And witches.
We do have around seven cases a year in the States, so locking down an entire city strikes me as a little bit of an overreaction, although I'm sure the authorities would love to know how the victim was infected. There isn't going to be an epidemic as long as the tetracyclines hold out.
Unless it's really zombies.
Plague first came to the United States in the 1850's. The rail companies were legally importing Chinese coolies to work on the transcontinental railway.
There was a small plague outbreak in San Fransisco's Chinatown district. An alert doctor spotted the outbreak almost immediately, and appealed to the city council to institute a quarantine and rat catching program.
The town fathers refused to believe there was plague in their fair city.
They screwed around long enough for it to infect the local ground squirrel population where there was no hope stopping it from spreading. Thanks to their inaction, now one can be exposed to bubonic plague anywhere in the western US.
Any parallels one wishes to draw with a more recent "gay plague" or flooding the country with disease infected children are left to the reader as an exercise.
Those who do not learn the lessons of the past...