Florida reported 38 new locally acquired cases of dengue fever — sometimes called breakbone fever — in one week, according to the latest update from the Florida Department of Health.
That brings the statewidetotal to 190 for the year as of Sept. 19, just shy of the highest number of cases in recent memory, which was 199 in 2023 and far higher than the 62 cases reported in all of 2025.
➤ How worried should Florida residents, visitors be about dengue?
Hillsborough County continues to lead the state with 170 confirmed cases, while other locally acquired cases have been reported in five other counties.
West Nile virus and chikungunya — which also are transmitted by mosquitoes— also have been reported in Florida this year but in far fewer numbers than
dengue and no new cases in the period Sept. 13-19.
➤ Meet the mosquito, the world's deadliest animal
Currently, 11 counties are under either a mosquito-borne illness advisory or mosquito-borne illness alert.
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Here's what you should know about mosquito-borne illnesses in Florida, symptoms to watch for, and how best to prevent mosquito bites, including advice from the Florida Department of Health.
Is dengue spreading in Florida? See counties reporting mosquito-borne illnesses
According to the Florida Department of Health, as of Sept. 19, there have been 190 cases of locally acquired cases of denguereported in six counties, which is up from 152 reported Sept. 12 .
There also have been five cases of West Nile virus and one case of chikungunya.
- Dengue: 190 cases
- 170 in Hillsborough County
- 7 in Miami-Dade County
- 7 in Pinellas County
- 2 in Pasco County
- 3 in Orange County
- 1 in Palm Beach County
- West Nile: 5
- 1 in Alachua County
- 2 in Duval County (1 an asymptomatic blood donor)
- 1 in Leon (asymptomatic blood donor)
- 1 in Walton County
- Chikungunya: 1
- 1 in Miami-Dade County
What's causing the Florida outbreak of dengue fever?
"The surge in dengue cases — along with a few West Nile and the first chikungunya — in Florida is chiefly driven by a combination of climatic and human factors that create ideal conditions" for the types of mosquitoes that spread dengue, West Nile and the chikungunya viruses, said Eva Buckner, associate professor and extension specialist with the UF/IFAS Florida Medical Entomology Laboratory via email Sept. 23.
The factors that creating ideal conditions for the mosquitoes responsible for transmitting the viruses include:
- Warmer temperatures: Summer high temperatures speed up mosquito life cycles and virus replication, allowing more mosquito generations in a single season and able to transmit viruses faster.
- Increased rainfall and standing water: Heavy rains and storm‑water runoff create abundant mosquito production sites in both natural and artificial containers.
- Outbreaks worldwide and human travel: Locations worldwide where Aedes aegypti-borne diseases like dengue and chikungunya are endemic (experience transmission every year usually year-round) are experiencing outbreaks, Buckner said.
"While dengue and chikungunya are not endemic in Florida, Aedes aegypti, the mosquito that transmits these viruses, is distributed primarily throughout south and central Florida. Tourists and travelers get infected with dengue or chikungunya outside of Florida then come to or return to Florida and get bit by the Aedes aegypti here, leading to infected mosquitoes present in Florida that can then potentially cause localized outbreaks of these viruses, like the dengue outbreak we are currently seeing in Tampa Bay."
Mosquito-borne illness alerts, advisories issued for these Florida counties
A mosquito-borne illness advisory has been issued for the following counties:
- Alachua
- Brevard
- Leon
- Palm Beach
- Pasco
- Walton
A mosquito-borne illness alert has been issued for the following counties:
- Duval
- Hillsborough
- Miami-Dade
- Orange
- Pinellas
"A mosquito-borne illness advisory means the public should take precautions to reduce mosquito bites due to factors indicating local disease such as positive sentinels, very few presumptive or positive human cases, or other justifications," according to Sarasota County.
"A mosquito-borne illness alert means that there has been heightened disease activity, a significant increase in vector (disease capable) mosquito populations, or an increase in locally-transmitted human cases.
"Residents should continue to take precautions, but exercise additional caution in preventing mosquito bites."
All Florida residents could take precautions to avoid mosquito-borne illnesses
"Residents throughout the state should continue to take precautions from mosquito-borne illnesses by appropriately applying bug spray, avoiding areas with high mosquito populations, and wearing long pants and shirts when possible — especially during sunrise and sunset when mosquitos are most active," said Isabella White, FDOH press secretary via email Sept. 23.
White said FDOH "continues to coordinate with local mosquito control partners to support surveillance and targeted response efforts in affected areas. These efforts help reduce mosquito populations, limit the risk of disease transmission, and protect residents across Florida."
