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Keeping Zika out of the nation’s blood supply

When the Zika crisis erupted last year, U.S. blood bank officials began to worry: What if the virus were to infiltrate the blood supply, as HIV, hepatitis C and other dangerous pathogens have done in the past? This could be particularly risky for pregnant women, as their babies could be born with severe brain defects caused by Zika infection.

The blood banking industry began preparing for this prospect in early 2016, said Lawrence Goodnough, MD, director of the transfusion service at Stanford Health Care and lead author of a new paper on the subject in the journal Anesthesia and Analgesia. The blood banks initially responded by deferring donations from people who had visited Zika-prone regions. But this wasn't an effective screening tool, as the virus can be sexually transmitted, meaning a potential blood donor could be infected through sexual contact and not know it, as Zika infection is often asymptomatic, he said.

In August 2016, the federal Food and Drug Administration began recommending that U.S. blood banks screen all donations for Zika using a new test, known as a nucleic acid test, which can detect the presence of the virus in blood. The test is considered investigational, as it hasn’t been fully validated by the FDA, but it remains the most current available technology, Goodnough said. The Stanford Blood Center began using it to screen all supplies at the end of September, according to blood center officials.

By November, the American Association of Blood Banks had reported 40 cases of donors whose blood was found to be positive for the virus. These were all discarded. But there has been at least one documented case in Brazil, the epicenter of the latest outbreak, in which the blood of an infected donor was given to three recipients, Goodnough reported. All three recipients tested positive for the virus but did not develop any symptoms of infection, he said.

“That does demonstrate that it (the Zika virus) is blood-transmissible, so that is the takeaway,” Goodnough told me.

He said the chance of acquiring Zika from a blood transfusion in the United States now is likely quite remote. “Patients should be reassured that although the current risk for Zika infection through blood transfusion is quantifiably unknown, it is very low,” he and his colleague wrote in the recent paper.

Goodnough said the Zika experience is yet another argument for effective patient blood management, or the use of blood supplies only for people who most need it. He said patients undergoing elective surgery can plan ahead by being tested for anemia at least a month before the procedure and being treated, if necessary, to reduce the likelihood of transfusion. Patients can also donate their own blood ahead of time for possible use during surgery.

In addition, Stanford has implemented a system to encourage conservative use of transfusions, Goodnough noted. Whenever physicians request blood, they receive an alert that notifies them of blood-use guidelines and asks them to justify the transfusion.

“I think the lessons learned is that blood is inherently risky,” he told me. “That’s why we have safeguards – donor screening and testing – but there are always going to be new pathogens coming along. The concept of patient blood management is timeless. We at Stanford have been leaders in the field in reducing unnecessary blood transfusion.”

Previously: Talking about the Zika virus and Thinking twice before doing blood transfusions improves outcomes, reduces costs
Photo by Erin Kunkel

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