Florida Governor Rick Scott said on Friday that four people likely contracted the Zika virus from a mosquito locally.
The cases, which involve one woman and three men, are in Broward and Miami-Dade counties, Scott said at a news conference.
"Florida has become the first state in our country to have a local transmission of the Zika virus," Scott said.
The Florida Department of Health said it believes that active transmission of the Zika virus is occurring in one small area in Miami-Dade County, just north of downtown. The area is NW 5th Avenue to the west, US 1 to the east, NW/NE 38th Street to the north and NW/NE 20th Street to the south.
No collected mosquitoes tested positive for Zika and emphasized that there have been no locally transmitted cases in Central Florida, according to officials.
"While no mosquitoes have tested positive for the Zika virus, DOH is aggressively testing people in this area to ensure there are no other cases," Scott said. "If you live in this area and want to be tested, I urge you to contact the county health department which stands ready to assist you."
The news conference comes as officials at Florida's main supplier of blood say they'll begin testing all blood collections for the Zika virus using an investigational donor screening test. In a statement, OneBlood said operations will remain business as usual and collections will continue uninterrupted throughout its service areas.
On Thursday, the U.S. Food and Drug Administration requested all blood donations in two South Florida counties be suspended. In Miami-Dade and Broward counties health workers are investigating mysterious cases of Zika infection that may be the first spread by mosquitoes on the U.S. mainland.
OneBlood suspended collections earlier this week in the areas of Miami-Dade and Broward counties being investigated, according to a statement.
Florida health officials have said the four infections may not be linked to travel, but they haven't confirmed how the virus spread.
The U.S. Food and Drug Administration on its website asks blood centers in Miami-Dade and Broward counties to immediately stop collecting blood until each unit of blood can be screened for the virus.
Blood banks in Texas and Hawaii have begun or soon will start testing blood donations for the Zika virus. Puerto Rico suspended blood donations and imported blood products for the month of March until U.S. health officials approved the use of an experimental test to screen blood donations for the virus.
In addition to the locally transmitted Zika cases, there are three new travel-related cases Friday in Miami-Dade County.
The following counties have confirmed Zika cases that are travel-related:
Palm Beach: 18
Santa Rosa: 1
St. Johns: 3
St. Lucie: 1
Total cases not involving pregnant women: 331
Cases involving pregnant women regardless of symptoms* 55
The number for the Zika Virus Information Hotline is 1-855-622-6735.
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