The Food and Drug Administration (FDA) announced Friday that all blood donated in the U.S. should be tested for Zika virus infection.
The move is a major expansion of the FDA's policy regarding Zika and an indication of the growing threat of the disease. The agency said in February that parts of Florida and all of Puerto Rico should be screened.
"The FDA is updating its guidance after careful consideration of all available scientific evidence, consultation with other public health agencies, and taking into consideration the potential serious health consequences of Zika virus infection to pregnant women and children born to women exposed to Zika virus during pregnancy," the agency said in a statement.
Zika is primarily transmitted via bites from the Aedes mosquito, although it also sexually transmitted. The disease has become a full-blown outbreak throughout Central and South America and travelers have carried the virus back to their homes across the U.S. It appears, however, that the disease has gained a small toehold in the continental U.S.
According to the Centers for Disease Control and Prevention, there have been only 29 locally acquired cases -- not acquired during international travel -- in the U.S. and all have been in Florida.
Although the quantity of cases is small, the FDA decided to take precautions due to the lack of information about how the disease spreads.
"There is still much uncertainty regarding the nature and extent of Zika virus transmission," Peter Marks, director of the FDA's Center for Biologics Evaluation and Research, said in a statement. "At this time, the recommendation for testing the entire blood supply will help ensure that safe blood is available for all individuals who might need transfusion."
Doctors believe as much as 80 percent of those infected with Zika never develop symptoms, while those who have symptoms suffer from fevers, joint pain and rashes. The disease is known to cause serious birth defects if pregnant women become infected.