The U.S. Centers for Disease Control (CDC) is advising pregnant women, women considering becoming pregnant, and their partners not to visit a small community just north of Miami, Florida, where the Zika virus is beginning to spread via mosquito bites.
The announcement marks the 1st time the CDC has warned people not to travel to an American neighborhood over concern of catching an infectious disease. 
Pregnant women infected with the Zika virus are at risk for giving birth to a child with microcephaly, a serious birth defect that typically causes babies to have smaller-than-normal heads and stunted brain development.
Read: Study: Babies with Zika-Related Brain Damage may Appear “Normal”
Last week, Florida and federal officials confirmed the 1st local spread of Zika through infected mosquitoes in the continental U.S. On July 29, Florida Gov. Rick Scott said transmission was confined to the small Wynwood neighborhood north of downtown Miami and, at the time, involved 4 individuals – 1 woman and 3 men. 
The travel warning came after 10 additional people in Florida were found to have been infected with the Zika virus after being bitten by local mosquitoes. The cases were discovered via door-to-door surveys of 200 people in their homes and businesses, and they were identified by urine and blood samples that tested positive for the virus or an antibody.
CDC Director Dr. Tom Frieden said:
“New test measurements over the weekend showed a risk of continued active transmission in that area. Because of this finding, we are advising pregnant women not to travel to that area and if they have traveled there on or after June 15 to visit their health care provider for testing.”
According to Frieden, June 15 is the earliest day that local health officials believe the mosquitoes could have transmitted the virus. The mosquitoes themselves were infected after biting someone who had returned to the United States with the disease.
“With 40 million travelers to and from areas where Zika is actively circulating, many can come back who feel perfectly fine. But the virus could be hitchhiking in their blood. That’s why everyone who travels to one of those areas should use insect repellent for at least three weeks after they return.”
The CDC recommended the following additional precautions:
- Pregnant women who live in or travel to the area should be tested for Zika infection in the first and second trimesters of pregnancy, even if they have no symptoms of the virus.
- Pregnant women and their male and female partners who live in the area should prevent mosquito bites and use proper sexual protection for the length of the pregnancy, or abstain from sex altogether.
- Male or female partners of pregnant women who have traveled to this area should use safe sex measures for the rest of the pregnancy.
- Women and men who have traveled to the affected area should wait eight weeks to conceive after their return, while men with symptoms should wait a full six months. 
Despite the warning to pregnant women, women considering becoming pregnant, and their partners, Frieden said no travel limitations in the U.S. are currently warranted. He explained:
“We don’t expect widespread transmission in the continental United States. That is not the situation we’re in today.”
That doesn’t mean it’s impossible.
Read: Zika Virus is “Scarier than the CDC Initially Thought”
Frieden said that if more people become infected with the Zika virus despite ongoing mosquito-control measures, “this would be concerning and warrant further advice and action.” He said the CDC will reassess the situation daily and revise its recommendations accordingly. 
Dr. William Schaffner, infectious disease specialist at Vanderbilt Medical School in Nashville, Tennessee, said there is indeed concern that the virus could spread to other areas of the country where Zika could then be transmitted through local mosquitoes there.
There are 2 types of mosquitoes in the U.S. that are known to transmit Zika: the Aedes aegypti and the Aedes albopticus. A graphic posted by The Washington Post shows the wide reach of either type of mosquito, or both, across the United States. 
In South Florida, the Wynwood area is a popular restaurant and entertainment hub. The individuals infected became sick a week later and were diagnosed a few days after that. At least 2 people were believed to have been bitten at work sites near each other in that area, Frieden said.
Gov. Scott said:
“We know this virus is most detrimental to expecting mothers. If you are pregnant or thinking of becoming pregnant and live in the impacted area, I urge you to contact your OB/GYN for guidance and to receive a Zika prevention kit. I also ask every Floridian to take proper precautions by eliminating any standing water and wearing insect repellent.”