November 28, 2006 WASHINGTON (AP) -- Patients with hemophilia and other blood-clotting disorders face an uncertain though probably very low risk of contracting the human form of mad cow disease from medicines made using donated plasma, health officials said Monday.
There are no known cases of variant Creutzfeldt-Jakob disease, as the human form of the disease is known, in patients who have received human plasma derivatives, the Food and Drug Administration said. But there have been three cases, all in the United Kingdom, of people developing the disease after they had received red blood cells from infected donors.
Since studies in animals have shown plasma -- the liquid part of blood -- also can carry the infection, that has the FDA concerned about the possible risk to the several thousand patients who rely on plasma products to treat hemophilia A as well as another clotting disorder called von Willebrand disease.
The FDA said it will seek the advice of an outside panel of experts Dec. 15 on its analysis of the risk and how to communicate its concern to the public.
In documents released Monday, FDA officials stressed that the risk of infection likely is low but is impossible to determine precisely. They note that mad cow is rare in U.S. cattle: there have been just three reported cases.
Humans likely contract the disease by eating products from cows infected with mad cow disease, or bovine spongiform encephalopathy. Because of that, the FDA restricts people who spent significant amounts of time in Europe, where the disease was prevalent in cattle, from donating blood and plasma.
That restriction removes much of the risk to patients; plasma product manufacturing techniques that reduce the number of abnormal proteins that cause the disease also help, the FDA said.
Still, officials worry that some infected donors could still slip through the screening process and pass along the disease.
Since 1996, there have been 195 cases worldwide of the fatal brain disease in humans. Of them, 162 were in the United Kingdom.
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