I wonder if the Romans would have tried to further exploit their victory against the Parthians in that war if that plague hadn’t broke out. It seems their territorial gains were minimal in light of the victory.
The Romans did not have much luck fighting the Parthians. Crassus, the third member of the Roman triumvirate of which Pompey and Julius Caesar were the other two, wanted to make a name for himself before he got too old. He was about 54. Pompey had Spain and the west, Caesar had the center and he had the East. The march into Parthian territory became a military disaster. He and his son were both killed, and young Cassius managed to bring about 10,000 troops back to Syria to preserve the Roman hold there. Years later you may recall that Cassius was one of the ringleaders who killed Caesar because he was “too ambitious.” I always wondered what his ambition was, until I read this piece of history. Then I realized that Caesar’s ambition was to restore Roman honor by conquering Parthia. Dumb move, and also a dumb move 200 years later. And also a dumb move 10 years ago.
Regarding rats. The rat of the plague was the black rat, which was primarily a house and roof rat. It lived rather intimately with its victims, spreading fleas in the house. The Norway gray rat which replaced the Black rat is a sewer and cellar rat which has less contact with humans. We have endemic Bubonic plague in around 17 western states among the wild rodent population. However it seems the Hanta virus is more dangerous as you can get it from dust while sweeping mouse droppings, rather than the flea bites needed for plague.