"There is a lot of evidence that suggests that Yersinia pestis may not have been the causative agent for the Black Death, and it was likely something else, and something else that is out there right now," said Brian Bossak, an environmental health scientist at Georgia Southern University.
He is among those who suspect a hemorrhagic virus — which causes bleeding and fever, like ebola — swept through 14th-century Europe. The high lethality, rapid transmission and periodic resurgences seen in the Black Death are characteristic of a virus, according to Bossak, who frames this as a question in urgent need of resolution.
Thanks for that link!