Harris County just got a second confirmed case of the Zika virus, and this time the virus was found in a person within Houston city limits.

A woman who traveled to Colombia in November has been diagnosed with Zika, according to the City of Houston Health Department. The woman is in her fifties or sixties. So far there haven't been any transmitted cases reported in the United States, except for Puerto Rico. The World Health Organization has said that about four million people could be infected with the virus by the end of this year.

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. 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. (It was traced to the Zika forest, hence the name.) 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.

The Zika virus causes a mosquito-borne illness that includes a rash, fever and joint pain, and the flu-like symptoms generally last about a week, but the virus isn't life-threatening, according to the CDC. The most recent identified victim in Harris County experienced something that sounded like a rather unpleasant flu, judging from the description by Kathy Barton of the Houston Department of Health. "The symptoms were mild — joint aches, rash, fever, headache. With Zika, only one in five people will be symptomatic, and most people aren't bad enough to go to the doctor," Barton told KHOU.

The outbreak has caused a panic in Brazil because researchers say the Zika virus may be tied 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.

So far the virus has been confirmed only in people who have recently traveled to Latin America, as we've previously reported. It hasn't been found here in Houston or in the rest of the United States yet except for locally transmitted cases in Puerto Rico. This isn't Harris County's first bout with a relatively new and far-too-exotic-sounding disease: Chikungunya showed up in travelers and then briefly in the Harris County mosquito population back in 2014, as we wrote in our cover story "Bad Blood."

In fact, when the first case of Zika was announced, local authorities managed to sound fairly relaxed about the virus showing up here. Of course, that was before everyone started really paying attention to the birth defects that may be tied to the disease. It's been a little less than two weeks since the first case was announced, but since then, word has spread that government officials in both Brazil and El Salvador have advised women to avoid getting pregnant for the next two years, according to ABC.