Florida authorities announced Thursday that mosquitoes in the Miami Beach area had tested positive for Zika indicating that the virus was still active in the area. This is the first time Zika-carrying mosquitoes have been identified on U.S. soil.

Florida Department of Agriculture and Consumer Services announced that the three mosquito samples that tested positive for the virus came from the Miami Beach area, previously identified as a site of local transmissions. The samples were part of 19 mosquito traps set up in the South Beach area.

“This is disappointing but not surprising,” Adam Putnam, Florida commissioner of agriculture, reportedly said.

“Florida is among the best in the nation when it comes to mosquito surveillance and control, and this detection enables us to continue to effectively target our resources,” he added.

Authorities said that mosquito-control efforts were already underway with inspectors spraying larvicide on a daily basis. Identifying positive mosquitoes does have an upside. It helps authorities figure out where active transmission is occurring.

“We already knew because of human cases [that] Zika transmission was occurring; positive pools are just further indication that transmission is still occurring in the area,” Centers for Disease Control and Prevention spokeswoman Candice Hoffmann reportedly said.

"The message remains the same,” Miami-Dade County Mayor Carlos Gimenez reportedly said. “If you have standing water, drain it, cover it; please wear adequate clothing; wear repellant.”

The Florida Department of Agriculture and Consumer Services has reportedly tested over 2,470 mosquito samples for the virus since May. The samples consisted of over 40,000 mosquitoes.

A Zika virus infection usually results in joint aches and rashes. But it can cause birth defects like microcephaly in the fetuses of pregnant women. So far, 1,500 pregnant women in the U.S. have been infected with the virus and at least 16 babies were born with birth defects.