Florida is experiencing its largest dengue outbreak in decades, with 252 locally acquired cases reported as of late September, among the highest totals seen in the continental U.S. in several decades.
The vast majority of cases have been reported in Hillsborough County, home to Tampa, where officials are ramping up mosquito-control efforts, according to the latest numbers released by state health officials. Florida has also recorded 245 travel-associated cases this year, while at least 13 Hillsborough County cases involved people who had recently traveled.
The surge has prompted Hillsborough, Pasco and Pinellas counties to declare local states of emergency and step up efforts to kill mosquitoes and eliminate standing water where they breed.
Florida's locally acquired case total has already surpassed the state's previous annual high of just under 200 cases, reported in 2023. The current outbreak also appears to be the largest reported by a state in the continental U.S. in a single year since at least the 1940s, based on available state health department data.
The total is nearing the 264 locally acquired cases reported in Hawaii over six months in 2015 and 2016, the largest outbreak reported by a U.S. state in decades. Federal health officials have cautioned that national dengue surveillance data is limited.
Dengue is a viral infection spread primarily through bites from infected Aedes aegypti and Aedes albopictus mosquitoes, both of which are found in Florida. Some people have no symptoms, while others can develop a sudden fever, severe headache, pain behind the eyes, muscle and joint pain, nausea or vomiting.
Most people recover, but dengue can sometimes become severe, causing bleeding, shock and death. Florida has reported one dengue-related death this year, involving an elderly Tampa woman who died on September 4.
Most dengue cases reported in the continental U.S. are linked to international travel. Local transmission has occurred in several states, including Florida, Texas, Hawaii, Arizona and California, according to the Centers for Disease Control and Prevention.
Florida regularly sees travel-associated dengue because of its large number of international travelers. Public health experts say it remains unclear why the record dengue outbreak has been concentrated around Tampa rather than its historical epicenter in South Florida, NBC Miami reports. Travel patterns could play a role, while warmer temperatures and other climate conditions can create more favorable environments for mosquitoes.
The CDC has provided Florida with $800,000 in emergency funding and is monitoring the outbreak. The agency has not sent disease investigators because state officials have not requested them.
People in areas experiencing local transmission should use EPA-registered insect repellent, wear loose-fitting clothing that covers their arms and legs, and remove standing water around their homes, according to the CDC.
The Florida outbreak comes as dengue continues to circulate at high levels globally. More than 2.2 million infections and nearly 1,200 deaths have been reported worldwide this year, according to the World Health Organization. The true number of infections may be higher because dengue can cause mild or no symptoms, meaning some people may never seek medical care or get tested.
