The Food and Drug Administration on Friday took steps to safeguard the nation’s blood supply from the Zika virus, calling for all blood banks to screen donations for the infection even in states where the virus is not circulating.
The recommendations are an acknowledgment that sexual transmission may facilitate the spread of Zika even in areas where mosquitoes carrying the virus are not present. Officials also want to prepare for the possibility that clusters of local infection will continue to pop up in parts of the United States for years to come.
“There could be multiple outbreaks of Zika happening outside the known current ones in South Florida, but because we are not actively looking they could be happening silently,” said Dr. Peter J. Hotez, the dean of the National School of Tropical Medicine at Baylor College of Medicine, who applauded the F.D.A.’s move.
Without federal funds, it is generally not possible for local health departments to conduct active surveillance for Zika virus in the blood or urine of patients with fever or rash, he added.
“In some ways the inaction from Congress has forced the F.D.A. to adopt this position,” Dr. Hotez added. “They have no other choice.”
The agency urged blood centers to use one of two experimental tests intended to detect active infections, called nucleic acid tests, before releasing donated blood for use in transfusions. As an alternative, banks may decontaminate plasma and platelets with so-called pathogen reduction technology.
But the recommendations are likely to pose a significant challenge for some blood banks and for the third-party labs that perform much of the blood screening nationwide, some experts said.
Eleven states must put the new safeguards into place within four weeks. They include Alabama, Arizona, California, Georgia, Louisiana, New York and Texas, which have many residents who travel to Zika-affected countries or are near an area that already has locally acquired mosquito-borne cases.
Other states have 12 weeks to carry out the recommendations.
“This is a bombshell, because this is extremely rapid introduction of a new test nationwide that’s almost unprecedented,” said Dr. Jeffrey McCullough, emeritus professor of laboratory medicine and pathology at the University of Minnesota Medical School. “To try to implement this, in four weeks, is really, really difficult.”
Yet the new safeguards also are necessary, Dr. McCullough said. Under current guidelines, it is too difficult to identify infected donors by “trying to sort out risky donors by history of where they’ve been or what they’ve exposed to.”