The first locally transmitted Zika case was confirmed in Dallas County on Tuesday.
The Texas Department of State Health Services reported the first case of Zika virus disease contracted in Texas, involving a Dallas County resident who had sexual contact with someone who acquired the Zika infection while traveling abroad. Case details are being evaluated, but the possibility of sexual transmission from an infected person to a non-infected person is likely in this case, according to a Department of State Health Services release.
There have been seven other Texas cases of Zika virus disease so far, all related to foreign travel to areas where Zika is currently being transmitted in South America, according to the Department of State Health Services. Zika virus is transmitted to people primarily through the bite of an infected mosquito, though there also have been reports of transmission through sexual contact. The disease can cause fever, rash, muscle and joint aches and red eyes, but also has been linked to the birth defect microcephaly and other poor birth outcomes in some women infected during their pregnancy.
Harris County Public Health and Environmental Services announced its first Zika case in early January. Since then, one case has been confirmed by the City of Houston Health Department and three more cases have been confirmed in Harris County, all of them contracted while people were traveling in South America.
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The disease is spread by the Aedes species of mosquito, a mosquito that used to be found only in tropical and subtropical areas but is now found on every continent except Antarctica. It's the same type of mosquito that carries chikungunya and dengue viruses, as we wrote in our 2014 cover story "Bad Blood". A mosquito becomes infected when it bites a person who already has the disease. Then it transmits the virus to other people through mosquito bites.
The Zika virus is relatively new on our radar. It was discovered in Uganda in the 1940s. Until last year, the Zika virus was mostly confined to Asia and Africa, but then it made the leap to the Western Hemisphere. More than one million people in Brazil were infected, and now the disease has spread across South America, showing up in Colombia, Venezuela, El Salvador and nine other countries, according to the Centers for Disease Control and Prevention. The first recorded case in Puerto Rico surfaced at the end of December.
Zika isn't the worst as tropical diseases go, but it's got people worried because of the ties to microcephaly, a condition in which babies are born with abnormally small heads and incomplete brain development. In 2015, Brazil saw more than 1 million cases of Zika, and then a few months later, there were about 3,000 babies born with microcephaly, about ten times the number of cases usually seen in the country each year. There's also a possibility that Zika causes Guillain-Barré syndrome, and it has been linked to seven deaths. Women in El Salvador and Brazil have been advised to avoid getting pregnant for the time being.
So far Texas health officials aren't going that far. They're just warning pregnant woman to avoid traveling to the countries known to have the disease, and for those who do go to these countries to do all the usual anti-mosquito stuff, including wearing long sleeves and pants, using insect repellent, staying in screened-in or air-conditioned rooms and avoiding being outside during "peak mosquito" time.