But researchers who have studied Zika and the mosquitoes that transmit it say that the country is currently in the calm before the calm. Damaging as Zika is to fetuses, they predict that autochthonous transmission will only affect a small swath of the country that stretches from Florida along the Gulf Coast to Texas. And the dynamics of mosquito-borne disease in the United States are so different from those in Latin America that the number of confirmed cases probably will be in the hundreds, if that, before autochthonous spread sputters out.