The World Health Organization has revised its advice for people seeking to prevent Zika’s transmission as the virus continues to proliferate in dozens of countries.
The guidance, issued on Monday, includes waiting a full eight weeks to have unprotected sex or attempt to conceive a baby even if one has no symptoms of the virus, if one has traveled to any country with a current outbreak of Zika. This advice changes from previous suggestions that included abstaining from sex only four weeks after travel.
The WHO’s policy describes the growing concern for the sexual transmission of Zika, whereas initially it was thought the virus was transmissible through mosquitos only:
The primary transmission route of Zika virus is via the Aedes mosquito. However, mounting evidence has shown that sexual transmission of Zika virus is possible and more common than previously assumed. This is of concern due to an association between Zika virus infection and adverse pregnancy and fetal outcomes, including microcephaly, neurological complications and Guillain-Barré syndrome.
That “mounting evidence” includes — as of May 19 — 10 countries with reported sexual transmission of the virus: the United States, France, Italy, Argentina, Chile, Peru, Portugal, New Zealand, Canada and Germany. The majority of transmission occurred in those countries via vaginal intercourse, with one confirmed case in Dallas, Texas of anal transmission and one suspected case of transmission via oral sex with ejaculation, according to CNN.
The unknowns about Zika remain somewhat scary; the WHO emphasized that it remains unknown if women or asymptomatic men can transmit the virus through sexual activity. So far, the aforementioned cases were all transmitted by men who had signs of the virus.