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GENEVA, Sept 6 The World Health Organization
said on Tuesday that men and women returning from where the Zika
virus is actively spreading should practise safer sex or
abstinence for six months, regardless of whether they are trying
to conceive or showing symptoms.
The guidance is a change from the WHO's interim
recommendation on June 7, which referred only to men and had a
shorter timeframe of at least eight weeks.
The WHO said the update was based on new evidence on Zika
transmission from asymptomatic males to their female partners
and a symptomatic female to her male partner, as well as
evidence that Zika is present in semen for longer than thought.
Zika infections in pregnant women have been shown to cause
microcephaly - a severe birth defect in which the head and brain
are undersized - as well as other brain abnormalities. The
connection between Zika and microcephaly first came to light
last autumn in Brazil, which has since confirmed more than 1,800
cases of microcephaly.
In adults, Zika infections have also been linked to a rare
neurological syndrome known as Guillain-Barre, as well as other
Sexual transmission of Zika had been reported in 11
countries by Aug. 26, mainly through vaginal intercourse. There
was a first documented case of a man catching the virus through
anal sex in February 2016 and a suspicion of Zika transmission
through oral sex in April.
Although one man had Zika found in his semen 188 days after
the onset of symptoms, the longest period that the virus has so
far been found to remain infectious was 24 days, and WHO said
its latest six-month advice was conservative.
In another Zika sufferer, the concentration of the virus in
his semen was 100,000 more than that in his blood 14 days after
he was diagnosed.
Evidence on persistence of the virus in semen and its
infectiousness and impact on sexual transmission remains limited
and the guidance will be updated again when there is more
information, WHO said.
WHO advises that pregnant women should not travel to areas
with ongoing Zika virus transmission, and it warned people
travelling to the Paralympic Games, which starts on Wednesday in
Rio de Janeiro, to take precautions against mosquito bites.
"We think that the risk for travellers and athletes is low,
but it's not zero," said WHO spokesman Tarik Jasarevic.
(Reporting by Tom Miles, additional reporting by Stephanie
Nebehay; Editing by Raissa Kasolowsky)