Greatest plague in history?
Worse than the Black Death (Bubonic plague epidemic)?
Perhaps in absolute numbers of victims, but probably not in the proportion of the population killed.
The lethality was pretty high, but not as deadly as some other diseases in terms of most locations. I think what made it so bad was it was probably first pathogen that could spread worldwide so quickly due to air travel, automobiles, faster ships, etc. By the time one population had started developing any resistance, it had already spread to ten more areas.
Don’t know if the Thieves story from the bubonic plague days is for real but I use a version of The Four Thieves oil