Florida's dengue outbreak tops 425 cases across 11 counties — largest in nearly a century

Florida has confirmed 425 locally acquired dengue fever cases across 11 counties as of October 17 — a toll that already dwarfs the 650 cases the state recorded across the entire fifteen-year span from 2010 to 2025, according to historic CDC data. The Florida Department of Health says Hillsborough County, which encompasses Tampa, accounts for 346 of those cases; Pinellas County, home to St. Petersburg, has reported 51.

This is the largest locally acquired dengue outbreak in Florida since the 1930s.— Laura Adams, DVM, MPH, Epidemiologist, CDC Dengue Branch

Adams made the remark on a CDC call convened specifically to brief clinicians on how to recognize and treat the disease. At the time of that call, on October 15, the CDC's own count stood at 368 cases in eight counties — the Florida Department of Health's tally, updated two days later, had already climbed to 425 in 11 counties, illustrating how quickly the outbreak is moving.

Seminole County recently confirmed its first locally transmitted case, according to iHeart/WIOD, joining Miami-Dade, Broward, Orange, Palm Beach, and Polk counties among the newly affected areas. Hillsborough, Pinellas, and Pasco counties have repeatedly extended dengue-related states of emergency to redirect funds into aerial spraying targeting mosquito larvae, according to Medscape. Pinellas County extended its local emergency through October 29, a declaration that allows officials to accelerate mosquito control and seek potential expense reimbursement, according to iHeart/WIOD.

Planned helicopter treatments in Pinellas County have been delayed by high winds, with operations expected to begin the following week if weather permits, according to iHeart/WIOD. Ground spraying and expanded surveillance are continuing across affected communities in the meantime.

The virus spreading through Florida is primarily dengue serotype 2, according to Adams. Cases have appeared across all age groups, but most patients are adults aged 30 to 49; half are men. About 47% of those infected have required hospitalization, Adams said on the CDC call.

Dengue — nicknamed 'breakbone fever' for the severity of its aches — is transmitted through the bite of the Aedes aegypti mosquito, which feeds during the day. Between 20% and 40% of people bitten by an infected mosquito develop symptoms, which typically appear 3 to 14 days after the bite and include abrupt fever, nausea and vomiting, rash, mucosal bleeding, and marked flushing of the face, neck, and chest, according to Medscape. The febrile phase lasts 2 to 7 days.

About 5% of symptomatic patients develop severe dengue, which can involve plasma leakage leading to shock, respiratory distress, severe bleeding, and damage to the heart, brain, and liver, according to Medscape. Older adults and those with conditions such as asthma, diabetes, obesity, or hypertension face higher risk, as do pregnant people, who have a greater chance of progressing to severe disease.

Any mucosal bleeding is a warning sign in dengue, and it is important to ask about bleeding that might not be obvious during the physical examination, including changes in the color of the urine or stools and changes in menstrual flow.— Liliana Sánchez-González, MD, MPH, CTropMed, CDC National Center for Emerging and Zoonotic Infectious Diseases

There is no approved dengue vaccine available in the United States, and no curative treatment. Standard care is supportive: intravenous fluids and close monitoring of fluid intake and output. Clinicians are advised not to give corticosteroids or nonsteroidal anti-inflammatory drugs — the former lack evidence of benefit and the latter can increase bleeding risk, according to Medscape. The CDC has published a dengue clinical management pocket guide with outpatient and inpatient algorithms.

Clinical management should not be delayed while waiting for laboratory confirmation.— Liliana Sánchez-González, MD, MPH, CTropMed, CDC National Center for Emerging and Zoonotic Infectious Diseases

Prevention remains the primary tool available to the public: eliminating standing water where mosquitoes breed, wearing protective clothing, and applying EPA-registered insect repellents, according to health officials.

Dengue incidence has risen sharply worldwide over the past two decades, driven in part by climate change, according to the World Health Organization. The illness is common in tropical and subtropical regions. Virginia reported its first locally acquired dengue case earlier in 2026, while six US territories and freely associated states — Puerto Rico, American Samoa, the US Virgin Islands, the Federated States of Micronesia, the Republic of the Marshall Islands, and the Republic of Palau — experience frequent or continuous transmission, according to the CDC.

Why it matters — With nearly half of symptomatic patients hospitalized and the outbreak already larger than anything Florida has seen in roughly 90 years, residents across an expanding set of counties face real exposure risk — and clinicians statewide need to know how to diagnose and treat a disease many have rarely encountered.

Reported by thehill.com, medscape.com, heraldtribune.com, wiod.iheart.com