[mvonfr]

Ironically, there is a well researched theory claiming that the Black Death was caused by Ebola-like virus, simply too many details contradict the official theory of rats spreading bacteria.

Ref:

Biology of Plagues -- Evidence from Historic Populations Susan Scott / Christopher Duncan (School of Biological Sciences, Univ of Liverpool, both) Cambridge University Press, 2001

[JohnBovenmyer]

At least some of it was Plague. IIRC they’ve identified fragments of Plague DNA from cemeteries of that time.