The Food and Drug Administration on Tuesday issued new guidelines for blood banks intended to help prevent the contamination of the nation’s blood supply with the Zika virus.
Among other measures, the agency called for blood banks in areas where the virus is transmitted locally — like Puerto Rico and the United States Virgin Islands — to import whole blood and red blood cells from regions without an outbreak instead of using local donations.
There have been no reports of the Zika virus entering the United States’ blood supply, but experts say it is most likely that the infection can be transmitted via contaminated blood. Recently, two possible cases of transmission via blood transfusion were reported in Brazil.
There is no F.D.A.-licensed test to screen blood donations for Zika virus. Once one becomes available, blood banks in Puerto Rico and other areas with locally transmitted Zika infections will be permitted to use local donations of red blood cells and whole blood, the agency said.
Blood plasma and platelets, however, can still be collected and used in Zika-endemic parts of the United States if pathogens in those components are first inactivated. The Intercept Blood System, developed by Cerus Corporation, is the only F.D.A.-approved pathogen-reduction device for plasma and platelets.
Only Puerto Rico, the United States Virgin Islands and American Samoa have reported local Zika transmission. The agency recommends that certain at-risk donors in the continental United States not donate blood for now.
Anyone with a confirmed Zika infection should not donate until a month after the illness has been resolved. Donors with signs of possible Zika infection, such as rash or fever, in the two weeks since returning from an area in which the virus is circulating should postpone blood donations until a month after their symptoms subside, the agency said.
Sexual transmission of the Zika virus has been reported, including a case in Dallas confirmed by the Centers for Disease Control and Prevention this month. The guidance advises that the sexual partner of a man who has been in a region with active Zika transmission in the three months before sexual contact should not donate until a month of abstinence.
The rationale is that the virus may linger in semen. Last year, scientists in French Polynesia reported finding Zika virus in semen at least two weeks and possibly up to 10 weeks after symptoms of infection began.
The F.D.A. counseled blood banks to update donor history questionnaires to ask about travel to Zika-affected regions in the past month or a history of residence there.
Officials also suggested that blood banks revise their educational materials to instruct donors to defer donation if they had sex with a man who had been found to have Zika virus infection, or even if a male sexual partner who had visited a Zika-endemic region had “symptoms suggestive” of Zika “in the three months prior to that instance of sexual contact.”
Common symptoms include rash, joint pain, fever and red eyes; however, only roughly one in five people infected becomes ill. Most are asymptomatic.
Blood banks in the continental United States were given no longer than four weeks to adopt the guidelines, while blood banks in areas with active transmission of the Zika virus have two weeks to comply, the agency said.