Zika virus was identified in Uganda in 1947. It has been present in Africa and Asia for at least that long. It tends to follow the distribution of Yellow Fever and the
Aedes aegypti mosquito, although the range of YF has been drastically reduced by vaccination and mosquito control.
Why Brazil and why now are good questions.
The purported sexual transmission in Texas should be subjected to intense skepticism, although asking that from the media is asking a lot.