About 1.1% of blood donors in Puerto Rico are testing positive for the Zika virus. The blood screening suggests that about 25% of the island’s population will catch Zika this year. The Zika virus is spreading “rapidly” in Puerto Rico and now likely afflicts 2% of the island’s population with active infections, public health officials reported on Friday, based on tests of blood donors. At current infection rates, one-quarter of the island’s 3.5 million people will eventually acquire the mosquito-borne illness, U.S. CDC officials said. Current estimates are that 1% to 13% of babies born to women infected with Zika...