(Reuters) – The U.S. Food and Drug Administration recommended on Friday that all blood donated in the United States and its territories be tested for Zika virus, as it moves to prevent transmission of the virus through the blood supply.

The agency’s move to expand its previous guideline for blood screening comes after Florida officials on Tuesday announced the first case of Zika transmitted by mosquitoes in Pinellas County, some 265 miles from Miami, where the first locally transmitted U.S. cases were reported.

The FDA last month ordered blood banks in Florida’s two most densely populated counties – Miami-Dade County and Broward County – to stop collecting blood.

The FDA also recommended that nearby counties implement the same measures.

Zika was detected in Brazil last year and has since spread across the Americas. The virus poses a risk to pregnant women because it can cause severe birth defects. It has been linked to more than 1,800 cases of microcephaly in Brazil.

Health officials warned pregnant women last week not to travel to Miami Beach after Florida confirmed the mosquito-borne Zika virus was active there.

The agency had recommended in February that blood should no longer be collected from regions where the Zika virus is circulating, and that blood needed for transfusions be obtained from areas of the country without active transmission.

The FDA has authorized the emergency use of several investigational Zika screening tests, including products made by Hologic Inc <HOLX.O> and Roche Holding AG <ROG.S>.

(This version of the story corrects second paragraph to say Pinellas County is “some 265 miles from” Miami, not “near” Miami)

(Reporting by Ankur Banerjee in Bengaluru; Editing by Shounak Dasgupta and Saumyadeb Chakrabarty)