Florida reports 524 locally acquired dengue cases, largest US state outbreak in decades

Cases climb past 500

State surveillance logged 39 new local infections in the final week of October, taking the total from 485 on 24 October to 524.

One death has been confirmed in Hillsborough County: 80-year-old Gay Small, who died on 4 September of dengue infection along with septic shock and multi-organ failure, according to a death certificate.

Local transmission is no longer a single-county problem. Twelve counties have reported locally acquired cases, according to the health department data. Hillsborough has 407, Pinellas 80, Miami-Dade 12, Orange 10, Pasco 4, Citrus 3 and Manatee 2, with single cases in Brevard, Broward, Palm Beach and Polk. The published county list does not account for every case in the 524 total. Reported cases are also an undercount, because many infected people have no symptoms or mild illness and never seek care or testing.

Florida has also recorded more than 300 travel-associated dengue cases this year, the New York Post reported on 2 November. At least 13 Hillsborough cases involved people who had recently traveled, and Florida regularly sees travel-associated dengue because of its large number of international travelers, the Independent reported.

Dengue spreads through bites from Aedes aegypti and Aedes albopictus mosquitoes, both found in Florida, and not from person to person.

Why the outbreak is centred on Tampa

Hillsborough County, home to Tampa, accounts for about 78% of the 524 total. The New York Post, citing health department data for the week of 18 to 24 October, when the statewide total was 485, put the Tampa Bay area's share at roughly 95% of locally acquired cases.

Why the outbreak clustered around Tampa rather than South Florida is not settled. Travel patterns and warmer temperatures are possible factors, NBC Miami reported, according to the Independent. Most people in the Tampa area have no prior immunity to any form of dengue, Dawn Wesson, a Tulane University expert on mosquito-borne disease, told the Lawrence Journal-World. Chris Wilkerson, a spokesperson for Hillsborough County, called the surge "wildly unusual for us".

The Tampa-area outbreak first came to light in July.

The record it breaks

Florida's previous high in recent memory was 199 locally acquired cases in 2023; the state reported 62 in 2025.

The 524 cases exceed the 264 local infections Hawaii's Big Island recorded between September 2015 and March 2016. That had been the largest outbreak reported by a U.S. state in decades. Available state health department data and medical journals suggest the Florida total is the most cases in a calendar year for any state since at least the 1940s, the Lawrence Journal-World reported. Federal dengue surveillance data is limited, the Lawrence Journal-World noted. Puerto Rico consistently records far higher dengue numbers than any of the 50 states.

Global cases rose to 14.6 million in 2024 from 505,430 in 2000, according to the World Health Organization, which says about half the world's population is now at risk.

In 2009 and 2010, Key West reported the first locally acquired dengue in the continental U.S. outside the Texas-Mexico border since 1945.

Response, money and limits

The CDC has provided Florida with $800,000 in emergency funding and is monitoring the outbreak, the Independent reported. CDC spokesman Jason McDonald said the agency has not sent disease investigators because Florida officials have not requested them, the Lawrence Journal-World reported. Hillsborough, Pasco and Pinellas declared local states of emergency in late September, a step the New York Post reported allowed faster purchasing and spraying and requests for state and federal reimbursement. Hillsborough County Administrator Bonnie Wise issued the current order, which expires on 12 November unless the county extends it again.

The Florida Mosquito Control Association said teams are stepping up targeted ground spraying, aerial applications and property inspections. Aedes mosquitoes are container breeders that need as little as a tablespoon of standing water to lay eggs.

What happens next

Record rainfall has left roads flooded, ditches full and standing water in many Florida yards, and the health department's numbers may climb in the weeks ahead. Officials in Hillsborough and surrounding counties have been spraying day and night to reduce mosquito populations, the Lawrence Journal-World reported. USA Today reported that 20 counties are under mosquito-borne illness advisories or alerts.

Michael von Fricken, a University of Florida associate professor of environmental and global health, told AOL the threat is not likely to tail off: "I do think it's going to be somewhat the new normal".

The CDC advises people in areas with local transmission to use EPA-registered insect repellent, cover arms and legs with loose-fitting clothing, and drain standing water around homes.