Florida is in the midst of its largest dengue fever outbreak on record with more than 190 cases this year, including at least 38 new cases in September.

Dengue is a tropical viral infection caused by a virus transmitted to humans by infected mosquitoes. It is most common in tropical and subtropical climates, especially in urban and suburban communities.

An 80-year-old Hillsborough County woman died at Tampa General Hospital at the beginning of the outbreak as a result of a mosquito bite she received near Tampa Bay.

Kristi Miley, who teaches at USF's College of Public Health, told the Tampa Bay Times that this is the first reported death from a dengue infection this year and the first in Tampa Bay in almost a century.

Hillsborough County leads the number of cases in the state with 170, followed by seven each in Miami-Dade and Pinellas counties. Orange County recorded three cases, Pasco reported two and Palm Beach County reported a single case, through Sept. 19.

Orange County, where Orlando is located, issued its first mosquito-borne illness alert earlier this month for the first time since 2011's West Nile virus outbreak. Neighboring Polk County followed shortly after.

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Pasco, Hillsborough and Pinellas counties, located in Tampa Bay, have each declared local states of emergency to speed up their response.

Workers near Tampa have been spraying to kill mosquitoes day and night. They also have been checking properties for pooled water, including in tires, where mosquitoes might breed, said Paolo Pecora, senior environmental scientist for Hillsborough County Mosquito Management Services.

Dengue is not native to Florida, but the state's warm, humid climate makes it an ideal setting for mosquitoes to breed. Florida is not unfamiliar with other mosquito-borne diseases, including West Nile.

Mosquito activity typically peaks in the rainy season between June and September, but can remain high into the fall as standing water for mosquito breeding grounds slowly dries up. Mosquitoes can remain active year-round, especially in southern Florida.

The planet's warming temperatures are likely to expand both the geographical range and the active season of mosquitoes.

Mosquito activity dramatically increased in South Florida after 2017's Hurricane Irma, and scientists are investigating whether or not a similar increase followed after 2024's hurricanes Helene and Milton.

Florida's previous record was 186 locally acquired cases in 2023; this year's count has already passed it.

(MORE: Mosquitoes are heading to a city near you)

Dengue symptoms and prevention

Most people who are infected do not show symptoms, and cases are likely underreported. Symptoms include a high fever, body aches, nausea and a rash for less than two weeks. People infected multiple times are at a higher risk for severe symptoms.

Once you become symptomatic, dengue is treated through pain management, but there is no direct treatment for the disease.

The best way to avoid dengue is to repel mosquito bites.

Dengue exposure is rapidly increasing around the world with more than 14 million cases being reported in 2024 across more than 100 countries, according to the World Health Organization.

Across the world, more than 2.2 million infections have been reported so far this year, according to the Associated Press, and nearly 1,200 people have died.

(MORE: 'Mosquito disease days' for West Nile transmission becoming more frequent in US)

Florida's Department of Health said more than 200 cases have been reported across 23 counties in individuals that traveled internationally within two weeks of symptom onset. Most traveled to Cuba, but Colombia, Nicaragua, Puerto Rico and India are among the locations where cases likely originated.

Outbreaks can start when a person travels, gets infected and then is bitten back in the U.S. by a mosquito capable of spreading the virus. It can mushroom from there, said Michael von Fricken, a University of Florida associate professor of environmental and global health.

In the United States, there have been nearly 1,500 locally acquired cases, most of them in Puerto Rico, according to the Centers for Disease Control and Prevention.

The Associated Press contributed to this report.

Jonathan Belles has been a digital meteorologist for weather.com for 10 years. His favorite weather is tropical weather, but also enjoys covering high-impact weather and news stories and winter storms. He's a two-time graduate of Florida State University and a proud graduate of St. Petersburg College.