Florida's dengue outbreak: What physicians need to know now

Physicians in Florida now need to consider dengue in feverish patients who have not left the state, as health officials track what appears to be the biggest wave of locally acquired cases in decades.

The Florida Department of Health counted 425 locally acquired dengue cases this year from 11 counties, including 57 reported in the week of Oct. 11-17, according to its latest weekly arbovirus surveillance report. Hillsborough County, home to Tampa, accounts for 346 of them, or about 81%.

For physicians, that shift changes the first question in the exam room. Travel history still matters, but a negative answer no longer rules dengue out in parts of Florida.

“If dengue is suspected, clinicians should provide appropriate management without waiting for diagnostic test results,” according to clinical testing guidance from the Centers for Disease Control and Prevention (CDC).

Record local spread

Florida reported 62 locally acquired cases in all of 2025, according to the state’s final 2025 surveillance report. The state’s previous high in its published case history was 199 local cases in 2023.

Information from state health departments and medical journals suggests the outbreak marks the most locally acquired cases in a calendar year for any state since at least the 1940s, The Associated Press reported. For comparison, Hawaii reported 264 locally acquired cases over six months in 2015-2016, according to the AP.

Symptom onset was reported for 21 cases in July, 160 in August, 226 in September and 18 so far in October, a month the latest report covers only through Oct. 17.

Of 395 locally acquired cases typed by polymerase chain reaction (PCR) testing, 393 were dengue virus serotype 2 (DENV-2) and two were serotype 3. Health officials also have found DENV-2 in 20 pools of Aedes aegypti mosquitoes, 19 in Hillsborough County and one in Pasco County.

The state confirmed its first dengue-related death of the year on Sept. 18, in Hillsborough County. The patient was an elderly Tampa woman who died Sept. 4, the AP reported.

Beyond Tampa Bay

Pinellas County has 51 local cases and showed a substantial uptick in recent weeks, WUSF reported. The state also lists local cases in Miami-Dade (nine), Orange (eight), Pasco (four) and Citrus (two) counties, plus one each in Brevard, Broward, Manatee, Palm Beach and Polk counties.

Seminole County confirmed a locally acquired case after the state report’s cutoff, WFTV reported on Oct. 21. As of Oct. 17, eight counties were under a mosquito-borne illness alert and 10 more were under an advisory.

Hillsborough County declared a state of local emergency Sept. 24 to speed mosquito-control spending. Hillsborough and Pinellas counties have since extended their declarations through Oct. 29, according to WUSF.

Travel continues to seed the virus. The state has logged 320 travel-associated dengue cases in 2026, including 266 linked to Cuba and 200 reported in Miami-Dade County. Frequent travel makes reintroduction possible, the health department says.

Testing and diagnosis

The CDC advises clinicians to consider dengue in patients with fever who live in or recently traveled to areas with risk. Other common symptoms include severe headache, pain behind the eyes, muscle and joint pain, and rash. The state health department notes the disease is often misdiagnosed because it resembles influenza and other viral illnesses.

Testing depends on when symptoms started:

• In the first seven days, order a nucleic acid amplification test (NAAT), such as reverse transcription PCR, plus an IgM antibody test. A nonstructural protein 1 (NS1) antigen test plus an IgM test is the alternative.
• After day seven, IgM antibody testing is the primary test.
• A negative NAAT or NS1 result does not rule out infection.

Serum is the preferred sample, and testing is available through most state health departments and commercial laboratories, according to the CDC. Because the same mosquitoes carry chikungunya, the state health department urges physicians to consider both viruses in patients with relevant travel. Florida has logged 88 travel-associated chikungunya cases and one locally acquired case this year.

Warning signs to watch

The CDC’s clinical care guidance lists warning signs that point to progression toward severe dengue and should be checked at every encounter:

• Severe abdominal pain or tenderness
• Persistent vomiting
• Fluid accumulation, such as pleural effusion or ascites
• Mucosal bleeding
• Altered mental status
• Liver enlargement of at least 2 centimeters
• A progressive rise in hematocrit

Patients with warning signs should be managed in the hospital. The CDC says outpatient care fits patients without warning signs who are hemodynamically stable and tolerate oral fluids. It recommends acetaminophen for fever, avoiding aspirin and nonsteroidal anti-inflammatory drugs, plenty of oral fluids, regular follow-up, ideally daily, and complete blood counts as indicated.

Patients and caregivers should know that the critical phase typically falls three to eight days after fever begins. The CDC suggests considering inpatient care for patients older than 65 and some with chronic conditions. To keep the virus from spreading at home, the agency advises the patient sleep under a bed net and the household use repellent registered with the Environmental Protection Agency for three weeks.

Reporting obligations

Florida law requires practitioners to report diseases of public health significance to the Department of Health, and dengue fever is on the state’s practitioner reportable disease list. County health departments receive those reports. The CDC adds that all suspected cases should be reported because dengue is nationally notifiable.

What comes next

Cooler, drier fall weather could slow mosquito activity, but its effect will likely take time to appear in case counts, WUSF reported. Health officials also say the state tally undercounts infections, because many people never develop symptoms.

Michael von Fricken, an associate professor of environmental and global health at the University of Florida, told the AP that dengue’s threat in Florida is unlikely to tail off, given how abundant the mosquitoes that carry it remain in the state.