What are symptoms of dengue, breakbone fever?
"Dengue fever can be a painful, debilitating disease but is rarely fatal," the Florida Department of Health said. Symptomsappear three to 14 days after the bite of an infected mosquito and include:
- sudden onset of fever
- severe headache
- eye pain
- muscle and joint pain (giving the disease the nickname “breakbone fever”)
- bleeding
- Gastrointestinal symptoms like vomiting and diarrhea may also be present in some cases.
"Dengue fever symptoms usually last four to seven days. The disease is often diagnosed incorrectly because the symptoms are similar to influenza and other viruses," the CDC said.
"Around one out of every 20 people infected by a dengue virus develops severe dengue, a life-threatening medical emergency that requires immediate medical attention," according to YaleMedicine.
Why is dengue called 'breakbone fever?'
Dengue is sometimes called “breakbone fever” because, in addition to fever, "it can cause severe aches and pains, especially in the legs, joints, and back," according to YaleMedicine.
Dengue does not actually cause bones to break, according to YaleMedicine.
Is dengue contagious?
Dengue is spread by mosquitoes. Mosquitoes become infected with dengue after biting a person with the virus. Those infected mosquitoes then spread the virus to other people through bites.
The Centers for Disease Control said a woman who is infected with the dengue virus during pregnancy could pass the virus to her fetus, causing death to the fetus, low birth weight or premature birth.
Can dengue be treated?
"While there is no cure for dengue and there are no specific medications for the condition, getting adequate hydration and plenty of rest, and taking acetaminophen for pain and fever can help alleviate symptoms while the body’s immune system fights the virus," according to YaleMedicine.
"In most cases, people recover from dengue within a week. For those with severe dengue, treatment by health care professionals can significantly lower the risk of death."
What are symptoms of West Nile virus?
"West Nile virus is a mosquito-borne flavivirus that causes mild to severe illness," the Florida Department of Health said.
"Approximately 80% of people who are infected with WNV will not show any symptoms at all."
Mild symptoms include:
- fever
- headache
- body aches
- nausea
- vomiting
- Sometimes swollen lymph glands or a skin rash on the chest, stomach and back.
Symptoms can last from a few days to several weeks.
About one in 150 people infected with West Nile will develop severe illness. Symptoms include:
- high fever
- headache
- neck stiffness
- stupor
- disorientation
- coma
- tremors
- convulsions
- muscle weakness
- vision loss
- numbness
- paralysis
"These symptoms may last several weeks, and neurological effects may be permanent. Severe illness can also result in death," FDOH said.
"People usually do not get sick enough to go to the hospital. For this reason, many people might not realize they have been infected."
What are the best mosquito repellents to use?
According to the Florida Department of Health, repellentswith the following active ingredients provide the best protection:
- DEET
- Picaridin
- IR3535
- Oil of lemon eucalyptus
- Para-menthane-diol
- 2-undecanone, a plant-derived ingredient
'Drain and cover' helps keep mosquitoes away
The FDOH offered this advice to help keep mosquitoes away from your Florida home:
Drain
- Drain water from garbage cans, old tires, pool covers, or any other containers where water collects.
- Empty and clean birdbaths and pet water bowls at least once or twice a week.
- Protect boats and vehicles from rain with tarps that don’t accumulate water.
- Maintain swimming pools in good condition and ensure they are appropriately chlorinated.
- Empty plastic swimming pools when not in use.
Cover
- If you must be outside when mosquitoes are active, cover up.
- Apply mosquito repellent to exposed skin and clothing.
- Use mosquito netting to protect children younger than 2 months old.
How many types of mosquito-borne illnesses are there in Florida?
FDOH compiles weekly data on the following mosquito-borne viruses in a report called "Florida Arbovirus Surveillance":
- West Nile virus (WNV)
- Eastern equine encephalitis virus (EEEV)
- St. Louis encephalitis virus (SLEV)
- Dengue virus (DENV)
- Chikungunya virus (CHIKV)
- Zika virus (ZIKV)
- California encephalitis group viruses (CEV)
- Malaria
Cheryl McCloud is a journalist for the USA TODAY Network-Florida's service journalism Connect team. You can get all of Florida’s best content directly in your inbox each weekday day by signing up for the free newsletter, Florida TODAY, at https://heraldtribune.com/newsletters.
This article originally appeared on Sarasota Herald-Tribune: Dengue cases keep climbing in Florida. This is how to protect yourself
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