Florida is battling its largest dengue fever outbreak in decades, with health officials confirming 485 locally acquired cases this year. The mounting case count has intensified mosquito control work across the Tampa Bay area, where most of the infections have been recorded.

State surveillance identified 60 new infections between Oct. 18 and Oct. 24, according to the Florida Department of Health. The Tampa Bay area accounted for roughly 95% of all locally acquired cases reported statewide.

The surge prompted emergency declarations in Hillsborough, Pasco and Pinellas counties in late September. Those declarations allowed officials to accelerate purchasing and spraying while seeking state and federal reimbursement for the response.

Hillsborough County later extended its state of local emergency as transmission continued. Mosquito management teams have deployed aerial spraying to target the mosquitoes capable of carrying and spreading the virus.

The locally acquired infections are separate from more than 300 travel associated dengue cases reported in Florida this year. Those infections can continue introducing the virus to mosquito populations within the state.

The Florida Mosquito Control Association said abatement teams are increasing targeted ground spraying, aerial applications and inspections of individual properties. Crews across the Tampa Bay area have also expanded surveillance and treatment efforts as the number of locally acquired cases rises.

Dengue is a viral illness transmitted primarily through bites from infected Aedes aegypti and Aedes albopictus mosquitoes. According to the Centers for Disease Control and Prevention, the illness can cause fever, severe muscle and joint pain, nausea and rash.

Dangerous complications or death can occur in severe cases. The mosquitoes that transmit dengue behave differently from many species that are most active around dawn and dusk because they feed aggressively during daytime hours.

An entomologist spokesperson at the SC Johnson Center for Insect Science and Family Health previously said Aedes mosquitoes are active during the day. The spokesperson also said they thrive in warm, humid environments such as those found across Florida.

Public health officials describe Aedes mosquitoes as container breeders because they can lay eggs in very small amounts of standing water. As little as a tablespoon of water can provide a place for the mosquitoes to reproduce.

Residents are being urged to inspect their yards every week and remove potential breeding sites. Birdbaths, gutters, planters, discarded tires and other outdoor containers should be drained, covered or regularly cleaned.

Health authorities also recommend using EPA registered insect repellents containing active ingredients such as DEET, picaridin or oil of lemon eucalyptus. Residents should follow all directions printed on product labels when applying the repellents.

People using both sunscreen and insect repellent should apply sunscreen first and bug spray second. Officials also advise wearing loose fitting, light colored long sleeves, pants and closed toe shoes to reduce exposed skin while outdoors.

Outdoor vessels that collect water should be emptied and scrubbed regularly. Consistent protection against mosquito bites and awareness of local mosquito activity can help residents reduce their risk of infection.

Most people infected with dengue have mild symptoms or no symptoms and typically recover within two weeks, according to Mayo Clinic. When symptoms develop, they usually appear four to 10 days after the bite of an infectious mosquito.

Severe dengue can worsen quickly within 24 to 48 hours after the initial fever subsides. Warning signs include persistent vomiting, severe abdominal pain, difficulty breathing, mucosal bleeding and extreme lethargy.

Anyone experiencing those warning signs should seek emergency medical care immediately. With local infections concentrated around Tampa Bay, health officials and mosquito control crews are continuing efforts to limit transmission and remove breeding sites.