By: Jean Johnson It’s certainly nice to be able to count on the nation’s blood supply. And clearly, if we find ourselves in need of a blood transfusion, knowing the bag dangling from the IV pole is free from the West Nile virus is a relief.
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We can thank the American Red Cross. After realizing that the virus could be transmitted in blood transfusions in 2002, the Federal Drug Administration ordered the Red Cross to take action. The organization went to work and got a test up and running by the middle of 2003. Known by experts as the “nucleic acid and amplification test,” the monitoring system identified 519 donors who were positive for West Nile virus in the first 12 months of use from 2003 to 2004. More than half of those donors were from four counties in Southern California.
As far as 2005 goes, spokeswoman for the U.S. Centers for Disease Control and Prevention, Christine Pearson, said 34 potential blood donors have tested positively and thus been eliminated from the pool. More, experts have not had any reports of West Nile transmission through blood transfusions.
"The time period was very rapid," said executive scientific officer of the American Red Cross and lead author of the paper on the testing published in an August issue of the New England Journal of Medicine, Susan Stramer, Ph.D. "We acted on an infectious disease agent that's transmitted by blood in an unparalleled rapid action that was implemented very quickly."
Stramer pointed out that what she refers to as “minipool testing” or using the nucleic acid and amplication test for small groups or pools of blood donors is only one level at which the team screens for the West Nile virus.
"The concern was that minipool testing may not be sensitive enough during an epidemic period," Stramer said. "It's a good surveillance tool, but once West Nile virus is in an area, we have to do more sensitive testing" or individual testing in regions where the virus is prevalent. Stramer also says that testing early in the mosquito season when new infections are being spread and people have few antibodies to the virus appears to be an effective approach.
"In individual donation testing, the units identified that were most dangerous were those that were earliest in the epidemic period in any given area," Stramer explained.
As far as costs go, enjoying the highest standard of medical care in the world doesn’t come without a stiff price tag. Minipool testing ran $120,000 for each unit of intercepted blood in 2003 and $232,000 per unit in 2004.
Also individual screenings on around 60,000 donations in 2004 totaled $32,000 for each case detected.
Although inquiring minds may wonder about the almost doubling of minipool costs in the span of a single year from $120,000 to $232,000, we couldn’t locate comment on the steep increase. Instead, authors of the New England Journal of Medicine article concluded that the two-testing system seems to be cost-effective.
