Concerns are growing that the Zika virus is taking hold in Florida after four non-travel-related cases were reported there.
To date cases outside of Latin America and the Caribbean have been as a result of travel to the infected areas or sexual transmission.
However, the new cases of the virus, which can cause severe brain defects in new-born babies, are believed to have been transmitted via mosquito bites.
Florida officials investigating the new cases said they are yet to draw any conclusions.