Florida dengue outbreak hits 296 cases, largest in any US state in decades

Florida is in the midst of its largest dengue outbreak in decades. As of October 3, 2026, the Florida Department of Health reported 296 locally acquired dengue cases statewide this year, an increase of 44 cases in a single week. This is the largest such outbreak in the continental United States in decades, according to state health officials. The outbreak first came to light in July and has continued to grow despite intensifying mosquito control efforts.

The bulk of the cases, 259 out of 296, are in Hillsborough County, which includes Tampa. One death has been confirmed: an 80-year-old Hillsborough County woman named Gay Small, who died on September 4 at Tampa General Hospital. According to a death certificate, the cause was dengue infection along with septic shock and multi-organ failure. Her death is the only dengue-related fatality in Florida this year.

Other counties reporting locally acquired cases include Pinellas with 20 cases, Miami-Dade with 8, Orange with 3, and Pasco with 3. Broward, Palm Beach, and Polk counties each have one case. Broward County reported its first confirmed human dengue case on October 5. The previous highest number of Florida cases in recent memory was 199 in 2023; in 2025, Florida reported 62 cases for the year.

Three Tampa Bay area counties, Pasco, Hillsborough, and Pinellas, have declared states of emergency to expedite mosquito control operations. Sixteen counties are under either a mosquito-borne illness advisory or alert. The Florida Department of Health, or FDOH, is tracking both locally acquired and travel-associated cases. There have also been 262 travel-associated dengue cases in Florida this year, with 215 linked to travel to Cuba.

Key Facts

Florida Today reported on October 9 that the state added 44 new locally acquired dengue cases in one week, bringing the total to 296 as of October 3. This is the largest outbreak in the United States in decades. The previous highest number of Florida cases in recent memory was 199 in 2023; in 2025 Florida reported 62 cases for the year. The bulk of the cases have been in Hillsborough County, which has 259 confirmed cases, while other locally acquired cases have been reported in seven other counties.

The Watchers reported on October 8 that the FDOH Week 38 report showed 252 locally acquired dengue cases through September 26, including 223 in Hillsborough County. The state added 62 cases that week, up from 190 in Week 37. DENV-2 accounted for 230 of the 232 locally acquired cases serotyped by PCR; the other two were DENV-3. Twenty Aedes aegypti mosquito pools tested positive for DENV-2, with 19 in Hillsborough and one in Pasco.

Vector control efforts have intensified. According to The Watchers, Hillsborough scheduled nighttime helicopter applications of Dibrom adulticide over the Temple Terrace and University area and from Thonotosassa to Bloomingdale from October 7 to 8, flown at about 46 meters with an application rate of about 48 milliliters per hectare. Separate daytime flights from October 5 to 9 applied Bacillus thuringiensis israelensis, or Bti, to standing water to target larvae.

The Associated Press reported on October 10 that Florida's outbreak is the largest in several decades of any U.S. state. State health officials reported nearly 300 locally acquired cases of the mosquito-borne disease this year, with the vast majority in Hillsborough County. Available information from state health departments and medical journals suggests the Florida outbreak marks the most cases in a calendar year for any state since at least the 1940s. Puerto Rico is consistently hit harder, but in the continental U.S. Florida usually gets the most locally transmitted cases.

Travel-associated cases also remain high. Florida Today reported on October 9 that there have been 262 travel-associated dengue cases in Florida this year, with 215 from travel to Cuba. The Watchers reported on October 8 that through September 26, there were 245 travel-associated cases, including 201 linked to Cuba, so locally acquired cases slightly exceeded travel-associated cases at that point. The CDC has provided $800,000 in assistance to the state health department, though Florida has not asked for CDC disease investigators to come in, according to CDC spokesman Jason McDonald.

Analysis

What this really means is that Florida is facing a public health challenge unprecedented in modern times. The scale of the outbreak, with 296 cases and counting, has surpassed the previous record of 199 cases in 2023 and dwarfs the 62 cases in 2025. The concentration in Hillsborough County, which accounts for 259 of the 296 cases, points to intense local transmission. The presence of DENV-2 in 230 of 232 serotyped cases and in 20 mosquito pools confirms that the virus is circulating actively between mosquitoes and humans.

The declaration of states of emergency in Pasco, Hillsborough, and Pinellas counties, along with advisories or alerts in 16 counties, shows that officials are treating this as a serious threat. The use of aerial spraying, both at night for adult mosquitoes and during the day for larvae, is a significant escalation. However, the fact that the outbreak first came to light in July and has continued to grow suggests that containment efforts, while robust, have not yet turned the tide.

The bigger picture here is that dengue is no longer just a travel-related concern for Florida. With 262 travel-associated cases, 215 from Cuba, the state is seeing both imported and local transmission. The Aedes aegypti mosquito, which transmits dengue, is well established in Florida. Climate conditions, including warm and wet weather, favor mosquito breeding. The absence of a widely effective vaccine, complicated by the four dengue serotypes and the risk of antibody-dependent enhancement, means that vector control remains the primary defense.

Comparisons to Puerto Rico, which consistently reports more locally acquired cases, highlight that Florida's outbreak is still exceptional for the continental United States. The CDC's $800,000 assistance and the state's decision not to request CDC investigators could be interpreted as confidence in local capacity, but it also raises questions about whether additional federal expertise could help. The death of an 80-year-old woman underscores the severity of the disease, especially for the elderly and those with underlying conditions.

Why It Matters

The outbreak matters because it represents a shift in the epidemiology of dengue in the United States. For decades, locally acquired dengue in the continental U.S. was rare, with the largest prior outbreak being 264 cases in Hawaii over a six-month span in 2015 to 2016. Florida's 296 cases in a single year, still with months to go, signals that the virus can establish sustained transmission in new areas. This has implications for public health preparedness, mosquito control funding, and clinical awareness.

Residents and visitors in affected counties face a real risk of infection. Symptoms of dengue include high fever, severe headache, pain behind the eyes, joint and muscle pain, rash, and mild bleeding. Severe dengue can lead to shock, organ failure, and death. The elderly, infants, and those with prior dengue infection are at higher risk. With 16 counties under advisories or alerts, millions of people are potentially exposed.

Economically, the outbreak could affect tourism and outdoor activities in Tampa Bay and beyond. The response costs, including aerial spraying and emergency declarations, add up. The CDC's $800,000 contribution is a fraction of what might be needed if the outbreak continues to expand. The situation also highlights the importance of global dengue surveillance, as the World Health Organization reports more than 2.2 million infections and nearly 1,200 deaths worldwide this year. The CDC reports more than 1,600 locally acquired U.S. cases this year, most in Puerto Rico.

Next Up

Officials will continue to monitor case counts weekly. The Florida Department of Health's next update, expected in the coming days, will show whether the rate of new infections is slowing. Mosquito control operations in Hillsborough and neighboring counties will persist, with aerial and ground spraying as needed. The state may consider additional measures if cases continue to rise.

Longer term, the outbreak may spur discussions about vaccine development, improved vector control strategies, and better coordination between state and federal agencies. The CDC has offered assistance without sending investigators, but that could change if the situation worsens. For now, health officials urge residents to use repellent, wear long sleeves, and eliminate standing water to reduce mosquito breeding. The coming weeks will be critical in determining whether Florida's dengue outbreak sets a new normal or remains an exceptional event.