Florida mosquito control officials worry they won’t be able to keep up their efforts to contain the bugs that carry Zika without federal funding, even as concern mounts that the first infection from a mosquito bite on the U.S. mainland is near.

On Thursday, fogging trucks drove through a Miami-Dade County neighborhood where health officials are investigating a Zika diagnosis that doesn’t appear to have connection to travel outside the United States. Zika is usually spread by mosquitoes, but nearly all the Zika cases in the U.S. have been contracted in other countries or through sex with someone who got it abroad.