Florida has now recorded 524 locally acquired cases of dengue fever in 2026, after health officials reported 39 more cases in a single week, according to data from the Florida Department of Health released on November 6. The new total, which covers cases reported through October 31, makes the current outbreak the largest locally acquired dengue outbreak in the United States in decades. The increase from 485 cases reported on October 24 to 524 cases a week later shows that transmission was still continuing into late October, even as cooler and drier air began to arrive in parts of the state. Health officials have stressed that the figures describe cases acquired inside Florida, rather than infections brought in by travellers returning from places where dengue is common.
The scale of the outbreak stands out sharply against recent years. Florida reported 62 locally acquired dengue cases in all of 2025, and the previous recent high was 199 cases in 2023. The 2026 total of 524 is therefore more than two and a half times that earlier high, and more than eight times the total recorded last year. The comparison underlines why state and county officials have treated this year as an exceptional event rather than a normal seasonal rise. It also helps explain the emergency declarations, the expanded mosquito control work and the sustained public warnings that have accompanied the outbreak through the autumn.
Most of the cases remain concentrated in one part of the state. Hillsborough County, on Florida’s west coast and home to Tampa, has recorded 407 of the 524 cases, or more than three quarters of the statewide total. The concentration in the Tampa Bay area has shaped almost every part of the response, from where spraying has been focused to where health officials have urged residents most strongly to remove standing water and protect themselves from mosquito bites. The Tampa Bay region as a whole accounts for the overwhelming majority of the state’s locally acquired cases this year.
Florida dengue outbreak 524 cases: what the new figures show
The latest weekly surveillance report from the Florida Department of Health, covering October 25 to October 31, added 39 locally acquired cases to the statewide total. That followed an increase of 60 cases in the previous week, covering October 18 to October 24, when the total rose to 485. The two weeks together added 99 cases, a reminder that the outbreak was still growing through the second half of October. At the same time, the weekly increase of 39 was smaller than the 60 recorded the week before, and some reporting has noted that weekly case numbers appeared to be slowing as the state moved into cooler, drier conditions.
Locally acquired cases have now been reported in 12 counties. After Hillsborough County’s 407 cases, Pinellas County has the next highest total, with 80 cases. Miami-Dade County has reported 12 cases and Orange County has reported 10. Pasco County has four cases, Citrus County has three, and Manatee County has two. Brevard, Broward, Palm Beach, Polk and Seminole counties have each reported a single locally acquired case. The spread across 12 counties shows that the outbreak is not confined to a single neighbourhood or a single city, even though its centre of gravity is firmly in the Tampa Bay area.
The locally acquired cases are counted separately from travel-associated cases, and the distinction matters for understanding the outbreak. A travel-associated case involves a person who was infected while travelling abroad and then became ill after returning to Florida. A locally acquired case involves a person who was infected by a mosquito inside Florida. The 524 figure covers only the locally acquired cases. Florida has also reported more than 300 travel-associated dengue cases in 2026, which are recorded separately and do not form part of the outbreak total.
The surveillance report also recorded other mosquito-borne activity. There have been eight positive samples of locally acquired West Nile virus and one case of chikungunya, another mosquito-borne illness. Those figures are small beside the dengue total, but they are part of the same surveillance picture, and they help explain why health officials have issued advisories and alerts across a wide area rather than limiting their warnings to dengue alone.
Hillsborough County at the centre of the outbreak
Hillsborough County has been at the centre of the outbreak from the early stages, and its share of the total has grown steadily through the autumn. The county recorded 385 cases by October 24 and added further cases in the following week to reach 407. Pinellas County, its neighbour across Tampa Bay, has also carried a substantial burden, rising from 67 cases in the October 24 report to 80 in the latest figures. Together, Hillsborough and Pinellas account for 487 of the 524 cases statewide.
The outbreak prompted Hillsborough County Administrator Bonnie Wise to issue a state of local emergency, which has been extended repeatedly since it was first declared in late September. The current declaration expires on November 12 unless the county extends it again. The emergency declaration gives the county additional flexibility to direct resources towards mosquito control and the wider response, and its repeated renewal reflects the length of time transmission has continued. Hillsborough, Pasco and Pinellas counties all declared local emergencies in late September as case numbers climbed.
