Brazil warns pregnant women to avoid Rio Olympics over risk of catching Zika virus

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, President Dilma Rousseff's chief of staff said Monday.

"The risk, which I would say is serious, is for pregnant women. It is clearly not advisable for you (to travel to the Games) 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 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."

However, some health officials have also blamed the Zika virus for causing Guillain-Barre syndrome, a rare disorder in which the immune system attacks the nervous system, causing weakness and sometimes paralysis.

Most patients recover, but the syndrome is sometimes deadly.

Zika was first detected in Africa in 1947, but it was considered a relatively mild disease until the current outbreak was declared in Latin America last year.

Brazil was the first country to sound the alarm on the apparent link with birth defects after health authorities noticed a surge in babies born with microcephaly coinciding with the outbreak.

It has since become the worst affected country, with some 4,000 suspected cases of microcephaly, of which 270 have been confirmed, up from 147 in 2014.