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Jan. 30--The would-be blood donor was worried: he had eaten hamburger recalled as part of Washington's mad-cow investigation, but still wanted to donate blood to the Puget Sound Blood Center. Was his blood safe? the man asked.
For now, the answer is yes.
But the government's decision Monday to ban blood in cattle feed, prompted in part by the death of a British man from the human form of the disease after he received a possibly tainted transfusion, raises a disturbing question: Can the disease be transmitted through blood?
While much attention has focused on the risks of catching the human strain of mad-cow -- variant Creutzfeldt-Jakob disease, or vCJD -- from infected beef, food-safety regulators and scientists are now debating the less-known risks of infection from blood transfusion.
For years, such transmission has been considered only a theoretical possibility. But in December, a week before the United States' first mad-cow case was discovered in Yakima County, health officials learned that the British man who died of vCJD had received a blood transfusion in 1996 from another man who later died of the disease.
It could be coincidence. The man may simply have died after eating infected beef, as have 138 others in Britain, which has been hardest-hit by the disease. But if the death is proved to be the world's first case of infection via blood, as Dr. Peter Lurie thinks it is, the case will intensify a public-health debate on the safety of transfusions.
"Certainly the safest assumption -- and the most reasonable one -- is that this is a bona fide case of transfusion-related variant Creutzfeldt-Jakob disease," said Lurie, deputy director of the consumer-watchdog group Public Citizen and a former member of the Food and Drug Administration's mad-cow advisory committee.
British health officials are still investigating the source of the infection. But the FDA, which oversees blood safety, acknowledged the potential for such a case with its 1999 ban on blood donations from those who had lived in the United Kingdom. The ban was later expanded to include those who had lived in Europe, including American soldiers stationed at European bases.
The British case was a factor in the FDA's decision this week to prohibit feeding cow blood to cattle, confirmed Lester Crawford, the FDA's deputy commissioner.
"It caused a shock for us," Crawford said yesterday. "The British case sort of highlights the issue and makes us want to do more research."
As mad-cow disease emerged worldwide in the 1990s, researchers, hoping to pin down methods of transmission, injected blood from sick hamsters, mice and sheep into the brains of healthy animals.
Enough animals got sick -- four of 21 injected sheep, according to a 2002 Institute of Medicine study -- to lead many experts to believe blood is a vehicle for mad-cow disease, one of several transmissible spongiform encephalopathies (TSEs).
But there is no evidence of such transmission in humans, and scientists warn that extrapolating results from one species to another often doesn't pan out. Dozens of Britons have unwittingly gotten blood from infected people, yet they haven't been diagnosed with vCJD.
That's why the recent British death is troubling, said Niel Constantine, a pathology professor with the University of Maryland's medical school.
"The FDA is concerned, but they're not as concerned as they would be if they showed transfusion absolutely occurred," he said. If the British case is confirmed and a case of vCJD in the U.S. is diagnosed, "we would be on the edge of panic," he said.
Currently, the best test to detect vCJD in blood, according to the FDA's Crawford, involves injecting a mouse that is genetically engineered to be susceptible to the disease, and seeing if the animal dies.
Blood tests for vCJD must get a millionfold more accurate in order to be reliable, said Constantine, who is developing a test now.
"There is no test available, so what are you going to tell a blood bank?" said Constantine. "You're going to tell them to keep doing what they're doing. That doesn't mean there isn't concern. There's definite concern."
Dr. Mike Strong, executive vice president of the Puget Sound Blood Center, is keenly aware of the delicate balance between safety and supply.
He was in the blood-bank business in the early 1980s, when the transmission of HIV in blood wasn't clear. Blood-bank officials, who resisted shrinking the blood supply without conclusive scientific evidence of tainted donations, were later criticized for not acting more quickly to screen the blood.
But, Strong said, blood banks are already challenged "on a daily basis" by the many "deferrals," or banned donors. The 1999 ban on donors who had lived in European countries eliminated 5 percent of donors, he said. Blood donors now answer 120 questions and take tests designed to screen for maladies including HIV, malaria and anemia. About 17 percent of potential donors are screened out.
"If you took it to the extreme and deferred all donors from Washington, the (result) would be a lack of availability for those who need it, and many deaths," said Strong, who sits on the FDA's Blood Products Advisory Committee.
Few monitor that balancing act as closely as hemophiliacs. If the FDA overreacted to mad-cow risks, it could deplete blood stocks to the point that hemophiliacs would be barred from elective surgery, said Val Bias, past chairman of the National Hemophilia Foundation. But he also noted that at least 6,200 hemophiliacs got Hepatitis C from transfusions before a reliable test was created in 1992.
"We don't want to be exposed to any more viruses at all, but by the same token we don't want to be so cautious that we provoke a shortage," said Bias, who is also on the FDA's mad-cow advisory board. "It's a delicate balance."
What about Canadian blood?
In the late '90s, the FDA debated the risks and benefits of banning blood donations from people who had spent time in the United Kingdom and other countries where mad-cow occurred. As cows in country after country were found to have the disease, the agency's mad-cow advisory board argued about whether to expand the ban on donors.
The Yakima County cow diagnosed with mad-cow was born in Canada, and likely contracted the disease there by eating contaminated feed. That followed a case of mad-cow discovered last May in Alberta.
"The current question is what to do about the situation in Canada," Lurie said. "I think it should be resolved by the same kind of analysis we did in the first place."
Canadian health officials say no ban is necessary. Canadian blood stocks are protected by stringent controls installed after the European outbreak of mad-cow, including donor screening, said Dr. Antonio Guilivi, director of blood-safety surveillance for Health Canada.
"All the protections are already in place," Guilivi said.
If the British case resulted from a transfusion, the FDA may "take an additional step or two" to protect U.S. blood safety, Crawford said. He declined to be more specific.
The question of mad-cow in blood undoubtedly will come up at the next meeting of the FDA's mad-cow advisory committee, Feb. 12-13 in Maryland.
While some, like the hemophilia foundation's Bias, hope the FDA is cautious and guided by science, Lurie says the research is too mixed to provide a road map.
"The question is: How big is the risk? We'd like to know that in order to balance that against needed transfusions," he said. "Unfortunately, in this area of blood transfusion, in this whole TSE area, the data are lacking, more often than not. You have to make policy -- blind."
By Carol M. Ostrom and Jonathan Martin
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(c) 2004, The Seattle Times. Distributed by Knight Ridder/Tribune Business News.
