Explainer: What we know about hantavirus cruise ship outbreak

"This virus is not new to the world," U.S. virologist Thomas G. Ksiazek said. "If it were going to become an epidemic, it would have happened a long time ago."

BRUSSELS, May 12 (Xinhua) -- A hantavirus outbreak aboard a polar expedition cruise ship has killed three people, raising fears of a new pandemic. Though new cases may still surface during the virus's incubation period of up to six weeks,