Both Duval County and Nassau County are each reporting cases of the West Nile Virus, according to the Florida Department of Health.
In both counties, only one case has been confirmed Thursday.
These cases increase the concern for transmission.
Earlier this month, officials issued a mosquito-borne illness advisory after several sentinel chicken flocks tested positive for West Nile in Duval County.
Officials warn to protect your skin and the areas surrounding your home to keep mosquitos away.