New Zika Virus Cases Came From Mosquitoes In The U.S., Officials Confirm
CDC/ James Stewart

Florida health officials said today that four people living in the state who recently tested positive for the Zika virus, acquired it locally from mosquitoes in the area. This is the first time this type of transmission has been documented in the United States. Previously, all other cases have been traced back to the infected individual either acquiring the virus from traveling to a Zika-stricken country, or through sex. Officials had already confirmed that these four individuals had not contracted it through these methods.

In a statement released today by Flordia Governor Rick Scott to CNN, officials have been testing the mosquitoes in the area. However, as of yet, no mosquitoes have tested positive.

Yet officials still felt confident to confirm that these cases are from local transmission. The four individuals–one woman and three men–all come from either Miami-Dade or Broward County, Florida.

Local officials believe that a small outbreak of the Zika virus could be occurring within a small area within this region, which they estimate to be one square mile. That exact location will be released later. Other individuals living in this area have been tested for the virus, and no tests have come back positive.

While health officials hope to know more in the coming days and weeks, it is still unlikely that this will turn into a larger outbreak. The biggest concern over the Zika virus right now is the birth defects—particularly microcephaly—associated with the infection.