Dengue: Gaining a Foothold in Florida

“Human beings can easily destroy every elephant on earth, but we are helpless against the mosquito.”

Isaac Asimov, American author, professor of biochemistry at Boston University

“Incredibly, just one mosquito species, Aedes aegypti, is responsible for the spread of four known deadly viral diseases to human beings, yet this mosquito has been allowed to infest densely-populated urban centers.”

T.K. Naliaka, author

Two news articles involving mosquitoes caught my attention last week. The first was President Trump signing an executive order on September 29, 2026, directing federal agencies to reduce Washington, D.C.’s  invasive mosquito population by at least 90% and its tick population by at least 50% by 2028. (Borst, E, “Trump orders DC mosquito purge,” POLITICO, September 30, 2026). The second was Florida state health officials reporting that more than 250 locally acquired cases of the mosquito-borne disease dengue had been tallied in Florida this year, with the vast majority in Hillsborough County, home to Tampa. (Stobbe, M, “Florida dengue outbreak is now the largest in the continental US in decades,” The Associated Press, October 2, 2026). This is the largest outbreak of dengue in the continental U.S. since at least the 1940s. As mosquitoes were in the news, I decided it was a good time to revisit dengue.

What is dengue (a recap)? Dengue virus is one of the peskiest of arboviruses, meaning it is arthropod-borne. The virus is transmitted to humans by the bite of one of two Aedes mosquitoes that harbor the dengue virus (DENV): A. aegypti, or less commonly A. albopictus, a more cold tolerant mosquito that has been found as far north as Minnesota. 

Only the female Aedes mosquito, however, poses a risk of transmitting DENV. (Male Aedes mosquitoes feed on nectar; their proboscises can’t pierce the skin.) The females bite because their eggs require a protein in blood for development, and they can bite at any time of the day.

Dengue fever is characterized by a sudden onset of high fever, severe headache, muscle and joint pains, rash, nausea and vomiting. Because victims of dengue often have contortions due to the intense joint and muscle pain, it is also called “break-bone fever.”

There are four types of closely related DENVs (DENV-1, DENV-2, DENV-3, DENV-4) which all cause the same symptoms. It is possible to be immune to one form of DENV yet vulnerable to the others. And, strangely, if you’ve already had infection by one type of DENV and you become infected with another type, the earlier infection increases your risk of developing severe illness. This phenomenon complicates vaccine development for dengue.

Currently, there are no dengue vaccines available in the U.S. although globally, several dengue vaccines have been approved or are in different stages of development. And, to date, there is no specific antiviral therapy for dengue. Management of the disease is focused primarily on supportive care such as fluid replacement, pain and fever relief, and bed rest.

About 80% of infected people are asymptomatic or have only mild symptoms; the risk of death from the disease for these patients is extremely low. But as many as 5% of all patients develop severe, life-threatening dengue hemorrhagic fever, characterized by leakage of plasma from blood vessels or severe bleeding from the gastrointestinal tract resulting in shock. Supportive care in an intensive care unit is crucial for those with severe disease as the mortality rate can reach as high as 20% without treatment, but drops to 1%-2.5% with prompt medical treatment.

The best way to prevent dengue is to protect yourself from mosquito bites. Here are a few simple precautions you should take:

1. Use mosquito repellent—one containing 20%-30% DEET (Lemon eucalyptus or picaridin also work);

2. Wear long-sleeved shirts and long pants especially during the day when Aedes mosquitoes feed;

3. Use screens on all windows and doorways; and

4. Remove all containers that can hold water—even bottle caps—because mosquitoes may breed there.

Bottom line: Do whatever you can to protect yourself from A. aegypti and A. albopictus.

Dengue outbreak in Florida.  About half of the world’s population is at risk of dengue. A large majority of dengue cases occur in tropical or subtropical countries—areas of the world where Aedes mosquitoes thrive. But experts say that the Aedes mosquitoes are expanding their geographic reach because of climate change.

Dengue is not endemic in the continental U.S.—yet.  Here, most dengue cases are acquired by travelers returning to the U.S. from tropical or subtropical countries where dengue is endemic; locally acquired cases of dengue fever are quite rare. But Florida’s environment is a suitable breeding ground for the villainous Aedes mosquito, and climate change is making it even more so.

The 252 locally acquired cases of dengue in Hillsborough County, Florida, prove this point. (There were also 245 travel-associated cases in Florida.) In the Associated Press article cited above, Dawn Wesson, a Tulane University expert on mosquito-borne viruses, said: “Climate conditions and persistent mosquito populations will likely make local dengue outbreaks a more frequent problem. There is a good chance this is the new normal.”

Targeting ticks and mosquitoes.  As it targeted pathogen vectors, I read Executive Order 14433, Eliminating Disease-Carrying Pests and Restoring Enjoyment of the Great Outdoors—the first executive order I’ve ever read all the way through. Section 1 provides, in pertinent part: “Ticks and mosquitoes are among the deadliest animals worldwide, transmitting major diseases that impose growing health burdens on the American public.”  Finally, this administration wrote something I can agree with.