The Food and Drug Administration wants all U.S. blood banks to start screening for Zika virus, a major expansion intended to protect the nation's blood supply from the mosquito-borne disease. The new advisory means all U.S. states and territories will need to begin testing blood donations for Zika. Previously, the requirement was limited to areas with active Zika transmission, such as Puerto Rico and two Florida counties. Blood banks already test donations for HIV, hepatitis, West Nile virus and other blood-borne viruses. Last month, the FDA told blood centers in Miami and Fort Lauderdale to immediately stop collecting donations until they could begin screening each unit of blood for Zika. The order followed now-confirmed reports of local Zika transmission — the first in the continental U.S.