The CDC issued a Zika- related travel advisory today for a 1 square mile area in Miami, FL. This was issued as the CDC discovered more infected mosquitos and more cases than they had hoped. Mosquitos can only carry the virus to another person after biting a person infected with the Zika virus. The entire city of Miami is not under a travel advisory since mosquitos only fly 500 feet in their lifetime, so the infected mosquitos will not fly out of the advisory area.
The priority of the travel advisory is to protect pregnant women. If there are pregnant women in the area, they should use insect repellant to protect themselves.