I spoke too soon. We were clean for about a month and then half the remaining 35 dwarves were killed by the rotting plague. I have no idea what's spreading it or where it's coming from. Everything looks clean. Not fun.
I expect that everyone except that dude in traction at the hospital, are going to die to the illness before it's over.
And then that dude in traction will die too, when his caregivers stop bringing him food.
Congrats, fortress-wiping shitty forgotten beast?