Zika may have arrived in the continental United States by other means than travel.

Stat reported that two adjacent Florida counties, Broward and Miami-Dade, are the locations of four new cases of Zika that thus far have not been attributed to travel outside the United States but may be caused by the bites of infected mosquitoes in Florida.

This summer has brought much trepidation surrounding the spread of the Zika virus, forcing Congress to consider significant funding to combat the disease. Upon finding out about the presence of the virus in Florida, Senate Democratic Leader Harry Reid called for Congress to return to Capitol Hill and figure out next steps. In a tweet, Reid said, "Zika is public health emergency that requires immediate bipartisan action. Americans can’t afford to wait until Congress' vacation is over."