Health officials have confirmed a second locally acquired human case of West Nile virus in Duval County, and the Florida Department of Health is again coordinating ground spraying with Jacksonville Mosquito Control. The department announced the case on Tuesday, September 15, as reported by News4Jax, about two weeks after confirming the county's first on August 31.
Locally acquired is the phrase that should register with Jacksonville households. It means the patient was infected by a mosquito inside the county rather than while traveling. Two such cases in roughly two weeks indicate infected mosquitoes are circulating locally, a different situation from an imported case that carries no onward risk.
For families, that shifts the question from national statistics to the yard and the porch at dusk. West Nile does not pass from person to person. It spreads through bites, which makes the most effective household protection also the least glamorous: removing standing water, repairing screens and using repellent correctly.
A Second Case Changes the Local Picture
The health department did not say where in the county either patient was infected. It continues statewide surveillance for mosquito-borne illnesses including West Nile, Eastern equine encephalitis, St. Louis encephalitis, chikungunya, dengue and malaria, and publishes results in a weekly arbovirus surveillance report that lists which counties are under a mosquito-borne illness advisory or alert.
Expect state and county figures to differ briefly. County departments announce cases as investigations close, while the statewide report follows a fixed weekly cycle, so the two documents can disagree for several days without either being wrong.
Elsewhere in the state, Hillsborough County has been the center of Florida's locally acquired dengue activity this year, with 95 cases reported there and a possible dengue-related death under investigation.
Northeast Florida's Mosquito Season Runs Late
Nationally, this has been a comparatively quiet West Nile year. CDC surveillance recorded 504 human cases across 41 states as of September 8, including 363 of the more serious neuroinvasive form, well below the count at the same point in 2025. A lower national tally does not lower the risk on a street where infected mosquitoes bite.
Florida's peak arbovirus risk runs through the warm, wet late summer and early fall. Jacksonville's Mosquito Control Division provides free inspection and treatment to county residents, who can request service by calling 904-630-CITY. Requests can also be submitted online.
Repellent Mistakes Most Households Make
The biggest gap in household protection is not willingness but technique. A national survey released by the Annenberg Public Policy Center found 82 percent of adults correctly identify preventing bites and controlling mosquitoes around the home as the best defense against West Nile and dengue, and nearly two-thirds say they routinely take precautions. Yet only 18 percent know to look for a repellent registered with the Environmental Protection Agency, about a third know the CDC advises applying sunscreen first and letting it dry, and just 15 percent know repellent should not go on skin under clothing.
"The CDC needs to do a better job of informing the public about how to choose and apply insect repellent," said Patrick E. Jamieson, director of Annenberg's Health and Risk Communication Institute. Ken Winneg, the center's managing director of survey research, said that despite the drop in cases compared with last year, preventing bites remains important for community health.
The survey of 1,904 adults was conducted August 4 to 17 with a margin of sampling error of plus or minus 3.2 percentage points. The CDC recommends EPA-registered products containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol or 2-undecanone, advises a DEET concentration of 20 to 50 percent because more does not usually add protection, and says insect repellent should not be used on babies younger than two months.
Symptoms, Timing and Urgent Care
Most people infected never feel ill, and the CDC puts that share at about 80 percent. Roughly one in five develop fever with headache, body aches, weakness, rash, nausea, vomiting, or diarrhea, typically two to 14 days after an infected bite. Less common signs include neck stiffness, altered mental status, and disorientation. About one in 150 infected people develops severe illness affecting the central nervous system, which can cause tremors, vision loss, paralysis, coma or death.
Adults over 60 and people with weakened immune systems face the highest risk of severe disease. Mild symptoms can usually be discussed with a clinician by phone, while sudden confusion, severe headache with neck stiffness, seizures, or difficulty staying awake after recent mosquito exposure warrant urgent evaluation. There is no human vaccine and no specific antiviral treatment, so care is supportive, which is why bite prevention carries so much weight.
Households can drain garbage cans, gutters, buckets, pool covers, coolers, toys and flowerpots, empty birdbaths and pet bowls weekly, and keep screens intact. Residents are also encouraged to report dead birds to the Florida Fish and Wildlife Conservation Commission, since bird deaths can signal virus activity.
Key Questions Answered
What happened in Duval County? The health department confirmed a second locally acquired human case of West Nile virus and is coordinating ground spraying and surveillance with Jacksonville Mosquito Control. The first case was announced on August 31.
What does locally acquired mean? The person was infected by a mosquito within the county rather than while traveling, which indicates infected mosquitoes are present locally and additional residents could be exposed.
Can West Nile spread between people? No. It spreads through the bite of an infected mosquito and is not contagious between people.
Which symptoms should residents watch for? Fever, headache, body aches, weakness, rash, nausea, vomiting or diarrhea two to 14 days after a bite. Neck stiffness, confusion or altered mental status is less common and more serious.
How should repellent be applied? Choose an EPA-registered product, apply sunscreen first and let it dry, keep repellent off skin under clothing, and do not use it on babies younger than two months.