Mosquito control has been a central part of the county response. Aerial spraying operations have treated large areas, and ground spraying, inspections of individual properties and efforts to identify and remove standing water have all been expanded. By early October, Hillsborough County had already spent about 2.5 million dollars responding to the crisis, including nearly 2 million dollars on mosquito control products and more than 500,000 dollars on helicopter operations that treated nearly 330,000 acres. The spending figures illustrate the scale of the operation, and they also show how quickly the costs of a sustained mosquito-borne outbreak can accumulate for a single county.
The Centers for Disease Control and Prevention has also been involved, activating a Level 3 emergency response to support outbreak efforts in Florida. A Level 3 activation reflects the seriousness with which federal health officials view the situation, and it allows additional federal support to be directed towards the state response. The involvement of the CDC also reflects the national significance of the outbreak: it is the largest locally acquired dengue outbreak in the continental United States in decades, and in some reporting it has been described as the largest in nearly a century.
The death of Gay Small
One death has been confirmed in connection with the outbreak. The person who died was 80-year-old Gay Small, of Hillsborough County. According to a death certificate, she died of dengue infection along with septic shock and multi-organ failure. Her death was the first dengue-associated death confirmed in Florida this year, and it has been reported as the state’s first such death of the year. The confirmation of a death changed the public conversation around the outbreak, giving a human dimension to figures that had previously been discussed mainly in terms of case counts and county totals.
Health officials have not released extensive further detail about the circumstances of the death, and the available reporting has focused on the facts recorded on the death certificate. The case is a reminder that while many people who contract dengue experience a mild illness or recover without hospital treatment, the infection can in some cases become severe. Severe dengue can involve bleeding, organ damage and a sharp drop in blood pressure, and it requires urgent medical care. Older adults and people with other health conditions are among those at greater risk of a severe outcome, although severe illness can occur in other groups as well.
The death also underlines a point that health officials have repeated throughout the outbreak: the official case count is likely to understate the true number of infections. Many people infected with dengue experience mild symptoms or no symptoms at all, and some of those people never seek medical care and are never tested. As a result, the 524 confirmed cases represent the infections that have been detected and reported, rather than the full extent of transmission in the affected communities.
Twenty counties under mosquito-borne illness advisories and alerts
Twenty counties are now under mosquito-borne illness advisories or alerts, according to the state health department. The advisories and alerts are issued when surveillance shows that mosquito-borne illness is present or that conditions favour transmission, and they are intended to warn residents and visitors to take precautions. The number of counties covered shows that concern extends well beyond the 12 counties that have reported locally acquired dengue cases. Counties under advisory are generally urged to step up mosquito control and to remind residents about personal protection, while counties under alert face a higher level of concern.
The advisory system is one of the main tools the state uses to communicate risk to the public. An advisory or alert does not mean that every resident of a county is at high risk, and it does not mean that transmission is occurring evenly across a county. It does mean that health officials have seen evidence that justifies extra caution, and that residents should pay attention to the guidance that accompanies the notice. For people living in or visiting the Tampa Bay area in particular, the advice has been consistent for weeks: protect against bites, remove standing water, and seek care promptly if symptoms appear.
Why standing water and record rain matter
Record rainfall and flooding have been part of the background to the outbreak, leaving standing water in many places across the affected region. Standing water is where the mosquitoes that carry dengue lay their eggs, and even small amounts of water in containers, gutters, plant pots, discarded tyres and other objects can provide breeding sites. When heavy rain is followed by warm weather, mosquito numbers can rise quickly, and the risk of transmission increases with them. The combination of a wet period and warm temperatures created conditions in which the mosquitoes that spread dengue could thrive.
The pattern is one that mosquito control experts have described in other outbreaks as well. The mosquitoes that carry dengue, principally Aedes aegypti, are adapted to living close to people and to breeding in small containers of water around homes. That is why the public health advice in an outbreak places so much emphasis on what residents can do in their own yards and homes. Removing standing water, clearing gutters, emptying containers and covering water storage can reduce the number of mosquitoes near a home, and those steps complement the spraying and treatment work carried out by county mosquito control teams.
