Yersinia pestis, Direct Fluorescent Antibody Stain (DFA), 200x Magnification. CDC 2057. Wikimedia Creative Commons Attribution 3.0 License. “Black death was not spread by rat fleas, say researchers” reported in the Guardian Reportedly it was “pneumonic” rather than “bubonic” as previously thought. Fortunately it was a very, very long time ago, although there have been many …