As the Zika virus spreads to the United States, the potential for contracting the disease via blood transfusion has emerged as a serious concern. The problem of transfusion-related Zika virus transmission—and recommended strategies to reduce that risk—are outlined in a special article in Anesthesia & Analgesia, published by Wolters Kluwer.
In addition to blood screening tests, an approach called patient blood management (PBM) can provide further protection by reducing the need for blood transfusion during surgery, according to the article by Drs. Lawrence Tim Goodnough of Stanford University and Marisa B. Marques of the University of Alabama at Birmingham. They write, "The principles and practices of perioperative PBM will reduce the risks from not only known, but unknown risks of blood transfusion for our patients."
Since the first case in Brazil was reported in April 2015, Zika has spread rapidly throughout the Americas. Zika is a mosquito-borne virus that can also be transmitted by sexual activity. While the Zika virus typically causes a relatively mild illness, infection during pregnancy can cause microcephaly and other devastating congenital malformations. Zika can also cause a serious neurologic disorder called Guillain-Barré syndrome. (The Centers for Disease Control and Prevention offer up-to-date information about Zika.)
"Blood centers have been bracing for the arrival of the virus in the United States' blood supply since the beginning of 2016," Goodnough and Marques write. More than 4,000 Zika infections have been reported in the United States that were travel-related, along with mosquito-borne infections (3% of total) in Florida. Cases of Zika transmitted through blood transfusion have been confirmed in Brazil.
What's the best strategy to prevent transfusion-related Zika transmission? Several approaches have been suggested, all with limitations. For example, potential donors could be asked about recent travel to areas of active Zika infection—but could still potentially be infected by sexual contact with an individual at risk. Because up to 80 percent of Zika infections cause no symptoms, simply asking blood donors if they are sick, won't prevent infected people from donating. For this reason, the Food and Drug Administration has recommended screening of donor blood using a nucleic acid test (NAT). However, the NAT is still investigational (not formally approved by the FDA). As the blood donor test for Zika virus was rolled out nationally in the fourth quarter of 2016, blood banks were faced with the challenge of managing two inventories: tested (labeled) blood units and untested units.
Meanwhile, Goodnough and Marques suggest that a proven approach to reducing transfusion requirements during surgery can also reduce the risk of transfusion-related Zika transmission. That approach, called PBM, seeks to reduce the need for blood transfusion by "consistently and rigorously" following steps to ensure that patients don't have anemia before surgery; to reduce blood loss during surgery; and to use alternatives to transfusion, when possible.
While Zika-contaminated blood units are likely rare, they do exist. Initial experience with the NAT test detected about 40 cases of Zika in blood donors. In Puerto Rico, 1.8 percent of blood donors tested positive for Zika over the first few months after the NAT was introduced. For now, the uncertainty about Zika in the US blood supply is similar to that in previous outbreaks of blood-borne infections, such as HIV and West Nile virus.
"Patients should be reassured that while the current risk for Zika infection through blood transfusion is quantifiably unknown, it is very low," Goodnough and Marques write. They suggest that patients undergoing surgery can be informed about PBM, and the steps that can be taken to reduce the need for blood transfusion—and thus avoid Zika transmission and other potential risks of blood transfusion. The authors' hospitals have prioritized use of NAT-tested and labeled blood units for pregnant women and infants.
"The global threat of Zika will inevitably be followed by future outbreaks of other blood-borne pathogens," Goodnough and Marques conclude. "[T]he principles and practices of perioperative PBM will reduce the risks from not only known, but unknown risks of blood transfusion for our patients."
Source: International Anesthesia Research Society (IARS)