The role of weather also helps explain why officials have looked to the change of season with cautious hope. Cooler, drier air tends to reduce mosquito activity, and some reporting has noted that weekly case numbers were beginning to slow as those conditions arrived. That does not mean the outbreak is over, and health officials have been careful not to describe it in those terms. Case counts lag behind infections, because it takes time for a person to become ill, seek care, be tested and have the result reported. A fall in reported cases in one week can therefore reflect a genuine fall in transmission, a delay in reporting, or a mixture of both, and officials wait for several weeks of data before drawing firm conclusions.
What dengue is and how it spreads
Dengue is a viral illness spread by the bite of an infected mosquito. It is not spread directly from one person to another in the ordinary sense. A mosquito becomes infected when it bites a person who has dengue virus in their blood, and it can then pass the virus to other people it bites. Because the mosquitoes that carry dengue bite mainly during the day, and often indoors as well as outdoors, the usual advice about avoiding mosquitoes at dusk does not cover the full risk. Protection during daylight hours matters as much as protection in the evening.
The symptoms of dengue often resemble those of flu at first, which can make the illness hard to recognise in its early stages. Fever, headache, pain behind the eyes, muscle and joint pain, nausea and a rash are among the symptoms most commonly described. Most people recover within a week or two, but a small proportion develop severe dengue, which can be life threatening. Warning signs of severe illness include severe abdominal pain, persistent vomiting, bleeding from the gums or nose, blood in vomit or stool, and extreme tiredness or restlessness. Health officials advise anyone who develops those signs to seek urgent medical care.
There is no specific medicine that kills the dengue virus. Treatment focuses on relieving symptoms, keeping the person hydrated and monitoring for signs of severe illness. That is why early recognition matters: a person whose condition is worsening needs to be in medical care before the illness becomes critical. People who have recently been in an area with dengue transmission and who develop a fever are generally advised to tell a clinician about the possible exposure, so that dengue is considered alongside other causes of fever.
What residents are being told to do
The advice given to residents in the affected counties has been consistent throughout the outbreak, and it rests on two ideas: reduce the number of mosquitoes, and reduce the number of bites. Residents are urged to remove standing water from around their homes at least once a week, to clear blocked gutters, to empty and scrub containers that hold water, and to cover or remove items that can collect rainwater. Swimming pools that are not in use should be maintained or covered, and water in bird baths and pet bowls should be changed regularly.
For personal protection, the standard advice is to use an insect repellent, to wear long sleeves and long trousers when possible, and to make sure that windows and doors have screens that are in good repair. People spending time outdoors, particularly during the day, are advised to reapply repellent as directed on the product label. Parents are advised to protect young children with the same measures, and to dress them in clothing that covers arms and legs where practical.
People who develop a fever after being in an affected area are advised to seek medical advice, and to mention the possible exposure to dengue. Early testing and monitoring can help clinicians decide on the right care, and reporting confirmed cases helps health officials track where transmission is occurring. The advice is the same for residents and for visitors to the Tampa Bay area and other affected counties, and it applies whether or not a county is under a formal advisory.
What happens next
The immediate question is whether the weekly case numbers will continue to fall as the weather cools, and whether the Hillsborough County emergency declaration will need to be extended beyond November 12. The county will have to decide before that date whether the situation still justifies an emergency declaration, and the decision will depend on the latest surveillance data and on the advice of health and mosquito control officials. The declaration has already been renewed several times, and each renewal has reflected a judgement that the response still needed the flexibility it provides.
The wider question is what the outbreak means for Florida in the longer term. The state has dealt with small numbers of locally acquired dengue cases in previous years, and the 2026 total dwarfs all of them. Whether the coming year brings a return to the low numbers of the past, or whether the Tampa Bay area will need to maintain a higher level of mosquito control and surveillance, will depend on how much of the virus remains in local mosquito populations over the winter, and on the weather in the months ahead. For now, the official position is that residents should continue to take precautions, and that surveillance will continue through the surveillance season.
For the people of Hillsborough and Pinellas counties in particular, the outbreak has been a long and disruptive episode, running from late summer through the autumn and into November. It has brought repeated emergency declarations, extensive spraying operations, millions of dollars in response costs, and the loss of at least one resident. The new total of 524 cases confirms that the outbreak is the largest the United States has seen in decades, and it leaves Florida’s health officials with a clear task: to bring transmission to an end, and to learn from an outbreak that arrived at a scale few had expected.
Sources
USN reviewed reporting from multiple outlets for this story. Read more from Sarasota Herald-Tribune, Outbreak News Today and NPR Illinois.