An obstetrician and gynecologist who is herself pregnant, Maguire has become scrupulous about following the advice that she gives patients to protect against Zika, which can cause a rare but devastating birth defect. Maguire works near the city's Wynwood neighborhood identified on Friday as the first site of local Zika transmission in the continental United States.

"It is frustrating to spend a lot of time avoiding mosquitoes," said Maguire, a physician at the University of Miami Miller School of Medicine, noting the discomfort of wearing long sleeves during Florida's steamy summer. "You just end up being inside a lot."

Physicians in Miami and beyond have seen this week a spike in concerned calls from pregnant women, particularly after health officials advised them not to travel to Wynwood and said any expecting mothers who had done so since mid-June should be tested for Zika.

On Wednesday, Florida said it would provide Zika testing to pregnant women at county health departments at no cost, and make available additional lab services to handle "the expected increase in tests being administered."

The warnings raised anxiety in a city already on high alert for Zika's arrival from Latin America, where it has spread quickly since first being detected in Brazil last year. The threat to newborns aside, Zika is otherwise considered a mild illness, and up to 80 percent of people infected have no symptoms.

All summer, Florida health officials have issued daily notices tallying the rise in cases acquired through travel to countries where Zika is widespread and advised the public to protect against mosquito bites. Along with 15 local cases, Florida is monitoring 391 picked up through travel abroad, which include 55 cases involving pregnant women.

One baby born in the state to a woman infected in Haiti has been diagnosed with the birth defect microcephaly, a condition defined by small head size that can lead to developmental problems.