Zika Transmitted via Anal Sex

The virus can be transmitted by unprotected anal sex between men, according to a CDC report.

Apr 15, 2016
Tanya Lewis

Zika virusCDC, CYNTHIA GOLDSMITHIn addition to being transmissible through vaginal sex, Zika virus can also be transmitted by anal sex, according to a report released yesterday (April 14) by the US Centers for Disease Control and Prevention (CDC). The report describes the case of a man in Dallas who had become infected after returning from an area where Zika is circulating locally and then transmitted the virus to his male partner, suggesting a new route of infection for the mosquito-borne pathogen.

“The take-home message is you have to consider any kind of intimate contact between an infected person with Zika and a non-infected person as a potential risk situation, regardless of gender,” epidemiologist Michael Osterholm the University of Minnesota, who was not involved in the report, told STAT News.

This case of Zika being spread through sex was first reported earlier this year, but was not at the time revealed to be male-male transmission. A Dallas man became infected with the virus after returning from a trip to Venezuela. The man and his partner had anal sex one day before and one day after he developed symptoms—two days after his return. His partner (who had not recently traveled abroad) became sick after a week.

Researchers ruled out mosquito transmission of the virus after they set up mosquito traps near the man’s home that did not catch any Aedes aegypti, which are believed to be the main vector for Zika.

Sexual transmission of Zika has been described previously, but this was the first time it has been reported between two men. The case doesn’t change the CDC’s guidelines on preventing sexual transmission of Zika, report coauthor John Brooks of the agency’s division of HIV/AIDS prevention told STAT.

A study published in The New England Journal of Medicine this week (April 13) reported sexual transmission of Zika between an infected man and his female partner after they had unprotected vaginal sex without ejaculation and oral sex with ejaculation. While the virus has been found in semen and saliva, it’s not yet known whether Zika can be transmitted through kissing or oral sex.