The US is investigating 14 more cases of sexually transmitted Zika virus

The agency in early February revised its guidelines for pregnant women to include a recommendation that even those without symptoms of the Zika virus should be tested after returning from affected areas.

The WHO says because no big Zika outbreaks were recorded before 2007, little is known about complications caused by infection.

For most people, Zika is not serious.

But the recent increase in both cases and severe brain birth defects among thousands of newborns in Brazil has prompted health officials to reassess their thinking about Zika and pregnant women.

Eraldo Peres/AP Director General of the World Health Organization Margaret Chan speaks to the press before a meeting on the Zika virus at the National Center for Risk Management and Disaster in Brasilia, Brazil, Tuesday.

It would take considerable research to understand how frequently Zika is spread through sex, given that four out of five people who are believed to be infected never develop symptoms, Dr. McQuiston said.

Sexual contact was confirmed as the only risk factor for the women infected in virtually all of the suspected USA cases: The woman’s male partner had recently returned from one of the infected countries.

While the mosquito-borne virus causes only a mild illness that passes quickly, it can confer lifelong damage on a developing fetus.

“In all events for which information is available, travelers were men and reported symptom onset was within two weeks before the non-traveling female partner’s symptoms began”, the CDC said in a statement.

Sexual transmission of the Zika virus from men to women may be a more common mode of the virus’s spread than researchers previously thought, officials said today. House Republicans have said that would be the best way to fund a fight against Zika, the AP said.

For non-pregnant women, the CDC recommended couples concerned about sexual transmission of the Zika virus should always wear a condom during sex or abstain from having sex. 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. To be clear, that doesn’t mean he was infectious the whole time. “The good news is this virus spreads through the bite of a type of mosquito we don’t have in Washington state, so it is very unlikely that this virus would spread widely here”. But with scant scientific literature published on the matter, some doctors in Brazil and elsewhere say there is not yet enough scientific data to prove the connection.