The first documented case of Zika virus transmitted from a woman to a man through sex was reported by US health authorities Friday, raising new concerns about how the epidemic might spread.
The US Centre for Disease Control (CDC) said the case in New York City was the first known instance of a woman infected with Zika passing the virus to her sex partner. All previously reported cases of sexual transmission of Zika had involved men infecting their partners.
In the New York City case, a woman in her 20s who had returned ill from a country where Zika is endemic had sex with her male partner, who had not traveled with her. Both were subsequently diagnosed with Zika.
Zika is normally transmitted by the Aedes aegypti mosquito. But cases of sexual transmission of the virus have been documented in 11 countries, according to the New York Times.
The finding contradicts the previously held assumption that Zika could only be sexually transmitted by a man to a "receptive partner," CDC investigators said in a preliminary report. The CDC said it was updating its recommendations for Zika prevention.
While Zika infection in adults is not known to cause serious health risks, the virus has been proven to cause severe birth defects in babies born to infected mothers.