ORLANDO, Fla. (AP) -

Orlando's major theme parks are now offering free bug repellent to visitors, as concerns about mosquito-transmitted Zika virus mount in Florida.

Walt Disney World, Universal Orlando Resort, and SeaWorld Orlando, on Sunday, began offering the mosquito spray and lotion free of charge at their parks.

No mosquito-transmitted case of the Zika virus has been found in central Florida. Theme park officials say they're offering the repellent as a precaution and to ease the fears of visitors.

The Department of Health is investigating mosquito-transmitted Zika cases in Miami-Dade and Palm Beach counties in South Florida, as well as in Pinellas County in the Tampa area.

Zika causes a mild illness in most people but can lead to severe brain-related birth defects if women are infected during pregnancy.