Andre Mourao/Courtesy of Rio2016/Handout via ReutersLONDON (Reuters) - More than 100 health experts have called for the Rio Olympic Games to be postponed or moved because of the threat to public health from Brazil's Zika virus outbreak, according to a public letter published online. "Our greater concern is for global health," the letter says. "The Brazilian strain of Zika virus harms health in ways that science has not observed before.