Free Zika testing is now available in Florida to help pregnant women, as it emerged 33 members of the US military have contracted the virus while overseas.
Florida Governor Rick Scott has directed health officials to make the tests available at county health departments, with additional lab services on hand to ensure test results are processed quickly.
Health officials last Friday announced that mosquitoes have started spreading Zika on the US mainland, with a total now of 15 cases they strongly believe were caused by bites.
In an unprecedented warning, federal health officials have directed pregnant women to avoid a Zika-stricken part of Miami.
The Zika virus can cause severe brain-related defects, including disastrously small heads, called microcephaly. Even if the brain appears to be developing normally, studies also have linked Zika to stillbirths, poor fetal growth and other problems.
Scott promised in a statement on Wednesday to "aggressively fight against the Zika virus".
The free tests announced by the governor are only available at county health departments and do not apply to physicians in private practice.
The governor said more than 2,400 have been tested statewide and more than 140 people have been tested in the past three days in the impacted area of Wynwood, an area known for art galleries and hip shops and restaurants.
He also announced increased spraying in the area and other mosquito abatement.
However, federal health officials have said the mosquitoes have been harder to eradicate than they anticipated, leading them to suspect that the pests are resistant to the insecticides or are still finding standing water in which to breed.
US health authorities have said they don't expect major outbreaks in this country, in part because of better sanitation and the use of air conditioners and window screens. But experts cautioned that many questions about the virus remain.
Meanwhile, CNN has reported that 33 members of the US military have contracted the Zika virus overseas in countries where it has been identified.
One US service member who contracted the virus is a pregnant woman, the broadcaster said.
