A record for the mainland
Florida's dengue outbreak now looks like the largest in the continental United States in several decades. State health officials reported 252 locally acquired cases this year in an update this week.
That number is close to the national record of 264 cases, set in Hawaii over six months in 2015 and 2016. Federal health officials caution that dengue surveillance data is patchy across states, so the true count may differ.
For comparison, Florida recorded 62 locally acquired cases in all of 2025.
Where the cases are
Hillsborough County, which includes Tampa, has the highest count. Officials there report 223 locally spread cases. County administrator Bonnie Wise extended a state of emergency this week as crews work to control the mosquito population.
Other cases have been reported in Miami-Dade, Pinellas and Palm Beach counties.
A locally acquired case means the person was infected by a mosquito in Florida, not while traveling abroad. That shows the virus is circulating in local mosquitoes.
How dengue spreads and what to do
Dengue is spread mainly by Aedes aegypti mosquitoes, which bite during the day. Symptoms usually appear within 14 days of a bite and include high fever, headache, muscle and joint pain, and a rash.
Most people recover in about a week, but severe dengue can be deadly and needs hospital care. Health officials advise emptying standing water around homes, using repellent and wearing long sleeves.
Puerto Rico has reported 922 of the 2,145 locally acquired cases recorded in the United States this year. Scientists say warming temperatures and urban water storage help the mosquitoes spread into new areas.