Dengue-carrying mosquitoes expand their reach into new territories – including Florida

The Tampa Bay Times reported the death of an elderly woman on Sept. 8, 2026. Her family says local doctors attributed her death to dengue fever, although the Florida Department of Health has not yet confirmed that.

This death was likely part of a larger dengue outbreak in Hillsborough County, where there have been 95 documented cases of dengue since July 2026. In August, the Hillsborough County Health Department issued a mosquito-borne illness alert due to reports of multiple locally acquired cases.

This cluster of locally spread cases is a stark reminder that a disease which most Americans associate with faraway tropical vacations is increasingly being caught at home.

Dengue is often called “breakbone fever,” and the nickname is earned. People who get sick typically develop a sudden high fever along with a pounding headache, pain behind the eyes and deep aches in the muscles, joints and bones. Many also feel nauseated, throw up or break out in a blotchy rash a few days in.

As an infectious diseases physician and tropical medicine specialist who directs a travel clinic, I see how easily dengue slips past both patients and doctors. In parts of the U.S. where the disease is still uncommon, it is easily mistaken for the flu or COVID-19, and that delay can be dangerous.

How it spreads

Dengue is not passed from person to person like a cold. It spreads through the bite of infected Aedes mosquitoes, mainly Aedes aegypti, a species commonly found in Florida. These mosquitoes thrive in warm cities and can breed in as little as a bottle capful of standing water. These mosquitoes bite during the day, not just at dusk.

The cycle is simple and hard to break: A mosquito bites an infected person, then bites someone else days later, giving them the virus.

Dengue is especially tricky because most infections cause no symptoms at all. Roughly 3 in 4 people who catch the virus never feel sick. For the 25% who are symptomatic, those symptoms don’t appear until four to 10 days after being bitten.

In addition, there are four different strains of the dengue virus, and surviving one gives you lasting protection against only that one. A second infection with a different type actually raises the odds of severe disease.

A life-threatening turn

Most people suffer with dengue for a miserable week and then recover on their own. But about 1 in 20 patients progress to severe dengue, a life-threatening turn that tends to strike just as the fever breaks – often around days three to seven, when patients and their families may wrongly assume the worst is over.

In severe dengue, tiny blood vessels throughout the body start leaking fluid, blood pressure can crash and dangerous bleeding or organ damage can follow. Warning signs that someone is sliding into this phase include severe belly pain, repeated vomiting, bleeding from the gums or nose, extreme drowsiness or restlessness, and blood in vomit or stool.

Some groups face higher risk, including infants, pregnant women, adults over 65 and people with conditions like diabetes, obesity or kidney disease. Left untreated, severe dengue can kill up to 10% of patients. With prompt hospital care, that number drops below 1 in 100 – which is why recognizing it early matters so much.

A dengue vaccine exists, but it is not recommended for the average American traveler. The available shots are used only in select cases, such as children who live in high-transmission areas and have already had dengue once. So prevention still rests mostly on avoiding mosquito bites.

How dengue is treated

There is no antiviral drug that cures dengue. Care is all about supporting the body while it fights the virus. For people well enough to stay home, that means rest, plenty of fluids and acetaminophen, commonly known in the U.S. by the brand name Tylenol, for fever and pain.

Patients who may have dengue must avoid aspirin, ibuprofen and other non-steroidal anti-inflammatory drugs. These drugs raise the risk of bleeding, which is already a danger with dengue.

Patients who develop more severe symptoms need to be admitted to the hospital, where doctors give carefully measured intravenous fluids and watch closely. Too little fluid and the patient can go into shock; too much and the lungs can flood.

A worsening global problem

Dengue is surging worldwide. The World Health Organization recorded more than 14 million cases in 2024, its worst year on record, across some 100 countries. That’s a 2,600% increase from the more than 505,000 cases reported in 2000.

Warmer temperatures, rapid urban growth and global travel are all helping the mosquitoes – and the virus – expand into places where it has never been a problem before. South Asia, Southeast Asia and Latin America carry the heaviest burden, but the map is spreading north.

Why the U.S. should pay attention

Most U.S. dengue cases are still picked up abroad. Travelers return home sick. In 2023 alone, the Centers for Disease Control and Prevention reported nearly 1,900 such travel-related cases.

But every infected traveler is a spark, and in warm states the tinder is already there.

In the U.S. territories, Puerto Rico and the U.S. Virgin Islands see the most cases by far. Florida has the highest risk among the 50 states, with Miami-Dade County recording more than 300 locally acquired dengue infections between 2010 and 2024. Local cases have also turned up in Texas, California, Arizona and Hawaii.

What to do if you think you have dengue

If you develop a sudden fever after traveling to a dengue-prone area, or after mosquito exposure in South Florida, see a doctor and mention where you’ve been. Rest, drink fluids and use acetaminophen – not ibuprofen or aspirin.

Most importantly, watch for the warning signs. Severe belly pain, repeated vomiting, bleeding or sudden drowsiness means get to an emergency room right away.

And to protect yourself and your neighbors: Use insect repellent, wear long sleeves and dump out any standing water in your yard where mosquitoes breed.