The Texas Department of State Health Services (DSHS) has announced the first case of Zika virus disease likely transmitted by a mosquito in that state, making Texas the second state in the continental United States, after Florida, to report local transmission of the virus. The patient, a woman living in Cameron County, was confirmed by a laboratory test to have been infected. She reported no recent travel to Mexico or anywhere else with ongoing Zika virus transmission and no other risk factors.
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. There are no other cases of suspected local transmission at this time, but Texas health officials continue to conduct disease surveillance activities as part of the state’s ongoing Zika response.
“We knew it was only a matter of time before we saw a Zika case spread by a mosquito in Texas,” said Dr. John Hellerstedt, DSHS commissioner. “We still don’t believe the virus will become widespread in Texas, but there could be more cases, so people need to protect themselves from mosquito bites, especially in parts of the state that stay relatively warm in the fall and winter.”
Cameron County is the southernmost county in Texas, and travel back and forth across the Mexican border is common. News reports from Mexico have indicated Zika virus transmission by mosquitoes in multiple communities on the Mexican side of the border, according to the DSHS announcement. Because of the risk of birth defects associated with Zika, the DSHS recommends that pregnant women should avoid traveling to Mexico and should avoid sexual contact or should use condoms with partners who have traveled there.
Dr. Amesh Adalja, an infectious disease expert at the University of Pittsburgh Medical Center, told the Reuters news service that local Zika transmission in Texas was “totally expected.”
Both dengue and chikungunya, two closely related viruses, have already spread locally in Texas, and the state “is a well-established home” of Aedes mosquitoes, the carriers of the Zika virus, he said.
Texas has had 257 confirmed cases of Zika virus disease. Until now, all of the cases were associated with travel, including two infants born to women who had traveled during their pregnancy and two people who had sexual contact with infected travelers.