Pregnant women should not travel to Brazil for the Olympics because of the risk posed by the Zika virus, suspected of causing fetal brain damage, Brazilian President Dilma Rousseff's chief of staff said. "The risk, which I would say is serious, is for pregnant women. It is clearly not advisable for you [to travel to the Olympics] because you don't want to take that risk," said cabinet chief Jaques Wagner.

The unprecedented warning, issued just over six months from the opening ceremony in Rio de Janeiro, came after the World Health Organization (WHO) declared an emergency over the mosquito-borne virus, suspected of causing microcephaly, or abnormally small heads, in babies. Wagner said Rousseff viewed the WHO's move as "positive" because it "alerts the whole world, including the scientific world, to the danger of the new virus." He sought to downplay fears for any travelers who are not expecting mothers. "If you're an adult, a man or a woman who isn't pregnant, you develop antibodies in about five days and [the disease] passes," he said. "I understand that no one needs to be afraid if you are not pregnant."