Comment actually, it was the fleas. (Score 5, Informative) 135
Pneumonic plague being transmitted by air isn't news. It's a form of the disease that gets into your lungs, after all. Also, the primary vector isn't rats at all, but fleas, which often go directly from person to person.
The article's credibility is not helped at all when it mentions the plague virus, when it is actually caused by a bacterium.