Florida's Record Dengue Outbreak Is the Largest in Decades

A dengue outbreak in Florida has grown into the largest the continental United States has seen in decades, with state health officials logging 252 locally acquired cases so far this year. Federal health officials say it is the highest annual count for any state since the 1940s. Most of the infections trace to the Tampa Bay area, where three counties have declared local emergencies, and the outbreak has already claimed one life.

Locally acquired means patients were bitten by infected mosquitoes inside Florida rather than while traveling abroad, which is what alarms epidemiologists. The state has recorded 497 dengue cases in total this year, including 245 infections picked up during international travel, as reported by Becker's Hospital Review. The mosquito-spread portion alone tops Florida's previous record of 189 local cases in 2023 and exceeds the 198 local cases Hawaii reported in 2015, according to CDC data cited in the same report. Officials tracking this dengue outbreak caution that the true count is likely higher because many people with mild symptoms never get tested, so the published numbers are a floor rather than a ceiling.

How Tampa became the epicenter of the dengue outbreak

Every one of this year's local cases appeared after July, and the Tampa Bay region absorbed nearly all of them. Hillsborough County, home to Tampa, accounts for 233 of the statewide local cases, and a single late-September week added 62 new local infections across Florida, according to state health data. Three mosquito pools in Hillsborough have tested positive for the virus. For perspective on this dengue outbreak, the county recorded just one locally acquired case in all of 2025, and a public health professor at the University of South Florida says the area has not seen this level of dengue infection since the 1930s.

Pasco County declared a local state of emergency first, with Hillsborough and Pinellas counties following a day later. The orders were extended into early October, freeing money and resources for mosquito control while the dengue outbreak kept spreading. Hillsborough has asked for outside help: the Lee County Mosquito Control District sent helicopters and crews to expand aerial spraying, and the county is running day-and-night spraying operations. "This is wildly unusual for us," a Hillsborough County spokesperson told ABC News, as reported by LADbible.

The outbreak turned deadly early on. An 80-year-old Hillsborough County woman died at Tampa General Hospital after a mosquito bite near Tampa Bay, the area's first dengue death in nearly a century, according to the Tampa Bay Times as reported by weather.com. Her death is the only fatality recorded in this year's outbreak, and it underscores why officials are treating the surge as a serious public health event rather than a seasonal nuisance.

Why mosquitoes are winning new ground

Dengue has historically been a tropical and subtropical disease, but the mosquitoes that carry it are expanding their range as the climate warms. The World Health Organization notes that dengue vectors can adapt to new environments and that shifting disease risks follow climate change, especially alongside rapid urbanization. Florida's dengue outbreak fits that pattern, and it is not the only American preview. Long Beach and Pasadena in California reported their first locally acquired dengue cases in 2023, and Orange County, home to Orlando, issued its first mosquito-borne illness alert in more than a decade earlier this year.

The Florida dengue outbreak is also lifting national numbers. CDC data shows dengue case counts rising in at least 15 states, with Florida driving the trend and California posting the second-largest increase, according to Newsweek's analysis of the data as summarized by KFF Health News. Prevention options remain limited: the WHO notes that one vaccine, QDenga, is licensed in some countries but recommended only for children aged 6 to 16 in high-transmission settings, so mosquito control is still the main line of defense in the United States.

What dengue feels like, and how to avoid it

Dengue carries the nickname break-bone fever for good reason. According to the World Health Organization, most infections cause no symptoms at all, but those who do get sick typically develop high fever, severe headache, pain behind the eyes, muscle and joint pain, nausea and a rash, beginning 4 to 10 days after the bite. Most people recover within one to two weeks, and there is no specific cure. Doctors manage pain with acetaminophen, and patients should avoid ibuprofen and aspirin because they raise the risk of bleeding.

One counterintuitive detail matters for repeat travelers: a prior dengue infection raises the risk of severe dengue the second time around, because the immune response to a different viral serotype can make the illness worse. Severe cases bring persistent vomiting, severe abdominal pain, bleeding and breathing trouble, and they need hospital care. Anyone with those warning signs should seek medical help immediately.

The mosquitoes that spread dengue bite mainly during the day, so the usual nighttime precautions are not enough. The WHO recommends repellents containing DEET, picaridin or IR3535, clothing that covers as much skin as possible, and window screens. Just as important is removing breeding sites: empty, cover or clean any container that holds standing water every week, from plant saucers to buckets. Florida health officials give the same advice, urging residents to drain stagnant water, wear protective clothing and use bug spray.

What happens next in the dengue outbreak

Mosquito season is far from over, and health officials expect this dengue outbreak to keep adding cases. Emergency orders, aerial spraying and property inspections aim to break the breeding cycle before the virus reaches more neighborhoods. The undercount caveat cuts both ways: the published tally is likely an underestimate, but it also means most infections are mild enough to go unnoticed.

Outbreaks are making unusual headlines this season: a suspected plague case in Russia recently put the White House on watch. For now, the most effective protection in Florida remains the least glamorous. Dump the standing water, spray the repellent and cover up. Read more in our health section.