Yersinia pestis: the active ingredient in Bubonic Plague.
Variola major: the major cause of smallpox.
Mycobacterium leprae: Hanson's Disease, earlier known as leprosy.
Tabin: Nerve Gas, a/k/a VX.
Sarin: Nerve Gas first used by the Nazis, a/k/a GB.

And Necrotizing Fasciitis sound to me like a gentle, creeping, flowering ground cover. (It's also known as flesh-eating bacteria and very, very nasty indeed.)