A new case of the Zika virus reveals that it can be transmitted through anal sex. After returning home to Dallas after a trip to Venezuela, a man experienced a fever, pinkeye and a rash on his upper body and face. Just days before these symptoms, he had had anal sex with his partner.
Although the man felt fine after three days, about a week later his partner developed similar symptoms in addition to joint pain in his hands and feet.
Samples from the blood, semen, urine and saliva were gathered from both men, and although the virus itself could not be detected in either of the men's samples, subsequent testing revealed that the man who had not travelled was infected with the Zika virus.
Researchers were unable to determine whether the traveller picked up Zika, a type of dengue virus or both, but believe that the man who did not travel could not have contracted the virus through a mosquito due to the cold Dallas weather and numerous traps around the couple's home.
"The second man had had a Zika virus infection and the only way he could have gotten it was from his sexual partner," said John Brooks, the medical epidemiologist with the Centers for Disease Control and Prevention (CDC) behind the institute's case report on the incident.
"We know that most STIs can be transmitted through anal sex and oral sex as well as vaginal sex," he added, suggesting that the fact that Zika can too is not a surprise. Furthermore, this transmission is not limited to just gay men.
"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," Brooks said. "A woman who has anal sex could become infected with Zika virus."
Doctors and researchers must now determine how long the virus can last in the semen of an infected man in order to determine how long he will be at risk of transmitting it to someone else through sexual contact.
Another recent case outlines the incident of a woman in Paris contracting Zika through sexual contact with a partner who had traveled to Brazil. However, the couple did not participate in anal sex - just oral and vaginal without ejaculation.
"We cannot rule out the possibility that transmission occurred not through semen but through other biologic fluids, such as pre-ejaculate secretions or saliva exchanged through deep kissing," the authors wrote.
Further research could reveal the nature of Zika's spread through sexual contact including anal sex and vaginal sex.
