“New research”.
Wow, ABC. REALLY???
http://www.nature.com/scitable/blog/viruses101/could_the_black_death_actually
From November 08, 2013.
The book cited in the article, Biology of Plagues: Evidence from Historical Populations, was published in 2005.
http://www.amazon.com/Biology-Plagues-Evidence-Historical-Populations/dp/0521017769
Consider feces and food-landing flies as vectors vs rats... winged vectors have 100% speed transmission going for them.