Texas health officials have reported the state's first case of Zika transmitted by local mosquitoes, making Texas the second state within the continental United States to report local transmission of the virus that has been linked to birth defects.
The case involved a woman living in Cameron County near the Mexico border who is not pregnant, the Texas Department of State Health Services said.
Pregnancy is the biggest concern with Zika because the virus can cause severe, life-long birth defects, including microcephaly, in which a child is born with an abnormally small head, a sign its brain has stopped growing normally.
Texas said it currently has no other suspected cases of local Zika transmission, but officials there plan to step up efforts to watch for the virus.
Texas is one of several US states where Aedes aegypti mosquitoes, which carry Zika, are present.
Florida's Miami Dade County has been battling Zika within local mosquito populations since mid-summer. As of today, the state has had 238 cases of locally transmitted Zika.
"We knew it was only a matter of time before we saw a Zika case spread by a mosquito in Texas," Dr John Hellerstedt, Texas Department of State Health Services commissioner, said in a statement.
There is no vaccine or treatment for Zika, which causes mild fever, rash and red eyes. An estimated 80 percent of people infected have no symptoms, making it difficult for individuals to know whether they have been infected.
The connection between Zika and microcephaly first came to light last year in Brazil, which has since confirmed more than 2000 cases of the birth defect.
In adults, Zika infections have also been linked to a rare neurological syndrome known as Guillain-Barre, as well as other neurological disorders.