Dear diary, today I learned an important lesson: always check your reports twice!
Story:
A werebuffalo attacks my new fortress, before I have time to build a proper army or a decent defense.
Three people are caught outside: the three fishermen of the fortress, fishing in the only lake they can find.
The three can't really run away, so the beast proceeds to fight them; it hits the first one and then starts destroying the second one.
As he is being massacred, the first one is on the ground. The second one dies, and the beast starts attacking the first one again, until the curse ends and the now-human monster flees.
The first fisherman and the third (who was punched) are taken to the hospital and healed. I immediately start building an outside shelter for the first one, now a werebeast, and I assign it to a burrow forcing it to stay there, fishing all day and never leaving.
Then, the day comes: the first dwarf transforms, locked inside his cell... and the third one does too... in the middle of my dining room.
Apparently, I mixed up names when reading the reports (in my defense, the names were something like Odom the Fisherman, Omob the Fisherman and Otob the fisherman; I can't even remember the right ones, and I studied those for a good 15 minutes to understand where I f***ed up...)
My fortress went from 37 dwarfes to 6, and one of those six was the other werebeast, that I immediately killed (I was quite paranoid after that).
"Luckily", the werebeast did a very good job, killing every single dwarf he could touch, and staying alive until the turned into a dwarf again, so the curse didn't spread anywhere.
So, yeah, kids, always check your reports!