Florida reports surge in locally transmitted dengue cases, officials warn of possible undercount
Florida health authorities confirmed at least 190 locally acquired dengue infections for the week ending Sept. 19, with experts saying the actual number may be higher due to mild cases and reporting delays.
The Florida Department of Health said 190 locally acquired dengue cases were confirmed for the week ending Sept. 19, up 38 from the previous week. Hillsborough County, which includes Tampa, reported the largest share with 170 cases, followed by Miami-Dade, Orange, Palm Beach, Pasco and Pinellas counties.
"There's evidence of local transmission of dengue in several counties in Florida," said Natalie Dean, an associate professor of biostatistics and informatics at Emory University’s Rollins School of Public Health. "Dengue is not endemic to the United States. That means that it doesn't typically cause local transmission."
Dean added that while occasional outbreaks occur in the U.S., the current one is notable for its size. The state recorded its first dengue-related death this year, though details about the patient were not released.
Three counties—Hillsborough, Pasco and Pinellas—declared local states of emergency, allowing officials to bypass standard procedures, secure emergency resources and intensify mosquito-control efforts. In Pinellas, crews have been conducting door-to-door visits and spraying areas with high mosquito activity.
"I don't recall a period of time when it's been this high in such a concentrated area before," said Cameron Wolfe, an infectious diseases specialist and professor of medicine at Duke University.
Wolfe warned that the true case count could be underestimated because mild dengue infections may go untested, and reporting to state health departments or the CDC can lag. "For every case that we know, there's going to be a bunch that we never find out about," he said.
Dean likened the known cases to the tip of an iceberg, noting that many infections remain undetected. The Centers for Disease Control and Prevention said it is closely monitoring the situation and has allocated $800,000 in emergency funding for the response. The agency emphasized that Aedes aegypti mosquitoes, which transmit dengue, are common in many U.S. regions, and recommended personal protection measures such as EPA-registered repellents, loose clothing, and eliminating standing water.
Researchers have linked the rise in dengue to climate change, which can expand mosquito habitats through higher temperatures, increased rainfall and humidity. Wolfe said the warming climate makes Florida more conducive to mosquito breeding and could make such outbreaks more frequent.