Texas has become the second state in the continental United States to confirm a locally transmitted case of the Zika virus, state and federal health officials said Monday.
Lab results confirmed the virus in a non-pregnant female resident of Brownsville last week. She has not traveled to an area where the virus is circulating and has no other known exposure to the virus that would have put her at risk for infection.
Health officials said they are not surprised to confirm local transmission of this virus in South Texas, near the Mexico border.
“We knew it was only a matter of time before we saw a Zika case spread by a mosquito in Texas,” state Health Commissioner Dr. John Hellerstedt said. He added that more cases are expected, but officials do not believe the virus will be widespread.
“Laboratory testing found genetic material from the Zika virus in the patient’s urine, but a blood test was negative, indicating that the virus can no longer be spread from her by a mosquito,” the Texas Department of State Health Services said in a statement.
It is, however, investigating where the woman became infected by testing mosquitoes found around her home and knocking on her neighbors’ doors to request voluntary urine samples and other information to determine whether others are infected.
It is also sharing information about the virus and how to protect against it. This includes using mosquito repellant, wearing long sleeves, keeping windows closed, using air conditioning and eliminating standing water. Spraying has also been done in the area.
In addition to ongoing disease surveillance efforts, which are part of the state’s Zika action plan, the state medical operations center has been activated to offer support through education and expertise as well as personnel and equipment resources.
The US Centers for Disease Control and Prevention is working with state and local officials to increase mosquito surveillance and vector control. The female Aedes aegypti mosquito, which lives in the area, is primarily responsible for the transmission of Zika, dengue virus and some other diseases. The related Aedes albopictus is also believed to transmit these diseases.
State health officials say travel across the border is frequent in the area. Zika transmission has been reported in multiple communities on the Mexican side of the border.
“Even though it is late in the mosquito season, mosquitoes can spread Zika in some areas of the country,” said Dr. Tom Frieden, director of the CDC. The weather and climate in Texas are conducive to year-round mosquito activity.
It is possible that someone could have Zika without knowing, since an estimated 80% of those infected have no symptoms. When symptoms occur, they can include fever, rash, joint pain and red eyes, and they can last from a few days to about a week.
Pregnant women are at greatest risk because they can unknowingly pass the virus to their fetus, leaving devastating consequences including miscarriage and neurological deficits that last a lifetime.
Because the virus can also be sexually transmitted, pregnant women or those trying to become pregnant should avoid unprotected sex with a partner who has been infected or who has lived in or traveled to an area where the virus is circulating, as recommended by the CDC.
There is no treatment or vaccine for Zika, although research efforts are underway to develop one.
The only other US state where the virus is known to be circulating is Florida, where state health officials are reporting 238 locally transmitted cases to date.