CDC Issues Travel Warning for Florida After Zika Virus Outbreak First local Zika outbreak in the continental U.S. has been reported in Florida.

 -- A travel advisory has been issued by the U.S. Centers for Disease Control and Prevention warning pregnant women against visiting an area with ongoing Zika virus transmission in northern Miami, Florida.

At least 14 people have been infected in the first locally transmitted Zika outbreak in the continental United States. Some countries, including the United Kingdom, have already issued travel warnings for their pregnant citizens about traveling to the affected area in Florida.

After 10 new cases were reported today, in addition to four cases reported last week, the CDC is advising pregnant women to avoid traveling to a 1-square-mile area in northern Miami where the outbreak occurred. CDC Director Tom Frieden also advised women who were in that area within the last month to avoid trying to get pregnant, to reduce the risk of having an infant who develops Zika-related microcephaly, a birth defect characterized by an abnormally small head and brain, leading to significant developmental problems.

"Women who were in this area and left this area recently should wait at least eight weeks before trying to get pregnant," Frieden said during a news conference today.

While some have questioned why the CDC did not issue a travel advisory last week when the outbreak was first recorded, he explained that the agency had not yet seen continued transmission of the virus and that new information received this weekend led to the travel advisory.

"What we have learned over past 48 hours is mosquito control efforts don’t appear to be as effective as we have previously hoped," Frieden said today. He said that since the Aedes aegypti mosquito, which spreads Zika, rarely flies beyond 150 meters in its lifetime, health officials did not feel the need to expand the area included in the travel advisory.

"We will continue to look at this data every single day, including additional testing. If that changes, we will adjust the warning," he said.