The theory is that in Africa, by the time a woman is having children, she's probably already been exposed to the Zika virus and her body knows how to deal with it, whereas here it’s a different story. Basically, Westerners were kind of caught off guard with this Zika business.
Does the whole thing about sexual transmission mean it's an STD?
At this point, it’s pretty much a done deal that the Zika virus can spread through sex, based on that case in Texas, and more that the Centers for Disease Control (CDC) is looking at. In the US, this seems scarier than the mosquito thing because you’re probably more likely to have sex than go on a tropical vacation. That’s important, and the CDC gives advice on what to do. Basically, for heterosexual couples, it’s condoms or no fun for a while if the dude has traveled to one of the areas where Zika-infected mosquitos are active. And condoms are generally a good idea for everyone.
You have to be careful on an individual level, but as Dr. Gordon points out, sexual transmission isn’t likely to have a major impact on the US population: “One of the big things is that usually -- not always, but usually -- people don't have sex with that many people... in a short period of time.” She has lots of confidence in your game, folks! “Most sexually transmitted diseases, like HIV, syphilis, and gonorrhea, have adapted to that in that you are infectious for a very long period of time. With Zika, we still think it’s a short period of time that you’re infectious.”