Florida is seeing a dengue fever outbreak. Tulane mosquito researcher breaks down the rise in cases

Florida is experiencing one of its most significant dengue fever outbreaks in years, with case numbers rising statewide and the state’s first dengue-related death confirmed by the Florida Department of Health in September.

Tulane University medical entomologist Dawn Wesson, who directs Tulane’s Vector-Borne Infectious Diseases Initiative, called it “one of the worst years for dengue that Florida has had in some time.”

“They’ll have a few locally transmitted cases most years, but not this many,” said Wesson, associate professor of tropical medicine at Tulane’s Celia Scott Weatherhead School of Public Health and Tropical Medicine. “It’s also a little unique in that it’s further north than where most previous outbreaks have hit, which tend to be closer to the Miami-Dade area.”

Wesson has studied dengue and other vector-borne viruses for more than three decades and said the outbreak is being driven by a combination of rising temperatures and human travel that allows Aedes mosquitoes to thrive and spread the virus.

“Part of it is climate, but it’s also that people travel all over the world,” Wesson said. “People coming into airports like Miami disperse into the surrounding area, and some of them are infected with dengue. They bring the virus in and set off local transmission.”

Two Aedes species of mosquitoes spread dengue: Aedes aegypti, the primary vector, which originated in Africa, and Aedes albopictus, the tiger mosquito, native to Southeast Asia, which is believed to have arrived in the U.S. in the mid-1980s in shipments of used scrap tires. Unlike many mosquitoes found in the U.S., Aedes bite during the day and are recognizable by their black-and-white banded markings. They lay their eggs in natural containers like tree holes as well as man-made ones such as tires.  

“Tires tend to be a real problem for all these container-inhabiting mosquitoes,” Wesson added.

Wesson said the mosquitoes are especially difficult to control, and current tools remain limited. Medical entomologists like Wesson are pursuing ways to curb mosquito populations or alter them genetically or bacterially so they can’t transmit the virus as well.  

“That’s the kind of stuff that keeps me up at night and keeps me busy,” Wesson said.

Wesson has traveled the world researching new tools to fight dengue, including projects in South America, and has served in advisory roles with local parish and regional mosquito control boards.

For everyday protection from mosquitoes, Wesson recommends DEET-based repellent as well as long sleeves and a hat.  

Dengue outbreaks are also surging elsewhere in the world, including a major outbreak currently ongoing in Bangladesh. In the U.S., locally acquired dengue cases have also been reported in Hawaii, Texas, California and Arizona in past years.