The first case of a woman sexually transmitting the Zika virus to a man is now in the books. Before the New York City case occurred, officials believed only males could transmit the virus sexually (either to women or to other men). But then, the CDC reports, a man developed Zika symptoms even though he hadn't traveled outside the United States any time during the prior year. His female partner, however, had just returned from an area where Zika is present, and had developed the illness herself the week prior. Before realizing she had the virus, she'd had unprotected sex with the man. He saw the same doctor as her, who suspected she'd passed the illness to him sexually; the city's health department confirmed that suspicion.
CNN calls the development "startling." The CDC is now changing its guidance for pregnant women, since this means woman-to-woman transmission may also be possible: All pregnant women, whether their sexual partners are male or female, should use barrier methods when having sex if they live in or their partner has recently traveled to an area where Zika is present. The virus can cause birth defects, may cause developmental problems post-birth, and may also be linked to pregnancy loss, the New York Times reports. There have now been 1,305 travel-related cases of Zika reported in the US, and 14 known cases of sexually transmitted Zika in the US, per CNN. (Read more Zika virus stories.)