The Centers for Disease Control and Prevention (CDC) on 19 August 2016 advised pregnant women and their partners to avoid Miami-Dade County in Florida over fears of the spread of Zika virus:
Pregnant women and their sexual partners who are concerned about potential Zika virus exposure may also consider postponing nonessential travel to all parts of Miami-Dade County.
All pregnant women in the United States should be evaluated for possible Zika virus exposure during each prenatal care visit. Each evaluation should include an assessment of signs and symptoms of Zika virus disease (acute onset of fever, rash, arthralgia, conjunctivitis); their travel history; as well as their sexual partner's potential exposure to Zika virus and history of any illness consistent with Zika virus disease to determine whether Zika virus testing is indicated.
According to the CDC, there are areas of active Zika transmission in Miami Beach and Wynwood, which are both in Miami-Dade County. A dangerous birth defect associated with Zika virus infection during pregnancy is microcephaly, a condition in which a baby is born with a smaller head and brain in comparison to normal births.
CDC Director Tom Frieden said the region is in the "height" of mosquito season and officials expect there will be more transmissions:
It’s difficult but important that pregnant women make every effort to avoid mosquito bites and avoid going to areas where Zika is spreading. Florida and Miami-Dade County are taking appropriate steps to control mosquitoes and protect pregnant women. It is difficult to predict how long active transmission will continue. CDC disease control experts are doing everything they can to support state and local control programs to stop the spread of Zika. Every community in the United States that has the Aedes Aegypti mosquito present must monitor for infections and work to control the mosquitoes.
While microcephaly is the most pronounced birth defect caused by Zika infection, other defects can include the baby being born with overall growth, hearing and vision impairment.
The CDC said it is possible other areas on the county have Zika virus but it's impossible to detect whether this is the case right away., because: "The incubation period for Zika infection is up to two weeks, a high proportion of infected people have no symptoms," and "diagnosis and investigation of cases takes several weeks."