The public health sector is presently on high alert for evidence of local transmission of the Zika virus in the continental United States as well as infections that have been acquired elsewhere and imported into the U.S. A number of national, state, and local health officials are actively engaged in vector control, surveillance, and diagnostic and communication activities focused on the Zika virus. Even if major outbreaks do not materialize, public health officials are concerned about the possibility of a sharp increase in babies born with congenital birth defects and other neurological deficits linked to Zika viral infections among pregnant women.