New York City – The Centers for Disease Control and Prevention (CDC) announced Friday that the first case of female-to-male sexual transmission of the Zika virus was reported in New York City. It was previously known that the virus could be transmitted by unprotected sexual intercourse, but only male-to-female and male-to-male cases were reported.

A woman in her twenties told officials that she had unprotected vaginal sex with a male partner the day she returned home from travel to a country with high risk of Zika transmission. According to her account of the events, she had a headache and abdominal cramping while waiting in the airport. The next day, she reported feeling ill, with probable Zika symptoms, such as fever, fatigue, rash and muscular pain. She also got her period that day. On day three of development, she went to her primary care provider and got samples of her blood and urine. Results tested positive for Zika virus RNA in both samples.

An investigation made by the New York City (NYC) Department of Health and Mental Hygiene (DOHMH) identified the case, and the report was published by the CDC on Friday. Photo credit: ABC 7 Chicago

Almost a week later, the male partner developed similar symptoms, including fever, rash, and also conjunctivitis. Three days later, he went to the same care provider as his partner, where he got samples of urine and blood serum collected. The Zika virus RNA was detected in urine, but not serum.

After being interviewed by the New York City health department, the man declared that he had not been outside the United States for over a year. He also told authorities that he had condomless vaginal sex only one time with her female partner, identified as the previous patient, the day she returned to NYC. He had not other recent sexual encounters or had been bitten by a mosquito.

After corroborating the histories, health officials concluded that “the timing and sequence of events support female-to-male Zika virus transmission through condomless vaginal intercourse.” The virus was transmitted either by the young woman’s vaginal fluids or menstrual blood. The couple is now included in the 309 cases of Zika reported in New York City, all associated with travel.

This is the first female-to-male sexual transmission of the virus reported, but it may not be the first ever occurred

This is the first documented case of a woman transmitting the Zika virus to a man, but it was not a surprise for scientists since most of the sexually transmitted diseases can be transmitted between men and women both ways.

Previous studies and reports have suggested that the Zika virus can remain in vaginal fluids while not showing presence in urine or blood tests. However, male-to-female transmission is more likely to occur, according to experts, since the virus remains present in semen for over two months, while it is thought that it lingers only for two weeks in vaginal fluid.

The majority of infected patients show no symptoms of the virus, so the real number could be much larger.

CDC have reported only 14 cases of sexual transmission of the virus, but they are highly warning people, especially pregnant women for the dangerous repercussions the virus could have on the unborn children, to use “barrier methods” while maintaining sexual encounters with a partner who could be exposed to the virus by traveling.

“As up to 80% of patients infected with ZIKV (Zika virus) remain asymptomatic, the level of sexual transmission could play a more important role than expected in the overall dynamic of ZIKV circulation,” French researchers wrote in the journal Eurosurveillance, according to Forbes.

To date, there haven’t been reported cases of woman-to-woman sexual transmission of the virus.

Source: CNN