The WHO said today that pregnant women are "advised not travel to areas of ongoing Zika virus outbreaks" and women with partners who live in or travel to areas affected by Zika should abstain from sex or use safe-sex practices for the duration of the pregnancy. The WHO previously warned pregnant women to discuss travel plans with their health provider and consider delaying travel.
The U.S. Centers for Disease Control and Prevention have already issued similar guidelines for women in the U.S.
The announcement comes after new studies strengthened the link between the Zika virus and the birth defect mircocephaly, which is characterized by an abnormally small head and brain. The birth defect can lead to developmental delays.
WHO Director-General Dr. Margaret Chan and Dr. David Heymann, chair of WHO's Emergency Committee, spoke to reporters today about the new guidelines. They said there has been a growing body of evidence linking the virus to microcephaly after it was found in amniotic fluid. Recent studies have found the virus to be "neurotropic," meaning it affects tissues in the brain and brain stem of a developing fetus and that microcephaly is just one abnormality that is associated with Zika infections during pregnancy.
Chan also said that new reports "strongly suggest" sexual transmission of the Zika virus is more common than previously thought.
The virus has also been linked to an increase in a rare paralysis syndrome called Guillain-Barré syndrome. Chan said nine countries are reporting an increase of cases of Guillain-Barré syndrome and that some labs have seen an increase of the syndrome in patients with Zika symptoms.
The Zika virus usually results in mild symptoms including fever, headache, rash and fatigue that last about a week. Approximately four out of five people infected show no symptoms of the virus.
The virus has been associated with an increase in rates of microcephaly in Brazil.