U.S. health officials are warning pregnant women to avoid Miami Beach, where Florida officials say mosquitoes have spread the Zika virus to five people.
In a statement Friday, the U.S. Centers for Disease Control and Prevention said pregnant women should avoid travel to the South Beach area, which has been identified as an infection zone.
The CDC said pregnant women also should continue to avoid travel to Miami's Wynwood arts district. That neighborhood was the first site on the U.S. mainland where health officials determined mosquitoes were transmitting Zika.
The CDC also said pregnant women and their partners may want to consider postponing nonessential travel to all of Miami-Dade County if they're concerned about potential exposure to the virus.
In the agency's statement, CDC Director Tom Frieden said it's "difficult to predict how long active transmission will continue."
Gov. Rick Scott told reporters Friday that five Zika infections have been linked to an area that encompasses most of tourist-friendly South Beach.
Florida Department of health spokeswoman Mara Gambineri says officials believe the cases were transmitted by mosquitos.
Scott says two of the Miami Beach cases involved Miami-Dade County residents, and three involved tourists from New York, Texas and Taiwan. He did not say whether mosquito bites caused the infections.
Scott says the county has begun an aggressive mosquito eradication plan in Miami Beach.
The director of the U.S. Centers for Disease Control and Prevention says officials will not be able to spray the South Beach area to prevent Zika as they have in other areas because of high-rise buildings and strong winds.
Miami-Dade County officials have been spraying pesticide from planes flying over Miami's Wynwood arts district since early this month, when Zika transmissions by mosquitoes were confirmed there.
Dr. Tom Frieden says planes can't fly low enough among Miami Beach's high-rises to spray pesticides that kill mosquitoes and their larvae. He says strong winds over the narrow island city also hinder such flights.
Frieden also says the large numbers of residents and visitors in the area will make it challenging to control the spread of Zika there.