The unfolding Zika epidemic demonstrates how we learn about any “emerging infection.” Ongoing surveillance, close clinical observation, and follow-up of recovering individuals steadily refine our understanding of its epidemiology, the public health measures needed, and management of the disease and its sequelae.

Local transmission in the U.S.

The U.S. has seen more than 1800 travel-related cases of Zika infection. Regular travel between countries and the presence of genus Aedes mosquitoes in much of the U.S. made the establishment of local transmission here inevitable, especially in the warmest and most mosquito-abundant parts of the country. Since early July, the Florida Department of Health has identified 15 cases of local Zika transmission in Miami-Dade and Broward counties. Testing of close contacts of cases as well as of asymptomatic people in the community continues in an effort to confirm the extent of the outbreak.

An epidemic of locally acquired cases in the U.S. remains unlikely; window and door screens and the widespread use of air conditioning decrease (though don’t eliminate) human exposure to mosquitoes.

But even with limited local spread, the possibility of microcephaly or other neurological injury in utero is serious, and the CDC has issued its first ever infectious disease–related travel advisory inside U.S. borders. Pregnant women are cautioned to avoid travel to parts of Florida where there is active […]