Mosquito-Borne Diseases in South Florida: A Comprehensive Guide

The mosquito-borne diseases that matter most in South Florida are dengue, chikungunya, West Nile virus and Zika, with occasional eastern equine encephalitis, St. Louis encephalitis and, rarely, locally acquired malaria. Dengue is by far the most common right now, but every one of these infections starts the same way: a bite from an infected mosquito that grew up in standing water.

South Florida is a crossroads for these viruses. Travelers bring them in all year, our urban neighborhoods are full of the container-breeding mosquitoes that spread them, and heat and rain keep mosquito populations high most of the year. This guide covers each disease, which mosquito spreads it, the symptoms to watch for, who is most at risk, how health officials track outbreaks and what you can do around your home.

Which Mosquito-Borne Diseases Occur in South Florida?

Not all mosquitoes carry the same diseases, and knowing which one spreads what tells you where to focus. Miami-Dade County alone is home to more than 50 mosquito species, according to Miami-Dade County Mosquito Control, and only a handful are serious disease carriers.

The split between Aedes and Culex is the most useful thing to remember. Aedes aegypti and the Asian tiger mosquito breed in small containers around homes and bite during the day. The southern house mosquito, Culex quinquefasciatus, is found in all 67 Florida counties, feeds at night and lays its eggs in nutrient-rich water such as old tires, birdbaths and storm-water catch basins, according to UF/IFAS. For a broader look at local species, see our pest library page on mosquitoes.

Florida’s 2026 Mosquito-Borne Disease Numbers

The Florida Department of Health publishes a weekly arbovirus surveillance report. Through October 17, 2026, it showed dengue far ahead of every other mosquito-borne illness:

Miami-Dade is the main entry point for travel-related infections: 200 of the state’s travel-associated dengue cases and 54 of its travel-associated chikungunya cases in 2026 were reported there. Each imported case is a chance for a local Aedes mosquito to pick up the virus and pass it on.

Dengue: South Florida’s Biggest Mosquito-Borne Threat

Dengue is a viral infection spread mainly by Aedes aegypti. The CDC says about one in four infected people get sick. Symptoms start with fever plus at least one of the following: eye pain, muscle, joint or bone pain, headache, nausea or vomiting, or a rash. They typically last 2 to 7 days.

About 1 in 20 people who get sick develop severe dengue, which can cause shock, internal bleeding and death. The dangerous part is the timing: warning signs usually begin 24 to 48 hours after the fever goes away, just when people think they are recovering.

In 2026 Florida reported 425 locally acquired cases from eleven counties, led by Hillsborough (346) and Pinellas (51), with 9 in Miami-Dade and 1 each in Broward and Palm Beach. For where local dengue has appeared over the years and who is most at risk, read are Floridians at risk for dengue fever.

Chikungunya: Fever and Long-Lasting Joint Pain

Chikungunya is spread by the same Aedes mosquitoes as dengue. According to the CDC Yellow Book, symptoms usually appear 3 to 7 days after infection, and only about 15% to 35% of infected people never develop symptoms.

The hallmark is joint pain, which can persist for months or even years; studies report ongoing joint pain and fatigue in 5% to 80% of patients. Deaths are rare and occur most often in older adults with other conditions and in newborns. Adults over 65 and people with diabetes, heart disease or high blood pressure face a higher risk of severe disease.

One chikungunya vaccine, VIMKUNYA, is currently licensed and available in the US for people 12 and older, mainly recommended for travelers to outbreak areas. Florida reported 88 travel-associated cases and one locally acquired case, in Miami-Dade, in 2026.

Zika: The Pregnancy Risk

Zika usually causes mild illness or none at all. Many infected people have no symptoms or only mild ones, such as fever, rash, headache, joint pain and red eyes. The concern is pregnancy: Zika infection during pregnancy can cause serious birth defects, and the virus can also spread through sex.

South Florida knows this virus well. In 2016, Miami-Dade saw the first recognized outbreak of mosquito-borne Zika in the continental United States, with 29 infected people, most within an area of about six blocks. The CDC advised pregnant women to avoid nonessential travel to a one-square-mile area. After two aerial adult mosquito treatments, female Aedes aegypti counts fell more than tenfold.

Florida reported no Zika cases in 2026, but the mosquito that spreads it is still common in our cities. Our article on Zika in Florida covers how the community responded.

