New filter against mad cow-tainted blood won't come soon

Materials Management in Health Care

A new filter to protect the blood supply from the human variant of “mad cow” disease was unveiled just months after authorities confirmed the first cases of blood-borne transmission.

But it will probably take a year or more for the device to win approval and be available in the United States , according to a spokesperson for the manufacturer, the Pall Corporation in East Hills , N.Y.

In contrast, Marcia Katz, director of public relations at Pall, said the device is expected to win approval as early as February in the United Kingdom , where the first blood-borne transmissions were confirmed and where almost all human deaths from the disease have occurred.

Pall unveiled its Leukotrap Affinity Prion Reduction Filter on Oct. 25. The device, which can fit into the palm of a hand, removes different strains of infectious prions that cause Variant Creutzfeldt-Jakob Disease, or vCJD, the scientific name of the disease.

Katz said the filter, which also removes leukocytes, or white blood cells, has not been priced yet, but it would cost more than Pall's currently available leukocyte filter.

The company says its prion filter is currently the only reliable way to detect the disease, short of an autopsy. Experts in Manchester , England , recently publicized a heart test that they say can determine which patients have vCJD, but this method cannot test the blood.

A blood test for vCJD is important because of news that blood supplies can become infected. There have been two confirmed cases of transmission through blood transfusions for British patients who died in December 2003 and this July.

By this fall, British authorities had alerted 17 people who received blood transfusions from donors who later developed vCJD. And in September, thousands of British hemophiliacs were notiifed that they may have received vCJD-tainted blood products. Then in October, French authorities discovered a mad cow-infected donor whose blood was used to transfuse 10 people as well as to manufacture medicines.

But there have been no cases of vCJD-infected blood in the United States . Neither have there been any cases of the disease itself contracted on U.S. soil. Also, there is only one confirmed U.S. case of mad cow disease, involving a Canadian-born cow

Mad cow is an incurable brain-wasting disease that is 100% fatal. The disease passed to humans in England in the 1980s and so far has killed more than 150 people -- all but 10 of them British.

Victims typically contract the disease from eating brain matter from infected cows. The disease then can take years to show any clinical signs. Many experts dismissed the theory that vCJD could be contracted through blood transfusions until the two British cases were confirmed.

Pall presented a study on the effectiveness of its prion filter at the October meeting of the American Association of Blood Banks. The study found that the filter reduces infectious prions to below the limit of detection of the Western blot assay.

The company reports that additional research at the New York Institute of Basic Research found that the filter reduces infectious scrapie prions from blood. Both vCJD and scrapie are transmissible spongiform encephalopathies.

The Pall filter may eventually have competitors. Chronix Biomedical, a functional genomics company with offices in San Jose , Calif. , and Goettingen , Germany , announced on Oct. 12 that it has applied for a patent for its Chronix CJD test of genetic material, which the company says can detect vCJD in blood.

Katz said Pall's application to the U.S. Food and Drug Administration could not be filed earlier than this coming July. She estimated that the FDA approval process could then take six to 12 months. Katz expected Health Canada 's approval process to go faster.

Meanwhile, a panel of FDA advisers agreed unanimously on Oct. 14 that current U.S. safeguards against vCJD blood transmission are sufficient. These include barring blood donations from people who lived more than three months in Britain or received transfusions there after 1979.

But David M. Asher, M.D., chief and supervisory medical officer with the FDA's Division of Emerging and Transfusion-Transmitted Diseases, recently expressed concerns about vCJD transmission by blood due to the two British cases.

Also, British scientists have found signs of an undetected vCJD “epidemic” in Britain that could more easily spread to the United States than the relatively few cases discovered so far. T esting 14,964 appendices of normal British surgical patients, the scientists found that three were tainted, for a rate of 237 people per million British residents. That rate translates into as many as 25,000 undetected cases in Great Britain .