An Old Disease Returns: Dengue Is in Florida and May Be Heading North

This month, Slate has been running an intermittent series on pandemics under the guidance of new science editor Laura Helmuth. The latest entry in the series is one that I wrote (my first time writing for Slate, which is exciting). It’s about the under-appreciated threat to the United States of a disease that we barely think about: the mosquito-borne illness called dengue, formerly known as “breakbone fever.”

Dengue was once endemic in the United States. When I started researching it for this piece, I discovered a whole series of historical outbreaks I knew nothing about: Charleston, SC, 1828; Savannah, Ga., 1850; Austin, 1885; Galveston, 1897; most of Louisiana, 1922; Miami, 1934. Dengue was not eliminated here until the government undertook mass mosquito-eradication programs in the 1940s, because mosquito-borne illnesses were making so many military members so sick that the toll was hampering the war effort. (Public-health history buffs: Those were the campaigns that gave rise to the CDC, which grew out of a government agency called the Office of Malaria Control in War Areas.)

Dengue has always been a serious disease in the tropics — the World Health Organization estimates there may be 100 million cases and 50,000 deaths per year — but in the US, it hasn’t been taken seriously. That may be about to change. From my story:

At the annual meeting of the American Society of Tropical Medicine and Hygiene last month, researchers from the University of Florida revealed that dengue has reappeared in Key West, Fla. The virus they found was not a one-time visitor imported by a tourist or a stray mosquito; it has been on the island long enough to become a genetically distinct, local strain.

The Florida researchers didn’t want to talk about their presentation because they hope to get it published soon in a medical journal. But it turns out other tropical-disease experts have been watching dengue’s return to the United States for a while and wondering what it will mean.

“It really is just a matter of time until dengue re-establishes itself in certain areas here,” says Amesh Adalja of the Center for Biosecurity of the University of Pittsburgh Medical Center. “The U.S. has been lucky that it has escaped so far.”

There is no vaccine against dengue, and our ability to stop its movement is limited. But we could make it more of a public health priority, and more of a priority for the development of better diagnostics, than we do now. And we could, as I’ve argued before, pay more attention to the risks of diseases transmitted by insects and arthropods. Dengue is back; chikungunya is advancing; tickborne diseases are expanding their range. We tend to let those, forgive me, fly under the radar. We should rethink that, while we have time.



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