Experts Debate Cleansing Blood
The giants of America's blood-banking world, along with the makers of medical devices and federal regulators, convened Wednesday at the National Institutes of Health for a workshop on cleaning blood of HIV, hepatitis C and a host of viruses, bacteria and parasites. The meeting comes on the heels of an announcement by Florida Blood Services that HIV-positive blood went undetected and infected two transfusion recipients.
Since 1999, American blood banks using highly sensitive nucleic acid have tested for HIV in donated blood, cutting the transfusion transmission risk to just 1 in 2 million. The procedure works very well except when a donor gives blood up to ten days after becoming infected, as is believed to have happened in the Florida Blood Services case. Within that window there may not be enough virus in the sample for the test to detect.
Over 100 deaths and hundreds of illnesses each year stem from transfusions due to a wide array of bacteria, from staphylococcus to streptococcus. Most susceptible are platelets, the blood's clotting agent. Unlike other blood products, which are chilled or frozen, platelets must be stored at room temperature, allowing bacteria to grow.
"This is the most common cause of morbidity and mortality from blood transfusion, way more than HIV, way more than hepatitis, way more than anything you've heard of," said Dr. Rosalyn Yomtovian, director of the blood bank and transfusion medicine at University Hospitals of Cleveland.
Experts are turning to a new procedure called pathogen inactivation. The process works by infusing blood products with chemicals that make pathogens vulnerable to destruction. The goal is not to filter the blood, but to destroy the DNA of any bugs in it, rendering them inert.
Experts from the United States, Europe and Canada, however, have misgivings about pathogen inactivation. Cleansing could double or triple blood processing costs. Also, the treatment damages blood cells, meaning more blood would have to be collected. And it will take years of testing to determine the procedure's safety.
Cerus Corp.-Baxter Healthcare has cleared the first of several regulatory hurdles for approval of its Helix pathogen inactivation system in the European Union. And three companies have submitted early test results to the FDA. FDA licensing of one system or another will likely lead to its becoming the de facto standard of care.