A sexually transmitted case of the Zika virus earlier this year involved two men, Centers for Disease Control and Prevention researchers have revealed. The CDC says the case, the first proof that the virus can be transmitted by anal as well as vaginal sex, involved a Dallas man who transmitted the virus to his partner through unprotected sex after he was bitten by a mosquito during a trip to Venezuela, the New York Times reports. After the partner became ill with a rash, pinkeye, and joint pain a week after the traveler reported similar symptoms, a physician assistant suspected Zika. Researchers confirmed that the man had the virus and determined that sex was the only way he could have been infected.
A CDC epidemiologist says the finding is not surprising. "We know that most STIs can be transmitted through anal sex and oral sex as well as vaginal sex," he tells NPR, stressing that the finding also applies to heterosexual couples. "Anal sex is practiced not only by men who have sex with men, but also by heterosexual couples, and so it's important to consider not the person's sexual preference but the activity in which they're engaging," he says. "A woman who has anal sex could become infected with Zika virus." Researchers are still trying to determine how long the virus remains in the semen of an infected man. (The CDC has confirmed that the virus causes birth defects.)