TL;DR
The CDC has activated a Level 3 emergency response for dengue outbreaks in Florida and the Republic of the Marshall Islands. Florida has reported 745 cases this year, including 425 acquired locally, with most concentrated around Tampa; the CDC says continued transmission is a concern after hurricane-related rainfall.
The CDC has activated a Level 3 emergency response for dengue outbreaks in Florida and the Republic of the Marshall Islands, its eighth emergency activation this year. Florida has reported 745 dengue cases in 2026, including 425 acquired locally, and the agency says mosquito presence and recent hurricane-related rainfall make continued domestic transmission a concern.
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Florida’s locally acquired cases are concentrated mostly in the Tampa area. The reported 745 cases include infections acquired both locally and elsewhere; 425 were locally acquired. The CDC said the total is the largest dengue outbreak in the continental United States since 1935, according to the report by MedPage Today. Local transmission in Florida has occurred before, but experts described this year’s scale as exceptional.
During a call with clinicians, CDC experts said locally acquired infections in Florida primarily involve DENV-2, one of four dengue virus serotypes. About 54% of cases were in men, the median age was 43, and 45% were among people aged 30 to 49. The CDC reported that 47% of cases required hospitalization; the agency said that proportion may indicate infections are being under-reported.
The CDC’s response also covers the Republic of the Marshall Islands, where authorities declared a state of emergency on the two largest islands, Ebeye and Majuro. Chris Braden, acting director of the CDC’s National Center for Emerging and Zoonotic Infectious Diseases, said the agency has provided programmatic support and deployed an Epi-Aid team there. The activation adds to a year of CDC responses involving several other disease outbreaks and public-safety events.
Florida Faces Sustained Local Transmission
The response highlights that dengue is being transmitted within the continental United States, not only among travelers returning from areas where the virus is common. The scale reported in Florida matters to residents and local health services because locally acquired infections can continue where mosquitoes capable of carrying dengue are established.
Adam Waickman, a dengue expert at SUNY Upstate Medical University, told MedPage Today that the mosquito species able to transmit the virus have become more prevalent in Florida. He said 70% to 90% of dengue infections are asymptomatic, meaning reported cases may not capture the full number of infections. That estimate is expert context, not a CDC count of undiagnosed cases in Florida.
Waickman also cautioned that routine spraying may not reach mosquitoes that live in and around homes. He recommended personal steps to reduce bites, including using mosquito repellent and wearing clothing that covers the skin. The CDC’s activation puts additional agency attention on the outbreaks, but the source report does not specify the full operational measures or resources assigned to Florida.
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How Florida’s Outbreak Grew
Dengue is spread primarily through bites from infected Aedes aegypti mosquitoes; Aedes albopictus can also transmit the virus. Waickman told MedPage Today that Aedes aegypti is the more effective vector and that its range has extended as far north as Virginia. He said the range of Aedes albopictus reaches into Pennsylvania. Those ranges describe mosquito distribution, not confirmed dengue transmission across every state.
The CDC’s Level 3 activation is part of a broader set of emergency responses managed this year by its National Center for Emerging and Zoonotic Infectious Diseases. Braden’s email cited responses involving Cyclospora, Ebola, measles, hantavirus and New World screwworm, as well as safety planning for the World Cup and a wastewater spill near Washington, D.C. The CDC described the dengue activation as the agency’s eighth emergency response activation of the year.
There is no dengue vaccine licensed in the United States, according to the report. Sanofi Pasteur’s vaccine was found to raise the risk of severe disease in people without prior dengue infection. Takeda’s vaccine is approved in several countries but not in the United States; the company withdrew its U.S. license application in 2023 after discussions with the FDA about aspects of data collection. Researchers are also testing antivirals and monoclonal antibodies, but the report does not identify an approved treatment arising from those trials.
“The reason we’re seeing this sustained transmission now is that the species of mosquito that are capable of transmitting the infection are now much more prevalent in Florida.”
— Adam Waickman, dengue expert at SUNY Upstate Medical University
Case Counts and Response Details
The reported figures do not establish how many people in Florida have been infected but were never diagnosed. Waickman said most dengue infections are asymptomatic, while the CDC noted that the high hospitalization share may indicate under-reporting. The source report does not provide a separate estimate of undetected infections or a detailed breakdown of cases by county.
It is also not clear from the report what additional CDC resources or specific field measures will be used in Florida under the Level 3 activation, or how long the response will remain in place. The CDC has said continued transmission is a concern, but the available information does not establish how many new locally acquired cases may follow the rainfall or whether transmission will persist beyond the current outbreak.
Vaccine availability remains limited in the United States: the vaccines discussed in the report are not licensed domestically. Several potential treatments are in clinical trials, including a monoclonal antibody that showed promise in a phase II trial among hospitalized patients, but the report does not say when those studies may produce a treatment available to patients.
CDC Support and Local Prevention
The CDC’s emergency response is ongoing. In the Marshall Islands, the agency has deployed an Epi-Aid team and is providing programmatic support; the source report gives fewer details about the specific measures planned for Florida. Further information from the CDC or state and local health departments could clarify response activities, updated case totals and how the outbreak is changing.
For people in affected areas, the immediate prevention advice cited by Waickman is to reduce mosquito bites by using repellent and wearing long sleeves or other covering clothing. Residents should follow guidance from local public health officials and seek clinical advice if they develop symptoms after possible exposure. The report does not provide a forecast for when Florida’s outbreak will end or a date for the next CDC update.
Key Questions
What did the CDC announce?
The CDC activated a Level 3 emergency response for dengue outbreaks in Florida and the Republic of the Marshall Islands. It was the agency’s eighth emergency response activation of 2026, according to the report.
How many dengue cases has Florida reported?
Florida has reported 745 cases this year, of which 425 were locally acquired. Most locally acquired cases are concentrated around Tampa, according to the source report.
What does locally acquired dengue mean?
It means the infection was contracted within the area being reported, rather than acquired while traveling elsewhere. The 425 locally acquired cases indicate that dengue transmission has occurred within Florida.
What can people do to reduce their risk?
Waickman recommended using mosquito repellent and wearing clothing that covers the skin to reduce bites. People should also follow public health guidance in their area; the report says routine spraying may not reach mosquitoes living in and around homes.
Is a dengue vaccine available in the United States?
The report says that no dengue vaccine is licensed in the United States. A vaccine from Takeda is approved in several other countries, but its U.S. application was withdrawn in 2023 after discussions with the FDA.
Source: rss
