[Travis McGee]

Under certain limited conditions, Y. Pestis could be a very effective weapon. That is, when used against a poor people in crowded 3rd world conditions, who do not have ready access to large amounts of antibiotics and quality medical care. The plague could do enormous damage, and still be easily contained.

Plus, the use of the weapon would be deniable, with the outbreak being blamed on naturally occurring plague vectors. (Unlike anthrax, smallpox etc). If scores of flea-infested rodents were injected with Y. Pestis and released in dozens of locations around the target city, the result would be horrible to see.

[hiredhand]

Good points...

Not to elevate paranoia, but I know somebody who is qualified to suggest that Y. Pestis is "relatively easy" to engineer such that it's antibiotic resistant. This person suggested that perhaps Al Qaeda did this based on the supposition that if they're messing with plague, they "should" have had the necessary antibiotics to fight it if they had an "oopsie". Either they didn't have the antibiotics necessary to combat an exposure, or they designed it to be antibiotic resistant and then had the "oopsie".

[Mom MD]

The usual form of the plague, carried by insect vectors, is rarely fatal and easily treated (bubonic plague). However, when arasolized (pneumonic plague) it is almost uniformly fatal, even with modern ICU and antibiotic therapies. On any given day in our city, hospital beds are at a premium, ICU beds even more so. Just 100 people in a city needing an ICU bed all at once would swamp the system. Now imagine a few thousand needing an ICU bed. I’m sorry, in an attack like this one almost everyone infected would die, modern medicine or no.