A look at Texas' first homegrown case of Zika

DALLAS -- Health officials are going door-to-door in the Texas neighborhood of a woman who is believed to be the first person to contract the Zika virus by getting bitten by a mosquito in that state.

Officials are offering to test the woman's neighbors in Brownsville, which is on the border with Mexico, and are educating them about how to fight the spread of the disease, including how to reduce the breeding habitats of the mosquito that transmits it. But experts don't expect big outbreaks in the U.S. like those that have happened in parts of Latin America and the Caribbean.

Thus far, Florida is the only other state with homegrown cases of the disease. It typically causes only mild symptoms at worst, but the disease is especially dangerous to pregnant women, as it can cause severe birth defects, including babies born with unusually small heads.

Zika is transmitted to people primarily through the bite of an infected Aedes aegypti species mosquito, but it also can be spread during sex. Most infected people don't have symptoms, but for those who do, it's usually a mild illness, with fever, rash and joint pain.

Although it's late in the season, mosquitoes still can spread Zika in some areas of the country, said Dr. Tom Frieden, director of the Centers for Disease Control and Prevention.

Chris Van Deusen, a spokesman for the Texas Department of State Health Services, said because of the warm conditions in South Texas, mosquitoes can be a concern year-round, but much of Texas is at the end of its mosquito season.

State health officials announced the Brownsville case Monday, noting testing showed at this point, the virus no longer can be spread from her by mosquitoes.

Although Brownsville is on the Mexico border, the woman said she hadn't traveled recently to Mexico or anywhere that was experiencing a Zika outbreak, and she didn't have any other risk factors, health officials said.

Officials said further investigation is necessary to figure out how she was infected. But Van Deusen said the most likely scenario is someone who got infected in an area where Zika is widespread traveled to South Texas and was bitten by a mosquito, which later bit the woman.

One reason health officials don't think Zika will become widespread in Texas is because of the state's experience with dengue fever, Van Deusen said. He said the same mosquito species spreads both diseases, and when there are dengue epidemics in Mexico, cases have spilled over to South Texas but haven't been widespread.

The mosquito likes to bite indoors, and the widespread use of screens and air conditioners in the U.S. keeps them out.