Black Death and plague ‘not linked’. A US research team studied church records and other documents from the UK and concludes that, although it had similar symptoms, the Black Death was not a rat-borne disease but some organism spread by human-to-human contact. The plague was not accompanied by the enormous die-offs of rats which have historically accompanied epidemics of bubonic plague, and its pattern of geographic spread along roadways and waterways was not impeded by the kinds of geographic barriers to rodent movement. People died too rapidly for the infectious agent to be something that would first have to establish itself at high prevalence in the wild rodent population before spilling over to humans in a locality. BBC