Travellers should practice safe sex for at least eight weeks after returning from areas with Zika infections, the World Health Organisation says, doubling the time period that was recommended in its previous guideline.
New studies had shown that the virus is present in body fluids for longer than previously known, a WHO spokesman said in Geneva on Tuesday.
The Zika outbreak in Latin American countries including Brazil has raised concerns among scientists and athletes about the infection risk during the Olympics in Rio de Janeiro in August.
Zika is mostly spread through mosquitoes, but WHO noted in a new guidance document that "mounting evidence has shown that sexual transmission of the Zika virus is possible and more common than previously assumed".
Men and women who are planning to conceive a child or who experienced the flu symptoms associated with Zika should practice safe sex for at least six months after returning from Zika regions, WHO recommended.
While most Zika patients recover quickly, the virus can cause brain malformations in unborn children, as well as other neurological disorders.
An international group of 151 scientists demanded in an open letter last week that the games in Rio be postponed or moved to avoid intensifying the spread of the Zika virus.
WHO disagreed and argued that the best way to stem the spread was to take precautionary measures, especially personal protection against mosquitoes and practising safe sex.
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