Reports of Zika transmission through sex

24ZIKA-master675Health authorities in the United States said they were investigating 14 new reports of the Zika virus possibly being transmitted by sex, including to pregnant women. If confirmed, the unexpectedly high number would have major implications for controlling the virus, which is usually spread by mosquito bites.

Scientists had believed sexual transmission of Zika to be extremely rare. Only a few cases have ever been documented. But if all the women in the cases the Centers for Disease Control and Prevention is examining test positive for the virus — as two women already have, and four others have done in preliminary lab tests — officials believe there is no way other than sex that they could have contracted it.

The specter of so many cases — all in the continental United States — brings fresh complexity to the medical mystery of Zika. The virus is suspected to cause birth defects and a rare condition of temporary paralysis.

“We were surprised that there was this number,” Dr. Anne Schuchat, the deputy director at the C.D.C., said in an interview. “If a number of them pan out, that’s much more than I was expecting.”

In all the cases the C.D.C. is examining, women in the continental United States had sex with men who had traveled to countries where the virus is circulating, and developed symptoms associated with the virus within about two weeks of their male partners’ symptoms.

Officials at the C.D.C. reported the potential cases in an alert to health care providers on Tuesday.

The agency did not say exactly how many of the women were pregnant, but it reiterated its recommendation that people returning from Zika-infected areas use condoms or abstain from sex for the duration of their partner’s pregnancy. The alert said there was no evidence that women could transmit Zika virus to their sex partners, but added that more research was needed to be sure.

This country has become a laboratory of sorts to test the sexual transmission of Zika, as scientists race to understand the disease. Transmission by mosquitoes is not yet happening in the continental United States because it is still winter, so health officials say they believe that any infection of an American resident who has not traveled to a place where Zika is circulating has probably been contracted through sex.

“In the U.S., where most people aren’t traveling to these areas, we may be able to uncover the potential risk,” Dr. Schuchat said. (Courtesy New York Times)