Public health officials are concerned about the new blood-borne pathogens making their way into the U.S. and onto the shelves at blood banks across the country. A parasite called babesiosis has been linked to 10 deaths from blood transfusions since 2006, and there is no way to test for it. Officials are also worried about a dangerous virus called Chikungunya, which recently spread to the U.S. and Europe from Africa, the Wall Street Journal reports.

About a dozen European and Asian countries use a combination of ultraviolet light and chemicals to kill pathogens in donated blood, but the Food and Drug Administration declined to approve the method without more testing.

Health officials are urging the government to more aggressively protect the blood supply in the U.S. Researchers found 68 emerging infectious agents last year that pose a threat to the blood supply. New screening tests for individual agents are difficult to develop, and the approval process is time-consuming, adding to the concerns of public health officials.