Social media around the world are being flooded with rumors of Fidel Castro's death. But there's no sign in Cuba that the reports are true, even if the 88-year-old former leader has not been seen for months.

Similar speculation has swept across Cuban expatriate communities repeatedly over the decades, particularly after illness forced Castro to leave his duties as president in 2006.

The new wave was prompted in part by his failure to comment after the U.S. and Cuba declared on Dec. 17 that they would restore full diplomatic relations.

Some websites abroad reported Cuba had called a news conference, likely to discuss Castro's health.Cuban officials told news media in Havana that no press conference had been called, and there were no obvious signs of official preparations for mourning.