Also, WHO guidance today addresses breastfeeding, microcephaly, and Guillain-Barre syndrome.
WHO and PAHO leaders continue assessing Brazil's response to its Zika outbreak.
The findings underscore advice regarding strict precautions in returning travelers, the CDC says.
Also, a microcephaly study launches in Brazil and new mosquito control efforts are being explored.
The WHO said though Zika virus has circulated in Africa before, the effect of an importation from the Americas is unclear.
Also, the CDC shares new guidance on babies and children with acute infections.
Pope Francis's comments coincide with WHO guidance on preventing sexual transmission of the virus.
The finding of the virus in amniotic fluid adds evidence to a possible link between Zika and microcephaly.
The agency says even though the virus has not been confirmed in the US blood supply, the risk is real.
A robust immune response in mice clears the way for tests in nonhuman primates.
