Florida's current dengue outbreak appears to be the largest in several decades in the continental United States, state health officials reported this week.

More than 250 locally acquired cases of the mosquito-borne disease have been tallied so far this year. The vast majority were in Hillsborough County, home to Tampa.

Federal health officials say their data on dengue outbreaks is limited. But available information suggests the Florida outbreak marks the most cases in a calendar year for any state since at least the 1940s. The state's previous worst year was 2023, when just under 200 locally spread cases were reported.

Officials in Hillsborough and surrounding counties have declared local emergencies. Workers in the Tampa area are spraying day and night to reduce the population of disease-transmitting mosquitoes.

Dengue, nicknamed "breakbone fever" for the excruciating pain some people experience, is caused by a virus spread by a type of mosquito. Many infected people do not get sick, but some experience fever, flu-like symptoms and aches. Severe cases can cause bleeding, shock and death.

There has been one dengue death in Florida this year – an elderly Tampa woman on September 4.

Health officials say the real number of cases is likely higher because many people with mild symptoms never get tested.