Sexual Spread of Zika May Be More Common than Thought, CDC Warns

USA health officials are investigating whether 14 new Zika virus infections may been transmitted through sex, raising questions about the role of sex in spreading a disease that has been linked to birth defects in Brazil. In all the cases, women in the continental United States had sex with men who had traveled to countries where the virus is circulating and the travelers reported symptoms within two weeks of the onset of their non-traveling female partners symptoms. Four other women have initially tested positive for the virus and are awaiting further results, and eight women are under investigation.

Of the confirmed cases, 141 were attributable to the Zika virus.

“We think mosquito-borne spread is the most common route of transmission, but we want to make people aware that sexual transmission is also a risk”, Jennifer McQuiston, deputy incident manager for CDC’s Zika response, said in a telephone interview. The reminder comes as more potential cases of sexual transmission are being investigated. “Zika virus can be sexually transmitted by a man to his sex partners”, reads a recent post.

In other Brazil-related developments, researchers from the CDC and Brazil’s health ministry today launched a case-control study in Brazil in search of more definitive evidence on the possible link between Zika virus and microcephaly, or undersized heads, the Associated Press (AP) reported today.

Generally, men who have traveled or live in areas with local Zika transmission who are anxious about sexual transmission should consider using condoms or abstain. An estimated 4 out of 5 people infected never have symptoms; when symptoms occur they may last from several days to one week. This includes any history of Zika-like infection.

There’s also evidence that Zika could eventually be spread by the Asian tiger mosquito (Aedes albopictus), which is more prevalent in the US.

Zika virus illness is usually mild.

Although sexual transmission of Zika virus infection is possible, mosquito bites remain the primary way that Zika virus is transmitted. “The science is not clear on how long the risk should be avoided”, the agency said.

Despite Tuesday’s rocky start, the CDC’s Harrist said the generosity and openness of the two young mothers her team managed to contact gave her hope. ODH’s Zika page suggests covering up with long-sleeved shirts and trousers, staying in places with window and door screens to keep mosquitoes outside, using a mosquito bed net and wearing Environmental Protection Agency-registered insect repellents. “We were concerned enough that we thought it was important to share that information…” The U.S. cases may help scientists figure out more about how the virus tends to move.