In the autumn of 1885, people in Austin, Texas, began to feel sick. One after another, they developed a chill and then a soaring fever. They vomited and broke out in rashes. Their most distinctive symptom was agonizing pain behind their eyes and in the bones of their arms and legs. And when the fever subsided, lack of appetite and deep exhaustion left them unable to work for weeks or months.
Austin had been founded only 46 years before, and it was still small, with just 22,000 people. By the time the epidemic was over, 16,000 of them had fallen ill. A local doctor who described the outbreak in the Journal of the American Medical Association the following year added: “I am informed that other cities ... had as many cases in proportion to the population as did Austin.”
The illness that took out Texas that fall had already devastated Charleston, S.C., in 1828 and Savannah, Ga., in 1850, and it would go on to sicken half the population of Galveston, Texas, in 1897; one-quarter of Monroe, La., in 1922; and one out of every nine people in Miami in 1934.
It was dengue—a mosquito-borne virus popularly known as “breakbone fever” for the pain it caused. From the 1820s to the 1940s, it caused recurring epidemics roughly every 10 years.
World War II mosquito-eradication programs broke the chain of transmission between humans and insects, and by the time the war ended, dengue had retreated to the tropics and was no longer a problem in the United States.
That may be about to change. 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.