Zika is usually spread by mosquitoes, and health officials have known for some time that men can spread it through sex. The Centers for Disease Control and Prevention reported the case Friday and updated its advice for pregnant women.
The CDC now advises them to use protection if their sex partner has traveled to a Zika-infected region, whether the partner is a man or a woman.
The Zika virus causes only a mild illness, at worst, in most people. But infection during pregnancy can lead to severe brain-related birth defects for the fetus. The New York woman was not pregnant.
While this is the first documented case of a woman spreading Zika through sex, health experts say it is not surprising because most diseases that can be spread through sex can be spread by men and women. It has likely been happening throughout the recent Zika outbreaks in Brazil, Latin America and elsewhere, though experts say it is probably not very common.