Florida Zika cases rise to 25

Florida's caseload of Zika spread by Miami mosquitoes has risen to 25, and US health officials continue to warn pregnant women to avoid the infection zone despite the governor's assurances the area of concern is shrinking.

Florida's Department of Health says active transmission has been only happening in a 1-square-mile (2.5 square kilometres) area encompassing Miami's Wynwood arts district.

Scott's office also announced that the health department has declared four blocks in the southwest corner of Wynwood to be clear of infections as preventative measures continue, in addition to another 10-block section cleared last week.

The US Centres for Disease Control and Prevention, however, still advises pregnant women to avoid the entire neighbourhood.

"All I can say is the travel advisory is still in effect," CDC spokesman Tom Skinner said.

Zika is a mosquito-borne virus that only causes mild, flu-like symptoms in most people. But it can cause severe brain-related defects, including disastrously small heads, if women are infected during pregnancy.

Back-to-school day is August 22 in Miami, and while students returning to class in Wynwood will be allowed to wear pants and long-sleeved shirts that don't match their school uniforms, they still can't bring mosquito repellent to campus.

Miami-Dade County Public Schools Superintendent Alberto Carvalho said at a school board meeting on Wednesday that "aggressive application" of repellent should be done at home, not at school where some students may be allergic to the spray.

The Miami Herald reports that state health workers will be stationed at each school to check for mosquito breeding sites and provide parents with repellent.