[throw310822]

Indeed. I wrongly assumed it would be bubonic as it seems to be the most common form (and because it qualifies a bit the term "plague" which can be perceived as generic, I think).

[lazide]

Yes, many types of bacteria can cause ‘a plague’, but at least in the western world, only one was ‘The Plague’.

Probably anyway, there is some debate on that. But it’s pretty likely.