The UN health agency says sexual transmission of Zika is more common than first thought, so its updated advice to women who have been in areas hit by the virus tells them to wait even longer to conceive.

The World Health Organization said Tuesday that couples or women planning pregnancy who live in or are returning from Zika-hit areas “are strongly recommended to wait at least eight weeks before trying to conceive” to ensure the virus has cleared their bodies.

Previously, WHO recommended a four-week minimum period before trying to conceive in such circumstances.

If the male partner in a couple planning pregnancy has symptoms of the Zika virus, the period of safe abstinence should be six months, spokesman Christian Lindmeier told a news briefing.

The symptoms include rash, fever, arthralgia (pain in a joint), myalgia (muscle pain) or conjunctivitis.

“The new guidelines reflect what we have learned about Zika disease and its complications,” Lindmeier said.

The current outbreak of Zika has been linked to microcephaly, a rare defect in which babies are born with abnormally small heads and brain damage, and an unusual paralyzing condition known as Guillain-Barré syndrome.

Asked if this new advice amounted to an effective ban on pregnancies in Brazil, where the virus first appeared a year
ago, Lindmeier said: “The guidance is to delay or consider delaying pregnancy, certainly recognizing that this is tough for some populations.”

Sexual transmission documented in men with symptoms

The spokesman said scientists are still investigating how long the virus can be traced in saliva but these tests have so
far been inconclusive.

“All this is being studied to see where else we find the virus and how long it sustains there,” he said.

WHO said safer sexual practices include:

• Postponing sexual debut.
• Non-penetrative sex.
• Correct and consistent use of male or female condoms.
• Reducing the number of sexual partners.

So far, all published cases of sexual transmission have been from symptomatic males, whose sexual activities may have occurred before, during or after Zika symptom onset, to their partners. It remains unknown if women or asymptomatic men can transmit the virus through sexual activity, WHO said.

Zika is a mosquito-transmitted virus that generally causes mild symptoms, but is associated with microcephaly in infants whose mothers contracted the virus during pregnancy.

The Public Health Agency of Canada advises pregnant women and women considering becoming pregnant to take precautions against mosquito bites if travelling to Zika-affected countries cannot be postponed.

There have been no confirmed cases of locally acquired Zika virus through mosquitoes in Canada.