Something strange is happening along the Gulf Coast.
Florida's health department has issued mosquito-borne illness alerts in multiple counties this year, and Texas has confirmed locally acquired dengue cases in areas that historically never saw them.
These are people who got sick in their own backyards.
For decades, Americans were told dengue was a tropical problem — something that happened in Southeast Asia or Latin America.
The CDC's own data shows locally acquired cases in the continental U.S. were vanishingly rare before 2000.
Now Florida reports hundreds of cases annually, and the mosquito that carries dengue, Aedes aegypti, has been found as far north as Washington, D.C.
A warming climate expanded the mosquito's range, yes.
Critics point out that federal funding for vector control programs has been cut repeatedly over the past two decades.
Many county mosquito control districts operate on shoestring budgets with outdated equipment.
Meanwhile, the same agencies responsible for tracking outbreaks are also responsible for downplaying them to avoid panic.
Here's what makes dengue different from other mosquito-borne illnesses.
It has four distinct serotypes, and getting infected with one doesn't protect you from the others.
In fact, a second infection with a different serotype can trigger something called antibody-dependent enhancement — where your own immune system makes the second infection worse.
This is why dengue is sometimes called "breakbone fever," and why public health experts quietly worry about a scenario where multiple serotypes circulate simultaneously in the U.S.
A dengue vaccine exists, but it's complicated — it's only recommended for people with prior confirmed infections, and it carries its own risks.
Sanofi's Dengvaxia was pulled from the Philippine market after controversy over deaths linked to vaccinated children who had never been infected before.
Takeda's Qdenga is approved in several countries but not yet in the U.S.
The FDA is reviewing it, but approval has been slow.
Some speculate that the economics don't work — dengue is still perceived as a "developing world" disease, and vaccine manufacturers need guaranteed markets.
Others note that the U.S. has historically underinvested in diseases that primarily affect poor countries, until they show up on our doorstep.
In the meantime, local health departments are scrambling.
Miami-Dade County has conducted aerial spraying campaigns.
Harris County, Texas, has expanded its mosquito surveillance.
The mosquitoes are already here, breeding in discarded tires, flower pots, and anything that holds a quarter-inch of water.
Eliminate standing water around your home.
Support local vector control funding, because it's the first thing to get cut when budgets tighten.
And pay attention to local health alerts — not the national news, which tends to ignore this until it becomes a crisis.
The uncomfortable truth is that dengue is a symptom of a larger problem.
We've spent decades dismantling public health infrastructure while patting ourselves on the back for emergency responses.
They just need warm weather and standing water.
Final Thoughts
Stay skeptical of anyone who tells you this is under control.