A second case of Zika virus possibly acquired locally is being investigated in south Florida, just days after the first potential case was announced in Miami.

While there have been hundreds of cases of Zika virus in Florida, all of them involved people who were infected while traveling to areas where the mosquito-borne virus is spreading. If confirmed, the Florida infections would mark the arrival of the homegrown virus on the US continent for the first time.

“The Florida Department of Health announced that it is conducting an epidemiological investigation into a possible non-travel related case of Zika virus in Broward County,” said a statement, referring to the county just north of Miami, which includes Fort Lauderdale and Hollywood.

Health officials are working with “mosquito control to ensure trapping, reduction and prevention activities are conducted in the area of investigation,” the department added.”…these results will help the department determine the number of people affected.”

Regarding the possible non-travel case of Zika in Miami-Dade county, a health department spokeswoman told AFP the investigation is ongoing, and that sexual transmission “related to travel has not been ruled out.”

Few other details have been released about that possible case, which was first announced Tuesday. The Zika infection has been confirmed, but the mode of transmission has not.

As of Thursday, mosquitoes in the Miami area have tested negative for Zika, the spokeswoman added.