There are 392 known cases of dengue fever in Florida with one death, according to the U.S. Centers for Disease Control and Prevention. The outbreak has been growing since July. Three Florida counties have declared states of emergencies, Pasco, Hillsborough, and Pinellas counties.

The epicenter of Florida’s outbreak is the Tampa Bay area with Hillsborough County recording 177 known cases. County officials have been using helicopters to spray for mosquitoes in high risk areas. Pinellas County has been sending mosquito control crews door-to-door in affected areas. The CDC also reports that Puerto Rico has 916 known cases and that there are over 2,000 known cases across the U.S. Worldwide there are at least 1.5 million cases and over 500 deaths.

Dengue is a viral infection spread through the bites of infected mosquitoes. Most cases have little or no symptoms, but dengue can cause internal bleeding and death.