given the wrong blood type, are much bigger concerns than vCJD, he said.

The ideal situation would be to have a test that could screen blood donations for vCJD, but Katz said that remains years away. By the time a reliable test is developed the outbreak of vCJD in the United Kingdom might have nearly disappeared and there could be no real use for a screening test, he said.

Copyright 2003 by United Press International.

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