Chris Van Deusen, a spokesman for the Texas Department of State Health Services, said there was no indication that the Texas patient had contracted the virus through sexual transmission, meaning that mosquitoes were nearly certainly the culprit.
Texas on Monday reported its first case of Zika virus that likely came from a mosquito bite within the state. It makes Texas the second USA state to be affected, after Florida, since the outbreak in Brazil previous year. While symptoms are usually minor, Zika can also cause severe birth defects, including microcephaly, and other poor birth outcomes in women infected during pregnancy.
Officials are conducting tests at the woman's home and the surrounding area.
Zika can also spread during sex between an infected person and his or her partner.
"We will do all that we can to protect Texans and slow the spread of the Zika virus", said HHSC Executive Commissioner Charles Smith.
Cameron County is the southernmost county in Texas, and travel back and forth across the Mexican border is common.
The agency's report said these findings highlight the importance of CDC's recent guidance on initial and continuing medical and developmental evaluations of infants with possible congenital Zika virus infection and the importance of early neuro imaging for infants who were exposed to Zika virus prenatally. The city is now taking steps to reduce the mosquito population, and DSHS and Cameron County officials are going door-to-door to educate citizens about Zika and reduce potential breeding zones for mosquitoes.
Texas has had 257 confirmed cases of the Zika virus, but until now, all had been linked to travel.
Those infected with the virus may suffer from a mild fever, rash, joint pain and red eyes that last for two to seven days. They should use an insect repellent registered by the Environmental Protection Agency containing one of the following ingredients: DEET, picaridin, IR3535, oil of lemon eucalyptus or para-menthane-diol, or 2-undecanone.
Both private companies and the federal government are racing to create a vaccine to prevent the Zika virus from infecting more people.