The World Health Organisation on Tuesday (Mar 8) advised pregnant women not to travel to areas affected by the Zika virus outbreak, saying the new advice was issued amid mounting evidence that Zika can cause birth defects.
"Pregnant women should be advised not travel to areas of ongoing Zika virus outbreaks," the UN agency said in a statement released after an emergency committee meeting on the rapid spread of the mosquito-borne virus.
Previous WHO guidelines issued after the first Zika emergency committee meeting on Feb 1 called for women to be warned of the risk of travel.
WHO chief Margaret Chan noted that link between Zika and microcephaly, a severe deformation of the brain among newborns, has not yet been definitively proven. But, she said, "we do not have to wait until we have definitive proof" before advising pregnant women against travel.
"Microcephaly is now only one of several documented birth abnormalities associated with Zika infection during pregnancy," she said. "Grave outcomes include foetal death, placental insufficiency, foetal growth retardation, and injury to the central nervous system," she added.
Despite the new travel guidelines for pregnant women, WHO said "there should be no general restrictions on travel or trade with countries (or) areas ... with Zika virus transmission."
Chan described the latest research on Zika as "alarming," including growing evidence that the virus triggers the severe neurological disorder Guillain-Barre Syndrome (GBS), which can cause paralysis or death in extreme cases.
Nine countries have reported rising incidents of GBS with a strongly suspected link to Zika. Two countries have registered a spike in microcephaly with a presumed connection to Zika, French Polynesia and Brazil, the hardest-hit country in the outbreak by far.
But Chan warned that incidents of microcephaly could spread, including possibly to Colombia, where "intense surveillance for foetal abnormalities is currently under way."
MORE RESEARCH, URGENT ACTION
The WHO meet, which included representatives from the Americas region where Zika is spreading rapidly, sought to prioritise areas for further research as public health officials seek to understand a virus which previously caused little concern.
Zika was first discovered in Uganda in 1947 and was only known to cause moderate cold and flu-like symptoms, but rising global anxiety about the virus has been driven by its presumed connection to multiple neurological disorders.
Because the current outbreak has marked a clear shift in the nature of the virus, WHO said "particular attention should be given to generating additional data on the genetic sequences and clinical effect of different Zika virus strains," in hopes of understanding what has changed.
Chan stressed that proving the causal link between Zika and certain neurological conditions was vital. But, she added, "strong public health action should not wait for definitive scientific proof."
Zika is spread among humans by the Aedes aegypti mosquito, which is found in 130 countries. But recent evidence appears to indicate that it can also be sexually transmitted by men carrying the virus.