A woman in Texas appears to have acquired the Zika virus from a local mosquito, which would make Texas the second state where the virus has spread from mosquitoes to humans (Florida was the first). There were 238 cases of locally acquired Zika reported in Florida as of Monday, according to the state’s Department of Health. As of Nov. 23, another 4,261 travel-associated cases — infections picked up in other countries or Puerto Rico — had been reported to the U.S. Centers for Disease Control and Prevention. Zika causes mild, flu-like symptoms in most people but has been linked to severe birth defects in the fetuses and newborns of women who were infected during pregnancy.
Cameron County, where the patient who was infected in Texas lives, is no stranger to infectious disease outbreaks from the Aedes aegypti mosquito, the species that is believed to be responsible for the majority of Zika cases. The county reported the state’s first case of locally acquired chikungunya earlier this year, and more than one dengue outbreak has been documented in the area over the past decade. “We knew it was only a matter of time before we saw a Zika case spread by a mosquito in Texas,” John Hellerstedt, commissioner of the Texas Department of State Health Services, said in a news release.
Tracking infectious diseases has historically been a challenge in Texas. It’s handled at the local level in the state, which means there’s a lot of variation by city or county, but studies of dengue looking at blood samples of randomly selected residents have shown evidence of outbreaks in the Cameron County area that went on much longer than was realized at the time, with some researchers even concluding that dengue may be endemic to the area. That’s not necessarily surprising; the area has Aedes aegypti mosquitoes, but also the kind of poverty and living conditions that can exacerbate mosquito-borne diseases. Systematically tracking the movement of a virus is expensive and resource-intensive. The state said it will join county health workers to go door to door in the infected woman’s neighborhood to collect voluntary urine samples, and Texas is seeking assistance from the CDC. We know how to keep the Zika virus at bay: by spraying for mosquitoes, getting rid of their breeding grounds, and protecting people with clothing and repellent. Still, it will be no easy task.