Florida health authorities have issued a mosquito warning after two locally transmitted cases of dengue fever were confirmed in the Florida Keys.

The warning came a week after the U.S. Centers for Disease Control and Prevention (CDC) issued a national health alert warning health care providers and the public about the increasing number of dengue fever infections in the Americas.

Dengue fever is a viral infection transmitted by mosquitoes. According to the World Health Organization, the virus infects up to 400 million people each year, resulting in up to 40,000 deaths per year. The disease is characterized by high fever, often associated with pain, nausea and vomiting, which can range from mild to severe (though they usually last only two to seven days).

Only about one in four people infected with dengue actually become ill, and symptoms usually appear within two weeks of the bite.

The disease occurs mainly in tropical and subtropical climates, although local transmissions have been reported in Florida, Texas, Arizona and California in the past.

In late June, two locally transmitted dengue cases were confirmed in Monroe County, bringing the total number of local cases in Florida to 10 since the beginning of 2024. So, in which other counties have local dengue cases been confirmed?

This year, Miami-Dade has seen the highest number of locally transmitted infections: two in January, one in February, two in March and one in April. Hillsborough and Pasco also had one confirmed case each, in June and January, respectively.

Although case numbers are still very low, the Monroe County Health Department and the Florida Keys Mosquito Control District are coordinating surveillance and prevention efforts to reduce transmission in the region. This includes door-to-door surveillance and targeted spraying of insecticides from trucks and, when necessary, aerial spraying to control mosquitoes.

The Florida Department of Health also recommends the following measures to protect against mosquitoes:

• Apply insect repellent to skin and clothing (some may not be suitable for children, so always read the label).
• Remove or cover any standing water where mosquitoes can breed, such as buckets, gutters, rain barrels, old tires, and birdbaths. Even a bottle cap filled with standing water is enough for mosquitoes to breed.
• Use air conditioning and fly screens to keep insects out.

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