PBS: There are alarming signs the Zika virus is spreading rapidly in Puerto Rico, the Centers for Disease Control and Prevention reported Friday.
Blood banks on the island have seen a steady rise in the portion of donations that have to be rejected because they contain Zika virus. Last week, 1.1 percent of the donated units were contaminated.
If that many people are infected with Zika when they go to give blood, its a sign of how much virus spread there is going on in Puerto Rico, CDC Director...