West Nile Virus and St. Louis Encephalitis

West Nile virus cycles between birds and Culex mosquitoes, and people are infected when those mosquitoes bite them. The CDC estimates that 80% of human infections cause no symptoms. Symptoms, when they appear, typically start 2 to 6 days after the bite and most often take the form of a feverish illness.

Fewer than 1% of infected people develop neuroinvasive disease such as meningitis or encephalitis, and about 10% of those patients die. Risk climbs with age: about 2% of people 65 or older who are infected develop neuroinvasive disease, compared with under 0.5% of younger people. Cancer, diabetes, high blood pressure, kidney disease and a weakened immune system also raise the risk. There is no licensed human vaccine or medicine.

Florida’s 2026 human West Nile cases were in North Florida, but sentinel chickens, which counties use to detect virus activity, tested positive for West Nile 359 times statewide. St. Louis encephalitis virus, spread by the same southern house mosquito, turned up in sentinel chickens in two counties with no human cases. Learn more in West Nile virus in South Florida.

Eastern Equine Encephalitis, Malaria and Dog Heartworm

These three are less common but worth knowing:

• Eastern equine encephalitis (EEE) is rare but very serious. The CDC says about 30% of people who develop severe EEE die, and many survivors have lasting neurologic problems. Florida reported one human case and seven horse cases in 2026. Horses can be vaccinated, and UF/IFAS advises that every horse in Florida be vaccinated at least twice a year.
• Malaria is spread by Anopheles mosquitoes. In 2023, Sarasota County had seven locally acquired cases, the first in Florida since eight cases in Palm Beach County in 2003, according to the CDC. The Florida Department of Health notes that the state has 14 Anopheles species, all potentially capable of carrying it.
• Dog heartworm is spread by mosquitoes, and dogs in Florida can be infected in any season. Year-round prevention from your veterinarian is the answer.

How Health Officials Track and Announce Outbreaks

Florida tracks mosquito-borne viruses through human case reports, mosquito testing and sentinel chicken flocks. When activity rises, county health departments issue two levels of warning, as described in the Florida Department of Health’s arbovirus response guidebook:

• Mosquito-borne illness advisory: surveillance shows rising transmission, or a single locally acquired human case has been confirmed. Risk of human infection in the area has increased.
• Mosquito-borne illness alert: a cluster of two or more local human cases, or intense animal surveillance activity. Mosquito control concentrates on high-risk areas and may add aerial spraying.

As of October 17, 2026, Miami-Dade was under an alert, and Broward and Palm Beach were under an advisory. When your county is on either list, it is time to tighten every habit below.

How to Protect Your Family From Mosquito-Borne Diseases

Every disease in this guide shares one weak point: the mosquito has to breed and bite first. The Florida Department of Health’s Drain and Cover approach covers both sides.

1. Drain: empty buckets, coolers, toys, flowerpots and pool covers after rain; discard old tires and unused containers; empty and clean birdbaths and pet bowls at least twice a week.
2. Cover your skin: wear long sleeves, long pants, shoes and socks when mosquitoes are active, and use a repellent with 10-30% DEET, picaridin, oil of lemon eucalyptus or IR3535.
3. Cover your home: repair window and door screens and keep doors closed.
4. Protect the daytime hours: Aedes mosquitoes, the dengue, chikungunya and Zika carriers, bite during the day, not only at dusk.

Our practical tips to keep mosquitoes away from your South Florida home go through these habits in detail. After hurricanes and heavy rain, risk changes over the following weeks; see preventing mosquito-borne diseases after storms for that timeline.

When Professional Mosquito Control Helps

If you drain and cover faithfully and still get bitten in your own yard, mosquitoes are breeding or resting somewhere you cannot see. Toro’s mosquito control service starts with a free inspection to find those spots, from gutters and bromeliads to pool covers and shady shrubs. Technicians treat breeding sites with larvicide granules and growth regulators and apply a barrier treatment made with plant oils to the plants where adults rest. You can choose a one-time event treatment or the 3-month plan of four visits, and if the bugs come back, so will Toro, at no additional cost to you.

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Frequently Asked Questions

Educational content. This article is for general information about pests in South Florida and is not medical, legal or professional advice. If you have a bite, sting or allergic reaction, contact your doctor; in an emergency, call 911. Pest problems vary from home to home, so a licensed professional should inspect before treatment. When using any pesticide, always read and follow the product label.

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